In day-to-day life, we come across many processes where we see the usage of heat exchangers. Some
examples where heat exchangers are extensively utilized are air conditioning plants, thermal power plants, food
processing plants etc. The basic requirement in these industries is to utilize the heat energy used in the heat
exchangers efficiently. This can be done either by developing new designs that are energy efficient or by
modifying the present designs in such a manner that they give better performance under the same working
conditions. Hence, heat exchangers that would provide more heat transfer at the minimum size and cost are
requirement of the present industries. Hence they use the various heat transfer technique for enhance the heat
transfer rate. In this paper review of research work in last decade on heat transfer enhancement.
IRJET- CFD Analysis of Double Pipe Heat Exchanger with and with out DimplesIRJET Journal
This document analyzes the performance of a double pipe heat exchanger with and without dimples using computational fluid dynamics (CFD). CFD simulations were performed using ANSYS Fluent to model the heat transfer of water through double pipe exchangers with and without dimples on the inner pipe. The results showed that the heat exchanger with dimples had higher heat transfer and lower outlet temperatures compared to the exchanger without dimples. Therefore, the addition of dimples enhances the heat transfer performance of double pipe heat exchangers.
Comparative Study of ECONOMISER Using the CFD Analysis IJMER
This paper presents a simulation of the economizer zone, which allowsstudying the flow
patterns developed in the fluid, while it flows along the length of the economizer. The past failure
details revelsthat erosion is more in U-bend areas of Economizer Unit because of increase in flue gas
velocity near these bends. But it isobserved that the velocity of flue gases surprisingly increases near
the lower bends as compared to upper ones. The model issolved using conventional CFD techniques by
FLUENT software. In which the individual tubes are treated as sub-gridfeatures. A geometrical model
is used to describe the multiplicity of heat-exchanging structures and the interconnectionsamong them.
The Computational Fluid Dynamics (CFD) approach is utilised for the creation of a three-dimensional
modelof the economizer coil of single column tube. With equilibrium assumption applied for
description of the system chemistry. The flue gastemperature, pressure and velocity field of fluid flow
within an economizer tube using the actual bounda
IRJET - Review of Entropy Generation Minimization in Heat ExchangerIRJET Journal
This document reviews entropy generation minimization in helically coiled heat exchangers. It derives a dimensionless function for the entropy generation number involving four dimensionless variables. It then minimizes the entropy generation number to derive analytical expressions for the optimal values of these variables for both laminar and turbulent flows. For laminar flow, it finds an optimal inner tube diameter ratio of 10 and shows the entropy generation is minimal for annulus diameter ratios from 3.5-5. For turbulent flow, it finds optimal inner tube and annulus diameter ratios of 16.5 and around 2, respectively.
This document summarizes a research paper that analyzed heat transfer in an economizer using computational fluid dynamics (CFD). It discussed how fins can be added to economizer tubes to increase the heat transfer surface area between flue gases and boiler feedwater. The document reviewed previous research on economizer design optimization and failures. It described the working of CFD analysis using equations of continuity, momentum, and energy to model fluid flow. The study used the k-ε turbulence model in CFD software to analyze heat transfer with and without fins on an economizer.
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.
Enhancing heat transfer surface are used in many
engineering applications such as heat exchanger, air conditioning,
chemical reactor and refrigeration systems, hence many
techniques have been investigated on enhancement of heat
transfer rate and decrease the size and cost of the involving
equipment especially in heat exchangers. One of the most
important techniques used are passive heat transfer technique.
These tchniques when adopted in Heat exchanger proved that the
overall thermal performance improved significantly. This paper
reviews experimental and numerical works taken by researchers
on this technique since 2004 such as twisted tape, wire coil, swirl
flow generator, etc. to enhance the thermal efficiency in heat
exchangers and useful to designers implementing passive
augmentation techniques in heat exchange. The authors found
that variously developed twisted tape inserts are popular
researched and used to strengthen the heat transfer efficiency for
heat exchangers. The other techniques used for specific work
environments are studied in this paper. Twisted tape inserts
perform better in laminar flow than turbulent flow. However, the
other several passive techniques such as ribs, conical nozzle, and
conical ring, etc. are generally more efficient in the turbulent flow
than in the laminar flow.
Experimental study of heat transfer enhancement in a pipe using twisted tapesIAEME Publication
This document summarizes an experimental study on heat transfer enhancement in a pipe using twisted tapes and wire coils. Twisted tapes were used to generate swirl flow while wire coils along with twisted tapes were used to generate co-swirl flow. Experiments were conducted with different twist ratios for the tapes and pitch ratios for the wire coils. Results showed that both techniques increased heat transfer compared to a plain pipe, with wire coils and twisted tapes together providing more efficient heat transfer than twisted tapes alone. Friction factor and thermal enhancement increased with decreasing twist ratio and Reynolds number.
IRJET- Experimental Investigation of Enhancement of Convective Heat Trans...IRJET Journal
This document presents an experimental study that investigates heat transfer enhancement in a circular tube with internally placed pin fin elements. The experiments were conducted with air as the working fluid in a circular tube fitted with 36 pin fins measuring 10mm in length and 4mm in diameter inserted orthogonally along the entire length of the tube. Theoretical and experimental heat transfer coefficients were calculated and compared between the plain tube and tube with pin fins under varying flow conditions. The results show that the tube with pin fins achieved higher Nusselt numbers and heat transfer coefficients compared to the plain tube across all Reynolds numbers, demonstrating that the pin fins are effective at enhancing heat transfer.
The document presents information on helical baffle heat exchangers. It begins with introducing heat exchangers and defining a helical baffle heat exchanger. It then discusses the design of helixchangers, including thermal analysis of the helical baffles and tube side as well as hydrodynamic analysis of the shell side. Overall heat transfer coefficient is also examined. Key advantages of helixchangers are reduced bypass effects, fouling, vibration, and maintenance compared to traditional shell and tube exchangers. Future areas of research include CFD optimization and analysis of flow patterns and velocities.
Enhancement of heat transfer in tube in-tube heat exchangers using twisted in...Ijrdt Journal
Heat exchangers have several industrial and engineering applications. There are different methods to enhance heat transfer in heat exchangers. Passive technique of heat transfer is the most economical and best suited one. The role of inserts in internal forced convection has been widely acknowledged as a passive device in the heat transfer enhancement. One of such technique is introduction of twisted inserts which enhances the heat transfer coefficient. Twisted aluminium inserts when placed in the path of the fluid flow, creates a high degree of turbulence resulting in an increase in the heat transfer rate. By placing inserts, it is expected that the benefits due to the increased heat transfer coefficient overcome the higher cost involved because of the increased frictional losses. The work mainly focuses on increasing the heat transfer of tube-in-tube heat exchangers by using twisted aluminium inserts. The results obtained from the tube with twisted aluminium insert are compared with those without twisted insert using standard properties of heat transfer (LMTD & Effectiveness). The relations based on the data gathered during this work for predicting the heat transfer coefficient of the horizontal pipe with twisted taped insert are proposed. According to the results, in order to obtain maximum heat transfer, the twist ratio must be at the lowest level.
This document provides guidance on the design and rating of shell and tube heat exchangers. It discusses fundamentals of heat transfer calculations and selection of appropriate heat transfer models. Key considerations in the thermal design of shell and tube heat exchangers include process parameters, mechanical design factors such as tube dimensions and layout, and selection of heat transfer correlations. Software tools can help optimize the design but require experience to achieve practical designs.
IRJET- An Experimental Investigations of Twisted Tape Inserts in Square and C...IRJET Journal
This document describes an experimental investigation of twisted tape inserts in square and circular helical coil heat exchangers. The study aims to compare the heat transfer performance of square and circular patterned helical coils with twisted tape inserts. Experiments were conducted to calculate heat transfer coefficients, develop Nusselt number correlations, and analyze how Nusselt number varies with Reynolds number for each coil geometry. The results will provide insights into which geometry and twisted tape configuration performs better to enhance heat transfer in helical coil heat exchangers.
ENHANCEMENT OF HEAT TRANSFER IN SHELL AND TUBE HEAT EXCHANGER WITH TABULATOR ...IAEME Publication
The present work reported the use of variant twisted tapes fitted in a double pipe heat exchanger to improve the fluid mixing that leads to higher heat transfer rate with respect to that of the plain-twisted tape. Heat transfer, flow friction and thermal enhancement factor characteristics in a double pipe heat exchanger fitted with plain and variant twisted tapes using water as working fluid are investigated experimentally. Tests are performed for laminar flow ranges. The experimental data for a plain tube and plain-twisted tapes are validated using the standard correlations available in the literature. Two different variant twisted tapes which include V cut-twisted tape and Horizontal wing cut-twisted tape with twist ratios of y = 2.0, 4.4 and 6.0 are used. In addition, the variation of heat transfer coefficient of copper–nanofluids with different of Reynold's number and volume concentration of nanoparticles in plain tube without twisted tape.
1) The document discusses shell and tube heat exchangers and provides calculations for their basic design.
2) It defines key terms like Btu, calorie, joule, watt, temperature scales, pressure units, and specific heat.
3) The main heat exchanger equation is presented along with the process for designing a heat exchanger through an iterative approach to calculate the required heat transfer area.
IRJET- Parametric Investigation to Evaluate the Effect of Baffle Configuratio...IRJET Journal
This study evaluated the effect of baffle configuration on heat transfer rate in a shell and tube heat exchanger using computational fluid dynamics (CFD). Simulations were conducted for baffle spacings of 66mm, 76mm, and 86mm at mass flow rates of 0.5 kg/s, 1 kg/s, and 2 kg/s. The 86mm spacing had the highest heat transfer rate and outlet temperature, indicating better performance compared to the closer spacings. Maximum heat transfer rate was 219.47kW for the 86mm spacing at 2kg/s, a 52.2% increase over the 66mm spacing. Closer baffle spacing allowed for more uniform flow distribution but restricted flow compared to wider spac
IRJET - Numerical Analysis of Overall Heat Transfer Co-Efficient in Tube in T...IRJET Journal
This document summarizes a numerical analysis of the overall heat transfer coefficient in a tube-in-tube helical coil heat exchanger. A helical coil heat exchanger was modeled and analyzed using ANSYS software to determine the effects of varying mass flow rate and pitch on the overall heat transfer coefficient. The results showed that increasing the mass flow rate increased the overall heat transfer coefficient, while increasing the pitch decreased the overall heat transfer coefficient. Therefore, it is important to select an optimal pitch or other design parameters to achieve good heat transfer performance in such a heat exchanger.
A general interest to reduce fossil fuel consumption and to limit combustion
emissions, increase the efficiency of combustion chambers. One of the most important
processes in a gas turbine combustor, influencing to a large extent the efficiency of the
entire combustion process is the mixing between a swirling annular jet (primary air) and
the non-swirling inner jet (fuel).In normal swirling combustor, primary swirling air is
only supplied to the chamber and is mixed with the fuel but we here introduce a small
duct in the chamber containing a small amount of air without swirl and make it to mix
with the fuel and the primary swirling air. We have modified the design of the swirl
combustor by introducing a bluff body over the flow of the turbulent jet through which the
turbulent air will pass causing the axial velocity. For the purpose of simulation of the
required model of swirl combustor we are using the recent tools like ANSYS, ICEM, CFD
and FLUENT software’s. Using these tools the numerical investigation has been done.
The various values that are obtained are compared with the previous results of the swirl
combustor and the increase in the efficiency of the combustion has been noted
Experimental Analysis Of Heat Transfer From Square Perforated Fins In Stagger...IJERA Editor
This project gives the experimental analysis of heat transfer over a flat surface equipped with Square perforated
pin fins in staggered arrangement in a rectangular channel. The Fin dimensions are 100mm in height & 25mm in
width. The range of Reynolds number is fixed & about 13,500– 42,000, the clearance ratio (C/H) 0, 0.33 and 1,
the inter-fin spacing ratio (Sy /D) 1.208, 1.524, 1.944 and 3.417. Sy i.e. stream wise distance is varies and Sx i.e.
span wise distance is constant. The friction factor, enhancement efficiency and heat transfer correlate in
equations with each other. Here we are comparing Square pin fins with cylindrical pin fins. Staggered
arrangement and perforation will enhance the heat transfer rate. Clearance ratio and inter-fin spacing ratio affect
on Enhancement efficiency. Both lower clearance ratio and lower inter-fin spacing ratio and comparatively lower
Reynolds number give higher thermal performance. Friction factor & Nusselt number are Key parameter which
relates with efficiency enhancement and heat transfer rate.
Validation of Design Parameters of Radiator using Computational ToolIRJET Journal
This document discusses the validation of design parameters for automobile radiators using computational tools. It presents two case studies where the thermal performance of radiators is analyzed using the log mean temperature difference (LMTD) and number of transfer units (NTU) methods and the results are compared to those from a computational software tool (HXCombine). The results show good agreement between the manual calculations and software outputs, validating the use of computational tools for radiator design. Parameters like heat transfer rate, outlet temperatures, effectiveness and heat transfer area are compared for both case studies. This research demonstrates that computational tools can accurately analyze and design radiator performance.
This document summarizes a study that used computational fluid dynamics (CFD) to analyze heat transfer and flow characteristics in a solar air heater duct with ribbed surfaces. CFD simulations were performed for ducts with different rib configurations and Reynolds numbers. It was found that roughening the duct surface increased heat transfer but also increased friction losses. An optimal rib design was identified that provided maximum heat transfer enhancement with minimum pressure drop. Turbulence kinetic energy and intensity contours helped explain the increased turbulence near ribs that augmented heat transfer.
The Effect of insertion of different geometries on heat transfer performance ...IJMER
Abstract: Under turbulent flow conditions, the increase in heat transfer rate is more significant than that under laminar flow conditions. The turbulent effects become a dominant factor over secondary flow at higher Reynolds number. The turbulent flow can be produced by inserting different geometries in the circular pipe. This study focuses on the various methods or geometries used to produce turbulent geometries and its effect on the heat transfer. The turbulent generators with different geometrical
configurations have been used as one of the passive heat transfer enhancement techniques and are the most widely used in tubes in several heat transfer applications. Insertion of such geometries may lead to increase the friction factor and pressure drop which directly enhances the heat transfer characteristics.
This document summarizes a numerical investigation of a jet pump with twisted tapes. A 3D numerical model was developed using ANSYS Fluent to simulate flow through a jet pump with variations in nozzle profile and the addition of single or double twisted tapes in the primary nozzle. Results showed that a double twisted tape increased jet pump efficiency the most, by around 10%, compared to a nozzle without tape. Higher velocities, turbulent kinetic energy, and vorticity were observed with twisted tapes, enhancing entrainment of the secondary flow and improving performance.
Numerical simulation and enhancement of heat transfer using cuo water nano fl...IAEME Publication
This document summarizes a study on enhancing heat transfer using CuO/water nanofluid and a twisted tape insert with alternate axis in a circular tube. Numerical simulations were performed using ANSYS FLUENT to analyze heat transfer, friction, and thermal performance of the nanofluid at various concentrations from 0.3-0.7% by volume. The simulations also examined using nanofluid with a typical twisted tape, the twisted tape alone, and nanofluid alone. Results showed that using nanofluid together with the twisted tape with alternate axis can further improve heat transfer compared to using them individually.
This document summarizes a study on improving heat transfer in tubes by using different types of twisted tape inserts. Experiments were conducted to assess heat transfer and pressure drop in a tube fitted with alternating clockwise and counter-clockwise twisted tapes (C-CC tapes) as well as serrated twisted tapes (STT). For C-CC tapes, heat transfer increased with higher twist ratios and lower twist angles. For STT, heat transfer increased with higher serration depth ratios but decreased with higher serration width ratios. Thermal performance factors above unity indicated STT provided advantages over plain tubes or twisted tapes. Correlations for Nusselt number and friction factor were determined for both C-CC and STT.
Experimental Investigation on Heat Transfer Enhancement in Laminar Flow in Ci...IDES Editor
An experimental investigation of heat transfer and
friction factor of a smooth tube fitted with full length twisted
tape inserts for laminar flow have been studied under uniform
wall heat flux condition. The experiments has been carried
out to study the tape fin effect by using full length tape inserts
of different materials namely Aluminum, Stainless steel and
insulated tape. The tapes have twist ratios from 5.2 to 3.4. It is
found that, for the flow in smooth tubes, full length twisted
tapes yield improvement in average Nusselt number, for
Reynolds number range of 200 to 2000.For Aluminum tapes,
the maximum improvement in Nusselt number range from
50% to 100%; for Stainless steel tapes, maximum
improvement in Nusselt number range from 40% to 94% and
for insulated tapes, maximum improvement in Nusselt
number range from 40% to 67%. The isothermal friction factor
for the flow with the twisted tape inserts are 340% to 750 %
higher as compared with those of smooth tube flow, in the
given range of twist ratios.
NUMERICAL SIMULATION OF ENHANCEMENT OF HEAT TRANSFER IN A TUBE WITH AND WITHO...IAEME Publication
The heat transfer augmentation techniques are widely utilized in many applications in the heating process to enable reduction in weight and size or increase the performance of heat exchangers. These techniques are classified as active and passive techniques. The active technique required external power such as surface vibration and electric or acoustic fields, whereas the passive techniques required fluid additives, special surface geometries, or swirl/vortex flow devices, that is, twisted tape inserts. Computational heat transfer flow modeling is one of the great challenges in the
classical sciences.
Experimental study on heat transfer and friction factor characteristics in la...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
A comprehensive review on passive heat transfer enhancementsMohamed Fadl
This document reviews experimental and numerical works on passive heat transfer enhancement techniques in pipe heat exchangers published since 2004. The most popular and researched technique is the use of twisted tape inserts, which can strengthen heat transfer efficiency. Other techniques reviewed include coiled wire, swirl generators, conical rings, and ribs. While twisted tape inserts perform better in laminar flow, techniques like ribs are generally more efficient in turbulent flow. The review finds that passive enhancement techniques can significantly improve the overall thermal performance of heat exchangers.
HEAT TRANSFER AUGMENTATION OF LAMINAR NANOFLUID FLOW IN HORIZONTAL TUBE INSER...IAEME Publication
In this paper, an experimental study on the heat transfer enhancement and friction factor characteristics for fully developed laminar CuO/distilled-water (DI-water) nanofluid flow through horizontal tube inserted with different geometries of twisted tapes under constant heat flux condition ranged from 4483 to 10000 W/m^2. φ=0.08% and 0.35% volume concentrations of CuO nanoparticles are suspending in distilled water to prepare nanofluid. Twisted types made from copper material with twist ratios Y=2.6 and 5.3 twist ratios, thickness t=1 and 2mm and with semicircular and triangular cuts shape were used to study their effect on twisted tape performance. Results showed that both convective heat transfer in terms of average Nusselt number (Nu) ̅ and friction factor have significantly increasing with inserting twisted tape with nanofluids as working fluid comparing with nanofluids or DI-water in smooth tube case and this enhancement increases as both Reynold number and volume concentration increases.
The document reviews heat transfer enhancement techniques using twisted tape inserts. It discusses heat exchangers and classifications. Twisted tape is described as a passive enhancement method that induces swirl and turbulence to disrupt the thermal boundary layer. Attributes of twisted tape like pitch, twist ratio and shape are examined. Using twisted tape can increase heat transfer rate in a heat exchanger by up to 188% but also increases friction loss. Different tape configurations are evaluated and it is found that optimization of parameters like twist ratio can improve thermal performance.
A Review on Experimental and CFD Analysis for Heat Transfer Enhancement in He...IRJET Journal
This document reviews experimental and computational fluid dynamics (CFD) analyses that have evaluated methods to enhance heat transfer in heat exchanger tubes. Specifically, it focuses on the use of drilled twisted tape inserts of various geometries within the tubes. It provides background on heat exchangers and heat transfer enhancement techniques, including passive techniques like twisted tape inserts. The literature review summarizes several studies that have examined twisted tape inserts computationally or experimentally, finding that inserts can increase turbulence and heat transfer but also pressure drop. The present study aims to contribute additional CFD and experimental analysis of drilled twisted tape inserts of different dimensions to further understand their impact on heat transfer and fluid friction characteristics in heat exchanger tubes.
Irjet v4 i12326Effect of External Threaded Inside Tube on Heat Transfer Rate ...IRJET Journal
This document reviews the use of an internal threaded tube in a concentric tube heat exchanger to enhance heat transfer rates. It discusses how passive heat transfer augmentation techniques like threaded tubes can increase turbulence and disrupt boundary layers to improve heat transfer efficiency. The review analyzes previous studies that experimentally compared heat transfer performance and pressure drop between plain and threaded inner tubes. Results indicated that threaded tubes increased heat transfer coefficients and Reynolds numbers while potentially reducing fouling compared to plain tubes. Further experimentation and CFD simulation were proposed to validate theoretical predictions and determine the threaded tube design's feasibility for applications like radiators and air conditioners.
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
DESIGN, ANALYSIS AND PERFORMANCE INVESTIGATION OF HEAT EXTRACTION UNIT USING ...Journal For Research
Over the last years, there has been growing interest in applying new technologies to improve the heat transfer from the various heat sources such as geothermal energy, power plants, diesel engines, automobiles and other industrial heat-generating process. The heat transfer enhancement by means of extended surface type heat exchanger is well established technology and at present being adopted by most of the waste heat recovery system. Different types of heat transfer enhancement techniques using fins are available in extended surface type heat exchanger but each of this technique having different heat transfer enhancement ratio. Different researchers have analyzed the effect of fin geometry and combination of fins on heat transfer enhancement technique. In present research, find out the effect of fins on heat transfer augmentation or heat transfer coefficient for extracting heat from various waste heat sources.
IRJET - Analysis of Forced Convection Heat Transfer to Improve the Thermal Pe...IRJET Journal
This document summarizes research on improving heat transfer through forced convection using pipe inserts. It discusses heat transfer enhancement techniques used to increase turbulence and convection, including triangular fin inserts. The document reviews related studies on topics like twisted tape inserts, rib turbulators, mesh inserts, and more. It also outlines the experimental setup used, including a copper pipe test section with dimensions and thermocouple placement. The goal is to optimize heat transfer through forced convection while minimizing pressure drop.
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.
The heat transfer and friction factor were
experimentally investigated in a louvered strip inserted tube in
turbulent flow region. A copper tube of (I.D=28mm, O.D=32mm)
and 900mm length was used. A louvered strip insert with
different geometrical configuration was inserted into the smooth
tube. A uniform heat flux condition was created by wrapping
heating tape of 2500 watt around the test section. Fibre glass
cloth was used as a thermal insulator which surrounds the
heating tape. Outer surface temperature of the tube were
measured at five different equally spaced points of test section by
k-typethermocouples. Two thermocouples were used to measure
the inlet and outlet temperature of water. The Reynolds numbers
were varied in the range of 2500 to 4000 with constant heat flux
of 24 kw/m2 for smooth tube and louvered strip inserted. Nusselt
number and friction factor obtained for louvered strip (with
forward backward arrangement) > Nusselt number and friction
factor for louvered strip (with semi-forward semi-backward
arrangement)> Nusselt number and friction factor for louvered
strip (with forward arrengement).
HEAT TRANSFER ANALYSIS OF EFFECTS OF LONGITUDINAL FINS ON HEAT TRANSFER IN DO...IRJET Journal
This document analyzes heat transfer in a double pipe heat exchanger with and without longitudinal fins. It was found that using longitudinal fins improves heat transfer performance. Specifically:
1) Heat transfer rate and LMTD increased by 28.42 watts and 12.5 watts respectively with fins compared to without fins.
2) Effectiveness, which is a measure of heat exchanger performance, increased from 0.3211 without fins to 0.3533 with fins.
3) Overall heat transfer coefficient and rate of heat transfer were higher with fins, showing fins enhance heat transfer in double pipe heat exchangers.
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.
CFD Investigation of Compact Heat Exchanger Having Different Fins with Nanofl...IRJET Journal
This document summarizes research on using computational fluid dynamics (CFD) to investigate heat transfer in a compact heat exchanger with different fin types and titanium dioxide nanofluid. It discusses past research on various techniques for enhancing heat transfer and reducing pressure losses in heat exchangers. The document then outlines the objectives, methodology, and potential implications of research using CFD and limited experimental data to develop new heat transfer and pressure drop correlations for plain, offset strip, and wavy fins, which are common in applications like cryogenics and aerospace. These new correlations could provide more accurate and broadly applicable insights for heat exchanger design compared to existing correlations.
IRJET- Heat Transfer Enhancement with Flag Vortex GeneratorIRJET Journal
The document discusses heat transfer enhancement using flag vortex generators. It begins with an abstract that outlines how flexible plates or "flags" inside a duct can successfully enhance heat transfer as a passive technique. However, further investigation is needed to fully understand the thermal characteristics of this approach.
The introduction provides background on different heat transfer enhancement techniques and discusses how flags act as vortex generators to improve heat and mass transfer at a surface. It presents the objectives of the study, which include experimentally investigating heat transfer enhancement and pressure drop using inline and staggered flag arrangements and comparing results to a smooth flat plate.
The literature review summarizes several previous studies. These analyzed the dynamics of flexible flags numerically but noted a lack of experimental validation. They also
An experimental study of heat transfer in plane circular tube fitted with the V-Shaped Aluminum
turbulators is performed for plane circular tube. The objective of this Project work is to analyses heat transfer
coefficient and friction characteristics in a plane circular tube fitted with the V-Shaped Aluminum turbulators.
The experimentations are firstly carried out on the plane circular pipe and heat transfer augmentation were
recorded and then the v-shaped Aluminum turbulators are fitted in the same plane pipe and then again the heat
transfer augmentation is recorded and then both of them is compared. Experimental investigations have been
carried out to study the effects of the V-Shaped Aluminum turbulators on heat transfer, friction and
enhancement efficiency, in a circular tube. We used the V-Shaped aluminum turbulators with the turbulator
element length of 200mm, 160mm and 120mm.We found the heat transfer argumentation.The mean heat
transfer rates obtained from using the V-Aluminum turbulators are 198%, 213% and 241% for turbulator
element Length of 200mm, 160mm and 120 mm respectively. All of the experiments are carried out at the
same inlet conditions with the Reynolds number, based on the tube diameter (Re), in a range of 3000 to
10000
IRJET-Enhancement of Heat Transfer through Pipe with the Help of Various Type...IRJET Journal
This document reviews research on enhancing heat transfer through pipes using various types of turbulators. It begins with an abstract discussing using active or passive techniques to increase heat transfer rates in heat exchangers. The paper then discusses using modified baffled twisted tape inserts to change heat transfer rates. It provides equations for heat transfer and reviews several studies that experimentally analyzed heat transfer and pressure drop when using twisted tapes, baffled twisted tapes, and other turbulator inserts in pipes. The studies found that inserts can increase heat transfer by inducing swirl and disrupting boundary layers, but also increase pressure drop. The level of increased heat transfer and pressure drop depended on turbulator design and fluid properties like Reynolds number.
This document summarizes an experimental study on heat transfer augmentation from dimpled surfaces. Six test plates with varying dimple densities were used to study the heat transfer characteristics and pressure drop. It was found that the Nusselt number, a measure of heat transfer, increases with increasing dimple density. Staggered dimple arrangements produced greater increases in heat transfer than inline arrangements. The results show that dimpled surfaces can enhance heat transfer with only a small increase in pressure drop, making them useful for applications like compact heat exchangers.
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.
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 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 provided for modeling heat transfer rate, Reynolds number, Nusselt number, and friction factor. Results showed that plates with 50 dimples had the highest average heat transfer coefficient and Nusselt number across all test conditions.
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.
IRJET- Thermal and Fluid Flow Analysis of a Heat Exchanger: “A Comprehensive ...IRJET Journal
This document provides a comprehensive literature review and analysis of thermal and fluid flow performance in heat exchangers. It discusses several types of heat exchangers and techniques used to enhance heat transfer, such as surface textures, channel designs, and nanofluids. The document reviews experimental, numerical, and computational studies on fluid flow characteristics and heat transfer for different heat exchanger configurations and applications. It also provides governing equations for fluid flow and heat transfer analysis and compares experimental results to analytical predictions using correlations.
Similar to [IJET-V2I3P20] Authors: Pravin S.Nikam , Prof. R.Y.Patil ,Prof. P.R.Patil , Prof.P.N.Borse (20)
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1. International Journal of Engineering and Techniques - Volume 2 Issue 3, May – June 2016
ISSN: 2395-1303 http://www.ijetjournal.org Page 123
Heat Transfer Enhancement Techniques with Inserts Different
Geometries – A Review
Pravin S.Nikam1
, Prof. R.Y.Patil 2
,Prof. P.R.Patil3
, Prof.P.N.Borse 4
1(M.E Scholar SGDCOE Jalgaon (MS), India)
2(Professor & Head of Mechanical Engg. Department SGDCOE, Jalgaon (MS), India)
3(Asst.Prof. SGDCOE Jalgaon (MS), India)
4 (Asso. Prof. SGDCOE Jalgaon (MS), India)
I. INTRODUCTION
The need to develop efficient heat exchangers
has been partially fulfilled by using increased heat
transfer rates. In the recent years, considerable
emphasis has been placed on the development of
various augmented heat transfer surfaces and
devices.
The heat exchanger industry has been striving for
enhanced heat transfer coefficient and reduced
pumping power in order to improve the thermo
hydraulic efficiency of heat exchangers. A good
heat exchanger design should have an efficient
thermodynamic performance, i.e. minimum
Generation of entropy or minimum destruction of
energy in a system incorporating a heat exchanger.
The major challenge in designing a heat exchanger
is to make the equipment compact and to achieve a
high heat transfer rate using minimum pumping
power.
Augmented surfaces can create one or more
combinations of the following conditions that are
indicative of the improvement of performance of
heat exchangers
II.NOMENCLATURE:
A convective heat transfer area (πDL), (m2)
A0 area of orifice, (m2)
Ap test section inner tube area, (π/4 D2 ) (m2)
Cp specific heat of air, (J/kg K)
d air discharge through test section (m3/sec)
Dh hydraulic diameter (4A/P), (m)
D Inner diameter of test section, (m)
H pitch ,(mm)
w width of tape insert,(mm)
RESEARCH ARTICLE OPEN ACCESS
Abstract:
In day-to-day life, we come across many processes where we see the usage of heat exchangers. Some
examples where heat exchangers are extensively utilized are air conditioning plants, thermal power plants, food
processing plants etc. The basic requirement in these industries is to utilize the heat energy used in the heat
exchangers efficiently. This can be done either by developing new designs that are energy efficient or by
modifying the present designs in such a manner that they give better performance under the same working
conditions. Hence, heat exchangers that would provide more heat transfer at the minimum size and cost are
requirement of the present industries. Hence they use the various heat transfer technique for enhance the heat
transfer rate. In this paper review of research work in last decade on heat transfer enhancement.
Keywords — Enhancement; heat transfer; twisted tape inserts; pressure drop; flow.
2. International Journal of Engineering and Techniques - Volume 2 Issue 3, May – June 2016
ISSN: 2395-1303 http://www.ijetjournal.org Page 124
H/D twist ratio
H/w modified twist ratio
f the friction factor(theoretical) for plain tube
f friction factor(experimental) for plain tube
fi friction factor obtained using tape inserts
h experimental convective heat transfer coefficient,
(W/m2K)
hw manometer level difference,(m)
hair equivalent height of air column, (m)
k thermal conductivity, (W/mK)
L length of test section, (m)
m. mass flow rate of air, (Kg/sec)
Nui Nusselt number (experimental) with tape
inserts, (hDh/k)
Nu Nusselt number (experimental) for plain tube
Nuthe Nusselt number for plain tube (theoretical)
Pr Prandtl number
p pitch, (m)
P wetted perimeter, (m)
ΔP pressure drop across the test section, (Pa)
Q total heat transferred to air (Qc + Qr), (W)
Qc heat transferred to air by convection, (W)
Qr heat transferred to air by radiation, (W)
Re Reynolds number, (ρ u D/μ)
T1, T6 - air temperature at inlet and outlet, (°C)
T2, T3, T4, T5 - tube wall temperatures, (°C)
Ts average Surface temperature of the working fluid,
(°C)
Tb bulk temperature, (°C)
U air velocity through test section, (m/sec)
Greek symbols
ν Kinematic viscosity of air, (m2/sec)
εC emissivity of Copper
μ dynamic viscosity, (kg/m s)
η Over all enhancement ratio
III.HEAT TRANSFERVENHANCEMENT
TECHNIQUES:
Heat transfer enhancement techniques are generally
divided into two main categories: active and passive
enhancements. Passive enhancement technologies
are “installed” during the manufacturing process of
the heat exchanger and require no further input
during operation whereas active technologies
require some mechanical or electrical power input
during operation. Recently a new technique named
as compound technique is also used for heat
transfer enhancement. Two or more of the active
and passive techniques may be utilized
Simultaneously in compound techniques to
produce an enhancement that is larger than the
individual technique applied separately.
Active Heat Augmentation Techniques include:
Mechanical aids
Surface vibrations
Fluid vibration
Electrostatic fields (DC or AC)
Passive Heat Augmentation Techniques include:
Treated surfaces
Rough surfaces
Extended surfaces
Displaced enhancement devices
Swirl flow devices
Coiled tubes
Surface-tension devices
Additives for gases
Additives for liquids
Some examples of compound techniques are given
below:
Rough tube wall with twisted tape
Rough cylinder with acoustic vibrations
Internally finned tube with twisted tape insert
Finned tubes in fluidized beds
Externally finned tubes subjected to vibrations
Gas-solid suspension with an electrical field
Fluidized bed with pulsations of air.
IV.PERFORMANCE EVALUATION
CRITERI A:
In most of the practical applications of enhancement
techniques, the following performance objectives, along
with a set of operating constraints and conditions, are
usually considered for evaluating the thermo hydraulic
performance of a heat exchanger:
All paragraphs must be indented. All paragraphs
must be justified, i.e. both left-justified and right-
justified.
Increase in the heat duty of an existing heat
exchanger without altering the pumping
power or flow rate requirements
Reduction in the approach temperature
difference between the two heat exchanging
fluid streams for a specified heat load and size
of exchanger
3. International Journal of Engineering and Techniques - Volume 2 Issue 3, May – June 2016
ISSN: 2395-1303 http://www.ijetjournal.org Page 125
Reduction in the size or heat transfer surface
area requirements for a specified heat duty and
pressure drop
Reduction in the process stream pumping power
requirements for a given heat load and
exchanger surface area.
Different Criteria used for evaluating the performance of
a single - phase flows are:
* Fixed Geometry (FG) Criteria: where the physical
envelope of the heat exchanger is fixed and the
performance enhancement comes from better surface
designs (for example).
* Fixed Number (FN) Criteria: where the cross-sectional
envelope of the heat exchanger is fixed but the length is
allowed to vary.
* Variable Geometry (VG) Criteria: the net tube side
cross-sectional flow area is allowed to increase to
accommodate a higher friction factor.
FG criteria is used for evaluating the performance
of single phase flows.
V. TWISTED TAPES:
To enhance the heat transfer rate for the equation of heat
transfer is Q = h.A. ΔT . in this equation we increase the
heat transfer mean we want to increase the Q i.e. heat
transfer rate we need to increase (
h, A , ΔT ) these parameter after that the heat
transfer rate increases but in this equation the h i.e.
heat transfer coeff. And ΔT i.e. change in
temperature these two term we can't increases hence
only one parameter we increase i.e. A to improve
the heat transfer rate if A increase then and then Q
increase hence for improving area we uses the fin
are the extended surfaces and inserts the twisted
tape. Twisted tape is placed in the flow passages
but it also reduce the hydraulic diameter of the flow
passage. Heat transfer enhancement in the tube is
due to the flow blockage ,partioning of the flow and
secondary flow .flow blockages increases the
pressure drop and leads to viscous effects,because
of a reduced free flow area.
Different types of twisted tape insert
Fig.1. Different types of twisted tape
VI. HEAT TRANSFER CALCULATIONS:
Ts= (T2+T3+T4+T5)/4 (1)
Tb= (T1+T6)/2 (2)
Equivalent height of air column,
hair= (ρ w* hw)/ ρa (3)
Discharge of air,
d=Cd Ap Ao √ (2ghair)/ √ (Ap2- Ao2) (4)
Velocity of air flow, U=d/Ap (5)
Reynolds number, Re=U D/ν (6)
(To calculate Re while using tape inserts, Dh
instead of D is used)
Nu the= 0.023 Re0.8 Pr 0.4 (7)
Q =m*Cp*(T1-T6) (8)
Qr=σ*A*εC*(Ts4-Tb4) (9)
H = (Q- QR )/(A (TS - TB)) (10)
Nu = h D /K (11)
(To calculate Nu while using tape inserts, Dh
instead of D is used)
fthe = 0.25 (1.82 * log10 ReD -1.64)-2 (12)
f =ΔP / ((L/D) (ρaU2/2)) (13)
η = (Nui/Nu)/ (fi/f)0. 333 (14)
VII. PIPE WITH INTERNAL THREADS:
4. International Journal of Engineering and Techniques - Volume 2 Issue 3, May – June 2016
ISSN: 2395-1303 http://www.ijetjournal.org Page 126
To produce the turbulent flow through the pipe for
good heat transfer characteristics one of the method
used is to use a pipe with internal threads. Shrirao
[7] studied heat transfer and friction factor
characteristics of horizontal circular pipe using
internal threads of pitch 100mm, 120mm and
160mm with air as the working fluid. The
transitional flow regime is selected for this study
with the Reynolds number range 7,000 to 14,000.
VIII. HEAT TRANSFERV ENHANCEMENT
USING DELTA WINGLET TWISTED TAPE :
High performance heat transfer system is of great
importance in many industrial applications.
Therefore, the heat transfer enhancement
techniques are widely applied in heat exchangers, in
order to
improve heat transfer coefficient All tapes used in
the present work are made of aluminium strip with
0.8 mm thickness (d) and 19.5 mm width (w).
Firstly, aluminium strip was twisted to produce a
typical twisted tape. A tape was subsequently
modified to obtain the DWT by cutting at the
edge of the tape with oblique shape and straight
shape to produce an oblique delta-winglet twisted
tape (O-DWT) and a straight delta- winglet twisted
tape (S-DWT), respectively. Then the outer part
of the cut was arranged to 90o (degree) relatively to
the inner part, forming delta-winglet shape. The
length between the two cuts was set equally to the
pitch length (y). heat transfer rate, friction factor
and thermal performance factor behaviours in the
tubes fitted with the delta winglet
twisted tapes (oblique or straight delta-winglet
twisted tape) for different twist ratios (y/w) and
depth of wing cut ratios (DR) are reported
Various Types Of Delta Winglet Twisted Tape:
Fig. 2.Twisted tape vortex generator: (a) typical twisted tape (TT), (b)
straight delta-winglet twisted tapes (S-DWT) and (c) oblique delta-winglet
twisted tapes (O-DWT).
IX. PERFORATED TWISTED TAPE:
To obtain better heat transfer perforated twisted
tapes are also used. Bhuiya [5] worked on Nusselt
number, friction factor and thermal performance
factor in a circular tube equipped with perforated
twisted tape inserts with four different porosities of
Rp = 1.6, 4.5, 8.9 and 14.7%. He conducted
experiments in a turbulent flow regime with
Reynolds number ranging from 7200 to 49,800
using air as the working fluid under uniform wall
heat flux boundary condition.
5. International Journal of Engineering and Techniques - Volume 2 Issue 3, May – June 2016
ISSN: 2395-1303 http://www.ijetjournal.org Page 127
Fig.3.Geometry of test section fitted with perforated twisted tape insert; (b)
Geometric parameters of the perforated twisted tape insert
CONCLUSION:
In this paper the we study the various methods of heat
transfer and and modes of heat transfer and the
performance evaluation criteria and the various
techniques such as using delta-winglet twisted ,tapes and
pipes with internal threads , perforated twisted tape for
these study the performance of enhancement of heat
transfer with inserting the various geometry . and
conclude that the effect of inserting the various geometry
is enhance the heat transfer rate.
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