Hussam J. Rashid, Mohammed K. Al-Saadi, Ameer Abed Jaddoa^*

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.083008 - 29 June 2026

Abstract An extensive experimental investigation was performed on the thermal, exergetic, and thermo-hydraulic performance of a corrugated multi-duct solar air heater (SAH) incorporating constrained twisted tape inserts under real outdoor conditions. A photovoltaic (PV)-powered DC blower was employed to supply the airflow, and four setups were tested: a smooth absorber plate, corrugated ducts, and corrugated ducts with one or two twisted tape inserts. The Reynolds number ranged from 2000 to 10,000. The results indicate that the configuration with two twisted tape inserts achieved the highest value of thermal efficiency under optimal operating conditions, with the useful… More >

Wenxin Luo¹, Kaiwen Wang¹, Pugalenthiyar Thondaiman², Qianqian Wang^1,*

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.082228 - 29 June 2026

Abstract Hydrogen (H₂) crossover in proton exchange membrane fuel cells (PEMFCs) reduces performance and poses safety risks, but its behavior under rapidly changing loads, which are common in vehicles, is not well understood. To address this, we developed a three-dimensional, two-phase, non-isothermal model that tracks H₂ from dissolution in the anode, through transport across the membrane, to reaction at the cathode. The analysis shows that diffusion dominates whereas convection contributes little. Key findings are as follows: H₂ crossover reduces the open-circuit voltage by 210 mV and raises cathode temperature by approximately 0.2°C; reducing the membrane thickness from 20… More >

Min Li¹, Haijun Luan¹, Ming Chi¹, Sen Chen¹, Yang Chen¹, Jiarui Cheng^2,*, Tian Xie^2,*, Rui Wang²

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.081419 - 29 June 2026

Abstract This study used simulated formation water (15 g/L CaCl₂) from a certain area of Xinjiang Oilfield as the experimental medium., and employed a high-pressure sealed reaction vessel and a sapphire window to systematically investigate the effects of water content (30%–70%), initial pressure (2–14 MPa), and the intervention of CH₄ on the critical point of CO₂ hydrate formation. The differences between the ‘visual confirmation’ method and the temperature-pressure curve inflection point method for determining hydrate formation were also compared. The study found that in a single CO₂ system under a constant pressure of 5 MPa and a water… More >

Lihan Sun¹, Junze Gong², Jinteng Lv^3,*, Mingfei Mu^3,*

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.081417 - 29 June 2026

Abstract Geothermal-solar hybrid power generation has been widely recognized as a promising application within the realm of renewable energy, as such hybridization mitigates solar intermittency while enhancing the utilization of medium-temperature geothermal resources, thus enabling effective energy complementarity. To quantitatively investigate its performance enhancement over single-source systems, this study constructs and analyzes three Organic Rankine Cycle (ORC) based plants with a capacity of approximately 500 kW: a standalone solar ORC, a standalone geothermal ORC, and a hybrid geothermal-solar ORC system. A comprehensive analysis encompassing both design-point and annual off-design operations is conducted, followed by an economic… More >

Rukun Hu¹, Liao Zhang¹, Wenbin Han¹, Wei Chen¹, Bo Ma¹, Xuan Liu¹, Yongzhi Lei¹, Qian Lu¹, Yuanji Li², Xiaohu Yang^2,*

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.081154 - 29 June 2026

Abstract To enhance the efficiency of phase change heat storage, this study investigates the synergistic effects and parameter interactions of a coupled strategy integrating fins, metal foam, and nanoparticles. A validated numerical model is developed for a shell-and-tube heat storage unit. The influence of porosity and pore density of metal foam, as well as Al₂O₃ nanoparticle concentration, on melting behavior, heat storage rate, and fluid flow features are systematically analyzed. Results indicate that reducing porosity significantly enhances heat conduction, shortening the complete melting time by up to 53.71%. Conversely, increasing pore density markedly suppresses natural convection, reducing… More >

Haojie Ju, Ming Zhao^*

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.080844 - 29 June 2026

Abstract This paper employs the Lattice Boltzmann Method (LBM) to investigate the nonlinear characteristics of natural convection in toroidal spaces with radius ratios of 2.6, 1.6, 1.4, and 1.2. Based on the maximum Lyapunov exponent, runs test, and phase space trajectory, the transition from steady-state to chaotic state is analyzed. The results show that with increasing Rayleigh number (Ra), the toroidal system successively experiences a steady state, a periodic oscillation state, a quasi-periodic oscillation state, and finally enters a chaotic state. For example, when the radius ratio is 2.6, these transitions occur at Ra values of 5 More >

Lihao Lu^1,2, Yan Lu^1,2, Zhenhua Jiang^1,2, Shaoshuai Liu^1,2,*, Yinong Wu^1,2

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.080328 - 29 June 2026

Abstract Sub-Kelvin cooling technology is a critical prerequisite for high-sensitivity detection in deep space exploration and quantum computing. Operating identical sorption coolers in parallel is a common engineering approach to enhance cooling capacity and extend hold time for these cryogenic platforms. However, this study reports an unexpected “symmetry breaking” phenomenon observed in a parallel Helium-4 sorption cooling system where the cold heads are connected via Oxygen-Free High Thermal Conductivity (OFHC) copper linkages. Instead of the expected uniform load sharing, the system spontaneously evolves into an asymmetric “quasi-series” operational mode. In this state, one cooler preferentially consumes… More >

Kaiwen Cheng¹, Yi Sun², Dong Wang^3,*, Chen Zhu², Fuping Qian^2,*

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.080306 - 29 June 2026

Abstract Rotary gas-gas heat exchangers (GGHs) are pivotal for waste heat recovery in low- and medium-temperature denitrification systems of cement kilns. This study examines the performance of GGHs within such systems by coupling computational fluid dynamics (CFD) with the response surface method (RSM), introducing overall system performance (OSP) as the principal optimization criterion. The investigation systematically elucidates the effects of treated flue gas inlet temperature, inlet velocity, and rotor speed on GGH efficiency. Findings reveal that OSP increases with rotor speed but reaches a plateau beyond 1 rpm; it decreases with higher inlet velocity and increases… More >

Da Fang¹, Xianbing Chen^2,*, Chenxiao Chu^3,*, Xinhou Liu⁴, Mengyu Zhu⁵, Jinliang Zhu⁶

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.079777 - 29 June 2026

Abstract A three-dimensional numerical model of a water-driven steam ejector was developed using the Euler-Euler two-fluid framework. A direct-contact condensation (DCC) heat and mass transfer model was employed to simulate the complex two-phase flow and energy exchange. The distributions of gas-liquid phases, pressure, and temperature were obtained to evaluate performance. Results indicate that within the investigated operating range (p_p = 140–160 kPa), the entrainment ratio (ER) and temperature rise (DT) are highly coupled, with DT varying from 5.33 to 11.49 K. The maximum temperature rise of 11.49 K was achieved at p_p = 140 kPa, T_p = 310 K,… More >

Yanfeng Li^1,2, Xiaohui Zhang^1,2,*, Luyang Chen^3,*, Rong Chen⁴, Shan Qing³

Frontiers in Heat and Mass Transfer, Vol.24, No.3, 2026, DOI:10.32604/fhmt.2026.079549 - 29 June 2026

Abstract Highly integrated micro-nano electronic devices suffer from severe heat dissipation challenges, and flow cooling in nanochannels is an effective solution. During convective heat transfer at liquid-solid interfaces, surface wettability and rough morphology are key parameters governing thermal transport; however, their combined effects remain unclear. In this study, molecular dynamics simulations are utilized to examine the synergistic effects of surface wettability and nanopillar arrays on thermal transport and fluid dynamics within nanochannels. The results show that increasing surface hydrophilicity and roughness reduces the thermal slip length and increases the Nusselt number, thereby enhancing heat transfer performance… More >