L. Berrin Erbay | Eskisehir Osmangazi University, Turkey (original) (raw)

Papers by L. Berrin Erbay

Journal of Thermal Engineering, Nov 18, 2021

Energy-saving and heat transfer enhancement considerations are more crucial due to nearly running... more Energy-saving and heat transfer enhancement considerations are more crucial due to nearly running out energy resources and ensuring the sustainability of nature. The heat exchangers are one of the main components and directly affect the thermal efficiency of the systems. To enhance the heat transfer rate, the fin and plate structure is widely used. Various vortex generators may be involved generally on the surface of fins, like ribs, baffles, delta winglets, and perforations. Turbulators make the heat transfer performance better significantly but increase the friction of the fluid on the contacting surfaces and cause the pressure drop-down which depends on thermal properties of the fluid characteristics. This paper presents general protrusion vortex generators overview to heat transfer augmentation with pressure loss as an extensive literature review. The correlations are derived in terms of some parameters of turbulators like; angle, pitch, shape and combinations of an array. The target of this study is consolidating the verified outputs of the literature and support the increasing thermal performance of the heat exchangers. In conclusion, two tables are made for the first time and summarizing the crucial features of solid, perforated baffles/blockages and winglet turbulators, mentioned in the literature are presented. Obstacles such as winglets and vortex generators are used commonly to increase the heat transfer rate per unit volume for finned to tube exchangers with various types. In order to augment the heat transfer, the design parameters of important consideration are attack of angles, height and array structure in both laminar and turbulated fluid characteristics. Involving perforation forms on the surface may be used for winglets with variable angles both decrease the pressure loss and increase the heat transfer performance.

IOP conference series, Aug 1, 2019

In hermetic reciprocating compressors, it is possible to improve the sound quality of the compres... more In hermetic reciprocating compressors, it is possible to improve the sound quality of the compressor as well as to minimize the discharge line flow losses of the compressor by optimization of the pressure pulsations in the discharge line. Pressure pulsation induced vibrations significantly affect both the sound quality and the vibration level of the entire cooling system. This study is prepared to minimize the pressure pulsations in the discharge line of the compressor by comparing and determining the effects of alternative designs on pressure pulsations with the numerical results of base and alternative designs formed by differentiation of crankcase orifice diameter and discharge muffler channel diameter from the discharge line design parameters. In this paper, the design parameters that affect the discharge line pressure pulsations and flow losses were investigated with a transient CFD analysis methodology, which was developed and confirmed by experimental measurements in previous study. At the end of the study, the geometric characteristics of the different design parameters of the discharge line such as orifice diameters are presented with transient numerical analysis.

Entropy, Dec 31, 2003

The entropy generation during transient laminar natural convection in a square enclosure is numer... more The entropy generation during transient laminar natural convection in a square enclosure is numerically investigated. Two different cases are considered. The enclosure is heated either completely or partially from the left side wall and cooled from the opposite side wall. The bottom and the top of the enclosure are assumed as insulated. The Boussinesq approximation is used in the natural convection modelling. The solutions are obtained from quiescent conditions proceeded through the transient up to the steady-state. The calculations are made for the Prandtl numbers 0.01 and 1.0 and Rayleigh numbers between 10 2-10 8. The entropy generation and the active places triggering the entropy generation are obtained for each case after the flow and thermal characteristics are determined. It is found that the active sites in the completely heated case are at the left bottom corner of the heated wall and the right top corner of the cooled wall at the same magnitudes. In the case of partial heating, however, the active site is observed at the top corner of the heated section especially at lower Pr and Ra values.

InTech eBooks, Apr 26, 2017

The purpose of this chapter is to describe the basic physical features and the analysis of the th... more The purpose of this chapter is to describe the basic physical features and the analysis of the thermal-hydraulic performance of the louver fins. The terminology which is used widely in the field of compact heat exchanger with louvered fin is described. The flow phenomenon affected by the operating conditions and the geometric parameters of the louvered fin is examined using the flow visualization techniques found in the literature. A methodology is given to calculate the heat transfer and the friction factor. Stanton number, Colburn j-factor and friction factor are defined as a performance criteria and the variations of these criteria with respect to the Reynolds number and the geometric parameters of the louvered fin. The combinations of these dimensionless number such as area goodness factor (j/f), volume goodness factor (j/f 1/3) and JF number related with the volume goodness factor are discussed in terms of overall performance criteria. Finally, the correlations of the louvered fin heat exchanger and their tabulated data was summarized.

Applied Energy, Mar 1, 1999

An internally irreversible Ericsson engine, with a realistic regenerator, has been analyzed. The ... more An internally irreversible Ericsson engine, with a realistic regenerator, has been analyzed. The study considers internal irreversibilities with the introduction of turbine and compressor thermal-eciencies and pressure-drops present in realistic regenerators. The eects of internal irreversibilities on the power output and thermal eciency of the cycle have been determined using the ®nite-time thermodynamics. Maximum power-density, rather than maximum power, was used as the criterion for optimization, with the objective of having a more ecient small-sized engine.

Energy, Jul 1, 1997

The Stirling heat engine operating in a closed regenerative thermodynamic cycle is analyzed. Poly... more The Stirling heat engine operating in a closed regenerative thermodynamic cycle is analyzed. Polytropic processes are used for the power and displacement pistons. Following regeneration, the maximum power density and efficiency are found and the compression ratio at maximum power density is determined.

DergiPark (Istanbul University), Mar 1, 2012

Heating and cooling are one of the fundamental research area for the engineers. Due to increment ... more Heating and cooling are one of the fundamental research area for the engineers. Due to increment of the energy demand and decrement on the sources leads the researchers to develop the recent systems and find out new systems. In the study, performance of a commercial heat pump water heater is studied. The performance of system under various conditions is analyzed with a program prepared in MATLAB 7.3 software by using exergy analysis method. The exergy destruction of the system is calculated by using collected data for each component of the system as well as considering the whole states of entire system. The analyses represents effective conditions and components on the destruction of the performance. It is found that performance of system decreases for low temperature and high humidity ambient conditions.

Journal of Thermal Engineering, Sep 3, 2021

This paper presents a numerical simulation to determine the air-side heat transfer and the pressu... more This paper presents a numerical simulation to determine the air-side heat transfer and the pressure drop characteristics of a flat tube heat exchanger with offset strip fin. The effects of the fin bending ratio such as 29%, 36%, 44%, 50%, and the fin spacing such as 2.10 mm, 2.35 mm, 2.60 mm on the performance of the heat exchanger are studied by using a commercial CFD software. The air having constant viscosity, thermal conductivity, and density enters the heat exchanger at 298 K and the wall temperature of the strip fins is considered as constant at 314 K. Variations of the heat transfer coefficient and the pressure drop in the airside are presented with respect to the frontal air velocity while Colburn j-factor and the friction factor f are presented with respect to the airside Reynolds number ranging from 200 to 1200. Finally, the thermal-hydraulic performance of all investigated cases is compared by using the volume goodness factor, j/f 1/3. The results show that the air-side heat transfer coefficient and the pressure drop increase when the frontal air velocity ascends. The air-side heat transfer coefficient decreases with the increase of fin spacing. The fin bending ratio does not have a significant effect on the pressure drop in the considered fin spacing. Both the Colburn j-factor and friction factor reduce with the increment of Reynolds number and fin spacing.

Journal of building engineering, Dec 1, 2021

Abstract The aim of the study is to reduce the amount of refrigerant and energy consumption of a ... more Abstract The aim of the study is to reduce the amount of refrigerant and energy consumption of a household refrigerator by conserving the desired temperature inside the fresh food and freezer compartments . In this study, two novel condensers with different offset strip fin configurations on a mini-channel flat tube are used instead of a conventional wire-on-tube condenser. The impact of this novel application on the performance of the refrigerator is investigated experimentally by following the norms defined by IEC 62552:2015. The tests are conducted in a wide range of refrigerant charges (48–64 g) with three different capillary lengths (2800, 3300, and 3800 mm). Alternative couples of refrigerant charge and capillary length for the novel condensers are determined to decrease the daily energy consumption under the level of the original system with the wire-on-tube condenser. One of the aims of the study is achieved by 5.7% of energy-saving when one of the novel condensers is coupled with a 3300 mm length capillary tube and 50 g of refrigerant. The other aim of the study related with the environmental effect is achieved by reducing 10.7% of the refrigerant amount with the application of the novel condenser with offset strip fins on a mini channel flat tube.

Science and Technology for the Built Environment, Jan 20, 2021

In this work, the effect of flow circuitry on the performance of a household freezer with a tube-... more In this work, the effect of flow circuitry on the performance of a household freezer with a tube-on-sheet evaporator is investigated. The evaporator used in the freezer is a tube-on-sheet type where the tubes are bent and attached underneath the shelves, as in the serpentine heat exchanger. The evaporator is composed of six shelves that are located inside the cabin with a particular distance between each. Four different refrigerant circuitries are modeled to identify the one that provides a homogeneous temperature distribution while consuming less energy, and experiments are conducted by switching the refrigerants flow route between the shelves. The uniform temperature distribution at around the target temperature and the energy consumption of the entire system while achieving this target are monitored as the major performance measures of the investigation. The tests are conducted according to IEC 62552:2015, standard clause 8. The experiments found that the change of the flow circuitry has a crucial impact on the temperature distribution’s uniformity and energy consumption. The type in which the refrigerant circuitry between the shelves is 2-1-6-5-4-3 has the best performance in terms of temperature distribution and energy consumption.

Compact heat exchangers are the devices that allow having larger surface area density which is pr... more Compact heat exchangers are the devices that allow having larger surface area density which is provided by the enlargement of the fins. Frequently plate fins are chosen to achieve this and several forms of this fin types are used in several applications such as rectangular plain fin offset strip fin, wavy fin, louvered and perforated fins. In this particular work, the effect of the fins on the performance of a compact heat exchanger is studied. In order to determine distinguishing features of the fins, 2D models of a plain fin, louvered fin and offset strip fin with 3 and 4 offsets are calculated numerically by a commercially available CFD software. In the study, 6 offset strip and 3 louver and 3 plain fin cases are run for five different air velocities and the results are summarized for the heat transfer coefficient, pressure drop, Colburn j and friction factors (f) with regard to The changing velocities. The results are summarized for varying fin pitches which allows to determine the impact of it on the performance of the heat exchangers.

InTech eBooks, Apr 26, 2017

Journal of Thermal Engineering, Mar 28, 2015

This paper focuses on the effect of inlet temperature of the cold fluid on the thermal performanc... more This paper focuses on the effect of inlet temperature of the cold fluid on the thermal performance of two mini channel flattube with multi-louvered fin compact heat exchangers experimentally. Two louvered fin heat exchangers in the same sizes with different number of fin rows are tested in a constant temperature test room by a wind-tunnel. The cold fluid flowing on the external side of the heat exchanger is air. The hot fluid flowing through the mini channels is water. The inlet temperature of the water passes through the mini channel flattube is predetermined and supplied at a temperature of 42 o C. Mass flow rate of the water is regulated by a water circulator at a rate of 0.025 kg/s. The mass flow rate of the air is measured 0.0472 kg/s. It is found that the model which has two fin rows is more effective in terms of overall thermal conductance, number of transfer units and effectiveness at all values of inlet temperature of the air. In addition, both of the heat exchangers have the highest thermal performance at an air inlet temperature of 24 o C.

Sustainable Energy Technologies and Assessments, Dec 1, 2020

In this study, thermodynamic inefficiencies of the components and the whole system are quantified... more In this study, thermodynamic inefficiencies of the components and the whole system are quantified by exergy destruction. The performance of an air source heat pump water heater (ASHPWH) is examined experimentally under varying ambient conditions from the exergy destruction aspect. The exergy destruction is calculated for each moment through the entire heating period with regard to collected temperature and pressure data under various ambient conditions. The exergy destructions are examined continuously in a sequence from the beginning to the end of the water heating process. This approximation allows the designer and the manufacturer to see the progress of exergy destruction through the entire heating period to evaluate the performance of every component for avoiding irreversibilities and improving the ASHPWH. During these observations, three individual zones are observed in which the exergy destruction characteristics have changed. Furthermore, the impact of the ambient conditions on these zones is identified either. The thermodynamic properties and exergy destruction values are computed for all data collected by a MATLAB code. The results would be helpful to picture out the true evolution of the exergy destruction from component aspect either solely or combined effect of them during the water heating period.

International Journal of Refrigeration-revue Internationale Du Froid, Feb 1, 2019

In this study, two types of mini-channel condenser are integrated into a household refrigerator i... more In this study, two types of mini-channel condenser are integrated into a household refrigerator in order to increase the performance of the system. Since the integration process requires the substitution of capillary tube which will be followed by charging a different amount of refrigerant, this work focuses on finding the right amount of the refrigerant and the right size of the capillary as well. This experimental study is carried out on a commercial household refrigerator in a climatic chamber with respect to IEC standards. During the experiments, two types of mini-channel condensers have been analyzed with five different capillary lengths and five varying coolant amounts in order to find the best combination for better performance. The outcomes of the study release the thresholds for either capillary length or refrigerant amount, which are 3.25 m and 50 g respectively, that will enlighten the further studies on the same investigations.

Applied Thermal Engineering, Aug 1, 2019

In this particular work, the flat tube with mini-channel compact heat exchangers with offset stri... more In this particular work, the flat tube with mini-channel compact heat exchangers with offset strip fins by non-uniform uninterrupted fin length are investigated experimentally. The tests are performed by four different types of flat tube compact heat exchangers. The tests are conducted in the range of 600<Re a <2000, while water as the heat transfer fluid is circulated at the inlet of the heat exchanger and regulated by a water bath at a temperature of 42 o C. The performance of the heat exchangers is assessed by using Colburn j-factor, friction factor f, area goodness factor j/f and volume goodness factor j/f 1/3. According to the obtained outcomes, the compact heat exchanger with bigger pass number provides better heat transfer. Two different types of strip fins with non-uniform uninterrupted fin length have been tested. The heat exchanger group with 1.55 m length of flat tube shows almost 40% higher performance than the heat exchanger group with 1.20 m length of flat tube.

Energy Conversion and Management, Feb 1, 2017

The duplex Stirling refrigerator is an integrated refrigerator consists of Stirling cycle engine ... more The duplex Stirling refrigerator is an integrated refrigerator consists of Stirling cycle engine and Stirling cycle refrigerator used for cooling. The equality of the work generation of the heat engine to the work consumption of the refrigerator is the primary constraint of the duplex Stirling. The duplex Stirling refrigerator is investigated thermodynamically by considering the effects of constructional and operational parameters which are namely the temperature ratios for heat engine and refrigerator, and the compression ratios for both sides. The primary concern is given to the parametric effects on the overall coefficient of performance of the duplex Stirling refrigerator. The given diagrams provide a design bounds and benchmark results that allows seeing the big picture about the cooling load and heat input relation. Moreover they ease to determine the corresponding work rate to the target cooling load. As regard to the obtained results, a definite region for coefficient of performance of the refrigerator and a definite region for the thermal efficiency of the heat engine of the duplex Stirling are identified.

Applied Energy, Mar 1, 2001

Heat and Mass Transfer, Jan 23, 2004

Journal of Thermal Engineering, Nov 18, 2021

Energy-saving and heat transfer enhancement considerations are more crucial due to nearly running... more Energy-saving and heat transfer enhancement considerations are more crucial due to nearly running out energy resources and ensuring the sustainability of nature. The heat exchangers are one of the main components and directly affect the thermal efficiency of the systems. To enhance the heat transfer rate, the fin and plate structure is widely used. Various vortex generators may be involved generally on the surface of fins, like ribs, baffles, delta winglets, and perforations. Turbulators make the heat transfer performance better significantly but increase the friction of the fluid on the contacting surfaces and cause the pressure drop-down which depends on thermal properties of the fluid characteristics. This paper presents general protrusion vortex generators overview to heat transfer augmentation with pressure loss as an extensive literature review. The correlations are derived in terms of some parameters of turbulators like; angle, pitch, shape and combinations of an array. The target of this study is consolidating the verified outputs of the literature and support the increasing thermal performance of the heat exchangers. In conclusion, two tables are made for the first time and summarizing the crucial features of solid, perforated baffles/blockages and winglet turbulators, mentioned in the literature are presented. Obstacles such as winglets and vortex generators are used commonly to increase the heat transfer rate per unit volume for finned to tube exchangers with various types. In order to augment the heat transfer, the design parameters of important consideration are attack of angles, height and array structure in both laminar and turbulated fluid characteristics. Involving perforation forms on the surface may be used for winglets with variable angles both decrease the pressure loss and increase the heat transfer performance.

IOP conference series, Aug 1, 2019

In hermetic reciprocating compressors, it is possible to improve the sound quality of the compres... more In hermetic reciprocating compressors, it is possible to improve the sound quality of the compressor as well as to minimize the discharge line flow losses of the compressor by optimization of the pressure pulsations in the discharge line. Pressure pulsation induced vibrations significantly affect both the sound quality and the vibration level of the entire cooling system. This study is prepared to minimize the pressure pulsations in the discharge line of the compressor by comparing and determining the effects of alternative designs on pressure pulsations with the numerical results of base and alternative designs formed by differentiation of crankcase orifice diameter and discharge muffler channel diameter from the discharge line design parameters. In this paper, the design parameters that affect the discharge line pressure pulsations and flow losses were investigated with a transient CFD analysis methodology, which was developed and confirmed by experimental measurements in previous study. At the end of the study, the geometric characteristics of the different design parameters of the discharge line such as orifice diameters are presented with transient numerical analysis.

Entropy, Dec 31, 2003

The entropy generation during transient laminar natural convection in a square enclosure is numer... more The entropy generation during transient laminar natural convection in a square enclosure is numerically investigated. Two different cases are considered. The enclosure is heated either completely or partially from the left side wall and cooled from the opposite side wall. The bottom and the top of the enclosure are assumed as insulated. The Boussinesq approximation is used in the natural convection modelling. The solutions are obtained from quiescent conditions proceeded through the transient up to the steady-state. The calculations are made for the Prandtl numbers 0.01 and 1.0 and Rayleigh numbers between 10 2-10 8. The entropy generation and the active places triggering the entropy generation are obtained for each case after the flow and thermal characteristics are determined. It is found that the active sites in the completely heated case are at the left bottom corner of the heated wall and the right top corner of the cooled wall at the same magnitudes. In the case of partial heating, however, the active site is observed at the top corner of the heated section especially at lower Pr and Ra values.

InTech eBooks, Apr 26, 2017

The purpose of this chapter is to describe the basic physical features and the analysis of the th... more The purpose of this chapter is to describe the basic physical features and the analysis of the thermal-hydraulic performance of the louver fins. The terminology which is used widely in the field of compact heat exchanger with louvered fin is described. The flow phenomenon affected by the operating conditions and the geometric parameters of the louvered fin is examined using the flow visualization techniques found in the literature. A methodology is given to calculate the heat transfer and the friction factor. Stanton number, Colburn j-factor and friction factor are defined as a performance criteria and the variations of these criteria with respect to the Reynolds number and the geometric parameters of the louvered fin. The combinations of these dimensionless number such as area goodness factor (j/f), volume goodness factor (j/f 1/3) and JF number related with the volume goodness factor are discussed in terms of overall performance criteria. Finally, the correlations of the louvered fin heat exchanger and their tabulated data was summarized.

Applied Energy, Mar 1, 1999

An internally irreversible Ericsson engine, with a realistic regenerator, has been analyzed. The ... more An internally irreversible Ericsson engine, with a realistic regenerator, has been analyzed. The study considers internal irreversibilities with the introduction of turbine and compressor thermal-eciencies and pressure-drops present in realistic regenerators. The eects of internal irreversibilities on the power output and thermal eciency of the cycle have been determined using the ®nite-time thermodynamics. Maximum power-density, rather than maximum power, was used as the criterion for optimization, with the objective of having a more ecient small-sized engine.

Energy, Jul 1, 1997

The Stirling heat engine operating in a closed regenerative thermodynamic cycle is analyzed. Poly... more The Stirling heat engine operating in a closed regenerative thermodynamic cycle is analyzed. Polytropic processes are used for the power and displacement pistons. Following regeneration, the maximum power density and efficiency are found and the compression ratio at maximum power density is determined.

DergiPark (Istanbul University), Mar 1, 2012

Heating and cooling are one of the fundamental research area for the engineers. Due to increment ... more Heating and cooling are one of the fundamental research area for the engineers. Due to increment of the energy demand and decrement on the sources leads the researchers to develop the recent systems and find out new systems. In the study, performance of a commercial heat pump water heater is studied. The performance of system under various conditions is analyzed with a program prepared in MATLAB 7.3 software by using exergy analysis method. The exergy destruction of the system is calculated by using collected data for each component of the system as well as considering the whole states of entire system. The analyses represents effective conditions and components on the destruction of the performance. It is found that performance of system decreases for low temperature and high humidity ambient conditions.

Journal of Thermal Engineering, Sep 3, 2021

This paper presents a numerical simulation to determine the air-side heat transfer and the pressu... more This paper presents a numerical simulation to determine the air-side heat transfer and the pressure drop characteristics of a flat tube heat exchanger with offset strip fin. The effects of the fin bending ratio such as 29%, 36%, 44%, 50%, and the fin spacing such as 2.10 mm, 2.35 mm, 2.60 mm on the performance of the heat exchanger are studied by using a commercial CFD software. The air having constant viscosity, thermal conductivity, and density enters the heat exchanger at 298 K and the wall temperature of the strip fins is considered as constant at 314 K. Variations of the heat transfer coefficient and the pressure drop in the airside are presented with respect to the frontal air velocity while Colburn j-factor and the friction factor f are presented with respect to the airside Reynolds number ranging from 200 to 1200. Finally, the thermal-hydraulic performance of all investigated cases is compared by using the volume goodness factor, j/f 1/3. The results show that the air-side heat transfer coefficient and the pressure drop increase when the frontal air velocity ascends. The air-side heat transfer coefficient decreases with the increase of fin spacing. The fin bending ratio does not have a significant effect on the pressure drop in the considered fin spacing. Both the Colburn j-factor and friction factor reduce with the increment of Reynolds number and fin spacing.

Journal of building engineering, Dec 1, 2021

Abstract The aim of the study is to reduce the amount of refrigerant and energy consumption of a ... more Abstract The aim of the study is to reduce the amount of refrigerant and energy consumption of a household refrigerator by conserving the desired temperature inside the fresh food and freezer compartments . In this study, two novel condensers with different offset strip fin configurations on a mini-channel flat tube are used instead of a conventional wire-on-tube condenser. The impact of this novel application on the performance of the refrigerator is investigated experimentally by following the norms defined by IEC 62552:2015. The tests are conducted in a wide range of refrigerant charges (48–64 g) with three different capillary lengths (2800, 3300, and 3800 mm). Alternative couples of refrigerant charge and capillary length for the novel condensers are determined to decrease the daily energy consumption under the level of the original system with the wire-on-tube condenser. One of the aims of the study is achieved by 5.7% of energy-saving when one of the novel condensers is coupled with a 3300 mm length capillary tube and 50 g of refrigerant. The other aim of the study related with the environmental effect is achieved by reducing 10.7% of the refrigerant amount with the application of the novel condenser with offset strip fins on a mini channel flat tube.

Science and Technology for the Built Environment, Jan 20, 2021

In this work, the effect of flow circuitry on the performance of a household freezer with a tube-... more In this work, the effect of flow circuitry on the performance of a household freezer with a tube-on-sheet evaporator is investigated. The evaporator used in the freezer is a tube-on-sheet type where the tubes are bent and attached underneath the shelves, as in the serpentine heat exchanger. The evaporator is composed of six shelves that are located inside the cabin with a particular distance between each. Four different refrigerant circuitries are modeled to identify the one that provides a homogeneous temperature distribution while consuming less energy, and experiments are conducted by switching the refrigerants flow route between the shelves. The uniform temperature distribution at around the target temperature and the energy consumption of the entire system while achieving this target are monitored as the major performance measures of the investigation. The tests are conducted according to IEC 62552:2015, standard clause 8. The experiments found that the change of the flow circuitry has a crucial impact on the temperature distribution’s uniformity and energy consumption. The type in which the refrigerant circuitry between the shelves is 2-1-6-5-4-3 has the best performance in terms of temperature distribution and energy consumption.

Compact heat exchangers are the devices that allow having larger surface area density which is pr... more Compact heat exchangers are the devices that allow having larger surface area density which is provided by the enlargement of the fins. Frequently plate fins are chosen to achieve this and several forms of this fin types are used in several applications such as rectangular plain fin offset strip fin, wavy fin, louvered and perforated fins. In this particular work, the effect of the fins on the performance of a compact heat exchanger is studied. In order to determine distinguishing features of the fins, 2D models of a plain fin, louvered fin and offset strip fin with 3 and 4 offsets are calculated numerically by a commercially available CFD software. In the study, 6 offset strip and 3 louver and 3 plain fin cases are run for five different air velocities and the results are summarized for the heat transfer coefficient, pressure drop, Colburn j and friction factors (f) with regard to The changing velocities. The results are summarized for varying fin pitches which allows to determine the impact of it on the performance of the heat exchangers.

InTech eBooks, Apr 26, 2017

Journal of Thermal Engineering, Mar 28, 2015

This paper focuses on the effect of inlet temperature of the cold fluid on the thermal performanc... more This paper focuses on the effect of inlet temperature of the cold fluid on the thermal performance of two mini channel flattube with multi-louvered fin compact heat exchangers experimentally. Two louvered fin heat exchangers in the same sizes with different number of fin rows are tested in a constant temperature test room by a wind-tunnel. The cold fluid flowing on the external side of the heat exchanger is air. The hot fluid flowing through the mini channels is water. The inlet temperature of the water passes through the mini channel flattube is predetermined and supplied at a temperature of 42 o C. Mass flow rate of the water is regulated by a water circulator at a rate of 0.025 kg/s. The mass flow rate of the air is measured 0.0472 kg/s. It is found that the model which has two fin rows is more effective in terms of overall thermal conductance, number of transfer units and effectiveness at all values of inlet temperature of the air. In addition, both of the heat exchangers have the highest thermal performance at an air inlet temperature of 24 o C.

Sustainable Energy Technologies and Assessments, Dec 1, 2020

In this study, thermodynamic inefficiencies of the components and the whole system are quantified... more In this study, thermodynamic inefficiencies of the components and the whole system are quantified by exergy destruction. The performance of an air source heat pump water heater (ASHPWH) is examined experimentally under varying ambient conditions from the exergy destruction aspect. The exergy destruction is calculated for each moment through the entire heating period with regard to collected temperature and pressure data under various ambient conditions. The exergy destructions are examined continuously in a sequence from the beginning to the end of the water heating process. This approximation allows the designer and the manufacturer to see the progress of exergy destruction through the entire heating period to evaluate the performance of every component for avoiding irreversibilities and improving the ASHPWH. During these observations, three individual zones are observed in which the exergy destruction characteristics have changed. Furthermore, the impact of the ambient conditions on these zones is identified either. The thermodynamic properties and exergy destruction values are computed for all data collected by a MATLAB code. The results would be helpful to picture out the true evolution of the exergy destruction from component aspect either solely or combined effect of them during the water heating period.

International Journal of Refrigeration-revue Internationale Du Froid, Feb 1, 2019

In this study, two types of mini-channel condenser are integrated into a household refrigerator i... more In this study, two types of mini-channel condenser are integrated into a household refrigerator in order to increase the performance of the system. Since the integration process requires the substitution of capillary tube which will be followed by charging a different amount of refrigerant, this work focuses on finding the right amount of the refrigerant and the right size of the capillary as well. This experimental study is carried out on a commercial household refrigerator in a climatic chamber with respect to IEC standards. During the experiments, two types of mini-channel condensers have been analyzed with five different capillary lengths and five varying coolant amounts in order to find the best combination for better performance. The outcomes of the study release the thresholds for either capillary length or refrigerant amount, which are 3.25 m and 50 g respectively, that will enlighten the further studies on the same investigations.

Applied Thermal Engineering, Aug 1, 2019

In this particular work, the flat tube with mini-channel compact heat exchangers with offset stri... more In this particular work, the flat tube with mini-channel compact heat exchangers with offset strip fins by non-uniform uninterrupted fin length are investigated experimentally. The tests are performed by four different types of flat tube compact heat exchangers. The tests are conducted in the range of 600<Re a <2000, while water as the heat transfer fluid is circulated at the inlet of the heat exchanger and regulated by a water bath at a temperature of 42 o C. The performance of the heat exchangers is assessed by using Colburn j-factor, friction factor f, area goodness factor j/f and volume goodness factor j/f 1/3. According to the obtained outcomes, the compact heat exchanger with bigger pass number provides better heat transfer. Two different types of strip fins with non-uniform uninterrupted fin length have been tested. The heat exchanger group with 1.55 m length of flat tube shows almost 40% higher performance than the heat exchanger group with 1.20 m length of flat tube.

Energy Conversion and Management, Feb 1, 2017

The duplex Stirling refrigerator is an integrated refrigerator consists of Stirling cycle engine ... more The duplex Stirling refrigerator is an integrated refrigerator consists of Stirling cycle engine and Stirling cycle refrigerator used for cooling. The equality of the work generation of the heat engine to the work consumption of the refrigerator is the primary constraint of the duplex Stirling. The duplex Stirling refrigerator is investigated thermodynamically by considering the effects of constructional and operational parameters which are namely the temperature ratios for heat engine and refrigerator, and the compression ratios for both sides. The primary concern is given to the parametric effects on the overall coefficient of performance of the duplex Stirling refrigerator. The given diagrams provide a design bounds and benchmark results that allows seeing the big picture about the cooling load and heat input relation. Moreover they ease to determine the corresponding work rate to the target cooling load. As regard to the obtained results, a definite region for coefficient of performance of the refrigerator and a definite region for the thermal efficiency of the heat engine of the duplex Stirling are identified.

Applied Energy, Mar 1, 2001

Heat and Mass Transfer, Jan 23, 2004