To assess and forecast the operational performance of a modified car seat for thermal management ... more To assess and forecast the operational performance of a modified car seat for thermal management using an air conditioning system, statistical and machine learning (ML) models were used. By extending evaporator/condenser coils beneath the back and cushion surfaces of the car seat and using operational data on the HVAC system, such as seat temperature readings, an interval of operation was gathered. Using a data mining approach, statistically relevant factors and varying the compressor speed from 500 to 1600 rpm under various scenarios to model the system were selected. Utilizing key feature variables, our data-driven approach yielded predictions with favorable accuracy for the Coefficient of Performance (COP) of the HVAC system. By using the Akaike Information Criterion (AIC) to improve the Linear Regression (LR) model, the Root Mean Square Error (RMSE) dropped to 0.20, the Mean Absolute Error (MAE) dropped to 0.16, and the Coefficient of Determination (R 2) increased to 98 %. The Random Forest (RF) model, optimized with hyperparameters, demonstrated moderate predictive capability, with RMSE (0.52), MAE (0.37), and R 2 (94 %). Furthermore, polynomial feature augmentation, individual and combined predictor analysis, and iterative predictor combinations all improved predictive accuracy. Detailed information on the algorithms was given for the sake of other researchers.
Journal of the Faculty of Engineering and Architecture of Gazi University, 2024
Almond kernel, with a continuously increasing consumption, and is also important for our country,... more Almond kernel, with a continuously increasing consumption, and is also important for our country, is a valuable agricultural product. Its production yields the hard shell as a by-product. The shell and the kernel have approximately the same weight. However, the shell is usually burned, or occasionally ground for use in the cosmetic industry or filters. Almond shell is a porous, hard, lignocellulosic, and a renewable resource. Particleboard industry is considered for sustainable, higher value-added, and environmentally lower-impact use of this resource. For this purpose, a detailed literature review was conducted, and the reviewed studies were compiled and summarized. The literature review reveals numerous studies on the re-evaluation of shells of hard-shell nuts as materials for various industrial sectors. However, studies on almond shells are limited in number. After the literature review and conceptualization stages, particleboards with different densities and almond shell contents were produced using almond shell particles. The thermal conductivities of the boards were determined experimentally. The thermal conductivity value increases with the increase in board density. The almond shell content, however, exhibits different effects depending on the board densities. The smallest thermal conductivity value obtained in the study was 0.07 W/mꞏK, while the highest value was found to be 0.19 W/mꞏK. Although the study was conducted with a constant temperature difference, the thermal conductivity value increases with increasing temperature values.
Kahramanmaras Sutcu Imam University Journal of Engineering Sciences, 2023
In this study, the air flow resistance acting on scaled agricultural tractor models using a wind ... more In this study, the air flow resistance acting on scaled agricultural tractor models using a wind tunnel was determined experimentally. Tractor models have the same shape, but three different designs were tried on the operator platform section. These are the platform surrounded by the cab, the sunshade platform and the platform with the protection bar to protect the user in case of overturning. Thus, depending on the design of the user section, the air resistance changes that the tractors are exposed to in on-road transportation are determined experimentally for the first time. Tractor models used in the wind tunnel were prepared in a ratio of 1:13 according to geometric similarity principles. In wind tunnel tests, kinematic and dynamic similarity cannot be achieved, but Reynolds number independence can be obtained. A Reynolds number range was surveyed by performing experiments at different air velocities in the wind tunnel air flow rate range. In this range, the aerodynamic resistance forces acting on the models and the air flow-induced pressure distributions in the symmetry axis of the tractors were measured. Dimensionless aerodynamic drag coefficient and pressure coefficient values were calculated from the measurements obtained. According to the calculations, the use of the cabin increases the aerodynamic resistance in the range of 3-15%. While the percentage of resistance increase due to cabin usage is high at low speeds, it decreases at high speeds. As a result of the use of the cabin, the tractor front projection area perpendicular to the flow increases. However, the increase in aerodynamic drag is one order lower than the increase in the frontal projection area. Considering the benefits of cabin use in terms of occupational safety, it is understood that the increase in aerodynamic resistance due to cabin use is an acceptable cost. It is expected that the results of the study will contribute to the separation of energy consumption in on-road transportation with agricultural tractors.
Süleyman Demirel University Journal of Natural and Applied Sciences, 2023
In the trials of the present work, a double-axle trailer with a carrying capacity of 6 tons and a... more In the trials of the present work, a double-axle trailer with a carrying capacity of 6 tons and a hydraulically effective mechanical brake were used as a tractor towed car. There is a hydraulic brake system on each axle of the agricultural trailer. In order to separate the brake system on the axles from each other, a hydraulic mechanically controlled 2/2 directional control valve was mounted on both hydraulic brake system inlets. The study was carried out at constant speed (25 km h-1), on stabilized road conditions, with 4 different braking modes and 4 different trailer loads. On stabilized ground, the braking acceleration (deceleration) of the tractor (without trailer) is 5.51 m s-2. The braking acceleration of the combination is 2.15 m s-2 under the condition that the trailer's carrying capacity was 30% more loaded and without brakes, and the braking acceleration of the combination was 3.26 m s-2 when braking on both axles (4 wheels). The deceleration of the combination was above 3.5 m s-2 under the condition of braking on both axles at the rated load of the agricultural trailer, while it was below the standard value in other braking approaches.
Journal of Engineering Science and Technology, 2022
Data reduction and mathematical analysis are always an important part of heat transfer related st... more Data reduction and mathematical analysis are always an important part of heat transfer related studies. Regression curve (RCF) and Artificial Neural Network (ANN) fitting methods are used extensively and regarded as reliable tools for this purpose. ANN and RCF approaches are used to predict the Nusselt number (Nu), and Darcy friction factor (f) based upon a single input, namely, the Reynolds number (Re) varying from 2.3×10 3 to 52×10 3. Experimental results from a previous comprehensive study on forced thermal convection through a hexagonal duct was used to develop models and test the efficacy of the methods. Several ANN architectures, hyperparameter values and RCF functions were tested. Normalized and non-normalized datasets were considered. Models were compared with each other by means of statistical indicators. Therefore, this work is distinguished from the literature by its experimental data driven assessment and comparison between RCFs and ANNs. Additionally, single input and double output design is very scarce in the literature. The results show that the regression schemes based upon RCF are sufficient and accurate for predicting Nu and f, and the trend associated with the variation to Re is captured. The best single output ANN yields better accuracy; but the best double output ANN is unable to capture the expected trend between Re and the targeted responses. In terms of correlation coefficients, 0.98-0.99 is possible for RCFs and 0.99 for ANNs when normalization is done. Normalization becomes prominent as neuron number increases. As a conclusion, regression is preferred over ANN for a single input relationship between Nu and f to Re for hexagonal duct flow and heat transfer. An ANN's worth will only potentially be seen if more inputs; e.g., geometrical factors such as the aspect ratio, surface roughness, ambient temperature, duct material and relative wall thickness, among others, are included.
New generation agricultural tractors contribute to transportation by increased travel speeds. The... more New generation agricultural tractors contribute to transportation by increased travel speeds. There is not any available aerodynamic data on authentic agricultural tractor form. On-road transportation by tractors is between 8 to 30% of their operational time. In this work, two agricultural tractors are modelled via computational fluid dynamics for nine different speeds to determine aerodynamic resistances. Corresponding speeds are 10 to 80 km/h with 10 km/h increments and additionally 5 km/h. Reynolds number changes between 1.6×105 and 2.98×106. The characteristic lengths are taken as the square root of the streamwise projected area of the tractor geometries. Aerodynamic forces exerted on the tractors change between 3 N to 746 N. The calculated drag coefficients are found as independent from Reynolds number and are 0.6 and 0.78 for the two different types of driver compartments. Constant speed travel scenarios are analysed. The approximated aerodynamic related fuel consumptions for ...
Transient conjugated heat transfer in simultaneously developing turbulent flow is analyzed involv... more Transient conjugated heat transfer in simultaneously developing turbulent flow is analyzed involving two-dimensional wall and fluid axial conduction. A thick walled semi-infinite circular pipe which is considered initially isothermal and the problem is handled for steady, hydrodynamically and thermally developing flow with a sudden change in the outer wall temperature. The flow field and heat transfer are numerically investigated. Nondimensional continuity, Navier-Stokes and energy equations are solved by discretization using finite volumes method. Exponential discretization scheme is selected for the discretization of fluid side differential equations. Staggered grid system and SIMPLE algorithm are used in the flow solution. New computer software is developed for the numerical solution of the problem. Non-dimensional parameters that define the problem are determined as Reynolds number, Prandtl number, Peclet number, wall to fluid thickness ratio, wall to fluid thermal conductivity ratio, and wall to fluid thermal diffusivity ratio. Effects of each parameter on the heat transfer and flow characteristics are investigated in detail. Results change depending on all parameters. Reynolds number changing between 5×103 and 1×105 is the only parameter for flow solution. Hydrodynamic development length gets longer, directly proportional to Reynolds number and a characteristic velocity profile is attained at pipe axis. Peclet number that appears as a parameter in the energy equation for flow field during heat transfer solution can be investigated in a wide interval (1×102-2.5×105). Therefore, Peclet number is found to be the most important parameter that affects heat transfer. Heat transfer is affected by simultaneously developing flow. Exponential discretization scheme that has no known application in the solution of the problem gives result successfully.
Heat exchanger tubes are essential for separating fluids, especially for cross flow compact heat ... more Heat exchanger tubes are essential for separating fluids, especially for cross flow compact heat exchangers. However their geometries can cause vibration and hence noise, specifically when air is the case for external flow. Enhancing pneumatic performance by aerodynamic approaches is possible for such case and present study focuses on ellipse geometry and its orientations according to flow direction. 7 different orientation angles are selected for the experimental investigation; namely 0o, 22.5o, 30o, 45o, 60o, 67.5o and 90o. A Stereo PIV system of Dantec Dynamics was utilized which can capture 3000 single frame images for 6 seconds. Spatial data were used for post processing and results were prepared accordingly. Reynolds Number calculated according to the characteristic length of ellipse cylinders was 6000. With 30o orientation, flow structures around the ellipse cylinder becomes similar to flow structures around a bluff body. Flow separation from the leading edge of the ellipse cylinder increases with increasing angle of attack. Swirling flow in the separated region induces the drag force while increasing the lift forces. Vortex formations and vortex shedding lead to Karman vortex streets since the leading edge has a positive pressure gradient at upward direction according to the figure plane and negative pressure gradient at downward direction. This feature is unique for this special case of heat exchanger tube similarity and it is more likely seen in turbo machinery applications. Therefore spatial data of the wake is not axisymmetrical.
Well known geometries are essential in fluid mechanics due to the fact that flow around these geo... more Well known geometries are essential in fluid mechanics due to the fact that flow around these geometries can be foreseen relatively easily. In order to provide better scientific ground for the advanced research, researchers are still working on these geometries with new measurement techniques such as PIV method. In this study, three cylinders having different cross sections; namely short diameter circular cylinder (a=20mm), long diameter circular cylinder (D=65mm) and 3.25 aspect ratio of the elliptical cylinder were placed in an open water channel in order to investigate flow characteristics around them for the Reynolds number 6500. Experimental setup is presented in Figure 1. A Stereo PIV of Dantec Dynamics System was utilized for the velocity field measurement. Time-averaged streamline topology of the wake regions and vortex shedding from the flow separation regions are illustrated at the flow measurement plane. Figures displays time averaged streamwise velocity contours of a circular cylinder and an elliptic cylinder under uniform flow condition at Re=6500. The third velocity component contours for the measurement plane are presented. The elliptical cylinder acted as a streamline geometry comparing to the circular cylinder. Separation point was retarded for the elliptical cylinder and the wake was very narrower and shorter than the wake of the circular cylinder. Foci occur in the circular cylinder wake region and it occupies around 1.5D area in streamwise direction. These foci combine and form a stagnation point. On the other hand, the foci and stagnation point do not exist in the case of the elliptic cylinder case due to the diminished flow separation of the modified ellipse geometry. Circular cylinder wakes are identical each other independent as well known. The wake region of the elliptic cylinder is was smaller than the cylinder, which can provide better convection heat transfer coefficient around the body. The corresponding velocity contours also reflect the similar flow structure in geometrical shape. The obtained results can be used for the interpretation of real world applications and validation of various numerical works in heat transfers, building structure, heat exchangers, on/off-shore structure, military vehicles, bridge legs and sculpture.
Periodicals of Engineering and Natural Sciences (PEN), 2020
Pressure sensors, converting pressure force to electrical outputs such as 4-20 mA or 0-10 V, are ... more Pressure sensors, converting pressure force to electrical outputs such as 4-20 mA or 0-10 V, are used in a vast variety of areas while being facing numerous challenging thermal conditions. A common way is to design a heat sink for establishing natural convection cooling to protect the sensor. This work assesses a heat sink design and conveys its performance as a heat sink for an application interval. Special orientation as well as design geometry is introduced. Computational fluid dynamics were utilized for evaluation and assessment. A core region of heat transfer was identified. Natural convection wake boundaries were detected. It is concluded that the design can successfully protect the pressure sensor at the pressure tap. Future projections and aspects are also described in the paper.
There are three certain problems in automotive applications that cause environmental effect, cost... more There are three certain problems in automotive applications that cause environmental effect, cost and comfort problems. Therefore, internal combustion engines are required to have not only a high specific power output but also to release less pollutant emissions. For these reasons, current light and medium duty engines are being highly turbocharged because of having negative environmental effects of internal combustion engines. Due to mentioned facts, there are studies going on to improve internal combustion engine performance. Studies for supercharging systems are also included in this range. One of the most important problems faced in supercharging systems is that air density is decreasing while compressing air. Also air with high temperature causes pre-ignition and detonation at spark ignited engines. Various methods have been developed to cool down charge air which is heated during supercharging process. One of these methods is to use a compact heat exchangers called as intercoolers to cool charging air. The purpose of an intercooler is to cool the charge air after it has been heated during turbocharging. As the air is cooled, it becomes denser, and denser air makes for better combustion to produce more power. Additionally, the denser air helps reduce the chances of knock. In this study, the intercooling concept was introduced and performance increase of a vehicle by adding intercooling process to a conventional supercharging system in diesel or petrol engine was analytically studied. Pressure drops, air density and engine revolution were used as input parameters to calculate the variation of engine power output. Also, possible downsizing opportunities of the cylinder volume were presented. It is found that the engine power output can be increased 154% by ideal intercooler while single turbocharger without intercooler can only increase 65%. Also a meaningful 50% downsizing of the cylinder volume possibility achieved by means of turbocharging and intercooling. Finally, future study needs about cycle characteristics of internal combustion engines with intercooling process and intercoolers were discussed
The common exercise in investigations and industrial applications for tires and specifically trac... more The common exercise in investigations and industrial applications for tires and specifically tractor tires is experimenting. However, there are difficulties which will be detailed in the text. Similar issues are encountered in fluid mechanics, but fluid mechanics studies sometimes involve scaled models and uses similarity approaches to overcome some of the difficulties. However only one significant study has been encountered in the literature about tire scaling and no study is encountered about tractor tires. In this report, scaling, similarity and dimensionless analyses are introduced first. Then the work about tire scaling is viewed. Points for scaling tractor tires are proposed. Some concluding remarks and propositions are made for future work.
Intercoolers have been increasingly used in internal combustion engines with supercharging since ... more Intercoolers have been increasingly used in internal combustion engines with supercharging since 1990s because of their positive effect on engine power and fuel consumption. In this study, a louvered fin and plate intercooler were experimentally investigated for heat capacity ratios between 0.027-0.125 and compactness value of 664.6 m/m for heavy duty engines. Heat transfer rate and pressure drop performance of the intercooler were determined with dimensionless indicators such as effectiveness, Nusselt number and friction factor. Temperature difference between fluids were changed between 50-110 C and Reynolds number for cooling air side was changed between Re=1500-5500 in louvered fins with having a hydraulic diameter of 0.0019 m for Prandtl number value of Pr=0.82 of the cooling air. Intercooler effectiveness was found between 94-98% and friction factor was in the range of 1.2-1.6. The intercooler was determined as favorable for heavy duty engines, especially agricultural tractor e...
Mathematical Modelling of Engineering Problems, 2021
Backward facing step arrangement is a classical case for fluid dynamics and heat transfer researc... more Backward facing step arrangement is a classical case for fluid dynamics and heat transfer research. It is well characterized and therefore, used for benchmarking. However, ongoing studies reveal that the geometry also provide advantages in industry, especially in combustion and burners. This work utilizes computational fluid dynamics to investigate a specific laminar back facing step flow heat transfer case. Aluminium oxide nano particles are considered as an additive to water base fluid, forming nanofluid with different volumetric concentrations. Laminar flow passes a back facing step and encounters three circular grooves at bottom surface. All surfaces are adiabatic except the grooves. Constant surface temperature applies to the grooves. According to the simulation results, a separation bubble after back facing step and a reattachment point occur. Grooves alter expected wake due to physical and thermal interference. Investigation parameters are nano-particle concentration and Reyn...
To assess and forecast the operational performance of a modified car seat for thermal management ... more To assess and forecast the operational performance of a modified car seat for thermal management using an air conditioning system, statistical and machine learning (ML) models were used. By extending evaporator/condenser coils beneath the back and cushion surfaces of the car seat and using operational data on the HVAC system, such as seat temperature readings, an interval of operation was gathered. Using a data mining approach, statistically relevant factors and varying the compressor speed from 500 to 1600 rpm under various scenarios to model the system were selected. Utilizing key feature variables, our data-driven approach yielded predictions with favorable accuracy for the Coefficient of Performance (COP) of the HVAC system. By using the Akaike Information Criterion (AIC) to improve the Linear Regression (LR) model, the Root Mean Square Error (RMSE) dropped to 0.20, the Mean Absolute Error (MAE) dropped to 0.16, and the Coefficient of Determination (R 2) increased to 98 %. The Random Forest (RF) model, optimized with hyperparameters, demonstrated moderate predictive capability, with RMSE (0.52), MAE (0.37), and R 2 (94 %). Furthermore, polynomial feature augmentation, individual and combined predictor analysis, and iterative predictor combinations all improved predictive accuracy. Detailed information on the algorithms was given for the sake of other researchers.
Journal of the Faculty of Engineering and Architecture of Gazi University, 2024
Almond kernel, with a continuously increasing consumption, and is also important for our country,... more Almond kernel, with a continuously increasing consumption, and is also important for our country, is a valuable agricultural product. Its production yields the hard shell as a by-product. The shell and the kernel have approximately the same weight. However, the shell is usually burned, or occasionally ground for use in the cosmetic industry or filters. Almond shell is a porous, hard, lignocellulosic, and a renewable resource. Particleboard industry is considered for sustainable, higher value-added, and environmentally lower-impact use of this resource. For this purpose, a detailed literature review was conducted, and the reviewed studies were compiled and summarized. The literature review reveals numerous studies on the re-evaluation of shells of hard-shell nuts as materials for various industrial sectors. However, studies on almond shells are limited in number. After the literature review and conceptualization stages, particleboards with different densities and almond shell contents were produced using almond shell particles. The thermal conductivities of the boards were determined experimentally. The thermal conductivity value increases with the increase in board density. The almond shell content, however, exhibits different effects depending on the board densities. The smallest thermal conductivity value obtained in the study was 0.07 W/mꞏK, while the highest value was found to be 0.19 W/mꞏK. Although the study was conducted with a constant temperature difference, the thermal conductivity value increases with increasing temperature values.
Kahramanmaras Sutcu Imam University Journal of Engineering Sciences, 2023
In this study, the air flow resistance acting on scaled agricultural tractor models using a wind ... more In this study, the air flow resistance acting on scaled agricultural tractor models using a wind tunnel was determined experimentally. Tractor models have the same shape, but three different designs were tried on the operator platform section. These are the platform surrounded by the cab, the sunshade platform and the platform with the protection bar to protect the user in case of overturning. Thus, depending on the design of the user section, the air resistance changes that the tractors are exposed to in on-road transportation are determined experimentally for the first time. Tractor models used in the wind tunnel were prepared in a ratio of 1:13 according to geometric similarity principles. In wind tunnel tests, kinematic and dynamic similarity cannot be achieved, but Reynolds number independence can be obtained. A Reynolds number range was surveyed by performing experiments at different air velocities in the wind tunnel air flow rate range. In this range, the aerodynamic resistance forces acting on the models and the air flow-induced pressure distributions in the symmetry axis of the tractors were measured. Dimensionless aerodynamic drag coefficient and pressure coefficient values were calculated from the measurements obtained. According to the calculations, the use of the cabin increases the aerodynamic resistance in the range of 3-15%. While the percentage of resistance increase due to cabin usage is high at low speeds, it decreases at high speeds. As a result of the use of the cabin, the tractor front projection area perpendicular to the flow increases. However, the increase in aerodynamic drag is one order lower than the increase in the frontal projection area. Considering the benefits of cabin use in terms of occupational safety, it is understood that the increase in aerodynamic resistance due to cabin use is an acceptable cost. It is expected that the results of the study will contribute to the separation of energy consumption in on-road transportation with agricultural tractors.
Süleyman Demirel University Journal of Natural and Applied Sciences, 2023
In the trials of the present work, a double-axle trailer with a carrying capacity of 6 tons and a... more In the trials of the present work, a double-axle trailer with a carrying capacity of 6 tons and a hydraulically effective mechanical brake were used as a tractor towed car. There is a hydraulic brake system on each axle of the agricultural trailer. In order to separate the brake system on the axles from each other, a hydraulic mechanically controlled 2/2 directional control valve was mounted on both hydraulic brake system inlets. The study was carried out at constant speed (25 km h-1), on stabilized road conditions, with 4 different braking modes and 4 different trailer loads. On stabilized ground, the braking acceleration (deceleration) of the tractor (without trailer) is 5.51 m s-2. The braking acceleration of the combination is 2.15 m s-2 under the condition that the trailer's carrying capacity was 30% more loaded and without brakes, and the braking acceleration of the combination was 3.26 m s-2 when braking on both axles (4 wheels). The deceleration of the combination was above 3.5 m s-2 under the condition of braking on both axles at the rated load of the agricultural trailer, while it was below the standard value in other braking approaches.
Journal of Engineering Science and Technology, 2022
Data reduction and mathematical analysis are always an important part of heat transfer related st... more Data reduction and mathematical analysis are always an important part of heat transfer related studies. Regression curve (RCF) and Artificial Neural Network (ANN) fitting methods are used extensively and regarded as reliable tools for this purpose. ANN and RCF approaches are used to predict the Nusselt number (Nu), and Darcy friction factor (f) based upon a single input, namely, the Reynolds number (Re) varying from 2.3×10 3 to 52×10 3. Experimental results from a previous comprehensive study on forced thermal convection through a hexagonal duct was used to develop models and test the efficacy of the methods. Several ANN architectures, hyperparameter values and RCF functions were tested. Normalized and non-normalized datasets were considered. Models were compared with each other by means of statistical indicators. Therefore, this work is distinguished from the literature by its experimental data driven assessment and comparison between RCFs and ANNs. Additionally, single input and double output design is very scarce in the literature. The results show that the regression schemes based upon RCF are sufficient and accurate for predicting Nu and f, and the trend associated with the variation to Re is captured. The best single output ANN yields better accuracy; but the best double output ANN is unable to capture the expected trend between Re and the targeted responses. In terms of correlation coefficients, 0.98-0.99 is possible for RCFs and 0.99 for ANNs when normalization is done. Normalization becomes prominent as neuron number increases. As a conclusion, regression is preferred over ANN for a single input relationship between Nu and f to Re for hexagonal duct flow and heat transfer. An ANN's worth will only potentially be seen if more inputs; e.g., geometrical factors such as the aspect ratio, surface roughness, ambient temperature, duct material and relative wall thickness, among others, are included.
New generation agricultural tractors contribute to transportation by increased travel speeds. The... more New generation agricultural tractors contribute to transportation by increased travel speeds. There is not any available aerodynamic data on authentic agricultural tractor form. On-road transportation by tractors is between 8 to 30% of their operational time. In this work, two agricultural tractors are modelled via computational fluid dynamics for nine different speeds to determine aerodynamic resistances. Corresponding speeds are 10 to 80 km/h with 10 km/h increments and additionally 5 km/h. Reynolds number changes between 1.6×105 and 2.98×106. The characteristic lengths are taken as the square root of the streamwise projected area of the tractor geometries. Aerodynamic forces exerted on the tractors change between 3 N to 746 N. The calculated drag coefficients are found as independent from Reynolds number and are 0.6 and 0.78 for the two different types of driver compartments. Constant speed travel scenarios are analysed. The approximated aerodynamic related fuel consumptions for ...
Transient conjugated heat transfer in simultaneously developing turbulent flow is analyzed involv... more Transient conjugated heat transfer in simultaneously developing turbulent flow is analyzed involving two-dimensional wall and fluid axial conduction. A thick walled semi-infinite circular pipe which is considered initially isothermal and the problem is handled for steady, hydrodynamically and thermally developing flow with a sudden change in the outer wall temperature. The flow field and heat transfer are numerically investigated. Nondimensional continuity, Navier-Stokes and energy equations are solved by discretization using finite volumes method. Exponential discretization scheme is selected for the discretization of fluid side differential equations. Staggered grid system and SIMPLE algorithm are used in the flow solution. New computer software is developed for the numerical solution of the problem. Non-dimensional parameters that define the problem are determined as Reynolds number, Prandtl number, Peclet number, wall to fluid thickness ratio, wall to fluid thermal conductivity ratio, and wall to fluid thermal diffusivity ratio. Effects of each parameter on the heat transfer and flow characteristics are investigated in detail. Results change depending on all parameters. Reynolds number changing between 5×103 and 1×105 is the only parameter for flow solution. Hydrodynamic development length gets longer, directly proportional to Reynolds number and a characteristic velocity profile is attained at pipe axis. Peclet number that appears as a parameter in the energy equation for flow field during heat transfer solution can be investigated in a wide interval (1×102-2.5×105). Therefore, Peclet number is found to be the most important parameter that affects heat transfer. Heat transfer is affected by simultaneously developing flow. Exponential discretization scheme that has no known application in the solution of the problem gives result successfully.
Heat exchanger tubes are essential for separating fluids, especially for cross flow compact heat ... more Heat exchanger tubes are essential for separating fluids, especially for cross flow compact heat exchangers. However their geometries can cause vibration and hence noise, specifically when air is the case for external flow. Enhancing pneumatic performance by aerodynamic approaches is possible for such case and present study focuses on ellipse geometry and its orientations according to flow direction. 7 different orientation angles are selected for the experimental investigation; namely 0o, 22.5o, 30o, 45o, 60o, 67.5o and 90o. A Stereo PIV system of Dantec Dynamics was utilized which can capture 3000 single frame images for 6 seconds. Spatial data were used for post processing and results were prepared accordingly. Reynolds Number calculated according to the characteristic length of ellipse cylinders was 6000. With 30o orientation, flow structures around the ellipse cylinder becomes similar to flow structures around a bluff body. Flow separation from the leading edge of the ellipse cylinder increases with increasing angle of attack. Swirling flow in the separated region induces the drag force while increasing the lift forces. Vortex formations and vortex shedding lead to Karman vortex streets since the leading edge has a positive pressure gradient at upward direction according to the figure plane and negative pressure gradient at downward direction. This feature is unique for this special case of heat exchanger tube similarity and it is more likely seen in turbo machinery applications. Therefore spatial data of the wake is not axisymmetrical.
Well known geometries are essential in fluid mechanics due to the fact that flow around these geo... more Well known geometries are essential in fluid mechanics due to the fact that flow around these geometries can be foreseen relatively easily. In order to provide better scientific ground for the advanced research, researchers are still working on these geometries with new measurement techniques such as PIV method. In this study, three cylinders having different cross sections; namely short diameter circular cylinder (a=20mm), long diameter circular cylinder (D=65mm) and 3.25 aspect ratio of the elliptical cylinder were placed in an open water channel in order to investigate flow characteristics around them for the Reynolds number 6500. Experimental setup is presented in Figure 1. A Stereo PIV of Dantec Dynamics System was utilized for the velocity field measurement. Time-averaged streamline topology of the wake regions and vortex shedding from the flow separation regions are illustrated at the flow measurement plane. Figures displays time averaged streamwise velocity contours of a circular cylinder and an elliptic cylinder under uniform flow condition at Re=6500. The third velocity component contours for the measurement plane are presented. The elliptical cylinder acted as a streamline geometry comparing to the circular cylinder. Separation point was retarded for the elliptical cylinder and the wake was very narrower and shorter than the wake of the circular cylinder. Foci occur in the circular cylinder wake region and it occupies around 1.5D area in streamwise direction. These foci combine and form a stagnation point. On the other hand, the foci and stagnation point do not exist in the case of the elliptic cylinder case due to the diminished flow separation of the modified ellipse geometry. Circular cylinder wakes are identical each other independent as well known. The wake region of the elliptic cylinder is was smaller than the cylinder, which can provide better convection heat transfer coefficient around the body. The corresponding velocity contours also reflect the similar flow structure in geometrical shape. The obtained results can be used for the interpretation of real world applications and validation of various numerical works in heat transfers, building structure, heat exchangers, on/off-shore structure, military vehicles, bridge legs and sculpture.
Periodicals of Engineering and Natural Sciences (PEN), 2020
Pressure sensors, converting pressure force to electrical outputs such as 4-20 mA or 0-10 V, are ... more Pressure sensors, converting pressure force to electrical outputs such as 4-20 mA or 0-10 V, are used in a vast variety of areas while being facing numerous challenging thermal conditions. A common way is to design a heat sink for establishing natural convection cooling to protect the sensor. This work assesses a heat sink design and conveys its performance as a heat sink for an application interval. Special orientation as well as design geometry is introduced. Computational fluid dynamics were utilized for evaluation and assessment. A core region of heat transfer was identified. Natural convection wake boundaries were detected. It is concluded that the design can successfully protect the pressure sensor at the pressure tap. Future projections and aspects are also described in the paper.
There are three certain problems in automotive applications that cause environmental effect, cost... more There are three certain problems in automotive applications that cause environmental effect, cost and comfort problems. Therefore, internal combustion engines are required to have not only a high specific power output but also to release less pollutant emissions. For these reasons, current light and medium duty engines are being highly turbocharged because of having negative environmental effects of internal combustion engines. Due to mentioned facts, there are studies going on to improve internal combustion engine performance. Studies for supercharging systems are also included in this range. One of the most important problems faced in supercharging systems is that air density is decreasing while compressing air. Also air with high temperature causes pre-ignition and detonation at spark ignited engines. Various methods have been developed to cool down charge air which is heated during supercharging process. One of these methods is to use a compact heat exchangers called as intercoolers to cool charging air. The purpose of an intercooler is to cool the charge air after it has been heated during turbocharging. As the air is cooled, it becomes denser, and denser air makes for better combustion to produce more power. Additionally, the denser air helps reduce the chances of knock. In this study, the intercooling concept was introduced and performance increase of a vehicle by adding intercooling process to a conventional supercharging system in diesel or petrol engine was analytically studied. Pressure drops, air density and engine revolution were used as input parameters to calculate the variation of engine power output. Also, possible downsizing opportunities of the cylinder volume were presented. It is found that the engine power output can be increased 154% by ideal intercooler while single turbocharger without intercooler can only increase 65%. Also a meaningful 50% downsizing of the cylinder volume possibility achieved by means of turbocharging and intercooling. Finally, future study needs about cycle characteristics of internal combustion engines with intercooling process and intercoolers were discussed
The common exercise in investigations and industrial applications for tires and specifically trac... more The common exercise in investigations and industrial applications for tires and specifically tractor tires is experimenting. However, there are difficulties which will be detailed in the text. Similar issues are encountered in fluid mechanics, but fluid mechanics studies sometimes involve scaled models and uses similarity approaches to overcome some of the difficulties. However only one significant study has been encountered in the literature about tire scaling and no study is encountered about tractor tires. In this report, scaling, similarity and dimensionless analyses are introduced first. Then the work about tire scaling is viewed. Points for scaling tractor tires are proposed. Some concluding remarks and propositions are made for future work.
Intercoolers have been increasingly used in internal combustion engines with supercharging since ... more Intercoolers have been increasingly used in internal combustion engines with supercharging since 1990s because of their positive effect on engine power and fuel consumption. In this study, a louvered fin and plate intercooler were experimentally investigated for heat capacity ratios between 0.027-0.125 and compactness value of 664.6 m/m for heavy duty engines. Heat transfer rate and pressure drop performance of the intercooler were determined with dimensionless indicators such as effectiveness, Nusselt number and friction factor. Temperature difference between fluids were changed between 50-110 C and Reynolds number for cooling air side was changed between Re=1500-5500 in louvered fins with having a hydraulic diameter of 0.0019 m for Prandtl number value of Pr=0.82 of the cooling air. Intercooler effectiveness was found between 94-98% and friction factor was in the range of 1.2-1.6. The intercooler was determined as favorable for heavy duty engines, especially agricultural tractor e...
Mathematical Modelling of Engineering Problems, 2021
Backward facing step arrangement is a classical case for fluid dynamics and heat transfer researc... more Backward facing step arrangement is a classical case for fluid dynamics and heat transfer research. It is well characterized and therefore, used for benchmarking. However, ongoing studies reveal that the geometry also provide advantages in industry, especially in combustion and burners. This work utilizes computational fluid dynamics to investigate a specific laminar back facing step flow heat transfer case. Aluminium oxide nano particles are considered as an additive to water base fluid, forming nanofluid with different volumetric concentrations. Laminar flow passes a back facing step and encounters three circular grooves at bottom surface. All surfaces are adiabatic except the grooves. Constant surface temperature applies to the grooves. According to the simulation results, a separation bubble after back facing step and a reattachment point occur. Grooves alter expected wake due to physical and thermal interference. Investigation parameters are nano-particle concentration and Reyn...
Selcuk University Institude of Science PhD Thesis, 2020
Transient conjugated heat transfer in simultaneously developing turbulent flow is analyzed involv... more Transient conjugated heat transfer in simultaneously developing turbulent flow is analyzed involving two-dimensional wall and fluid axial conduction. A thick walled semi-infinite circular pipe which is considered initially isothermal and the problem is handled for steady, hydrodynamically and thermally developing flow with a sudden change in the outer wall temperature. The flow field and heat transfer are numerically investigated. Nondimensional continuity, Navier-Stokes and energy equations are solved by discretization using finite volumes method. Exponential discretization scheme is selected for the discretization of fluid side differential equations. Staggered grid system and SIMPLE algorithm are used in the flow solution. New computer software is developed for the numerical solution of the problem. Non-dimensional parameters that define the problem are determined as Reynolds number, Prandtl number, Peclet number, wall to fluid thickness ratio, wall to fluid thermal conductivity ratio, and wall to fluid thermal diffusivity ratio. Effects of each parameter on the heat transfer and flow characteristics are investigated in detail. Results change depending on all parameters. Reynolds number changing between 5×103 and 1×105 is the only parameter for flow solution. Hydrodynamic development length gets longer, directly proportional to Reynolds number and a characteristic velocity profile is attained at pipe axis. Peclet number that appears as a parameter in the energy equation for flow field during heat transfer solution can be investigated in a wide interval (1×102-2.5×105). Therefore, Peclet number is found to be the most important parameter that affects heat transfer. Heat transfer is affected by simultaneously developing flow. Exponential discretization scheme that has no known application in the solution of the problem gives result successfully.
Most of the major cities in the world are coastal cities. This is a natural outcome of the needs ... more Most of the major cities in the world are coastal cities. This is a natural outcome of the needs of human civilization. Some of the mentioned needs are transporting goods (shipping in literal means) and resources such as fish. On the other hand, wind and solar energy systems are usually built on arid land, away from settlements. Since there is an inverse relation between the size of a settlement and the aridness of a field, renewable energy systems, particularly wind and solar, are far from major settlements and industrial facilities. This creates and increases transfer/transmit and storage duties. Accordingly, additional costs arise. The additional costs and hardship undermine the transition to a carbon dioxide neutral circular sustainable life. Another thing about the location of renewables on land is that transmitting generated energy may not be possible at all. Consequently, offshore renewable energy systems are being studied and also applied. In the present work, we review the concurrent literature about offshore floating wind turbines, present an idea on them, and lay out basic equations for evaluating the idea based on economics and physics.
Arrays of offshore renewables are being studied by academia to justify them economically in real-... more Arrays of offshore renewables are being studied by academia to justify them economically in real-world applications by private sector entities. Offshore renewables' initial and levelized costs are significantly higher than their on-land counterparts. Therefore, energy density per unit area should be dramatically increased and/or cost lowered. However, concurrent knowledge of offshore industries other than renewable energy, such as fish farms, offshore oil platforms, and marine shipping, implies that lowering costs will not be sufficient. In order to increase the energy density per unit area, multiple offshore renewable energy systems relying on different physics should be combined in threedimensional space, thus creating an array. Also, systems and structures of other marine industries can be included in the concept to benefit from their readily present infrastructure. Such arrays are the subject of scientific and engineering investigation and assessment since hydrodynamics, aerodynamics, mechanics, and economics are involved. The topic is highly multidisciplinary. In this work, we reflect on the present situation and project future aspects.
5. Internatinonal Conference on Materials Science, Mechanical and Automotive Engineerings and Technology (IMSMATEC’22), 2022
Production of almonds is increasing in a direct proportion to the increase in almond consumption ... more Production of almonds is increasing in a direct proportion to the increase in almond consumption of the world population. However, almond shells emerge as a byproduct since approximately half of the almond mass is the shell mass. Besides aiming financial gain, additional parameters should be considered due to sustainability issues and environmental concerns. Therefore, we are searching for alternative ways of almond shell utilization. Moisture value, porous structure, strength, and thermal conductivity of almond shells have a potential in respect of insulation purposes. In this work, particle boards from almond shell particles are investigated in terms of sound absorption and transmission properties. Experimental examination is utilized. In the measurements, transmission loss value can reach to 78 dB levels, making the boards a significant candidate for insulation purposes. Also, almond shell particle amount in the particle boards and variations in particle board densities greatly affect sound insulation properties of the boards.
Karabakh III. International Congress of Applied Sciences "Year Of Shusha- 2022", 2022
Almond shell is a ligneous byproduct of almond fruit production process. This byproduct is usuall... more Almond shell is a ligneous byproduct of almond fruit production process. This byproduct is usually used as solid mass fuel. Almond shell as one of the lignocellulosic origin resources is thought to be evaluated as an alternative constituent in particle board production instead of burning it as a solid biomass fuel, in order to obtain more economical benefit. In this work, almond shells from almond fruit production process were acquired and they were grinded to make them suitable for particle board production. After the grinding process, particles sizes changing between 0.4 mm and 3.4 mm were obtained. Particle board production was realized by mixing those particles with black pine chips in different ratios. Urea formaldehyde was used as binder. Additionally, ammonium sulphate was utilized in order to harden the binder. Particle boards were obtained in laboratory conditions by proper compression pressure and temperature values for particle board production. Some particular physical and mechanical tests were done for the produced boards after climatization process. Density, thickness swelling, and water absorption amount values of the physical properties were calculated after submerging boards into water for 2 hours. In terms of mechanical properties, bending resistance and elasticity modulus, bending stress, and force values depending on the deflection were calculated. According to the obtained results, effects of almond shell and black pine particle ratios on physical and mechanical properties are examined. Additionally, mechanical, and physical properties of particle boards that were produced in different densities are investigated. At the end of the study, it is determined that increase in almond shell particle amount in the particle board makes the board more brittle and rigid. It is concluded that almond shell particles can be used in particle board production where brittleness and rigidness are desired though bending strength decreases with almond shell ratio. Also, by the physical tests, lower thickness swelling, and water absorption amount were detected with increasing almond shell ratio. In general, a decrease in mechanical properties with increasing almond shell particles is apparent, however, an improvement in mechanical properties occur with increasing board density. This finding is regarded as a favorable aspect in terms of application. In future work, image capture trials for microstructure examinations are planned and physical mechanisms that lead to the present test results are aimed to be investigated.
Latin American International Conference on Natural and Applied Sciences-II (Colombia, Bogotá), 2022
Almond is a common fruit/nut worldwide while its shell accounts for about half the weight of the ... more Almond is a common fruit/nut worldwide while its shell accounts for about half the weight of the fruit (shell weight is about equal to the edible part). Massive bulk shells are produced as a byproduct of almond production. The primary usage field of the shells is burning as a biomass solid fuel. However, there are applications where shells are used for filtering with or without carbonization, as additives to chemicals or cosmetics products. In the present report, almond shell is evaluated as a main constituent in organic particle board composites. A domestic type of almond shell bulk material was acquired and grinded to obtain granular form of it. Attained granular almond shells were mixed with dark oak chips with different volumetric ratios. The mixture was used in particle board production by means of heated compression molds and formaldehyde as binder. Several geometrical and operational parameters were also changed and tested, such as board thickness. Produced almond shell containing particle boards were tested and experimentally investigated for determining their thermal conductivities. The thermal conductivity tests were done in a branded test setup and facility, built in consistence with an international standard for determining thermal conductivity values. Tests were carried out for fixed temperature difference at different temperature levels, particle board densities, and almond shell volumetric rations in the particle boards. It is seen that density directly increases thermal conductivity while almond shell ratio has a changing effect on thermal conductivity based on particle board density. Also, thermal conductivity of the particle boards increases linearly with increasing temperature. Measured thermal conductivity values change between 0.07 and 0.19 W/m•K.
International Conference On Engineering, Natural And Applied Science 2021 (ICENAS’21), 2021
Computational fluid dynamics, especially based on finite volumes method, is currently an industri... more Computational fluid dynamics, especially based on finite volumes method, is currently an industrial standard tool for thermal and hydraulic systems. Engineers, researchers, and sometimes graphic designers use this tool, mostly through commercially available software packages. However, computational fluid dynamics has serious limitations. The results from the method rely on significant assumptions. On the other hand, theoretical background of the method is somehow diverse and includes conservation laws, physics, statistics, numerical methods, computer science and some other fields. The real danger in terms of utilization of commercially available software packages is the robustness of those products. Most of the time, user receives results even if they are not correct and the user may not be aware of false situation. In this work, three engineering students were ordered to replicate a literature work with some modification on the case by means of computational fluid dynamics. The case has a boiler with three different fluid passages. Heat transfer and fluid flow are the phenomena to be solved. The students completed all computational fluid dynamics procedures by using a software package. Their report was then evaluated in terms of misconceptions, problems, and comprehension level. Characteristic problems are identified regarding the utilization of the method. Graphical outcomes from the student analyses are used for illustrating identified points. Self-experiences of the authors are blended with the case study identifications in order to list recommendations for better and effective practice of computational fluid dynamics.
Uluslararası Katılımlı 23. Isı Bilimi ve Tekniği Kongresi ULIBTK’21, 2021
Natural convection heat transfer is a heat transfer mechanism that is encountered frequently in d... more Natural convection heat transfer is a heat transfer mechanism that is encountered frequently in daily life with its applications since it does not necessitate an additional pumping power. There are intensively used instances in numerous fields such as heating and cooling systems, cooling electronics, heat exchangers, thermic power plants, hot and cold-water pipes, and vehicle engines. Extending heat transfer surfaces is one of the frequently used options in enhancing heat transfer for heat transfer by natural convection. Pins and fins in various geometries are implanted onto the surfaces for this purpose. Triangular, square, circular and elliptical pins are prominent among most used pin fins. Geometries, numbers, and orientations of the fins are the most important parameters that affect heat transfer rate. In this study, natural convection heat transfer of square, circular, elliptical, and triangular pin and plate heat sinks having same heat transfer surface area and two different pin order configurations, i.e., inline, and staggered, were experimentally investigated. Radiation heat transfer is considered in the analysis. Pin and plate heat sinks were examined at constant heating power and experiments were done with 9 different heating powers. Those heating powers were arranged between 10 W and 50 W with 5 W increments. Nusselt (Nu) and Rayleigh (Ra) numbers were calculated using measurements and tabulated data according to the measurements. Heat transfer results are evaluated according to the drawn graphics. It was found that more heat transfer rates are possible with staggered arrangements comparing to inline arrangements.
Uluslararası Katılımlı 23. Isı Bilimi ve Tekniği Kongresi ULIBTK’21, 2021
Almond shell appears as a byproduct of almond fruit market. Masses of almond shells are burned or... more Almond shell appears as a byproduct of almond fruit market. Masses of almond shells are burned or dumped as bio waste while a small portion is used for chemicals and other related industries. On the other hand, almond shells have a characteristic porous structure. This structure has strength properties and similarities to wooden particles. Therefore, utilizing almond shells in particle board production is an option. However, previous literature shows that almond shells in particle boards may reduce some strength properties. Evaluating all these together, almond shell reinforced or based organic composite particle boards are though as a candidate for thermal and noise insulation. This work presents some numbers about almond industry, reviews related literature and proposes a framework for investigating almond shells in particle boards as a candidate for insulation purposes. The porous structure of almond shells, having stationary air in the pores, indicates that this structure can provide low thermal conductivity. There are literature instances where almond shell reinforcements in particle boards have already proven to be relatively more resistant to water and thickness swelling. Also, urea formaldehyde emission of particle boards is reported to be less by utilization of almond shells. This review and framework will be used for a project proposal as a preliminary work for future studies on the topic.
Uluslararası Katılımlı 23. Isı Bilimi ve Tekniği Kongresi ULIBTK’21, 2021
This work presents a numerical scheme for investigating steady laminar natural convection heat tr... more This work presents a numerical scheme for investigating steady laminar natural convection heat transfer through a zero-wall thickness vertical pipe based on gravitational acceleration by a commercial Computational Fluid Dynamics (CFD) code. The pipe wall has constant temperature, being higher than the surrounding fluid temperature. A textbook approach is adapted to have dimensionless results from the code. This adaptation and the approach are explained in detail. Pipe geometry is held constant throughout the analyses while fluid thermophysical properties are changed between solutions in order to induce parametrical effects. However, those properties are kept constant during a solution. By arranging the properties, Grashof, Prandtl and accordingly Rayleigh numbers are set to certain values. A wide range of those numbers are aimed while laminar flow interval is not exceeded. Heat and mass transfer indicators such as dimensionless total heat transfer rate, mass flow rate, bulk temperature, wall heat flux, average and local Nusselt numbers are obtained. Temperature results also normalized in addition to the nondimensionalization. It is seen that momentum and energy solutions are highly related to each other. Therefore, laminar natural convection flow pattern changes greatly due to different Grashof and Prandtl numbers. The flow resembles to pipe forced convection for low values of the dimensionless numbers while it resembles to flat plate flow. Low values of the Prandtl number greatly increase the fluid axial conduction. Nusselt number is correlated with Rayleigh number by means of a simple mathematical expression. Conjugate heat transfer for a thick-walled pipe in a similar scenario is planned for future work.
23rd Congress on Thermal Science and Technology with International Participation (ULIBTK 2021), 2021
In this work, transient regime laminar natural convection heat transfer from horizontal plain fla... more In this work, transient regime laminar natural convection heat transfer from horizontal plain flat plate was experimentally investigated for different constant heat fluxes. In the work, effects of plain flat base plate proximities to experimental results were compared for two different experimental setups that were designed and produced for determination of thermal performances of finned heat sinks and that have different insulation boxes. Also, comparisons were conducted by using empirical correlations from literature in order to assess their feasibility for transient operation. Alongside of these, uncertainty of the experimental results that were reduced into Nusselt number were calculated for each time step in the transient period. Steady state period results after the transient regime were also given as reference conditions for further work. It is found that at least 150 minutes are necessary for reaching steady state. In order to detect this time, rate of change for average surface temperature as a criterion in 1000 seconds interval was assumed between 0.1-0.5%. It is also found that transient response of the natural convection heat transfer is quite different than the steady state. Deducing from the results, it is seen that proximity of the heat sink affects the heat transfer results. It is also seen that transient experimental Nusselt number trends are different from trends of empirical correlations from literature.
4TH INTERNATIONAL CONFERENCE ON LIFE AND ENGINEERING SCIENCES ICOLES 2021 , 2021
In this work, three types of computational fluid dynamics thermal boundary conditions, i.e., cons... more In this work, three types of computational fluid dynamics thermal boundary conditions, i.e., constant surface temperature (type I), constant heat flux (type II) and constant convection heat transfer coefficient (type III) were used for calculating heat transfer in pipes for flows ranging from laminar, through transition and towards turbulent. Zero wall thickness was assumed avoiding axial wall conduction heat transfer while fluid axial conduction was considered. According to the case design, spatial hydrodynamical and thermal development take place simultaneously. The developments are monitored by means of velocity and temperature changes. All the results are given nondimensional though a commercially available dimensional solver was used. The nondimensionalization procedure was based on a practical approach and it is explained. Prandtl number was kept constant at unity while Reynolds number was changed from 10 1 to 10 6 , covering the flow range of laminar, transition and turbulent flow regimes. Thermophysical properties were assumed constant and hence, the flow field only changes with Reynolds number. However, temperature distribution is affected from the boundary condition types. Accordingly, it is concluded that thermal development should be evaluated by the change of local Nusselt number or flow bulk temperature. Empirical and analytical correlations were used for comparison between numerical and literature data. It is anticipated that changing Prandtl number, inducing wall thickness and temperature dependent variables would further change development lengths. Future work is prescribed.
International Conference on Engineering Technologies (ICENTE'21), 2021
In this work, literature was surveyed in order to find convenient models of effective thermal con... more In this work, literature was surveyed in order to find convenient models of effective thermal conductivity for composites. Five different common models were compared with each other in terms of their consistency by using the same model inputs. Three levels of matrix thermal conductivities, three levels of filler thermal conductivities, and three levels of volume fraction ratios were used as inputs. Obtained trends were graphically plotted against each other. It is seen that models including effects solid-solid interface thermal resistance are giving results distinguishing from models excluding the effects of the interface thermal resistance. It is also understood that models dealing with the thermal conductivity of composites are becoming more complex by considering filler geometries, surface properties, and other interface interactions.
6th International Ege Energy Symposium & Exhibition, 2012
World population and the development of industry increase rapidly. In addition, the need for ener... more World population and the development of industry increase rapidly. In addition, the need for energy is growing every passing day. There are a vast number of studies about renewable energy resources for avoiding dependency to fossil fuels. Especially in internal combustion engines, it is extremely important to replace petroleum derivatives with alternative renewable fuels. In this study, the performance and emissions of diesel engine with four cylinders, four strokes, liquid cooling, naturally aspiration, direct injection operating on diesel fuel and different Soybean Methyl Ester blends (SME) with diesel fuel were investigated theoretically utilizing the simulation software Diesel-RK. Based on to the calculated models, it was found that 1.4 %, 2.7 % and 7.9 % reduction in the mean engine power were obtained with SME 20 %, SME 40 % and SME 100 % respectively, compared to pure diesel operation. Additionally, a reduction in indicated mean effective pressure was observed at a rate of 1.01%, 2.02 %, 5.94 % converse to specific fuel consumption which exhibited increase at a rate of 4.1%, 8.4 %, 24.2 % for the SME 20 %, SME 40 % and SME 100 % respectively, compared to pure diesel operation. In respect of particulate matter (PM) emissions, SME 20 % exhibited 26 % less PM, SME 40 % exhibited 44 % less PM and SME 100 % exhibited 70 % less PM than pure diesel operation. Contrary to PM emissions, NO x emission values were resulted between 160 to 420 % of pure diesel oil results when SME blends were used. According to the study, SME blends positively affected exhaust emissions while they were negatively affecting engine performance characteristics. Among blends, SME 20% and SME 40 % were more favorable than SME 100 %.
6th International Ege Energy Symposium & Exhibition, 2012
In this study, a convection type drying experimental setup was designed for using it in determini... more In this study, a convection type drying experimental setup was designed for using it in determining drying characteristics of agricultural products at different conditions. Experimental setup consisted of fresh air entrance, air conditioner unit, drying cabin, air mixing unit, automation unit and channel connections. Fresh air from the ambient environment was sucked via experimental setup and after conditioned to temperatures between-5 and 80 o C, velocities between 0 and 3 m/s and relative humidity between 3 and 50%, blown to the drying cabin. System was designed as it can provide air at desired temperature, velocity and relative humidity and maintain these values stable during experiments. For determining operational sensitivity, system was operated at 50, 60, 70 and 80 °C temperatures, 0.5, 1, 1.5, 2 m/s velocities and 5, 10, 20% relative humidity values and measurements were taken at predetermined time intervals. Measurement values showed that system can keep temperature, velocity and relative humidity values constant at desired rates. Designed experimental setup can be used confidently in determination of drying characteristics of agricultural products.
In this study, the performance and emissions characteristics of diesel engine with four cylinders... more In this study, the performance and emissions characteristics of diesel engine with four cylinders, four strokes, liquid cooling, turbocharger and direct injection operating on 20% soybean methyl ester (SME) and 80% diesel fuel blend as volume was theoretically investigated with different EGR ratios by utilizing the simulation software Diesel-RK. EGR ratios of 0%, 5%, 10%, 15% and 20% were used. As performance outputs of the study, engine power and specific fuel consumption (BSFC) changing with engine speed and in cylinder pressure and temperature changing with crank angle at maximum torque speed and maximum power speed were presented. As exhaust emission characteristic values, NO x , PM and carbon dioxide (CO 2) emissions changing with engine speed were provided. NO x emissions were reduced at a range of 16%-74%, PM emissions were increased at a range of 22%-154% and power output values were decreased at a range of 11%-38% with increased EGR rates. For the SME and diesel blend, EGR ratio of 10% strategy were found to be favorable in terms of NO x and engine performance.
Intercoolers have been increasingly used in internal combustion engines with supercharging since ... more Intercoolers have been increasingly used in internal combustion engines with supercharging since 1990s because of their positive effect on engine power and fuel consumption. In this study, a louvered fin and plate intercooler were experimentally investigated for heat capacity ratios between 0.027-0.125 and compactness value of 664.6 m 2 /m 3 for heavy duty engines. Heat transfer rate and pressure drop performance of the intercooler were determined with dimensionless indicators such as effectiveness, Nusselt number and friction factor. Temperature difference between fluids were changed between 50-110 o C and Reynolds number for cooling air side was changed between Re=1500-5500 in louvered fins with having a hydraulic diameter of 0.0019 m for Prandtl number value of Pr=0.82 of the cooling air. Intercooler effectiveness was found between 94-98% and friction factor was in the range of 1.2-1.6. The intercooler was determined as favorable for heavy duty engines, especially agricultural tractor engines. According to the experimental results, it was understood that designed and manufactured experimental setup can be effectively used for determining thermal and hydrodynamic performances of practically used intercoolers. The obtained results will be helpful for the validation and assessment of numerical methods and designing as well as testing new compact heat exchangers.
6th International Ege Energy Symposium & Exhibition, 2012
Heat exchangers are commonly used devices to heat transfer in various industries. Presently a wid... more Heat exchangers are commonly used devices to heat transfer in various industries. Presently a wide variety of studies has been developing for a better and precise method to determine and assess compact heat exchanger thermal and hydraulic performance indicators. An effective experimental setup is required for evaluation of ongoing studies and assessment of performance of new heat exchangers. In this work, a unique compact heat exchanger test setup was established with three different fluid flow channels operating with oil, atmospheric air and compressed air. By this way, performance of a compact heat exchanger can be experimentally investigated according to practical operational conditions. Empirical correlations acquired from the conducted experiments can be used directly by the manufacturers. In the present study, two different brazed compact heat exchangers were experimentally investigated for determining their thermal and hydraulic performances and comparing those results with empirical correlations in the literature. During experiments, oil flow channel and atmospheric air channel were used for the first type heat exchanger. Pressurized gas and atmospheric air channels were used for the second type heat exchanger. It is obtained that the effectiveness for the first and second type heat exchangers is changing from 35% to 75% while Number of Transfer Unit (NTU) is varied in the range of 0.6-1.9. Pressure drops across the oil, compressed air and atmospheric air lines are found in the range of 9-400 kPa for 20≤Re≤3000. The obtained results will be helpful for the validation and assessment of numerical methods and designing new compact heat exchangers.
2nd INTERNATIONAL BAKU CONFERENCE ON SCIENTIFIC RESEARCH, 2021
Pin fin heat sinks are passive cooling devices that are generally equipped in electronics cooling... more Pin fin heat sinks are passive cooling devices that are generally equipped in electronics cooling. Generally, pin geometries, numbers, orientations, and analysis methods are studied in the literature. In this work, two pin fin heat sinks were experimentally investigated for laminar natural convection heat transfer. Pin fin heat sinks consist of 64 unit of circular cross section pins in inline array on square base plates having 0.12×0.12 m2 area. Two different pin heights of 0.03 and 0.04 m were tried during experiments. Heating power was changed between 5 W and 50 W by 5 W increments. Rayleigh number interval of the investigation is 1.4-6.1×106. Surface and ambient temperatures were recorded for steady state operational conditions. Uncertainty analysis of the experimental system is provided. Radiation heat transfer was accounted during data reduction. Obtained results for different heating powers were compared from results by using empirical correlations from literature. Different characteristic length definitions were used for adapting the empirical correlations into the range of experimental results of the present work. It is concluded that empirical correlations can approximate experimental results with moderate discrepancies. Present experimental results can also be used for computational fluid dynamics benchmarking as validation tool.
International Conference on Engineering Technologies (ICENTE'20), 2020
A 1.2-liter gasoline spark ignition internal combustion engine of a Renault Symbol sedan vehicle ... more A 1.2-liter gasoline spark ignition internal combustion engine of a Renault Symbol sedan vehicle was adapted to Liquid Petroleum Gas (LPG) fuel system in 2016. The LPG system utilize LPG and gasoline fuels according to the operational needs. After modification, fuel consumption of the engine, fuel prices per liter, travelled distance in kilometers, dates and some additional data were recorded till November 2020. Collected data is processed for derivation of performance and economy indicators. Literature and web have been reviewed in order to find related works. Providing a solid application example of LPG conversion is aimed in this work. Also, a snapshot of fuel prices between 2016 and 2020 is being presented by graphical resolution. Approximately 12 to 15 times of initial investment cost has been returned till November 2020 by the LPG system. Also, slightly less CO2, i.e. 6%, has been emitted by the utilization of the system. Time resolution of the data is provided by graphics and integral data is also given. LPG conversion is found beneficial in terms of fuel cost. Also, viewed four years period does not reveal any performance problems in terms of energy spending per kilometer. However, engine additional amortization due to LPG system is not considered and this should be kept in mind.
INTERNATIONAL SCIENTIFIC CONFERENCE UNITECH11, 2011
In this study, an experimental setup was design to investigate Offset-Offset fin oil coolers. The... more In this study, an experimental setup was design to investigate Offset-Offset fin oil coolers. The main aim of the study is to determine thermal and hydrodynamic performance of commercially used oil coolers. To achieve this aim, mass flow rates of St42 oil in heavy duty machinery were detected. An automation unit which contains a programmable logic controller and frequency controller was used. Oil circulated via a gear pump and heated with electrical resistances. PT100 resistance thermometers and pressure transmitters were used in measurement system. Experiments were conducted at six different oil entrance temperature, three different cooling air mass flow rate and nine different oil mass flow rate. Results were given by the terms of total heat transfer, pressure drop and effectiveness values. Offset-Offset fin oil cooler configuration was found to be a good alternative among commercial competitors.
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Papers by Eyüb Canli
change in the outer wall temperature. The flow field and heat transfer are numerically investigated. Nondimensional continuity, Navier-Stokes and energy equations are solved by discretization using finite volumes method. Exponential discretization scheme is selected for the discretization of fluid side differential equations. Staggered grid
system and SIMPLE algorithm are used in the flow solution. New computer software is developed for the numerical solution of the problem. Non-dimensional parameters that define the problem are determined as Reynolds number, Prandtl number, Peclet number,
wall to fluid thickness ratio, wall to fluid thermal conductivity ratio, and wall to fluid thermal diffusivity ratio. Effects of each parameter on the heat transfer and flow characteristics are investigated in detail.
Results change depending on all parameters. Reynolds number changing
between 5×103 and 1×105 is the only parameter for flow solution. Hydrodynamic development length gets longer, directly proportional to Reynolds number and a characteristic velocity profile is attained at pipe axis. Peclet number that appears as a parameter in the energy equation for flow field during heat transfer solution can be investigated in a wide interval (1×102-2.5×105). Therefore, Peclet number is found to be
the most important parameter that affects heat transfer. Heat transfer is affected by simultaneously developing flow. Exponential discretization scheme that has no known application in the solution of the problem gives result successfully.
Surface and ambient temperatures were recorded for steady state operational conditions. Uncertainty analysis of the experimental system is provided. Radiation heat transfer was accounted during data reduction. Obtained results for different heating powers were compared
from results by using empirical correlations from literature. Different characteristic length definitions were used for adapting the empirical correlations into the range of experimental results of the present work. It is concluded that empirical correlations can approximate experimental results with moderate discrepancies. Present experimental results can also be used for computational fluid dynamics benchmarking as validation tool.