Heat TransferPub Date : 2025-07-10DOI: 10.1002/htj.70010
Santiago E. Ibáñez, Alberto E. Quintero, Marcos Vera
{"title":"Second-Law Analysis of Mini/Micro Counterflow Parallel-Plate Heat Exchangers: Optimizing Effectiveness by Minimizing Wall Entropy Production","authors":"Santiago E. Ibáñez, Alberto E. Quintero, Marcos Vera","doi":"10.1002/htj.70010","DOIUrl":"https://doi.org/10.1002/htj.70010","url":null,"abstract":"<p>We present an analytical and numerical study of the entropy production rate in laminar counterflow parallel-plate heat exchangers, aiming to investigate the interplay between multidimensional wall conduction, entropy production, and the optimum wall conductivity that leads to maximum effectiveness. The analysis assumes that the Peclet number is sufficiently large to neglect axial conduction in the fluids, while multidimensional wall conduction is retained as the main ingredient of this work. A parametric study is conducted to examine the influence of the two parameters that govern multidimensional wall conduction: the dimensionless wall thickness and the dimensionless wall thermal resistance. The overall entropy balance leads to an approximate relationship between the heat exchanger effectiveness and the rate of entropy production, reflecting the so-called entropy generation paradox. For moderately long heat exchangers with effectiveness above those of coflow systems, it is observed that the maximum effectiveness is correlated to a minimum in overall entropy production, but this result does not hold for shorter heat exchangers with smaller effectiveness. However, the analysis reveals a universal connection between maximum effectiveness and minimum wall entropy production not previously established in the literature, indicating that wall-related factors dominate over fluid-related entropy production in determining optimal heat exchanger operation. These findings are particularly relevant for the design and optimization of compact thermal systems in applications such as microelectronics cooling and aerospace thermal management.</p>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4536-4554"},"PeriodicalIF":2.6,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/htj.70010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heat TransferPub Date : 2025-07-10DOI: 10.1002/htj.70012
Nacer Chouchane, Hammam Chouchane, Saad Mekhilef
{"title":"Experimental Study of the Influence of Rectangular Trapezoidal Ribs on Pressure Drop in a Flat-Plate Air Collector","authors":"Nacer Chouchane, Hammam Chouchane, Saad Mekhilef","doi":"10.1002/htj.70012","DOIUrl":"https://doi.org/10.1002/htj.70012","url":null,"abstract":"<div>\u0000 \u0000 <p>This study experimentally investigates the influence of rectangular–trapezoidal rib configurations on the thermohydraulic performance of a flat-plate solar air collector. Tests were conducted across a Reynolds number range of 1000–12,000, considering variations in rib inclination (30°, 60°, 120°, and 150°), length, spacing, and arrangement (inline vs. staggered). The results show that staggered ribs with reduced spacing significantly improved heat transfer, achieving a maximum thermal efficiency of 39.2%, but at the cost of increased pressure losses reaching 55 Pa. Using Vaschy–Buckingham dimensional analysis, empirical correlations were developed to predict pressure drop and Nusselt number as functions of rib geometry and flow conditions. These correlations demonstrated excellent agreement with experimental data, with coefficients of determination exceeding 0.99. The findings provide valuable tools for designing and optimizing ribbed absorber surfaces in solar thermal systems, enabling a clear trade-off analysis between thermal enhancement and aerodynamic penalty. These results are especially relevant for applications, such as solar air heaters, crop dryers, and ventilation systems, where space and fan power are limited, and performance depends critically on managing both heat transfer and flow resistance.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4568-4587"},"PeriodicalIF":2.6,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237177","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}
Heat TransferPub Date : 2025-07-09DOI: 10.1002/htj.70011
Abdelrahman M. Mourad, Ibrahim M. M. El Moghazy, Ali A. M. Hassan
{"title":"Performance, Exergy, and Economic Analysis of an Evaporative Cooling System With Air Gap: An Experimental Investigation","authors":"Abdelrahman M. Mourad, Ibrahim M. M. El Moghazy, Ali A. M. Hassan","doi":"10.1002/htj.70011","DOIUrl":"https://doi.org/10.1002/htj.70011","url":null,"abstract":"<div>\u0000 \u0000 <p>As global energy demands rise and environmental concerns intensify, evaporative cooling systems emerge as a promising solution to reduce energy consumption and environmental impact. While some studies have demonstrated that air gap spacing between cooling pads improves the energy performance of direct evaporative cooling (DEC) systems, none have explored their exergy and economic performance. This study provides a comprehensive thermal, exergetic, and economic analysis of a DEC system across a broad range of operating circumstances, comparing configurations with and without an air gap between the cooling pads. Tests were carried out using water flow rates of 60 and 35 L/(min·m²) and air velocities ranging from 1 to 3 m/s, under constant inlet conditions of approximately 32°C−33°C dry-bulb temperature and 28%−30% relative humidity. The results showed that the outlet air temperature decreased by 4%–6%, while heat and mass transfer flux increased by 8.2%–10%, leading to improved cooling efficiency. Performance evaluation criterion and water consumption criterion analyses identified a 200-mm pad thickness with an air gap at a flow rate of 35 L/(min·m²) as the most thermally efficient configuration, striking a perfect equilibrium between thermal performance, power consumption, and water usage. Moreover, configurations with an air gap proved to be the most cost-effective, reducing the specific total cost by 6%–9.6%. These findings highlight the potential of air gap configurations to enhance the sustainability and performance of DEC systems, offering an energy-efficient cooling solution that is particularly suitable for environments with limited water resources.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4555-4567"},"PeriodicalIF":2.6,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237364","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}
{"title":"Thermal Stress Analysis and Heat Transfer Optimization in Functionally Graded Annular Fin With Memory-Dependent Effects","authors":"Sunil Prayagi, Pushpak Choudhari, Madhur Natekar, Sahil Gaikwad, Nitin Chandel","doi":"10.1002/htj.70009","DOIUrl":"https://doi.org/10.1002/htj.70009","url":null,"abstract":"<div>\u0000 \u0000 <p>This study examines the thermal stress behavior of functionally graded material (FGM) rectangular-shaped annular fins, utilizing memory-dependent derivatives (MDDs) as an alternative framework to traditional fractional-order theory. The MDD approach enhances physical interpretability and adaptability by incorporating single-phase-lag (SPL) and kernel functions, allowing for more accurate modeling of transient thermoelastic behavior. Material properties, including thermal conductivity, specific heat capacity, heat transfer coefficient, and modulus of elasticity, are expressed as power-law functions along the radial direction, while Poisson's ratio remains constant. Analytical solutions are derived for specific parameter values, and a detailed parametric study evaluates the influence of time delay, kernel functions, and inhomogeneity parameters on thermal stress distribution. The analysis focuses on an FGM structure composed of partially stabilized zirconia (PSZ) particles dispersed within a SUS304 matrix, emphasizing the importance of composition selection in reducing thermal stress. Its ability to withstand high-temperature gradients while minimizing thermal stress enhances durability and performance. Future research can explore advanced computational techniques and experimental validation to optimize its thermal efficiency and mechanical stability further.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4519-4535"},"PeriodicalIF":2.6,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237096","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}
Heat TransferPub Date : 2025-06-29DOI: 10.1002/htj.70013
Virendra Kumar, Paruchuri M. V. Subbarao
{"title":"On-Design and Off-Design Performance of Variable Area Ejectors: A Comparative Study of Constant Rate of Momentum Change and Constant Rate of Kinetic Energy Change Methods","authors":"Virendra Kumar, Paruchuri M. V. Subbarao","doi":"10.1002/htj.70013","DOIUrl":"https://doi.org/10.1002/htj.70013","url":null,"abstract":"<div>\u0000 \u0000 <p>The design of the ejector is crucial, as the overall performance and efficiency of the system depend on its internal geometry, dimensions, and flow characteristics. The present experimental study compares the performance of variable area ejectors developed based on the “constant rate of momentum change (CRMC)” and “constant rate of kinetic energy change (CRKEC).” The pressure recovery ratio (PRR) and entrainment ratio (<i>ω</i>) at on-design operating conditions were computed based on experimental results. The study also optimizes both the ejector's entrainment ratio at off-design conditions and the impact of nozzle exit positions. CRMC ejectors provide higher entrainment ratios (0.512) and lower PRRs (0.178), while CRKEC ejectors provide slightly higher PRRs (0.18) and lower entrainment ratios (0.5) at on-design conditions. The results indicate that both variable-area ejectors based on CRMC and CRKEC have their own advantages and limitations regarding performance and suitability for specific applications.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4588-4595"},"PeriodicalIF":2.6,"publicationDate":"2025-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237318","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}
Heat TransferPub Date : 2025-06-27DOI: 10.1002/htj.70003
C. M. Chaithra, G. K. Kalavathi, M. G. Vasundhara, Gurpartap Singh, Ankur Kulshreshta, M. Sunitha
{"title":"A Wavelet-Based Stochastic Interpretable Physics-Guided Neural Network to Study the Periodic Heat Transport in a Radiative Convex Fin","authors":"C. M. Chaithra, G. K. Kalavathi, M. G. Vasundhara, Gurpartap Singh, Ankur Kulshreshta, M. Sunitha","doi":"10.1002/htj.70003","DOIUrl":"https://doi.org/10.1002/htj.70003","url":null,"abstract":"<div>\u0000 \u0000 <p>The current study investigates the heat transport in the convex profiled fin with radiation and internal heat generation impact. The one-dimensional energy equation of the convex profiled fin is nondimensionalized utilizing appropriate nondimensional variables. The obtained nondimensional energy equation is solved by employing a computational analysis of periodic heat transfer in a radiative convex fin with internal heat generation using a wavelet-inspired physics-based neural network. Further, the influence of several dimensionless constraints on the temperature profile of the convex profiled fin is discussed with the aid of graphs. The convex fins' temperature profile declines as the value of the convection–conduction parameter and the radiation–conduction parameters escalates. The increase in the values of the internal heat generation parameter increases the temperature of the convex profiled fin, and the thermal variation in the convex fin oscillates periodically with varying time. The results of the proposed method are equated with numerical results to validate the efficacy of the approach, signifying accuracy.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4428-4443"},"PeriodicalIF":2.6,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237205","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}
Heat TransferPub Date : 2025-06-20DOI: 10.1002/htj.70006
Muhammed M. Hamza, Dahiru Sani, Godwin Ojemeri, Abdulsalam Shuaibu
{"title":"A Numerical Investigation of Porosity and Suction/Injection Effects on Magnetized Slip Flow Affected by Temperature-dependent Property","authors":"Muhammed M. Hamza, Dahiru Sani, Godwin Ojemeri, Abdulsalam Shuaibu","doi":"10.1002/htj.70006","DOIUrl":"https://doi.org/10.1002/htj.70006","url":null,"abstract":"<div>\u0000 \u0000 <p>Suction/injection impacts are extremely crucial in boundary layer control, especially in engineering, aerodynamics, space research, and medicine. These benefits prompted our quest to further dig into the effect of wall porosity in industrial working fluids. Therefore, this paper analyzes unsteady magnetized slip flow through an upstanding plate in the presence of suction/injection flow due to the actions of porosity effect and thermal conductivity property. The nonlinear partial differential leading equations are modeled and solved numerically using an unconditionally stable semi-implicit finite difference scheme, while the analytical component of the steady-state equations was calculated using the regular perturbation technique. The solutions obtained were presented and discussed in detail using various line graphs. It is concluded that the Darcy porous, injection, and slip flow parameters promote fluid velocity, respectively. However, a counter-feature can be observed: higher suction and magnetic parameter values lead to a drastic reduction in fluid movement, respectively. The outcomes of this study would be helpful for controlling fluid flow in channels as well as aiding the addition and removal of reactants during chemical reactions.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4471-4482"},"PeriodicalIF":2.6,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237367","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}
Heat TransferPub Date : 2025-06-17DOI: 10.1002/htj.70005
Rachid Bendaoud, Said Bounouar, Mohammadi Benhmida, Houssam Amiry, Yassine El Alami, Fatima Chanaa, Elhadi Baghaz
{"title":"Modeling and Experimental Investigation of PV Module Thermal Behavior Based on Energy Balance through Its Different Layers","authors":"Rachid Bendaoud, Said Bounouar, Mohammadi Benhmida, Houssam Amiry, Yassine El Alami, Fatima Chanaa, Elhadi Baghaz","doi":"10.1002/htj.70005","DOIUrl":"https://doi.org/10.1002/htj.70005","url":null,"abstract":"<div>\u0000 \u0000 <p>An increase in operating temperature of the crystalline photovoltaic modules (PVMs) has a significant impact on their electrical efficiency. Accurate determination of this parameter is crucial for a credible evaluation of PVM performance. Due to the difficulty of analytically solving the energy balance equations (EBEs) to determine the temperature profile of the various layers of the PVM, numerical solutions are often chosen. The exact analytical solution of these equations is challenging to achieve due to the complexity of some time-dependent parameters (solar irradiance, ambient temperature, wind speed, front and rear surface temperatures, …) and can only be reached in particular cases. To overcome this difficulty, some approximations are considered and permit the resolution of this problem analytically. In this study, a one-dimensional model is developed. It is based on an analytical solution of the steady-state EBEs. The analytical solution is reached by assuming that the time-varying parameters can be considered constant over more or less long time intervals, depending on the change rate of these parameters. The objective of this study is to propose an analytical model improving the prediction accuracy of the temporal and spatial evolution of the PVM operating temperature compared with literature results; meanwhile, simplifying the estimation process of the various photovoltaic system parameters. The experimental and modeling results obtained are compared with those evaluated using other relevant models. The compatibility between the experimental and model results attests to the reliability of the assumed approximations, with regard to calculated <i>RMSE</i> (0.78) and <i>MBE</i> (0.77) values.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4457-4470"},"PeriodicalIF":2.6,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237304","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}
Heat TransferPub Date : 2025-06-17DOI: 10.1002/htj.70007
Channarong Wantha
{"title":"Performance Enhancement of Refrigeration Systems Using Heat Pipe Subcoolers: An Experimental Investigation","authors":"Channarong Wantha","doi":"10.1002/htj.70007","DOIUrl":"https://doi.org/10.1002/htj.70007","url":null,"abstract":"<div>\u0000 \u0000 <p>This study investigates the performance enhancement of R134a vapor compression refrigeration systems through externally integrated heat pipe subcoolers (HPSCs). It addresses the growing demand for energy-efficient refrigeration by applying a passive subcooling technique that requires no internal system modifications. Four HPSC modules, each comprising three heat pipes and two heat sinks, were installed in series between the condenser outlet and the capillary tube. Experiments conducted at evaporator temperatures of 36°C and 42°C evaluated their effects on cooling capacity, power consumption, and coefficient of performance (COP). The results show that cooling capacity improved by 21%–37% at 36°C and 0.4%–32% at 42°C. At the optimal configuration using four HPSC modules, power consumption changed by only 0.077% at 36°C and 0.171% at 42°C. The normalized COP values increased to 1.38 and 1.32 at 36°C and 42°C, respectively, confirming the effectiveness of passive subcooling in enhancing system efficiency. Unlike previous approaches that required internal modifications or electrical power input, this study offers a simple, passive external retrofit solution suitable for practical subcooling applications without compromising system integrity.</p>\u0000 </div>","PeriodicalId":44939,"journal":{"name":"Heat Transfer","volume":"54 7","pages":"4483-4497"},"PeriodicalIF":2.6,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145237129","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}