Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
This document summarizes a study on the thermal analysis of circular inclined pipes subjected to natural convection using computational fluid dynamics (CFD). The study investigated the effect of parameters like tube diameter, heat supplied, and tube inclination on the temperature and heat transfer coefficient through experimental testing and CFD analysis. The experimental results were validated against CFD results, with less than 5% error found between the two. It was found that temperature increased with increasing pipe diameter and heat supply. The temperature was also strongly influenced by heat flux and diameter, and weakly dependent on tube inclination.
1) The document analyzes heat transfer in a double pipe heat exchanger with helical tape inserts in the annulus of the inner pipe using computational fluid dynamics (CFD).
2) A 3D model is developed and simulations are run using the SST k-ω turbulent model to analyze how helical tape inserts influence heat transfer and pressure drop at different pitch lengths and Reynolds numbers.
3) The results show that helical tape inserts increase the heat transfer rate but also increase pressure drop due to flow disruption. Nusselt number and friction factor are found to correlate well with Reynolds number for enhancing heat transfer.
Experimental Study of Heat Transfer Enhancement of Pipe-inPipe Helical Coil H...iosrjce
This document presents an experimental study of heat transfer enhancement in a pipe-in-pipe helical coil heat exchanger. Experiments were conducted with two different inner coil diameters (6mm and 8mm) under varying mass flow rates in the inner coil and annulus. The overall heat transfer coefficient and inner Nusselt number were found to increase with increasing mass flow rates. Counter-flow configuration resulted in higher heat transfer rates than parallel flow due to the larger log mean temperature difference, though overall heat transfer coefficients were similar between the two flow arrangements. Experimental results for inner Nusselt number agreed with established correlations in parallel flow but were higher in counter-flow.
This document appears to be the introduction or cover page of a lab manual for a Heat Transfer lab course. It provides information about the university and engineering college where the course is taught, and lists the name and identification information for the student. It also lists the experiments that will be conducted in the lab course, including determining thermal conductivity, studying heat exchangers, measuring emissivity, and analyzing heat transfer through fins, composite walls, and during convection. The document provides an overview of the lab course and experiments but no detailed information.
EXPERIMENTAL ANALYSIS OF HEAT TRANSFER AND FLUID FLOW IN MICRO-CHANNEL HEAT SINKijmech
In this paper heat transfer in single phase through micro-channels was studied. The validation of classical correlations of conventional channels to micro-channels is explored. It is found that classical approach is in good agreement with the experimental results of heat transfer in micro-channels .The material used for micro-channel heat sink (MCHS) is copper, experiments were conducted using water as cooling agent in
this study. Micro-channels are made with the help of EDM machine on the upper surface of MCHS. Variation of heat transfer rates, effect of friction factor, effect of pressure drop and variation in temperature distribution is investigated in this study. It is observed in the study that with decrease in
velocity flow friction also decreases.
Analysis of Coiled-Tube Heat Exchangers to Improve Heat Transfer Rate With Sp...IJMER
Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the impact of flow and thermal boundary conditions for the heat transfer rate in laminar and transitional flow regimes. Calculated results have been compared to existing empirical formula and experimental tests to investigate the validity of the numerical results in case of common helical tube heat exchanger and additionally results of the numerical computation of corrugated straight tubes for laminar and transition flow have been validated with experimental tests available in the literature. Comparison of the flow and temperature fields in case of common helical tube and the coil with spirally corrugated wall configuration are discussed. Heat exchanger coils with helically corrugated wall configuration show 80–100% increase for the inner side heat transfer rate due to the additionally developed swirling motion while the relative pressure drop is 10–600% larger compared to the common helically coiled heat exchangers. New empirical Co-relation has been proposed for the fully developed inner side heat transfer prediction in case of helically corrugated wall configuration.
This document summarizes an experimental study on heat transfer augmentation from surfaces with dimples. Six steel plates with varying dimple densities and arrangements were tested to analyze heat transfer and pressure drop characteristics. Temperature and pressure measurements were taken under varying air flow rates and heat inputs. It was found that heat transfer, as indicated by Nusselt number, increased with increasing dimple density. Staggered dimple arrangements provided greater enhancement than inline arrangements. Mathematical equations are presented for calculating key parameters like heat transfer coefficient, Reynolds number, and friction factor. Results are discussed and heat transfer is seen to increase with Reynolds number for all plates, with the 50 dimple plate performing best.
Heat exchangers are used widely in industrial application such as chemical,
food processing, power production, refrigeration and air-conditioning
industries. Helical coiled heat exchangers are used in order to obtain a large
heat transfer per unit volume and to enhance the heat transfer rate on the inside
surface. In the present study, CFD simulations are carried out for a counter
flow tube in tube helical heat exchanger where hot water flows through the
inner tube and cold water flows through the outer tube. From the simulation
results heat transfer coefficient, pressure drop and nusselt number are
calculated. The heat transfer characteristics of the same are compared with that
of a counter flow tube in tube straight tube heat exchanger of same length
under same temperature and flow conditions. CFD simulation results showed
that the helical tube in tube heat exchanger is more effective than the straight
tube in tube heat exchanger.
This document summarizes a study on the thermal analysis of circular inclined pipes subjected to natural convection using computational fluid dynamics (CFD). The study investigated the effect of parameters like tube diameter, heat supplied, and tube inclination on the temperature and heat transfer coefficient through experimental testing and CFD analysis. The experimental results were validated against CFD results, with less than 5% error found between the two. It was found that temperature increased with increasing pipe diameter and heat supply. The temperature was also strongly influenced by heat flux and diameter, and weakly dependent on tube inclination.
1) The document analyzes heat transfer in a double pipe heat exchanger with helical tape inserts in the annulus of the inner pipe using computational fluid dynamics (CFD).
2) A 3D model is developed and simulations are run using the SST k-ω turbulent model to analyze how helical tape inserts influence heat transfer and pressure drop at different pitch lengths and Reynolds numbers.
3) The results show that helical tape inserts increase the heat transfer rate but also increase pressure drop due to flow disruption. Nusselt number and friction factor are found to correlate well with Reynolds number for enhancing heat transfer.
Experimental Study of Heat Transfer Enhancement of Pipe-inPipe Helical Coil H...iosrjce
This document presents an experimental study of heat transfer enhancement in a pipe-in-pipe helical coil heat exchanger. Experiments were conducted with two different inner coil diameters (6mm and 8mm) under varying mass flow rates in the inner coil and annulus. The overall heat transfer coefficient and inner Nusselt number were found to increase with increasing mass flow rates. Counter-flow configuration resulted in higher heat transfer rates than parallel flow due to the larger log mean temperature difference, though overall heat transfer coefficients were similar between the two flow arrangements. Experimental results for inner Nusselt number agreed with established correlations in parallel flow but were higher in counter-flow.
This document appears to be the introduction or cover page of a lab manual for a Heat Transfer lab course. It provides information about the university and engineering college where the course is taught, and lists the name and identification information for the student. It also lists the experiments that will be conducted in the lab course, including determining thermal conductivity, studying heat exchangers, measuring emissivity, and analyzing heat transfer through fins, composite walls, and during convection. The document provides an overview of the lab course and experiments but no detailed information.
EXPERIMENTAL ANALYSIS OF HEAT TRANSFER AND FLUID FLOW IN MICRO-CHANNEL HEAT SINKijmech
In this paper heat transfer in single phase through micro-channels was studied. The validation of classical correlations of conventional channels to micro-channels is explored. It is found that classical approach is in good agreement with the experimental results of heat transfer in micro-channels .The material used for micro-channel heat sink (MCHS) is copper, experiments were conducted using water as cooling agent in
this study. Micro-channels are made with the help of EDM machine on the upper surface of MCHS. Variation of heat transfer rates, effect of friction factor, effect of pressure drop and variation in temperature distribution is investigated in this study. It is observed in the study that with decrease in
velocity flow friction also decreases.
Analysis of Coiled-Tube Heat Exchangers to Improve Heat Transfer Rate With Sp...IJMER
Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the impact of flow and thermal boundary conditions for the heat transfer rate in laminar and transitional flow regimes. Calculated results have been compared to existing empirical formula and experimental tests to investigate the validity of the numerical results in case of common helical tube heat exchanger and additionally results of the numerical computation of corrugated straight tubes for laminar and transition flow have been validated with experimental tests available in the literature. Comparison of the flow and temperature fields in case of common helical tube and the coil with spirally corrugated wall configuration are discussed. Heat exchanger coils with helically corrugated wall configuration show 80–100% increase for the inner side heat transfer rate due to the additionally developed swirling motion while the relative pressure drop is 10–600% larger compared to the common helically coiled heat exchangers. New empirical Co-relation has been proposed for the fully developed inner side heat transfer prediction in case of helically corrugated wall configuration.
This document summarizes an experimental study on heat transfer augmentation from surfaces with dimples. Six steel plates with varying dimple densities and arrangements were tested to analyze heat transfer and pressure drop characteristics. Temperature and pressure measurements were taken under varying air flow rates and heat inputs. It was found that heat transfer, as indicated by Nusselt number, increased with increasing dimple density. Staggered dimple arrangements provided greater enhancement than inline arrangements. Mathematical equations are presented for calculating key parameters like heat transfer coefficient, Reynolds number, and friction factor. Results are discussed and heat transfer is seen to increase with Reynolds number for all plates, with the 50 dimple plate performing best.
Heat exchangers are used widely in industrial application such as chemical,
food processing, power production, refrigeration and air-conditioning
industries. Helical coiled heat exchangers are used in order to obtain a large
heat transfer per unit volume and to enhance the heat transfer rate on the inside
surface. In the present study, CFD simulations are carried out for a counter
flow tube in tube helical heat exchanger where hot water flows through the
inner tube and cold water flows through the outer tube. From the simulation
results heat transfer coefficient, pressure drop and nusselt number are
calculated. The heat transfer characteristics of the same are compared with that
of a counter flow tube in tube straight tube heat exchanger of same length
under same temperature and flow conditions. CFD simulation results showed
that the helical tube in tube heat exchanger is more effective than the straight
tube in tube heat exchanger.
The document summarizes the fabrication and testing of a heat exchanger test rig. Key points:
- The test rig was designed and built to study a counter-flow tube heat exchanger using aluminum sheets and tubes.
- Finite element analysis was performed on the rig design to analyze stresses. Water was heated to 40°C and pumped through one side while tap water entered the other side.
- Effectiveness-NTU method was used to calculate theoretical outlet temperatures which were compared to experimental readings to determine error percentages.
An Experimental Research on Heat Transfer Enhancement of a Circular Tube with...IRJESJOURNAL
ABSTRACT:- In the literature, internal tube baffles are widely studied. There is a lack of data for baffles mounted on outside of the tubes. This study aims to fill this gap. Therefore, the effect of baffle inclination angles on heat transfer improvement has been studied experimentally. The experiments were carried out for forced convection of air on a circular tube with inclined baffles. Air has been used as the cold fluid. Experimental results for eight different velocities of air flow (2 – 20 m/s) are presented. Pitch between baffles is 12 mm.The baffle inclination angles with respect to the tube axis were 45º, 60º and 80º. Water temperature is fixed as 65 °C. According to the experimental results, the baffles with an inclination angle of 45º enhance the heat transfer over 60º and 80º around 13.7 % and 10.5 %, respectively. However, pressure drop values for 45º and 60º are 18 % higher than pressure drop values for 80º. The empirical correlations of the Nusselt number have also been obtained for each angle.
Numerical Analysis of Heat Transfer Enhancement in Pipe-inPipe Helical Coiled...iosrjce
This document presents a numerical analysis of heat transfer enhancement in pipe-in-pipe helical coiled heat exchangers. Computational fluid dynamics (CFD) was used to analyze the effect of varying parameters like inner tube diameter, mass flow rates, and flow configuration (parallel vs. counter flow). The results show that overall heat transfer coefficients increase with increasing inner Dean number and mass flow rates. Heat transfer rates also increase with higher inner mass flow rates. Counter flow configuration provides better heat transfer than parallel flow. Increasing the inner tube size decreases the total heat transfer rate due to a reduction in annulus cross-sectional area. Measured inner Nusselt numbers agree reasonably well with existing correlations.
1) The document presents an experimental study of heat transfer through a uniformly heated vertical tube air heater.
2) The study investigates the effect of tube length, diameter, and heat flux on heat transfer and buoyancy induced airflow.
3) It was found that the heat transfer coefficient increases with increasing heat flux but decreases with increasing tube diameter and length, while air outlet temperature increases with tube length and heat flux but decreases with diameter.
Natural convection heat transfer in inclined open annulus passege heated from...IAEME Publication
This document summarizes an experimental study on natural convection heat transfer in an open cylindrical annulus heated from both the inner and outer sides. The study examines the effects of inclination angle (0°, 30°, 60°, 90°) and heat flux (70-600 W/m2) on the local and average Nusselt number. The results show that the Nusselt number increases with both increasing heat flux and inclination angle from horizontal to vertical. Empirical correlations between the average Nusselt number and Rayleigh number are developed from the results.
Experiments were conducted to calibrate Schmidt-Boelter heat flux gauges in stagnation and shear air flows. A thermal model was developed that predicts the gauge sensitivity will have a nonlinear dependence on the heat transfer coefficient. Experimental calibration systems were built to simultaneously measure gauge response and heat flux. For stagnation flow, measured sensitivities matched the model and were used to estimate the internal thermal resistance of each gauge. For shear flow, the effect of varying gauge surface temperature on the boundary layer was included. Results matched the model with a lower effective heat transfer coefficient. The internal thermal resistance impacted gauges differently in each flow condition.
Experimental analysis of heat transfer enhancementin circulariaemedu
This document summarizes an experimental study on enhancing heat transfer in a circular double tube heat exchanger using rectangular inserts. Air was passed through the inner tube while hot water flowed through the outer tube. Heat transfer coefficients and friction factors were determined for the plain tube and with inserts. The results showed that heat transfer was enhanced by 0.9 to 1.9 times with the inserts due to flow disruption, while friction factors increased by 1 to 1.7 times. Heat transfer coefficients increased with Reynolds number whereas friction factors decreased. Validation experiments on a plain tube agreed well with theoretical predictions within 10% uncertainty.
Evaluation of Convective Heat Transfer Coefficient of Air Flowing Through an ...Bishal Bhandari
The document evaluates the convective heat transfer coefficient of air flowing through an inclined circular duct. It describes an experimental setup used to study the effect of inclination angle and air velocity on the convective heat transfer coefficient. Tests were conducted by forcing air through a copper duct at various angles (0°, 30°, 60°, 90°, 120°, 150°) and velocities while keeping heat input constant. Temperature readings were used to calculate parameters like Reynolds number, Nusselt number, and the convective heat transfer coefficient. Results showed that the heat transfer coefficient peaks at a 90° inclination for an air velocity of 12 m/s, and is lowest at a 30° inclination for a velocity of 8.38 m/s
Optimization of a Shell and Tube Condenser using Numerical MethodIJERA Editor
The purpose of this study was to investigate the effect of installation of the tube external surfaces, their parameter and variable in a shell-and-tube condenser. Variation of heat transfer coefficient with each variable of shell and tube condenser was measured each test. The optimization tube outside diameter size was analyzed and use extended surface area attached tube with tube material and tube layout and arrangement (Number of tube a triangular or hexagonal arrangement) on shell-and tube condenser. The computer programming was used to get faster output in less time. Results suggest that mean heat transfer coefficient in variable condition were mainly at velocity is fixed. And also average additional surfaces and tube layout and the arrangement comparison with the quantity of the heat transfer.
The document describes heat exchangers and experiments conducted using a shell and tube heat exchanger and a plate heat exchanger. It discusses three types of fluid flow - parallel, counter, and cross-flow. Experiments were conducted with both exchangers under parallel and counter-flow configurations. Temperature and flow rate data was collected and used to calculate effectiveness, heat transfer coefficients, and log mean temperature difference. The results showed that the counter-flow configuration had higher effectiveness compared to parallel flow in both exchangers.
Natural convection heat transfer inside inclined open cylinderIAEME Publication
This document summarizes an experimental study on natural convection heat transfer inside an inclined open cylinder. The study investigated the effects of inclination angle (0°, 30°, 60°, 90°) and heat flux (70-600 W/m2) on the heat transfer. Empirical correlations were developed relating the average Nusselt number to the Rayleigh number. Results showed that heat transfer, as measured by the local and average Nusselt number, increased with increasing heat flux and inclination angle from horizontal to vertical.
Hmt lab manual (heat and mass transfer lab manual)Awais Ali
This document describes procedures for 7 experiments on heat transfer:
1. Investigates Fourier's Law of heat conduction along a brass bar by measuring temperatures at points along the bar for different heat inputs.
2. Studies heat conduction along a composite bar and calculates the overall heat transfer coefficient.
3. Examines the effect of cross-sectional area changes on temperature profiles in a conductor.
4. Determines temperature profiles and heat transfer rates from radial conduction through a cylinder wall.
5. Measures thermal conductivity of non-metallic materials and compares to theory.
6. Determines thermal conductivity of liquids and gases.
7. Investigates the relationship between power input and surface temperature for free convection
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
The document discusses a tube-in-tube helical heat exchanger analysis using ANSYS CFD. It varies the curvature ratio from 8 to 25 and inlet velocity from 1 to 2 m/s to analyze parameters like Nusselt number, friction factor, and pressure drop. Graphs of these parameters versus Reynolds number are created and discussed to determine optimal heat exchanger performance. The analysis aims to improve heat transfer characteristics of coiled heat exchangers, which provide enhanced and compact heat transfer due to secondary flow effects from pipe curvature.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
The document proposes a hardware sharing architecture for programmable memory built-in self-test (P-MBIST) to reduce area overhead. A single address generator is used to test multiple memory instances by controlling chip selects. The controller can test different memory types that have the same read/write cycle. Two pipeline stages are added to the address generator to improve test speed. An automation flow generates the P-MBIST design from a user-defined configuration file. The proposed architecture significantly reduces area compared to an individual BIST circuit for each memory type.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
The document summarizes the fabrication and testing of a heat exchanger test rig. Key points:
- The test rig was designed and built to study a counter-flow tube heat exchanger using aluminum sheets and tubes.
- Finite element analysis was performed on the rig design to analyze stresses. Water was heated to 40°C and pumped through one side while tap water entered the other side.
- Effectiveness-NTU method was used to calculate theoretical outlet temperatures which were compared to experimental readings to determine error percentages.
An Experimental Research on Heat Transfer Enhancement of a Circular Tube with...IRJESJOURNAL
ABSTRACT:- In the literature, internal tube baffles are widely studied. There is a lack of data for baffles mounted on outside of the tubes. This study aims to fill this gap. Therefore, the effect of baffle inclination angles on heat transfer improvement has been studied experimentally. The experiments were carried out for forced convection of air on a circular tube with inclined baffles. Air has been used as the cold fluid. Experimental results for eight different velocities of air flow (2 – 20 m/s) are presented. Pitch between baffles is 12 mm.The baffle inclination angles with respect to the tube axis were 45º, 60º and 80º. Water temperature is fixed as 65 °C. According to the experimental results, the baffles with an inclination angle of 45º enhance the heat transfer over 60º and 80º around 13.7 % and 10.5 %, respectively. However, pressure drop values for 45º and 60º are 18 % higher than pressure drop values for 80º. The empirical correlations of the Nusselt number have also been obtained for each angle.
Numerical Analysis of Heat Transfer Enhancement in Pipe-inPipe Helical Coiled...iosrjce
This document presents a numerical analysis of heat transfer enhancement in pipe-in-pipe helical coiled heat exchangers. Computational fluid dynamics (CFD) was used to analyze the effect of varying parameters like inner tube diameter, mass flow rates, and flow configuration (parallel vs. counter flow). The results show that overall heat transfer coefficients increase with increasing inner Dean number and mass flow rates. Heat transfer rates also increase with higher inner mass flow rates. Counter flow configuration provides better heat transfer than parallel flow. Increasing the inner tube size decreases the total heat transfer rate due to a reduction in annulus cross-sectional area. Measured inner Nusselt numbers agree reasonably well with existing correlations.
1) The document presents an experimental study of heat transfer through a uniformly heated vertical tube air heater.
2) The study investigates the effect of tube length, diameter, and heat flux on heat transfer and buoyancy induced airflow.
3) It was found that the heat transfer coefficient increases with increasing heat flux but decreases with increasing tube diameter and length, while air outlet temperature increases with tube length and heat flux but decreases with diameter.
Natural convection heat transfer in inclined open annulus passege heated from...IAEME Publication
This document summarizes an experimental study on natural convection heat transfer in an open cylindrical annulus heated from both the inner and outer sides. The study examines the effects of inclination angle (0°, 30°, 60°, 90°) and heat flux (70-600 W/m2) on the local and average Nusselt number. The results show that the Nusselt number increases with both increasing heat flux and inclination angle from horizontal to vertical. Empirical correlations between the average Nusselt number and Rayleigh number are developed from the results.
Experiments were conducted to calibrate Schmidt-Boelter heat flux gauges in stagnation and shear air flows. A thermal model was developed that predicts the gauge sensitivity will have a nonlinear dependence on the heat transfer coefficient. Experimental calibration systems were built to simultaneously measure gauge response and heat flux. For stagnation flow, measured sensitivities matched the model and were used to estimate the internal thermal resistance of each gauge. For shear flow, the effect of varying gauge surface temperature on the boundary layer was included. Results matched the model with a lower effective heat transfer coefficient. The internal thermal resistance impacted gauges differently in each flow condition.
Experimental analysis of heat transfer enhancementin circulariaemedu
This document summarizes an experimental study on enhancing heat transfer in a circular double tube heat exchanger using rectangular inserts. Air was passed through the inner tube while hot water flowed through the outer tube. Heat transfer coefficients and friction factors were determined for the plain tube and with inserts. The results showed that heat transfer was enhanced by 0.9 to 1.9 times with the inserts due to flow disruption, while friction factors increased by 1 to 1.7 times. Heat transfer coefficients increased with Reynolds number whereas friction factors decreased. Validation experiments on a plain tube agreed well with theoretical predictions within 10% uncertainty.
Evaluation of Convective Heat Transfer Coefficient of Air Flowing Through an ...Bishal Bhandari
The document evaluates the convective heat transfer coefficient of air flowing through an inclined circular duct. It describes an experimental setup used to study the effect of inclination angle and air velocity on the convective heat transfer coefficient. Tests were conducted by forcing air through a copper duct at various angles (0°, 30°, 60°, 90°, 120°, 150°) and velocities while keeping heat input constant. Temperature readings were used to calculate parameters like Reynolds number, Nusselt number, and the convective heat transfer coefficient. Results showed that the heat transfer coefficient peaks at a 90° inclination for an air velocity of 12 m/s, and is lowest at a 30° inclination for a velocity of 8.38 m/s
Optimization of a Shell and Tube Condenser using Numerical MethodIJERA Editor
The purpose of this study was to investigate the effect of installation of the tube external surfaces, their parameter and variable in a shell-and-tube condenser. Variation of heat transfer coefficient with each variable of shell and tube condenser was measured each test. The optimization tube outside diameter size was analyzed and use extended surface area attached tube with tube material and tube layout and arrangement (Number of tube a triangular or hexagonal arrangement) on shell-and tube condenser. The computer programming was used to get faster output in less time. Results suggest that mean heat transfer coefficient in variable condition were mainly at velocity is fixed. And also average additional surfaces and tube layout and the arrangement comparison with the quantity of the heat transfer.
The document describes heat exchangers and experiments conducted using a shell and tube heat exchanger and a plate heat exchanger. It discusses three types of fluid flow - parallel, counter, and cross-flow. Experiments were conducted with both exchangers under parallel and counter-flow configurations. Temperature and flow rate data was collected and used to calculate effectiveness, heat transfer coefficients, and log mean temperature difference. The results showed that the counter-flow configuration had higher effectiveness compared to parallel flow in both exchangers.
Natural convection heat transfer inside inclined open cylinderIAEME Publication
This document summarizes an experimental study on natural convection heat transfer inside an inclined open cylinder. The study investigated the effects of inclination angle (0°, 30°, 60°, 90°) and heat flux (70-600 W/m2) on the heat transfer. Empirical correlations were developed relating the average Nusselt number to the Rayleigh number. Results showed that heat transfer, as measured by the local and average Nusselt number, increased with increasing heat flux and inclination angle from horizontal to vertical.
Hmt lab manual (heat and mass transfer lab manual)Awais Ali
This document describes procedures for 7 experiments on heat transfer:
1. Investigates Fourier's Law of heat conduction along a brass bar by measuring temperatures at points along the bar for different heat inputs.
2. Studies heat conduction along a composite bar and calculates the overall heat transfer coefficient.
3. Examines the effect of cross-sectional area changes on temperature profiles in a conductor.
4. Determines temperature profiles and heat transfer rates from radial conduction through a cylinder wall.
5. Measures thermal conductivity of non-metallic materials and compares to theory.
6. Determines thermal conductivity of liquids and gases.
7. Investigates the relationship between power input and surface temperature for free convection
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
The document discusses a tube-in-tube helical heat exchanger analysis using ANSYS CFD. It varies the curvature ratio from 8 to 25 and inlet velocity from 1 to 2 m/s to analyze parameters like Nusselt number, friction factor, and pressure drop. Graphs of these parameters versus Reynolds number are created and discussed to determine optimal heat exchanger performance. The analysis aims to improve heat transfer characteristics of coiled heat exchangers, which provide enhanced and compact heat transfer due to secondary flow effects from pipe curvature.
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
The document proposes a hardware sharing architecture for programmable memory built-in self-test (P-MBIST) to reduce area overhead. A single address generator is used to test multiple memory instances by controlling chip selects. The controller can test different memory types that have the same read/write cycle. Two pipeline stages are added to the address generator to improve test speed. An automation flow generates the P-MBIST design from a user-defined configuration file. The proposed architecture significantly reduces area compared to an individual BIST circuit for each memory type.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Research Inventy : International Journal of Engineering and Scienceinventy
Research Inventy : International Journal of Engineering and Science
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed
Analysis of Double Pipe Heat Exchanger With Helical FinsIRJET Journal
This document analyzes a double pipe heat exchanger with helical fins through computational fluid dynamics (CFD). It aims to study the flow and temperature fields inside the tubes for different helical fin angles. The geometry of the double pipe heat exchanger is modeled in CATIA V5 and meshed in Hypermesh. CFD simulations are performed in ANSYS Fluent to analyze the flow and temperature distributions for fin angles of 0, 5, 10, 15, 20, and 25 degrees. The results determine that heat transfer rate and overall heat transfer coefficient increase with helical fins compared to a smooth tube, with fins providing additional surface area to enhance heat transfer.
EXPERIMENTAL INVESTIGATION OF CONVECTION HEAT TRANSFER FOR LAMINAR FLOW IN AN...IAEME Publication
The document summarizes an experimental investigation of convection heat transfer for laminar flow in an inclined annulus. An annular copper pipe was exposed to a constant heat flux and rotated through inclination angles from 0° to 90° in 10° increments. Results showed that the heat transfer coefficient decreased inversely with inclination angle, with a maximum 6.6% reduction at 90°. Reynolds number also decreased inversely with angle from 1750 to 1700. Experimental results closely matched a correlation up to 40° inclination. The study analyzed the effect of inclination angle on heat transfer in laminar flow through an annulus.
The document summarizes an experimental investigation of convection heat transfer for laminar flow in an inclined annulus. An annular copper pipe was exposed to a constant heat flux and rotated through inclination angles from 0° to 90° in 10° increments. Results showed that the heat transfer coefficient decreased inversely with inclination angle, with a maximum 6.6% reduction at 90°. Reynolds number also decreased inversely with angle from 1750 to 1700. Experimental results closely matched a correlation up to 40° inclination. The study found inclination angle had a small effect on heat transfer for laminar flow in the annulus.
An Experimenatl Study on Heat Transfer Behaviors of A Welded - Aluminum Minic...ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
AN EXPERIMENTAL STUDY OF EXERGY IN A CORRUGATED PLATE HEAT EXCHANGERIAEME Publication
In the present work an attempt has been made to investigate the performance of a 3 channel 1-1 pass, corrugated plate heat exchanger. The plates had sinusoidal wavy surfaces with corrugation angle of 450. Hot water at different inlet temperature ranging from 400C to 600C was made to flow in the central channel to get cooled by water in the outer channels.
NATURAL CONVECTION HEAT TRANSFER IN INCLINED OPEN ANNULUS PASSEGE HEATED FROM...IAEME Publication
Natural convection is investigated experimentally in an open cylindrical annulus heated with both annulus inner and outer sides under same constant heat flux condition to study the effect of angle of inclination and heat flux on heat transfer. Heat transfer results are given for inclination angles of 0o
(horizontal), 30o , 60o and 90o (vertical) using annulus diameter ratio of 1.8, inner and outer tube length 50 cm and heat flux from 70 W/m2 to 600W/m2 . The results show that the local and average Nusselt number increase as the heat flux increase and when angle of inclination changed from 0o
(horizontal) to 90o (vertical).An empirical correlations of average Nusselt number as a function of Rayleigh number were deduced.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
The document compares the thermal performance of flat plate fins and inline strip fins heat sinks. It presents Nusselt number correlations from literature to model the convective heat transfer from the fins. The correlations consider heat transfer from the fins but not the bare heat sink base. The study includes an estimate of heat transfer from the base, providing a more realistic thermal resistance calculation. Results show inline strip fins have higher heat transfer coefficients that compensate for their reduced area, yielding lower thermal resistances than plate fins. Considering heat transfer from the base provides an even lower thermal resistance for both heat sink designs.
Heat Transfer Analysis of Refrigerant Flow in an Evaporator TubeIJMER
the paper aim is to presenting the heat transfer analysis of refrigerant flow in an evaporator
tube is done. The main objective of this paper is to find the length of the evaporator tube for a pre-defined
refrigerant inlet state such that the refrigerant at the tube outlet is superheated. The problem involves
refrigerant flowing inside a straight, horizontal copper tube over which water is in cross flow. Inlet
condition of the both fluids and evaporator tube detail except its length are specified. here pressure and
enthalpy at discrete points along the tube are calculated by using two-phase frictional pressure drop model.
Predicted values were compared using another different pressure drop model. A computer-code using
Turbo C has been developed for performing the entire calculation
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Effect of Wavy (Corrugated) Twisted Tape Inserts on Heat Transfer in a double...ijiert bestjournal
This document summarizes an experimental study on heat transfer in a double pipe heat exchanger with the use of wavy twisted tape inserts in the inner tube. Various wavy twisted tapes with different twist ratios were inserted into the inner copper tube to enhance turbulence and heat transfer. Temperature and pressure measurements were taken at varying flow rates and Reynolds numbers. The results showed that heat transfer, as measured by Nusselt number, increased with decreasing twist ratio of the insert. The wavy twisted tape with a twist ratio of 7.1 produced the highest 172% increase in Nusselt number but also the highest 32.11% increase in friction factor compared to the smooth tube. Correlations were developed for Nusselt number
Numerical Simulation of a Tube in Tube Helical Coiled Heat Exchanger using CFDCarnegie Mellon University
Heat exchangers are used widely in industrial application such as chemical,
food processing, power production, refrigeration and air-conditioning
industries. Helical coiled heat exchangers are used in order to obtain a large
heat transfer per unit volume and to enhance the heat transfer rate on the inside
surface. In the present study, CFD simulations are carried out for a counter
flow tube in tube helical heat exchanger where hot water flows through the
inner tube and cold water flows through the outer tube. From the simulation
results heat transfer coefficient, pressure drop and nusselt number are
calculated. The heat transfer characteristics of the same are compared with that
of a counter flow tube in tube straight tube heat exchanger of same length
under same temperature and flow conditions. CFD simulation results showed
that the helical tube in tube heat exchanger is more effective than the straight
tube in tube heat exchanger.
An experimental study of heat transfer in a corrugated plate heat exchangerIAEME Publication
1. The document discusses an experimental study of heat transfer in a corrugated plate heat exchanger. Experiments were conducted to analyze heat transfer characteristics for different flow arrangements of hot and cold fluids through the heat exchanger.
2. The effectiveness and exergy loss of the heat exchanger were calculated for parallel and counter flow arrangements. The average effectiveness was found to be 48% higher and exergy loss 33% lower in the counter flow arrangement compared to the parallel flow arrangement.
3. Maximum heat transfer was observed at the highest hot fluid inlet temperature of 70°C, being 5% greater in the parallel flow arrangement. However, the non-dimensional exergy loss and log mean temperature difference were both lower in the
This document presents a numerical analysis of heat transfer enhancement in pipe-in-pipe helical coiled heat exchangers. A computational fluid dynamics (CFD) analysis was conducted to determine the effect of varying parameters like inner tube diameter, mass flow rates, and flow configuration (parallel vs. counter flow) on heat transfer characteristics. The CFD results showed that decreasing the inner tube diameter and increasing the mass flow rates led to higher overall heat transfer coefficients. Counter flow configuration provided better heat transfer than parallel flow. Validation of the CFD model showed decent agreement with existing empirical correlations for heat transfer in helical coils.
This document presents a numerical analysis of heat transfer enhancement in pipe-in-pipe helical coiled heat exchangers. Computational fluid dynamics (CFD) was used to analyze the effect of varying parameters like inner tube diameter, mass flow rates, and coil configuration on heat transfer characteristics. The results show that overall heat transfer coefficient increases with increasing inner Dean number and decreasing inner tube diameter. Counter-flow configuration provides better heat transfer than parallel flow. Validation of CFD results was done using existing Nusselt number correlations from literature. Increasing tube size or annulus mass flow rate decreases the total heat transfer rate.
Analysis of Natural Convention Heat Transfer Enhancement in Finned Tube Heat ...journal ijrtem
ABSTRACT: Most of the engineering problems require high performance heat transfer components with progressively less weight, volumes, accommodating shapes and costs. Air cooled heat exchangers are subjected to air on outer side of heat exchanger surface on in heat recovery systems like economizers gases are subjected on one side of tube surface. On air or gas side heat transfer coefficient is less. Extended surface (fins) are one of the next exchanging devices that are employed extensively to increase heat transfer rates from tubular heat exchangers. The rate of heat transfer depends on the surface area of fin available for exchanging the heat transfer rate from the primary surface of cylindrical shape. Present study focuses on enhancement of heat transfer by using both circular and elliptical type of fins. The present paper attempts to examine trend of heat transfer coefficient experimentally and by using CFD software for various types of elliptical fins with i) varying elliptical ratio, ii) changing orientation of mounting of heat exchanger tube with elliptical fins, iii) varying spacing or fin density. KEY WORDS: Natural convection, Heat transfer enhancements, Elliptical fin, Fin orientation, Fin density.
Numerical Modeling and Simulation of a Double Tube Heat Exchanger Adopting a ...IJERA Editor
This document presents a numerical model and simulation of a double tube heat exchanger using a "black box" approach. It first uses commercial CFD software to simulate the heat exchanger and generate outlet temperature results. It then develops a linear model to predict the outlet temperatures based on governing equations, considering the heat exchanger a black box. The linear model assumes steady state, constant properties, and approximates the logarithmic mean temperature difference with an arithmetic mean. Results from both methods are generated and compared to experimental data to validate the linear approximation. Comparisons show the linear model agrees well with experiments, justifying its use to analyze double tube heat exchangers.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document describes an experimental study of heat transfer in a rectangular duct with and without internal V-shaped ribs. Experiments were conducted with air flow in turbulent regime (Reynolds numbers 3000-18000) in smooth duct and ducts with continuous or discrete internal V-shaped ribs. Temperature and pressure measurements were taken to determine heat transfer coefficients and friction factors for different configurations. Results showed that continuous ribs enhanced heat transfer more than discrete ribs, but also increased pressure drop more substantially. Heat transfer enhancement was dependent on rib geometry and position.
Similar to International Journal of Engineering Research and Development (20)
A Novel Method for Prevention of Bandwidth Distributed Denial of Service AttacksIJERD Editor
Distributed Denial of Service (DDoS) Attacks became a massive threat to the Internet. Traditional
Architecture of internet is vulnerable to the attacks like DDoS. Attacker primarily acquire his army of Zombies,
then that army will be instructed by the Attacker that when to start an attack and on whom the attack should be
done. In this paper, different techniques which are used to perform DDoS Attacks, Tools that were used to
perform Attacks and Countermeasures in order to detect the attackers and eliminate the Bandwidth Distributed
Denial of Service attacks (B-DDoS) are reviewed. DDoS Attacks were done by using various Flooding
techniques which are used in DDoS attack.
The main purpose of this paper is to design an architecture which can reduce the Bandwidth
Distributed Denial of service Attack and make the victim site or server available for the normal users by
eliminating the zombie machines. Our Primary focus of this paper is to dispute how normal machines are
turning into zombies (Bots), how attack is been initiated, DDoS attack procedure and how an organization can
save their server from being a DDoS victim. In order to present this we implemented a simulated environment
with Cisco switches, Routers, Firewall, some virtual machines and some Attack tools to display a real DDoS
attack. By using Time scheduling, Resource Limiting, System log, Access Control List and some Modular
policy Framework we stopped the attack and identified the Attacker (Bot) machines
Hearing loss is one of the most common human impairments. It is estimated that by year 2015 more
than 700 million people will suffer mild deafness. Most can be helped by hearing aid devices depending on the
severity of their hearing loss. This paper describes the implementation and characterization details of a dual
channel transmitter front end (TFE) for digital hearing aid (DHA) applications that use novel micro
electromechanical- systems (MEMS) audio transducers and ultra-low power-scalable analog-to-digital
converters (ADCs), which enable a very-low form factor, energy-efficient implementation for next-generation
DHA. The contribution of the design is the implementation of the dual channel MEMS microphones and powerscalable
ADC system.
Influence of tensile behaviour of slab on the structural Behaviour of shear c...IJERD Editor
-A composite beam is composed of a steel beam and a slab connected by means of shear connectors
like studs installed on the top flange of the steel beam to form a structure behaving monolithically. This study
analyzes the effects of the tensile behavior of the slab on the structural behavior of the shear connection like slip
stiffness and maximum shear force in composite beams subjected to hogging moment. The results show that the
shear studs located in the crack-concentration zones due to large hogging moments sustain significantly smaller
shear force and slip stiffness than the other zones. Moreover, the reduction of the slip stiffness in the shear
connection appears also to be closely related to the change in the tensile strain of rebar according to the increase
of the load. Further experimental and analytical studies shall be conducted considering variables such as the
reinforcement ratio and the arrangement of shear connectors to achieve efficient design of the shear connection
in composite beams subjected to hogging moment.
Gold prospecting using Remote Sensing ‘A case study of Sudan’IJERD Editor
Gold has been extracted from northeast Africa for more than 5000 years, and this may be the first
place where the metal was extracted. The Arabian-Nubian Shield (ANS) is an exposure of Precambrian
crystalline rocks on the flanks of the Red Sea. The crystalline rocks are mostly Neoproterozoic in age. ANS
includes the nations of Israel, Jordan. Egypt, Saudi Arabia, Sudan, Eritrea, Ethiopia, Yemen, and Somalia.
Arabian Nubian Shield Consists of juvenile continental crest that formed between 900 550 Ma, when intra
oceanic arc welded together along ophiolite decorated arc. Primary Au mineralization probably developed in
association with the growth of intra oceanic arc and evolution of back arc. Multiple episodes of deformation
have obscured the primary metallogenic setting, but at least some of the deposits preserve evidence that they
originate as sea floor massive sulphide deposits.
The Red Sea Hills Region is a vast span of rugged, harsh and inhospitable sector of the Earth with
inimical moon-like terrain, nevertheless since ancient times it is famed to be an abode of gold and was a major
source of wealth for the Pharaohs of ancient Egypt. The Pharaohs old workings have been periodically
rediscovered through time. Recent endeavours by the Geological Research Authority of Sudan led to the
discovery of a score of occurrences with gold and massive sulphide mineralizations. In the nineties of the
previous century the Geological Research Authority of Sudan (GRAS) in cooperation with BRGM utilized
satellite data of Landsat TM using spectral ratio technique to map possible mineralized zones in the Red Sea
Hills of Sudan. The outcome of the study mapped a gossan type gold mineralization. Band ratio technique was
applied to Arbaat area and a signature of alteration zone was detected. The alteration zones are commonly
associated with mineralization. The alteration zones are commonly associated with mineralization. A filed check
confirmed the existence of stock work of gold bearing quartz in the alteration zone. Another type of gold
mineralization that was discovered using remote sensing is the gold associated with metachert in the Atmur
Desert.
Reducing Corrosion Rate by Welding DesignIJERD Editor
This document summarizes a study on reducing corrosion rates in steel through welding design. The researchers tested different welding groove designs (X, V, 1/2X, 1/2V) and preheating temperatures (400°C, 500°C, 600°C) on ferritic malleable iron samples. Testing found that X and V groove designs with 500°C and 600°C preheating had corrosion rates of 0.5-0.69% weight loss after 14 days, compared to 0.57-0.76% for 400°C preheating. Higher preheating reduced residual stresses which decreased corrosion. Residual stresses were 1.7 MPa for optimal X groove and 600°C
Router 1X3 – RTL Design and VerificationIJERD Editor
Routing is the process of moving a packet of data from source to destination and enables messages
to pass from one computer to another and eventually reach the target machine. A router is a networking device
that forwards data packets between computer networks. It is connected to two or more data lines from different
networks (as opposed to a network switch, which connects data lines from one single network). This paper,
mainly emphasizes upon the study of router device, it‟s top level architecture, and how various sub-modules of
router i.e. Register, FIFO, FSM and Synchronizer are synthesized, and simulated and finally connected to its top
module.
Active Power Exchange in Distributed Power-Flow Controller (DPFC) At Third Ha...IJERD Editor
This paper presents a component within the flexible ac-transmission system (FACTS) family, called
distributed power-flow controller (DPFC). The DPFC is derived from the unified power-flow controller (UPFC)
with an eliminated common dc link. The DPFC has the same control capabilities as the UPFC, which comprise
the adjustment of the line impedance, the transmission angle, and the bus voltage. The active power exchange
between the shunt and series converters, which is through the common dc link in the UPFC, is now through the
transmission lines at the third-harmonic frequency. DPFC multiple small-size single-phase converters which
reduces the cost of equipment, no voltage isolation between phases, increases redundancy and there by
reliability increases. The principle and analysis of the DPFC are presented in this paper and the corresponding
simulation results that are carried out on a scaled prototype are also shown.
Mitigation of Voltage Sag/Swell with Fuzzy Control Reduced Rating DVRIJERD Editor
Power quality has been an issue that is becoming increasingly pivotal in industrial electricity
consumers point of view in recent times. Modern industries employ Sensitive power electronic equipments,
control devices and non-linear loads as part of automated processes to increase energy efficiency and
productivity. Voltage disturbances are the most common power quality problem due to this the use of a large
numbers of sophisticated and sensitive electronic equipment in industrial systems is increased. This paper
discusses the design and simulation of dynamic voltage restorer for improvement of power quality and
reduce the harmonics distortion of sensitive loads. Power quality problem is occurring at non-standard
voltage, current and frequency. Electronic devices are very sensitive loads. In power system voltage sag,
swell, flicker and harmonics are some of the problem to the sensitive load. The compensation capability
of a DVR depends primarily on the maximum voltage injection ability and the amount of stored
energy available within the restorer. This device is connected in series with the distribution feeder at
medium voltage. A fuzzy logic control is used to produce the gate pulses for control circuit of DVR and the
circuit is simulated by using MATLAB/SIMULINK software.
Study on the Fused Deposition Modelling In Additive ManufacturingIJERD Editor
Additive manufacturing process, also popularly known as 3-D printing, is a process where a product
is created in a succession of layers. It is based on a novel materials incremental manufacturing philosophy.
Unlike conventional manufacturing processes where material is removed from a given work price to derive the
final shape of a product, 3-D printing develops the product from scratch thus obviating the necessity to cut away
materials. This prevents wastage of raw materials. Commonly used raw materials for the process are ABS
plastic, PLA and nylon. Recently the use of gold, bronze and wood has also been implemented. The complexity
factor of this process is 0% as in any object of any shape and size can be manufactured.
Spyware triggering system by particular string valueIJERD Editor
This computer programme can be used for good and bad purpose in hacking or in any general
purpose. We can say it is next step for hacking techniques such as keylogger and spyware. Once in this system if
user or hacker store particular string as a input after that software continually compare typing activity of user
with that stored string and if it is match then launch spyware programme.
A Blind Steganalysis on JPEG Gray Level Image Based on Statistical Features a...IJERD Editor
This paper presents a blind steganalysis technique to effectively attack the JPEG steganographic
schemes i.e. Jsteg, F5, Outguess and DWT Based. The proposed method exploits the correlations between
block-DCTcoefficients from intra-block and inter-block relation and the statistical moments of characteristic
functions of the test image is selected as features. The features are extracted from the BDCT JPEG 2-array.
Support Vector Machine with cross-validation is implemented for the classification.The proposed scheme gives
improved outcome in attacking.
Secure Image Transmission for Cloud Storage System Using Hybrid SchemeIJERD Editor
- Data over the cloud is transferred or transmitted between servers and users. Privacy of that
data is very important as it belongs to personal information. If data get hacked by the hacker, can be
used to defame a person’s social data. Sometimes delay are held during data transmission. i.e. Mobile
communication, bandwidth is low. Hence compression algorithms are proposed for fast and efficient
transmission, encryption is used for security purposes and blurring is used by providing additional
layers of security. These algorithms are hybridized for having a robust and efficient security and
transmission over cloud storage system.
Application of Buckley-Leverett Equation in Modeling the Radius of Invasion i...IJERD Editor
A thorough review of existing literature indicates that the Buckley-Leverett equation only analyzes
waterflood practices directly without any adjustments on real reservoir scenarios. By doing so, quite a number
of errors are introduced into these analyses. Also, for most waterflood scenarios, a radial investigation is more
appropriate than a simplified linear system. This study investigates the adoption of the Buckley-Leverett
equation to estimate the radius invasion of the displacing fluid during waterflooding. The model is also adopted
for a Microbial flood and a comparative analysis is conducted for both waterflooding and microbial flooding.
Results shown from the analysis doesn’t only records a success in determining the radial distance of the leading
edge of water during the flooding process, but also gives a clearer understanding of the applicability of
microbes to enhance oil production through in-situ production of bio-products like bio surfactans, biogenic
gases, bio acids etc.
Gesture Gaming on the World Wide Web Using an Ordinary Web CameraIJERD Editor
- Gesture gaming is a method by which users having a laptop/pc/x-box play games using natural or
bodily gestures. This paper presents a way of playing free flash games on the internet using an ordinary webcam
with the help of open source technologies. Emphasis in human activity recognition is given on the pose
estimation and the consistency in the pose of the player. These are estimated with the help of an ordinary web
camera having different resolutions from VGA to 20mps. Our work involved giving a 10 second documentary to
the user on how to play a particular game using gestures and what are the various kinds of gestures that can be
performed in front of the system. The initial inputs of the RGB values for the gesture component is obtained by
instructing the user to place his component in a red box in about 10 seconds after the short documentary before
the game is finished. Later the system opens the concerned game on the internet on popular flash game sites like
miniclip, games arcade, GameStop etc and loads the game clicking at various places and brings the state to a
place where the user is to perform only gestures to start playing the game. At any point of time the user can call
off the game by hitting the esc key and the program will release all of the controls and return to the desktop. It
was noted that the results obtained using an ordinary webcam matched that of the Kinect and the users could
relive the gaming experience of the free flash games on the net. Therefore effective in game advertising could
also be achieved thus resulting in a disruptive growth to the advertising firms.
Hardware Analysis of Resonant Frequency Converter Using Isolated Circuits And...IJERD Editor
-LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region[5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits.
Simulated Analysis of Resonant Frequency Converter Using Different Tank Circu...IJERD Editor
LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region [5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits. The supported simulation
is done through PSIM 6.0 software tool
Amateurs Radio operator, also known as HAM communicates with other HAMs through Radio
waves. Wireless communication in which Moon is used as natural satellite is called Moon-bounce or EME
(Earth -Moon-Earth) technique. Long distance communication (DXing) using Very High Frequency (VHF)
operated amateur HAM radio was difficult. Even with the modest setup having good transceiver, power
amplifier and high gain antenna with high directivity, VHF DXing is possible. Generally 2X11 YAGI antenna
along with rotor to set horizontal and vertical angle is used. Moon tracking software gives exact location,
visibility of Moon at both the stations and other vital data to acquire real time position of moon.
“MS-Extractor: An Innovative Approach to Extract Microsatellites on „Y‟ Chrom...IJERD Editor
Simple Sequence Repeats (SSR), also known as Microsatellites, have been extensively used as
molecular markers due to their abundance and high degree of polymorphism. The nucleotide sequences of
polymorphic forms of the same gene should be 99.9% identical. So, Microsatellites extraction from the Gene is
crucial. However, Microsatellites repeat count is compared, if they differ largely, he has some disorder. The Y
chromosome likely contains 50 to 60 genes that provide instructions for making proteins. Because only males
have the Y chromosome, the genes on this chromosome tend to be involved in male sex determination and
development. Several Microsatellite Extractors exist and they fail to extract microsatellites on large data sets of
giga bytes and tera bytes in size. The proposed tool “MS-Extractor: An Innovative Approach to extract
Microsatellites on „Y‟ Chromosome” can extract both Perfect as well as Imperfect Microsatellites from large
data sets of human genome „Y‟. The proposed system uses string matching with sliding window approach to
locate Microsatellites and extracts them.
Importance of Measurements in Smart GridIJERD Editor
- The need to get reliable supply, independence from fossil fuels, and capability to provide clean
energy at a fixed and lower cost, the existing power grid structure is transforming into Smart Grid. The
development of a smart energy distribution grid is a current goal of many nations. A Smart Grid should have
new capabilities such as self-healing, high reliability, energy management, and real-time pricing. This new era
of smart future grid will lead to major changes in existing technologies at generation, transmission and
distribution levels. The incorporation of renewable energy resources and distribution generators in the existing
grid will increase the complexity, optimization problems and instability of the system. This will lead to a
paradigm shift in the instrumentation and control requirements for Smart Grids for high quality, stable and
reliable electricity supply of power. The monitoring of the grid system state and stability relies on the
availability of reliable measurement of data. In this paper the measurement areas that highlight new
measurement challenges, development of the Smart Meters and the critical parameters of electric energy to be
monitored for improving the reliability of power systems has been discussed.
Study of Macro level Properties of SCC using GGBS and Lime stone powderIJERD Editor
The document summarizes a study on the use of ground granulated blast furnace slag (GGBS) and limestone powder to replace cement in self-compacting concrete (SCC). Tests were conducted on SCC mixes with 0-50% replacement of cement with GGBS and 0-20% replacement with limestone powder. The results showed that replacing 30% of cement with GGBS and 15% with limestone powder produced SCC with the highest compressive strength of 46MPa, meeting fresh property requirements. The study concluded that this ternary blend of cement, GGBS and limestone powder can improve SCC properties while reducing costs.
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Multivendor cloud production with VSF TR-11 - there and back again
International Journal of Engineering Research and Development
1. International Journal of Engineering Research and Development
e-ISSN: 2278-067X, p-ISSN: 2278-800X, www.ijerd.com
Volume 10, Issue 6 (June 2014), PP.22-31
22
Experimental and Numerical Investigations of Forced
Convection in Tube-Type Heat Exchanger
Christian Okechukwu Osueke, IgbinosaIkpotokin,
Department of Mechanical Engineering, Landmark University, Omu-Aran, Kwara State Nigeria
Abstract:- Experimental and numerical studies of forced convectionheat transfer in tube-type heat exchanger
consisting four columns of five cylindrical tubes arranged so that every second column is displaced (i.estaggered
configuration) were carried out. Experiments were conductedtodeterminethe effects of flow pattern on heat
transfer and pressure dropwithin the heat exchanger and the heat transfer dependence on position. In the
analytical approach, the dimensionless representationsof the rates of forced convection (i.eNusselt number) and
pressure loss(i.e drag coefficient) were obtained. The numerical simulation is carried out using FEMLAB 3.0
and the results compared favourably with the experimental. The flow visualization featuressuch as boundary
layer developments between tubes, formation of vortices, local variations of the velocity and temperature
distribution within the heat transfer device were revealed by numerical solution. The resultsshowed that the
average Nusselt number increases with increasing Reynolds number and the heated element position in the
bank. The drag coefficient decrease with increasing Reynolds numbers.
Keywords:- Tube-type heat exchangers, staggered tube bank, forced convection.
I. INTRODUCTION
The process of forced convection heat transfer to or fromtube bankwas the subject of many theoretical
and experimental studies because of their relevance in many engineering applications. This process is significant
in the design of heat transfer process devices suchas boiler for steam generation and cooling coil of air
conditioning system.
The increasing interest in developing compact, and high efficient heat exchanger motivated researchers
to study heat transfer from tube bankof circular cross section (Keys and London, 1998).
The studied tube-type heat exchanger is astaggered arrangement of four columns of five parallel
cylinders. The configuration is determined by tube diameter and longitudinal and transverse pitches which are
distances between tube centres. In this heat transfer device, fluid flow perpendicular to the tube bank thus
simulating a typical cross flow heat exchanger, used in many industrial applications such as boilers, automotive,
air conditioner, etc.
The fluid flow conditions within the bank are dominated by turbulence because most heat exchangers
operate at high Reynolds numbers (Re) and inducedvortex sheddingwhich enhanced the heat transfer
process.The turbulence intensity and its generation are governed by the bank geometry and Re.It was observed
that with shorter transverse pitches, the velocity fluctuations become more intensive. The turbulence level of the
main flow can influence fluid flow only over the first and second rows (Mehrabian, 2007). A tube bank acts as a
turbulent grid and establishes a particular level of turbulence.The heat transfer conditions stabilize, such that
little change occurs in the convection coefficient for tube beyond the fifth row tube (Yoo et al, 2007).
For optimal design of heat transfer process device andthe determination of its operational performance
parameters, the drag, and heat transfer associated with fluid flow over the tube surfaces have to be
known.Because a sudden changes in these quantities can lead to hysteresisand poor device functionality (Yukio
et al, 2010).
Although reasonable number of researchers had conducted experiments and numerical analyses on
fluid flow and heat transfer at the tube bank, but different correlation equations have been proposed to predict
the heat transfer or the Nusselt number. The results obtained depend on the geometric configuration, number of
tube rows,and the Reynolds number. For example,(Žukauskas,1987) obtained acorrelation given as
25.0
)
Pr
(PrRe
Pw
CNu nm
1
wherePrw and Pr represent the Prandtl numbers evaluated at the wall temperature and the bulk mean
temperature, respectively.Re denotes the Reynolds number evaluated at the bulk mean temperature, and it is
based on the average velocity through the least cross section formed by the tube array. The constants C, m, and
n vary depending on the Reynolds number and tube bundle geometry and it can be found in many heat transfer
textbooks.
2. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
23
Generally, a correction factor is always introduced in heat transfer coefficient correlation for number of
tube rows because the shorter the bank, the lower the average heat transfer. The influence of the number of tube
rows becomesnegligible only for N>16 (Incropera and Dewitt 2004).
The pressure drop in tube-type heat exchanger is related to the drag coefficient according to the
following equation (Kays& London, 1998).
2
2
1
VNP R 2
The focusof this study is to conduct experimental and numerical investigations to determine the heat
transfer coefficient between a heated cylindrical copper element and the air flowcharacteristics as it passthrough
a tube-type heat exchanger.The experimental data was then correlated by power-law curve fitting to obtain the
Nusselt number. Furthermore, the experimental data was also used to compute the pressure loss coefficient
which represents the pressure drop imposed on the flow by each successive row of tubes. The numerical
technique allows flow visualization and temperature distribution within the heat exchanger.
II. MATERIALS AND METHODS
Experimental Technique
Theexperimental technique is essential to produce cooling curves of heated element for different flow
conditions. The primary component of the tube-type heat exchanger (i.e test apparatus) is valve controlled air
flow duct with a perspex test section of 125mm x 125mm through which air is drawn by a centrifugal fan, and
into which the heated element under investigation is inserted as shown in Fig 1.
Air temperature upstream of the test section and atmospheric pressure were obtained by means of
thermocouple and mercury barometer respectively.
Air pressure differential upstream and downstream of the test section were measured by inclined water
manometer connected to the head tube located in the centre upstream position with the tube itself on the
horizontal centerline of the test section, and it faced upstreamas shown in Fig 1.The velocity upstream the test
section is established from the pressure drop between atmosphere and upstream static pressure tapping (i.e
depression of water column the manometer) and is recorded H1in meters. The sampled result is as shown in
Table 3.
Heat transfer measurements were obtained by replacing one of the Perspex rodswith an externally
identical heated copper rod. The copper rod outer and inner diameter are 12.45mm and 11.5mmrespectively and
its length is 95mm. It is carried between two extension rods of fabricated plastic compound.The element
temperature is obtained by K-type 0.2 mm diameter thermocouple probe inserted at itscentre. The thermocouple
output is connected to a digital multimeter (MAS-34X model) which also was connected to a Pentium 3 desktop
computer as shown in Fig 1.
The test procedure involved heating the copper rod with electrical heater to 700
C above air flow
temperature outside the test section. Thereafter, it is was inserted at different desired positionsin the test section
(i.ecentre of 1st
, 2nd
, 3rd
and 4th
columns) under different flow conditions such as 10, 20, 30, 40, 50, 60, 70, 80,
90 and 100% throttle openings.Then its temperature and time of coolingwere recorded with the thermocouple
embedded at its centre.The heat transfer coefficient is then deduced from logarithm plot (Fig 3.0) of rate of
cooling together with the knowledge of the thermal capacity and surface area of the copper.
Fig.1: Cross flow tube-type heat exchanger experimental test rig.
3. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
24
Where
1. Fan, 2. Air discharge tube, 3. Throttle valve, 4. Working section, 5. Electric heater, 6. Total head tube,
7. Test element, 8. Thermometer, 9. Bellmouth, 10. Computer, 11. Digital multimeter, 12. Control
panel and 13. Inclined manometer.
Basic assumptions and problem formulation
It was assumed that the heat generated in the cylindrical copper element is transferred to the air that
flowing through it. However, a certain amount of heat is conducted from the element into the plastic extension
pieces. A correction factor of 8.4mm was used to compensate for plastic extension (Plint and Partners Ltd,
1981). Therefore:
L1 = L + 0.0084 3
It was further assumed that temperature gradients within the element are negligible, so that the
thermocouple embedded at the centre gives a true reading of the effective surface temperature. The justification
for this assumption is that the Biot number is very small(Bi < 0.1).
The rate of heat transfer from the element to the air stream is given by:
q = hA(T −Ta) 4
The temperature drop dTin a period of time dtis given by:
−qdt= mcdT 5
Combining Equations (4) and (5)gives:
dt
mc
hA
TT
dT
a
1
)(
6
whereA is replaced by A1 to allow for the tube plastic extensions. Integrating equation (6), we obtain:
mc
thA
TTTT aoeae
1
)(log)(log
7
Equation (7) suggests that a plot of )(log ae TT against t yield a straight line slope
mc
hA
M 1
8
and since we can obtained the other factors in this expression from the geometrical properties of copper in table
1.,the heat transfer coefficient is related to the slope M of this line by the following expression:
M
A
mc
h
1
8
A plot of log10(T – Ta) against time (t) was used, since logeN = 2.3026 log10N.
The effective velocity of the air across the element is determined by calculating the velocity
V1upstream. The velocity V1 developed by gas of density ℓ expanding freely from rest under the influence of
pressure difference P.When P is sufficiently small for compressibility to be neglected, then, applying
Bernoulli’s equation gives:
P
V
2
2
1
9a
the pressure head H1 was measured in centimeters of water. Since
1cm H2O = 98.1 N/m2
equation (9a) becomes
1
2
1
1.98
2
H
V
9b
The density of air under pressure Pa and at temperature Ta is given by ideal gas equation.
Pa = RTa10
where the gas constant R = 2875J/kmol.K
substituting equation (9) in (10) yields:
V1 = 237.3
A
A
P
TH1
11
Equation (11) is used for calculating local velocities upstream of the test section.
The calculation of the effective velocity through bank of tubes was based on the minimum flow area.
When all the tubes are in position, the minimum area occurs in a transverse plane. Therefore,
12VV 12
4. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
25
Dimensional analysis shows that the relationship between h and the independent variables is expressed as:
Nu
K
hD
13
VD
Re 14
K
Cp
Pr 15
The pressure drop is express as a proportion to the velocity head. It represents the pressure drop
imposed on the flow by each successive rank of tubeswhich is represented as:
213 HHH 16
and the drag coefficient is calculated as:
1
3
4/
4
H
H
CD 17
III. NUMERICAL MODELLING
Numerical simulation technique was essential for flow visualization and temperature distribution
within the heat exchanger. The simulation modeling was performed in a two-dimensional domain, which
represents the test section as shown in Fig2. FEMLAB 3.0software was used to draw all parts in computational
domain and to generate grids. The dimensions of computational domain were idealized to reveal the
fundamental issues and enable validation with the experimental data that was the reason why this computational
domain only cover thetest working section. Thiscomputational domain has a length andwidth as same size with
the experimentaltest section.
Fig.2: Schematic diagram of a staggered tube bank working section.
Since the governing equations are in spatial coordinates, the boundary conditions were provided for all
boundaries of the computation domain. At the up-stream boundary, uniform flow velocity Uinand temperature
Tinwere assumed. At the down-stream end of the computational domain, the Neumann boundary condition was
applied. At the solid cylinder surfaces represented by circles, no-slip conditions and thermal insulation were
applied, while constant temperatureTtubewas specified for the heated element. At the symmetry plane, normal
velocity and the temperature variation along the normal direction were set to zero.
5. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
26
IV. RESULTS AND DISCUSSION
Experimental and numerical simulations of heat transfer and fluid flow characteristics of tube-type heat
exchanger with staggered configuration are presented.
Forthese studies, the following dimension and fluid properties used are presented in tables1 and 2
respectively.
Table 1. Geometrical properties of the copper rod.
Description Quantity Unit
External diameter (d) 12.45 mm
Internal diameter (di) 11.5 mm
Thickness of tube (t) 0.5 mm
Length of tube (l) 95 Mm
Effective length (l1) 0.1304 M
Surface area (A) 0.00371 m2
Effective surface area (A1) 0.00404 m2
Specific heat (C) 380 J/kg.K
Mass (m) 0.0274 Kg
Table 2. Properties of the fluid (air).
Description Quantity Unit
Ambient temperature (Ta) 300 o
K
Barometric pressure (Pa) 99,042 N/m2
Density of air at Ta (ℓ) 1.1614 kg/m3
Dynamic viscosity(µ) 1.846X10-5
kg/ms
Thermal conductivity (K) 0.0263
J/msoC
In a particular test, the heated element was inserted at the centre position in the first column of tubes
with the apparatus running, the results obtained for different set flow rate are in the ranges of 10 – 100% and are
presented in table 3. The rate of cooling resulting from minimum flow rate of 10% is shown in Fig 3.The
pressure differentialH3imposed on the flow by each successive column of tubeacross the exchanger was
obtained with all the tubes in position and the test result is shown in Fig 4.
Table 3.0: Data Corresponding to Ten Different Throttle Openings when the Heated
Element is positioned at the centreof 1st
column.
Throttle
opening
(%)
H1
(cmH20)
V1
(m/s)
V
(m/s)
Re M
(s-1
)
H
(J/ms2o
C)
Nu
10 0.03 2.263 4.524 3543 -0.009 53.4182 25.28732
20 0.18 5.541 11.082 8680 -0.011 65.28891 30.90673
30 0.33 7.502 15.005 11753 -0.011 65.28891 30.90673
40 0.48 9.048 18.097 14175 -0.012 71.22427 33.71643
50 0.64 10.448 20.896 16367 -0.013 77.15962 36.52613
60 0.79 11.608 23.216 18187 -0.013 77.15962 36.52613
70 0.94 12.662 25.325 19836 -0.013 77.15962 36.52613
80 1.096 13.673 27.345 21418 -0.013 77.15962 36.52613
90 1.248 14.59 29.18 22856 -0.013 77.15962 36.52613
100 1.42 15.563 31.126 24380 -0.014 83.09498 39.33583
6. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
27
Fig. 3: A plot of log10(T-Ta) against t for 10% throttle opening.
Fig. 4: Pressure differential across the tube bank.
Dimensionless quantities such as Reynolds number, drag coefficient and Nusselt number were
calculated using the relevant equations. The drag coefficient which represents the pressure drop was calculated
using equation (17) and the results were plotted against Reynolds number is shown in Fig.5.In the case of
Reynolds number equation (14) was used, while equation (13) was used to calculate the Nusselt number. The
results are shown in table 3. Furthermore, empirical correlation for heat transfer coefficient was obtained with
power-law curve fitting. The curves are shown in Fig. 6 and the resulting correlation are shown in table 4.
y = -0.009x + 1.867
R² = 0.997
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 20 40 60 80 100 120
Log10(T-Ta)
Time(s)
Cooling curve for 10% throttle opening
y = 0.373x + 0.005
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.5 1 1.5 2 2.5 3 3.5 4
H1(cm)
H3 (cm)
7. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
28
Fig. 5: Drag coefficient vs. Reynolds number.
Fig. 6: Relationship between experimental Nu and Re for cross flow of air that past the tube bank
Table 4: Experimental results showing Nu and Re relationship.
Rows Experimental Correlations
1st
Nu = 4.125Re0.24
R2
= 0.952
2nd
Nu = 3.858Re0.25
R2
= 0.990
3rd
Nu = 4.758Re0.216
R2
= 0.972
4th
Nu = 4.258Re0.271
R2
= 0.993
Numerical results
Velocity Distribution
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 5000 10000 15000 20000 25000 30000
CD
Re
0
10
20
30
40
50
60
0 5000 10000 15000 20000 25000 30000
NussseltNumber(Nu)
Reynolds Number (Re)
1st rank
2nd rank
3rd rank
4th rank
8. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
29
Fig. 7: Velocity distribution in the tube bank at Re = 24380
Velocity patternin the bank isillustrated in Fig.7. Fluid velocity in the mid-plane of the tubes
wasobserved to be higher and weak near tube surface plane because of the boundary layer development on the
surface. A detailed inspection of the Figure shows that higher percentage of fluid stream is imposed upon the
heated tube surface. As a result of this, relatively smaller wake region was developed.It can also be seen that the
main flow that passed through every tube rank and the flow arewell mixed. This in turn enhances the heat
transfer. The streamline plot revealed that vortex formation occurs in the zones of recirculation. However, the
region was much larger behind the last column of cylinders for low Reynolds number.
Boundary Layer Separation
Fig. 8:The boundary layer separation point of first rank in tube bank at Re = 24380
Boundary layer separation occurat a point on the tubes where the fluid momentum is too weak to
overcome the adverse pressure gradient and then detached from the tubes surface as shown in figure 8.0. This
separation was observed shortly after (θ = 90°).By the nature of these flow separations, local heat transfer and
fluid mixing increase especially upstream of the tubes and cause low performance at the wake region located
downstream of the tubes.
Temperature Distribution
9. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
30
Fig. 9: Temperature distributions in the tube bank at Re = 24380.
Figure 9above shows the temperature distributions within the bank.The cooling rate of the heated
element is grater within the tube-mid planes where maximum local velocity occurs. This was evident by the low
temperature close to that of the free stream recorded. The temperature gradient near the upstream tube was
higher due to the thin boundary layer thicken, while the temperature gradient down stream along the tube is
lower than the upstream due to the wake flow.
The numerical data were essentially used to reveal temperature distribution and flow visualizations
such as velocity distribution, boundary layer separation occurring within the tube bank. The experimental test
was used to generate cooling curves. A logarithm plot for the rate of cooling was produced as shown in Fig. 3.
The slope obtained from Fig. 3.0, together with the knowledge of the copper thermal capacity, mass, and surface
area were used to calculate heat transfer coefficient between the heated copper element, and the air flow normal
to it.
Pressure drop across the tube-type heat exchanger increase with increasing Reynolds.Numerical results
were 12% higher than the experimental.
It is observed that the heat transfer coefficient increases, though at a diminishing rate, in successive
columns of tubes. This is caused by the increasing level of turbulence and stability as the air passes through the
tube bank.
Numerical Nusselt number was15% higher than that of the experimental results. The discrepancy in
result could be due to poor convergence resulting from inability of the software to handle high turbulent flow
that was obtained in the experimental work. Both the experimental and numerical predictions indicate that the
Nusselt number and pressure drop increase with the increasing Reynolds number.
V. CONCLUSION
The heat transfer coefficient was a function of the heated element position and Reynolds number in the
tube bank. Numerical and experimental results compared favourably.The present numerical and experimental
investigations suggest that changes in heat transfer fromcopper tube was dependenton the position and flow
pattern (Reynolds number) in the heat exchanger while the pressure drop was a function of the Reynolds
numbers.Downstream from the third column, the heat transfer stabilizes, such that little change occurs in the
convection coefficient from tube beyond the fourth.
10. Experimental And Numerical Investigations Of Forced Convection In Tube-Type Heat Exchanger
31
REFERENCES
[1]. Kays, W. S., London, A. L., 1998, Compact Heat Exchangers, 3rd Ed., KriegerPublishing Company,
Malabar, Florida.
[2]. M. A. Mehrabian, 2007, Heat Transfer And Pressure Drop Characteristics Of Cross Flow Of Air Over
An Circular Tube in Isolation And/Or in a Tube Bank, The Arabian Journal for Science and
Engineering, Volume 32.
[3]. S.Y. Yoo, H.K. Kwon, J.H. Kim, 2007, A study on heat transfer characteristics for staggered tube
banks in cross-flow, J. Mech. Sci. Technol. Vol. 21 pp505–512.
[4]. Yukio Takemoto, KeijiKawanishi, JiroMizushima, 2010, Heat transfer in the flow through a bundle of
tubes and transitions of the flow, International Journal of Heat and Mass Transfer, Vol. 53 pp 5411–
5419
[5]. Žukauskas, A.,1987, Convective Heat Transfer in Cross Flow, Handbook of Single-Phase
[6]. Convective Heat Transfer, Wiley & Sons, New York.
[7]. Incropera F.P. and Dewitt D.P.( 2004),Fundamental of Heat and Mass Transfer, 5th
ed., John Wiley &
Sons, Inc.