Open Access

ARTICLE

Hao Zhu^1,2, Xi Chen^1,2,*, Pengcheng Qu^1,2, Yifan Zhu^1,2, Haoyi Wang^1,2, Yingxia Qi^1,2
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2026.076127
Abstract Pulse tube cryocoolers are widely employed in cryogenic systems, where gas contamination has become a critical factor limiting both performance and service life. To further investigate the condensation behavior of contaminants, this study develops a two-dimensional axisymmetric model of a linear-type cryocooler to simulate the transport and deposition processes of trace CO₂, evaluating the impact of contamination on system pressure drop under various operating conditions. Results indicate that CO₂ diffusion is primarily driven by concentration gradients. The CO₂ deposition rate increases markedly at low temperatures and high concentrations, with over 90% of deposition occurring in the cold-end… More >

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ARTICLE

Luling Li¹, Minghui Li², Zhengxiang Xu², Haofeng Lin², Xuemei Lang², Peiming Li¹, Hengrong Zhang^1,*, Dongxu Ji^3,*, Jian Liu¹, Jianhui Liu¹, Guang Yang¹, Shuanshi Fan^2,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2026.075692
Abstract This study addresses the energy-intensive challenge of small-scale biogas upgrading by optimizing a chemical absorption process employing methyl diethanolamine (MDEA). Focusing on a typical distributed application of 300 Nm³/d, we developed an integrated simulation-optimization framework using Aspen HYSYS 14.0 to systematically evaluate the effects of critical operating parameters—absorption pressure, MDEA concentration, flow rate, temperature, number of trays, and reboiler duty—on methane purity and energy consumption. The key finding is the identification of an optimal parameter set: absorption pressure of 1200 kPa, MDEA concentration of 20 mol%, lean flow rate of 2.5 kmol/h, temperature of 298.15 K,… More >

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ARTICLE

Ratan Kumar Chanda¹, Rakesh Bhowmick², Giulio Lorenzini^3,*, Rabindra Nath Mondal^1,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.075311
Abstract Due to ample engineering and industrial applications involving electrically conducting fluids, such as in magnetic flow control devices, thermal magnetic systems, magnetic filtration and separation, and fluid transport in curved rotating channels, the present study examines the impacts of pressure-induced instability characteristics and chaotic nature of Magneto-hydrodynamic fluid flow in a rotating curved square duct (CSD), incorporating Hall and ion-slip currents. The rotational speed (Ω_T) around the vertical axis of the duct is constant while a variable transverse magnetic field is applied perpendicular to the fluid. The numerical solutions are obtained through the spectral method as a… More >

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ARTICLE

Linkang Wang¹, Bowei Xie^2,3,4,*, Zhiqiang Liu¹, Lijing Yi^2,3,4, Mu Du^2,3,4,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2026.076486
Abstract The Local Surface Plasma Resonance (LSPR) of spherical metal particles is typically only observed within the visible spectrum. This inherent property renders modulation through alterations in radius or material challenging, significantly constraining its practical applications. In this work, we propose a super-elliptic gold nanoparticle model that allows for the continuous modulation of particle geometry from spherical to star-like shapes using a single roundness parameter (e). Unlike conventional nanorods or discrete nanostars, this geometry provides a unified framework to investigate the evolution of multipole resonances. The radiation characteristics of super elliptic gold nanoparticles in the range of… More >

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Open Access

ARTICLE

Geqiang Li^1,2, Kai Wang¹, Juntao Liu³, Zhengyang Han^1,2, Shuai Wang^1,2,*, Donglin Li^1,2
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.075249
Abstract To explore the distribution law of the temperature field in the motor pump and the influence of the fan-shaped DC channel with spoiler in the pump housing on its heat dissipation performance. This study takes the arc-gear type hydraulic motor pump as the research object. In COMSOL, a coupled heat transfer simulation model of the motor pump’s fluid-solid coupling is established, and the internal temperature field characteristics are analyzed. To improve the heat dissipation effect of the motor pump, it is proposed to arrange spoiler in the fan-shaped DC channel of the pump housing to… More >

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Open Access

ARTICLE

Yendoubouame Lare^1,2,*, Koffi Sagna^1,2, Amah Séna d’Almeida³
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.074506
（This article belongs to the Special Issue: Heat and Mass Transfer on A Small Temporal and Spatial Scale)
Abstract This study presents a numerical investigation of the transient relaxation dynamics of a near-critical CO₂ droplet immersed in a warmer supercritical environment composed of the same fluid. Three thermodynamic regimes were analysed: quasi-critical (Tr=1.01,Pr=1.01), transitional (Tr=2.01,Pr=1.01), and deep supercritical (Tr=5.01,Pr=3.01). The evolution of density, temperature, and velocity fields was examined to characterize the internal structure and stability of the interfacial transition layer. The evolution of density, temperature, and velocity fields highlights the competition between thermal diffusion, compressibility, and mass confinement in shaping the stability of the interfacial transition layer. Near the critical point, strong More >

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REVIEW

Muhammad Waheed Azam^1,*, Uzair Sajjad^2,*, Faisal Maqbool³, Giovani Sempirini⁴
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.074690
Abstract Heat exchangers play a crucial role in thermal energy systems, with their performance directly impacting efficiency, cost, and environmental impact. A powerful technique for performance improvement can be given by passive enhancement strategies, which are characterized by their dependability and minimal external power requirements. This comprehensive review critically assesses recent advancements in such passive methods to evaluate their heat transfer mechanisms, performance characteristics, and practical implementation challenges. Our methodology involves a systematic and comprehensive analysis of various heat transfer enhancement techniques, including surface modifications, extended surfaces, swirl flow devices, and tube inserts. This approach synthesizes… More >

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ARTICLE

Wei Dong¹, Baoqi Guo², Weiwei Zhao², Hui Jian², Zhenzong He^2,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.075848
Abstract This study explores the design of a tapered cathode flow channel in a proton exchange membrane fuel cell (PEMFC), leveraging artificial intelligence and multi-objective optimization techniques to attain an optimal configuration. First, the influence of the channel height ratio and mass flow rate on PEMFC performance was systematically examined. The results reveal that decreasing the height ratio and increasing the mass flow rate lead to reduction in the standard deviation of current density, accompanied by a monotonic rise in pressure drop. The average current density initially rises before exhibiting a slight decline. Subsequently, a surrogate… More >

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Open Access

ARTICLE

Josmell Alva Alcántara¹, Elder Mendoza Orbegoso¹, Nattan Roberto Caetano², Luis Julca Verástegui¹, Juan Bengoa Seminario¹, Jimmy Silvera Otañe¹, Yvan Leiva Calvanapón¹, Giulio Lorenzini^3,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.074995
Abstract The continuous improvement of solar thermal technologies is essential to meet the growing demand for sustainable heat generation and to support global decarbonization efforts. This study presents the design, implementation, and validation of a real-time monitoring framework based on the Internet of Things (IoT) and cloud computing to enhance the thermal performance of evacuated tube solar water heaters (ETSWHs). A commercial system and a custom-built prototype were instrumented with Industry 4.0 technologies, including platinum resistance temperature detectors (PT100), solar irradiance and wind speed sensors, a programmable logic controller (PLC), a SCADA interface, and a cloud-connected… More >

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ARTICLE

E. V. Macias-Melo¹, P. R. Torres-Hernández², K. M. Aguilar-Castro¹, I. Hernández-Pérez¹, P. García-Alamilla³, C. E. Torres-Aguilar¹, M. I. Hernández-López⁴, S. Medina García⁴, J. Serrano-Arellano^4,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.074900
Abstract This study presents the design, construction, and thermal evaluation of a solar-powered cocoa roaster based on a Parabolic Cylinder Collector (PCC) with dual-axis solar tracking. The system integrates three functional subsystems: the cylindrical-parabolic reflecting surface, the stainless-steel absorber tube, and a microcontroller-based tracking mechanism. The prototype enables continuous acquisition of key thermal variables (solar irradiance, ambient temperature, absorber surface temperature, and bean temperature), allowing a detailed characterization of heat transfer processes during roasting. Roasting experiments were conducted at controlled durations of 40, 55, and 70 min between 10:00 and 14:00 h. Maximum roasting temperatures of… More >

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Open Access

ARTICLE

Kai Song¹, Lishan Feng¹, Shugang Duan¹, Weilong Zhao², Haikun Zheng^3,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.074404
（This article belongs to the Special Issue: Advances in Microscale Fluid Flow, Heat Transfer, and Phase Change)
Abstract This study experimentally investigates the influence of surface wettability on the frosting characteristics of three types of corrugated structures (Types A, B, and C) under controlled low-temperature conditions. The experiments were conducted in a constant-temperature bath at a cold surface temperature of –5°C, relative humidity of 90%, and ambient air temperature of 10°C. The results reveal that the variation trends of frost morphology, frost mass, and frost layer thickness are generally consistent across surfaces with different wettability. Among the tested surfaces, frost crystal formation and complete surface coverage occurred latest on the superhydrophobic surface (CA =… More >

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ARTICLE

Zheming Cheng^1,*, Xinping OuYang², Leren Tao², Zihao Wang², Ke Sun²
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2025.074325
Abstract Energy shortage has become one of the most concerning issues in the world today, and improving energy utilization efficiency is a key area of research for experts and scholars worldwide. Small-diameter heat exchangers offer advantages such as reduced material usage, lower refrigerant charge, and compact structure. However, they also face challenges, including increased refrigerant pressure drop and smaller heat transfer area inside the tubes. This paper combines the advantages and disadvantages of both small and large-diameter tubes and proposes a combined-diameter heat exchanger, consisting of large and small diameters, for use in the indoor units… More >

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