S. Deosarkar, S. Birajdar, R. Sawale, M. P. Pawar, A. Thakre
The paper deals with the calculation of molar refraction () and polarizability () of antibiotic drug ciprofloxacin hydrochloride ( = 0.001–0.029 mol·dm−3) solutions in ethanol-water mixtures of different compositions (30, 50, and 70% v/v) from measured density () and refractive index () at 30°C. The effect of drug concentration and composition of ethanol-water mixtures on density and optical properties of drug solutions has been described.
{"title":"Density and Optical Properties of {Ciprofloxacin Hydrochloride + Aqueous-Ethanol} Mixtures at 30°C","authors":"S. Deosarkar, S. Birajdar, R. Sawale, M. P. Pawar, A. Thakre","doi":"10.1155/2016/1575836","DOIUrl":"https://doi.org/10.1155/2016/1575836","url":null,"abstract":"The paper deals with the calculation of molar refraction () and polarizability () of antibiotic drug ciprofloxacin hydrochloride ( = 0.001–0.029 mol·dm−3) solutions in ethanol-water mixtures of different compositions (30, 50, and 70% v/v) from measured density () and refractive index () at 30°C. The effect of drug concentration and composition of ethanol-water mixtures on density and optical properties of drug solutions has been described.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91495990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research aims to study, analyze, design, and construct a solar air heater combined with an appropriate phase-change material (PCM) unit. This solar air heater is analogous to a collector integrating a thermal storage unit and a solar thermal collector. In this study, such single-pass solar air heater in amalgamation with PCM was constructed, and several tests were conducted on this device. During the experiments for the solar collector with PCM (spherical capsules), the temperature varied between 30°C and 35°C, and the air mass flow rate ranged between 0.03 and 0.09 kg/s. Results confirmed the predicted experimental findings. With the use of paraffin wax-aluminum composite, the thermal storage efficiency of the constructed solar air heater reached a maximum value of 71% at 0.05 kg/s mass flow rate, its charging time decreased by almost 70%, and its cooling rate increased. The thermal storage efficiency of the compound composite was 76.8% at 0.07 kg/s mass flow rate. The results also indicated that the time of charging decreased by almost 60% with the use of paraffin wax-aluminum composite.
{"title":"Enhancement of Integrated Solar Collector with Spherical Capsules PCM Affected by Additive Aluminum Powder","authors":"Fatah O. Al Ghuol, K. Sopian, S. Abdullah","doi":"10.1155/2016/1604782","DOIUrl":"https://doi.org/10.1155/2016/1604782","url":null,"abstract":"This research aims to study, analyze, design, and construct a solar air heater combined with an appropriate phase-change material (PCM) unit. This solar air heater is analogous to a collector integrating a thermal storage unit and a solar thermal collector. In this study, such single-pass solar air heater in amalgamation with PCM was constructed, and several tests were conducted on this device. During the experiments for the solar collector with PCM (spherical capsules), the temperature varied between 30°C and 35°C, and the air mass flow rate ranged between 0.03 and 0.09 kg/s. Results confirmed the predicted experimental findings. With the use of paraffin wax-aluminum composite, the thermal storage efficiency of the constructed solar air heater reached a maximum value of 71% at 0.05 kg/s mass flow rate, its charging time decreased by almost 70%, and its cooling rate increased. The thermal storage efficiency of the compound composite was 76.8% at 0.07 kg/s mass flow rate. The results also indicated that the time of charging decreased by almost 60% with the use of paraffin wax-aluminum composite.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89508164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present investigation deals with the deformation in micropolar thermoelastic diffusion medium due to inclined load subjected to thermal laser pulse. Normal mode analysis technique is used to solve the problem. The inclined load is assumed to be a linear combination of a normal load and a tangential load. The closed form expressions of normal stress, tangential stress, couple stress, temperature distribution, and mass concentration are obtained. A computer program has been developed to derive the physical quantities numerically. The variation of normal stress, tangential stress, coupled stress, temperature change, and mass concentration is depicted graphically to show the effect of relaxation times and mass concentration. Some particular cases of interest are deduced from the present investigation.
{"title":"Elastodynamic Response of Thermal Laser Pulse in Micropolar Thermoelastic Mass Diffusion Medium","authors":"Rajneesh Kumar, Arvind Kumar","doi":"10.1155/2016/6163090","DOIUrl":"https://doi.org/10.1155/2016/6163090","url":null,"abstract":"The present investigation deals with the deformation in micropolar thermoelastic diffusion medium due to inclined load subjected to thermal laser pulse. Normal mode analysis technique is used to solve the problem. The inclined load is assumed to be a linear combination of a normal load and a tangential load. The closed form expressions of normal stress, tangential stress, couple stress, temperature distribution, and mass concentration are obtained. A computer program has been developed to derive the physical quantities numerically. The variation of normal stress, tangential stress, coupled stress, temperature change, and mass concentration is depicted graphically to show the effect of relaxation times and mass concentration. Some particular cases of interest are deduced from the present investigation.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76943606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study focuses on the preparation of the water-based phase change material (PCM) with very small soya oil solution for low temperature latent heat thermal energy storage (LHTES). Soya oil ester is soluble very well in water and acts as nucleating agent for a novel solid-liquid PCM candidate that is suitable for low temperature cool storage in the range between −9°C and −6°C. Thermal energy storage properties of the water with very small soya oil ester solution were measured by T-history method. The experimental results show that very small amount of soya oil ester in water can lower the freezing point and trigger ice nucleation for elimination of the supercooling degree. The phase transition temperatures of the water-based PCMs with soya oil as nucleate agent were lower than those of individual water. The thermal properties make it potential PCM for LHTES systems used in low temperature cool energy storage applications.
{"title":"The Role of Soya Oil Ester in Water-Based PCM for Low Temperature Cool Energy Storage","authors":"I. Rasta, I. Wardana, N. Hamidi, M. N. Sasongko","doi":"10.1155/2016/5384640","DOIUrl":"https://doi.org/10.1155/2016/5384640","url":null,"abstract":"This study focuses on the preparation of the water-based phase change material (PCM) with very small soya oil solution for low temperature latent heat thermal energy storage (LHTES). Soya oil ester is soluble very well in water and acts as nucleating agent for a novel solid-liquid PCM candidate that is suitable for low temperature cool storage in the range between −9°C and −6°C. Thermal energy storage properties of the water with very small soya oil ester solution were measured by T-history method. The experimental results show that very small amount of soya oil ester in water can lower the freezing point and trigger ice nucleation for elimination of the supercooling degree. The phase transition temperatures of the water-based PCMs with soya oil as nucleate agent were lower than those of individual water. The thermal properties make it potential PCM for LHTES systems used in low temperature cool energy storage applications.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73824753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. M. Pérez, D. Lorenzo, L. P. R. Garcia, Manuel Cadavid Rodríguez, C. D. O. Lira, C. Hernández, Jesús Salomón Llanes
is a very useful radioisotope, which is used in nearly 80% of all nuclear medicine procedures. is produced from 99Mo decay. A potentially advantageous alternative to meeting current and future demand for 99Mo is the use of Aqueous Homogeneous Reactors (AHR). In this paper, a thermal-hydraulics study of the core of a 75 kWth AHR conceptual design based on the ARGUS reactor for 99Mo production is presented. As the ARGUS heat removal systems were designed for working at 20 kWth, the main objective of the thermal-hydraulics study was evaluating the heat removal systems in order to show that sufficient cooling capacity exists to prevent fuel solution overheating. The numerical simulations of an AHR model were carried out using the Computational Fluid Dynamic (CFD) code ANSYS CFX 14. Evaluation shows that the ARGUS heat removal systems working at 75 kWth are not able to provide sufficient cooling capacity to prevent fuel solution overheating. To solve this problem, the number of coiled cooling pipes inside the core was increased from one to five. The results of the CFD simulations with this modification in the design show that acceptable temperature distributions can be obtained.
{"title":"Thermal-Hydraulics Study of a 75 kWth Aqueous Homogeneous Reactor for 99Mo Production","authors":"D. M. Pérez, D. Lorenzo, L. P. R. Garcia, Manuel Cadavid Rodríguez, C. D. O. Lira, C. Hernández, Jesús Salomón Llanes","doi":"10.1155/2015/268034","DOIUrl":"https://doi.org/10.1155/2015/268034","url":null,"abstract":"is a very useful radioisotope, which is used in nearly 80% of all nuclear medicine procedures. is produced from 99Mo decay. A potentially advantageous alternative to meeting current and future demand for 99Mo is the use of Aqueous Homogeneous Reactors (AHR). In this paper, a thermal-hydraulics study of the core of a 75 kWth AHR conceptual design based on the ARGUS reactor for 99Mo production is presented. As the ARGUS heat removal systems were designed for working at 20 kWth, the main objective of the thermal-hydraulics study was evaluating the heat removal systems in order to show that sufficient cooling capacity exists to prevent fuel solution overheating. The numerical simulations of an AHR model were carried out using the Computational Fluid Dynamic (CFD) code ANSYS CFX 14. Evaluation shows that the ARGUS heat removal systems working at 75 kWth are not able to provide sufficient cooling capacity to prevent fuel solution overheating. To solve this problem, the number of coiled cooling pipes inside the core was increased from one to five. The results of the CFD simulations with this modification in the design show that acceptable temperature distributions can be obtained.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89785923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The universal scaling concept is applied to the low-temperature range of any liquid states and substances located between the melting () and normal boiling () points far away from the critical region. The physical reason to develop such approach is the revealed collapse of all low-temperature isotherms onto the single universal one argued by the model of fluctuational thermodynamics (FT) proposed recently by author. The pressure reduced by the molecular parameters of the effective short-range Lennard-Jones (LJ) potential depends here only on the reduced density. To demonstrate the extraordinary predictive abilities of the developed low-temperature scaling model it has been applied to the prediction of equilibrium and transport (kinetic and dynamic viscosity, self-diffusion, and thermal conductivity) properties not only for molecular liquids but also for molten organic salts termed ionic liquids (ILs). The best argument in favor of the proposed methodology is the appropriate consistency with the scarce experiments prediction of transport coefficients for ILs on the base of universal scaling function constructed for the simplest LJ-like liquid argon. The only input data of any substance for prediction are the linear approximations of -dependent density and isobaric heat capacity taken from the standard measurements at atmospheric pressure.
{"title":"Scaling Model of Low-Temperature Transport Properties for Molecular and Ionic Liquids","authors":"V. Rogankov","doi":"10.1155/2015/208486","DOIUrl":"https://doi.org/10.1155/2015/208486","url":null,"abstract":"The universal scaling concept is applied to the low-temperature range of any liquid states and substances located between the melting () and normal boiling () points far away from the critical region. The physical reason to develop such approach is the revealed collapse of all low-temperature isotherms onto the single universal one argued by the model of fluctuational thermodynamics (FT) proposed recently by author. The pressure reduced by the molecular parameters of the effective short-range Lennard-Jones (LJ) potential depends here only on the reduced density. To demonstrate the extraordinary predictive abilities of the developed low-temperature scaling model it has been applied to the prediction of equilibrium and transport (kinetic and dynamic viscosity, self-diffusion, and thermal conductivity) properties not only for molecular liquids but also for molten organic salts termed ionic liquids (ILs). The best argument in favor of the proposed methodology is the appropriate consistency with the scarce experiments prediction of transport coefficients for ILs on the base of universal scaling function constructed for the simplest LJ-like liquid argon. The only input data of any substance for prediction are the linear approximations of -dependent density and isobaric heat capacity taken from the standard measurements at atmospheric pressure.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88346919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A numerical study is conducted to clarify fluid-flow characteristics, pressure drop coefficient (), and the average skin friction coefficient () for wing-shaped-tubes bundle with longitudinal fins at downstream side of the tube using the commercial CFD FLUENT software package. The air-side ranges from 1800 to 9700. The tubes are employed with various fin heights () and fin thicknesses () such as 2 mm ≤ ≤ 12 mm and 1.5 mm ≤ ≤ 3.5 mm at the considered range. Results indicate that increases with for all . decreases with for all values for 1800 ≤ ≤ 4200 and then increases for 4200 ≤ ≤ 10000. Lowest values of , , and pumping power (PP) occurred at = 6 mm. Values of for = 6 mm are lower than those of NOF and = 2 mm by about 73 % and 32 %, respectively, at = 4000. decreases with . has negligible effect on . increases for 1.5 mm ≤ ≤ 2.5 mm while decreases with 2.5 mm < ≤ 3.5 mm for the considered range except for = 1850.
{"title":"Effect of Longitudinal-External-Fins on Fluid Flow Characteristics for Wing-Shaped Tubes Bundle in Crossflow","authors":"Sayed Ahmed, O. Mesalhy, Mohamed A. Abdelatief","doi":"10.1155/2015/542405","DOIUrl":"https://doi.org/10.1155/2015/542405","url":null,"abstract":"A numerical study is conducted to clarify fluid-flow characteristics, pressure drop coefficient (), and the average skin friction coefficient () for wing-shaped-tubes bundle with longitudinal fins at downstream side of the tube using the commercial CFD FLUENT software package. The air-side ranges from 1800 to 9700. The tubes are employed with various fin heights () and fin thicknesses () such as 2 mm ≤ ≤ 12 mm and 1.5 mm ≤ ≤ 3.5 mm at the considered range. Results indicate that increases with for all . decreases with for all values for 1800 ≤ ≤ 4200 and then increases for 4200 ≤ ≤ 10000. Lowest values of , , and pumping power (PP) occurred at = 6 mm. Values of for = 6 mm are lower than those of NOF and = 2 mm by about 73 % and 32 %, respectively, at = 4000. decreases with . has negligible effect on . increases for 1.5 mm ≤ ≤ 2.5 mm while decreases with 2.5 mm < ≤ 3.5 mm for the considered range except for = 1850.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77917724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thermodynamic modeling of surface tension of different electrolyte systems in presence of gas phase is studied. Using the solid-liquid equilibrium, Langmuir gas-solid adsorption and ENRTL activity coefficient model, the surface tension of electrolyte solutions are calculated. The new model has two adjustable parameters which could be determined by fitting the experimental surface tension of binary aqueous electrolyte solution in single temperature. Then the values of surface tension for other temperature in binary and ternary system of aqueous electrolyte solution are predicted. The average absolute deviations for calculation of surface tension of binary and mixed electrolyte systems by new model are 1.98 and 1.70%, respectively.
{"title":"Thermodynamic Modeling of Surface Tension of Aqueous Electrolyte Solution by Competitive Adsorption Model","authors":"M. J. Kamali, Zakarya Kamali, G. Vatankhah","doi":"10.1155/2015/319704","DOIUrl":"https://doi.org/10.1155/2015/319704","url":null,"abstract":"Thermodynamic modeling of surface tension of different electrolyte systems in presence of gas phase is studied. Using the solid-liquid equilibrium, Langmuir gas-solid adsorption and ENRTL activity coefficient model, the surface tension of electrolyte solutions are calculated. The new model has two adjustable parameters which could be determined by fitting the experimental surface tension of binary aqueous electrolyte solution in single temperature. Then the values of surface tension for other temperature in binary and ternary system of aqueous electrolyte solution are predicted. The average absolute deviations for calculation of surface tension of binary and mixed electrolyte systems by new model are 1.98 and 1.70%, respectively.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74467856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A Rijke tube with a distributed heat source is investigated. Driven by the widely existing thermoacoustic instability in lean premixed gas turbine combustors, this work aims to explore the physicochemical underpinning and assist in the elucidation and analysis of this problem. The heat release model consists of a row of distributed heat sources with individual heat release rates. The integrated heat release rate is then coupled with the acoustic perturbation for thermoacoustic analysis. A continuation approach is employed to conduct the bifurcation analysis and capture the nonlinear behaviour inherent in the system. Unlike the conventional approach by the Galerkin method, the acoustic equations are originally discretized using the Method of Lines (MOL) to build up a dynamic system. The model is first validated and shown to yield good predictions with available experimental data. Influences of multiple heat sources, time delay, and heat release distribution are then studied to reveal the extensive nonlinear characteristics involved in the case of a distributed heat source. It is found that distributed heat source plays an important role in determining the stability of a thermoacoustic system.
{"title":"Thermoacoustic Instability in a Rijke Tube with a Distributed Heat Source","authors":"Xiaochuan Yang, A. Turan, S. Lei","doi":"10.1155/2015/949384","DOIUrl":"https://doi.org/10.1155/2015/949384","url":null,"abstract":"A Rijke tube with a distributed heat source is investigated. Driven by the widely existing thermoacoustic instability in lean premixed gas turbine combustors, this work aims to explore the physicochemical underpinning and assist in the elucidation and analysis of this problem. The heat release model consists of a row of distributed heat sources with individual heat release rates. The integrated heat release rate is then coupled with the acoustic perturbation for thermoacoustic analysis. A continuation approach is employed to conduct the bifurcation analysis and capture the nonlinear behaviour inherent in the system. Unlike the conventional approach by the Galerkin method, the acoustic equations are originally discretized using the Method of Lines (MOL) to build up a dynamic system. The model is first validated and shown to yield good predictions with available experimental data. Influences of multiple heat sources, time delay, and heat release distribution are then studied to reveal the extensive nonlinear characteristics involved in the case of a distributed heat source. It is found that distributed heat source plays an important role in determining the stability of a thermoacoustic system.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78605930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
3D numerical investigations are performed to study the heat transfer, friction factor, and thermal performance of a fin-and-oval heat exchanger with punched delta wings for a range of 500 ≤ Re ≤ 2500 (based on the hydraulic diameter). The influences of the punched angles, 20°, 30°, and 45°, flow directions, wing tips pointing downstream and upstream, and pitch ratios, 2, 3, 4, 5, and 6, are investigated. The results show that the use of the punched delta wings in the fin-and-oval-tube heat exchanger leads to an enhancement in the heat transfer and friction loss as compared to the plain fin for all cases (/ and higher than 1). The enhancements of the heat transfer and friction factor are around 1.01–1.22 and 1.37–2.65 times higher than the base case, respectively. The punched delta wings create the vortex flows through the test section that helps enhance the strength of the impinging flow on the tube walls. The impingement of the fluid flow is an important key to augment the heat transfer rate and thermal performance in the heat exchanger.
{"title":"The Influence of the Punched Delta Wings on Flow Pattern and Heat Transfer Characteristic in a Fin-and-Oval-Tube Heat Exchanger","authors":"A. Boonloi","doi":"10.1155/2015/368960","DOIUrl":"https://doi.org/10.1155/2015/368960","url":null,"abstract":"3D numerical investigations are performed to study the heat transfer, friction factor, and thermal performance of a fin-and-oval heat exchanger with punched delta wings for a range of 500 ≤ Re ≤ 2500 (based on the hydraulic diameter). The influences of the punched angles, 20°, 30°, and 45°, flow directions, wing tips pointing downstream and upstream, and pitch ratios, 2, 3, 4, 5, and 6, are investigated. The results show that the use of the punched delta wings in the fin-and-oval-tube heat exchanger leads to an enhancement in the heat transfer and friction loss as compared to the plain fin for all cases (/ and higher than 1). The enhancements of the heat transfer and friction factor are around 1.01–1.22 and 1.37–2.65 times higher than the base case, respectively. The punched delta wings create the vortex flows through the test section that helps enhance the strength of the impinging flow on the tube walls. The impingement of the fluid flow is an important key to augment the heat transfer rate and thermal performance in the heat exchanger.","PeriodicalId":17290,"journal":{"name":"Journal of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77743570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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