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Jiangfeng Guo^1,2,3,*, Hongjie Yu¹
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1575-1595, 2024, DOI:10.32604/fhmt.2024.058179 - 19 December 2024
Abstract Based on the first and second laws of thermodynamics, the heat transfer and flow (thermohydraulic) characteristics of horizontal supercritical pressure CO₂ (S-CO₂) in a circular pipe under heating conditions were investigated numerically. Heating flows in two different diameters (d) of 4 and 6 mm were simulated in pipes with pressures of 8 MPa, mass fluxes (G) of 300 and 400 kg/(m²·s), and heat fluxes (q) of 50, 75 and 100 kW/m². In the d = 4 mm pipe, the peak heat transfer coefficient (h_b) was about 3 times higher than in the d = 6 mm pipe, while the entropy… More >

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Boris Borisov, Geniy Kuznetsov, Vyacheslav Maksimov^*, Tatiana Nagornova, Felix Salikhov
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1597-1612, 2024, DOI:10.32604/fhmt.2024.056758 - 19 December 2024
（This article belongs to the Special Issue: Heat and Mass Transfer in Energy Equipment)
Abstract One of the effective options for energy saving in terms of heat costs for the formation of routine thermal conditions of working areas of large-sized industrial premises is the replacement of traditional convective (water) heating systems with systems, the main part of which are gas infrared emitters. But the mass introduction of such systems based on emitters was held back until recently by the lack of scientific and technical foundations for ensuring not only the routine thermal conditions of local working areas, but also ensuring acceptable concentrations of carbon dioxide, which is formed during the… More >

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Long Huang^1,2,3,*, Junjia Zou³, Baoqing Liu¹, Zhijiang Jin^1,2, Jinyuan Qian¹
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1613-1643, 2024, DOI:10.32604/fhmt.2024.058231 - 19 December 2024
（This article belongs to the Special Issue: Machine Learning and Data-Driven Techniques for Mass and Thermal Transport)
Abstract This study explores the effectiveness of machine learning models in predicting the air-side performance of microchannel heat exchangers. The data were generated by experimentally validated Computational Fluid Dynamics (CFD) simulations of air-to-water microchannel heat exchangers. A distinctive aspect of this research is the comparative analysis of four diverse machine learning algorithms: Artificial Neural Networks (ANN), Support Vector Machines (SVM), Random Forest (RF), and Gaussian Process Regression (GPR). These models are adeptly applied to predict air-side heat transfer performance with high precision, with ANN and GPR exhibiting notably superior accuracy. Additionally, this research further delves into… More >

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Ivan Malakhov^1,*, Anton Surtaev^1,2, Vladimir Serdyukov^1,2, Ali Kosar³, Alexander Pavlenko¹
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1645-1660, 2024, DOI:10.32604/fhmt.2024.056664 - 19 December 2024
（This article belongs to the Special Issue: Boiling Heat Transfer: Fundamentals and Improvement Techniques)
Abstract To date, using biphilic surfaces is one of the most promising methods for enhancing heat transfer and critical heat flux during boiling simultaneously. However, most of studies on the effect of biphilic surfaces on boiling performance have been carried out under atmospheric pressure conditions. In this context, the issues of heat transfer enhancement and stabilization of the boiling process at subatmospheric pressures are particularly critical due to the interesting characteristics of boiling heat transfer and bubble dynamics at subatmospheric pressures and their practical significance including aerospace applications. This paper investigates the effect of the pitch… More >

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Xin Qi^1,2, Xingtao Shi¹, Yingwen Liu^1,*
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1661-1678, 2024, DOI:10.32604/fhmt.2024.058959 - 19 December 2024
（This article belongs to the Special Issue: Microscale Heat and Mass Transfer and Efficient Energy Conversion)
Abstract After optimizing the compressor design, condenser tube diameter, and tube row arrangement, air supply volumetric flow rate, and refrigerant charge of the domestic dehumidifier. The optimized design schemes were obtained from the original combinations by non-dominated sorting, and the optimized design schemes were experimentally verified under three environmental conditions according to the test method of T/CAS 342-2020 to obtain a complete idea of dehumidifier multi-component improvement. The results show that the dehumidifying capacity of Scheme 5 is slightly increased by 2.5% at 27°C/60% RH, and its energy factor is significantly increased by 24.6%. When the… More >

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Alexander Fedoseev^*, Mikhail Salnikov
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1679-1694, 2024, DOI:10.32604/fhmt.2024.056999 - 19 December 2024
（This article belongs to the Special Issue: Heat and Mass Transfer in Energy Equipment)
Abstract In order to research the process of boiling occurring on a porous surface, a model of multiple blocks was developed. The mathematical basis of these blocks is the lattice Boltzmann method in combination with heat transfer equation. The reported complex allows one to obtain the boiling curves for various wall superheats and to find the optimal parameters of a porous heater in terms of heat transfer enhancement. The porous heater structure is specified as a skeleton of square metal heaters located in the lower part of the computational domain. The calculations were performed for the… More >

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Victor Kozlov^1,2,*, Yuriy Litvinenko¹, Andrey Shmakov^1,2, Alexander Pavlenko¹
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1695-1717, 2024, DOI:10.32604/fhmt.2024.056866 - 19 December 2024
（This article belongs to the Special Issue: Heat and Mass Transfer in Energy Equipment)
Abstract The objective of the present study is an experimental investigation of diffusion combustion of round microjets, i.e., mixtures of hydrogen with methane, helium, and nitrogen. It is found that the evolution of burning microjets is associated with generation of a “bottleneck flame region” close to the nozzle exit, as it was observed earlier during hydrogen combustion. Combustion of a mixture of hydrogen and methane with increasing flow velocity occurs with the transformation of the torch. At first, a torch stabilized on the nozzle is observed, then it is divided into a stabilized part in contact… More >

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J. L. Rodríguez-Muñoz^1,*, J. S. Pacheco-Cedeño^1,*, J. F. Ituna-Yudonago², J. J. Ramírez-Minguela³, I. J. González-Hernández⁴
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1719-1741, 2024, DOI:10.32604/fhmt.2024.057924 - 19 December 2024
（This article belongs to the Special Issue: Modeling, Control, and Optimization of Energy Modules and Systems)
Abstract In conventional absorption refrigeration systems (ARS), the heat from the condenser is usually rejected by the environment in place to be used in the system, so recuperating this is a good alternative to enhance the system’s performance. For instance, in this paper, an alternative ARS in which LiBr/Water is used as a refrigerant mixture, where part of condensing heat is recovered via the solution heat recovery generator absorption cycle (HR-ARS) was energy and exergy evaluated. The influence of generator, condenser and evaporator temperatures, as well as the efficiency of the solution heat exchanger on the coefficient of… More >

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Xianzhi Chen¹, Dong Niu^1,*, Hongtao Gao¹, Mu Du^2,3,*
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1743-1760, 2024, DOI:10.32604/fhmt.2024.058274 - 19 December 2024
（This article belongs to the Special Issue: Microscale Heat and Mass Transfer and Efficient Energy Conversion)
Abstract Thermosensitive hydrogel can integrate vapor molecular capture, in-situ liquefaction, and thermal-induced water release for freshwater capture. This study aimed to examine the dynamic behavior of poly (N-isopropylacrylamide) (PNIPAM) single chain and cross-linking thermosensitive hydrogel through molecular dynamics simulation. Specifically, the impact of lower critical solution temperature (LCST) on the conformation of polymer chain and the interaction between water and polymer chain were also investigated. The polymer chain conformation underwent a transition from coil to globule when the temperature exceeded the LCST, indicating the temperature responsiveness of PNIPAM. Additionally, thermosensitive hydrogel samples with different cross-linking degrees (DOC) More >

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V. I. Zhukov^1,2,*, A. N. Pavlenko¹
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1761-1775, 2024, DOI:10.32604/fhmt.2024.056779 - 19 December 2024
（This article belongs to the Special Issue: Heat and Mass Transfer in Energy Equipment)
Abstract The results of an experimental study on critical heat fluxes (CHF) during the nucleate boiling of the HFE-7100 dielectric liquid in horizontal layers of different heights at atmospheric pressure are presented. The existence of a critical layer height has been established. In layers above the critical layer height, a hydrodynamic boiling crisis occurs; in thinner layers, a surface drying crisis occurs. At a layer height equal to the critical value, a dry spot first appears, followed by transition boiling, which gradually spreads to the entire heating surface. In these experiments, the critical layer height was More >

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Ahmed Dhafer Abdulsahib^1,*, Dhirgham Alkhafaji¹, Ibrahim M. Albayati²
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1777-1804, 2024, DOI:10.32604/fhmt.2024.057209 - 19 December 2024
Abstract The current study generally aims to improve heat transfer in heat sinks by presenting a numerical analysis of natural convection of an enclosure with hot right and cool left walls, and thermally insulated top and bottom walls. The cold wall included configurations (half circle/half square) in various sizes (S = 0.1, 0.2, and 0.3), numbers (N = 1, 2, 3, and 4), and locations (C = 0.35, and 0.65). A heat sink is constructed of Aluminum attached to the hot wall, and composed of five fins with protrusions. Fins of the heat sink will be… More >

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Yuri Ivochkin¹, Igor Teplyakov¹, Oleg Sinkevich^1,2, Sergei Shchigel¹, Stepan Yudin^1,2,*
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1805-1821, 2024, DOI:10.32604/fhmt.2024.056787 - 19 December 2024
（This article belongs to the Special Issue: Heat and Mass Transfer in Energy Equipment)
Abstract This study explores the mechanism behind the generation of pressure pulses on the outer surface of a molten metal droplet when immersed in water. The absence of any external trigger is assumed, and the droplet is surrounded by a vapor layer with surface hydrodynamic waves at the vapor-liquid interface. The study examines the heating conditions of a cylindrical column of water used to model a volume of cold liquid interacting with a hot metal surface, which explosively boils upon direct contact. Within the framework of classical homogeneous nucleation theory, the relationship between pressure pulse magnitude… More >

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Wenzhen Chen, Junjie Ma^*, Jianli Hao
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1823-1837, 2024, DOI:10.32604/fhmt.2024.057896 - 19 December 2024
Abstract The contact melting process of solid phase change material (PCM) has essential applications in some energy storage systems, which is related closely to the heat resource’s geometry and thermal boundary conditions. The contact melting of PCM in a horizontal elliptical tube under the second kind of thermal boundary condition, namely the constant surface heat flux, was investigated analytically. The analysis model is proposed based on the contact melting lubrication theory, and the model deduces the basic dimensionless equations. The variation rules of parameters such as contact melting speed, melting completion time, and boundary layer thickness More >

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P. Saila Kumari¹, S. Mohammed Ibrahim¹, Giulio Lorenzini^2,*
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1839-1863, 2024, DOI:10.32604/fhmt.2024.057760 - 19 December 2024
Abstract A wide range of technological and industrial domains, including heating processors, electrical systems, mechanical systems, and others, are facing issues as a result of the recent developments in heat transmission. Nanofluids are a novel type of heat transfer fluid that has the potential to provide solutions that will improve energy transfer. The current study investigates the effect of a magnetic field on the two-dimensional flow of Williamson nanofluid over an exponentially inclined stretched sheet. This investigation takes into account the presence of multi-slip effects. We also consider the influence of viscous dissipation, thermal radiation, chemical… More >

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Mouna Benshab¹, Said Bouchta^1,2,*, M’barek Feddaoui¹, Abdellatif Dayf¹, Jaouad Bouchta¹, Abderrahman Nait Alla¹
Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1865-1885, 2024, DOI:10.32604/fhmt.2024.056551 - 19 December 2024
（This article belongs to the Special Issue: Advances in Computational Thermo-Fluids and Nanofluids)
Abstract This paper presents a numerical study on natural convection and heat transfer using a hybrid nanofluid within a three-dimensional cavity under the influence of a magnetic field. The primary objective of this research is to analyze how various magnetic field conditions affect the thermal performance of the hybrid nanofluid, particularly in terms of heat transfer and fluid motion. Specific objectives include evaluating the effects of the Rayleigh number, nanoparticle volume fraction, and Hartmann number on the dynamic and thermal fields, as well as the overall heat transfer efficiency. The transport equations were discretized using the… More >

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