Yuze Xue¹, Li Kou^2,3, Guosheng Jia^4,*, Liwen Jin⁴, Zhibin Zhang⁴, Jianke Hao⁴, Lip Huat Saw^5,*

Energy Engineering, Vol.122, No.3, pp. 1005-1024, 2025, DOI:10.32604/ee.2025.059198 - 07 March 2025

Abstract Geothermal energy, a form of renewable energy, has been extensively utilized for building heating. However, there is a lack of detailed comparative studies on the use of shallow and medium-deep geothermal energy in building energy systems, which are essential for decision-making. Therefore, this paper presents a comparative study of the performance and economic analysis of shallow and medium-deep borehole heat exchanger heating systems. Based on the geological parameters of Xi’an, China and commonly used borehole heat exchanger structures, numerical simulation methods are employed to analyze performance and economic efficiency. The results indicate that increasing the… More > Graphic Abstract

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

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 >

Fayi Yan^*, He Lu, Shijie Feng

Frontiers in Heat and Mass Transfer, Vol.22, No.5, pp. 1493-1514, 2024, DOI:10.32604/fhmt.2024.055324 - 30 October 2024

Abstract Helically coiled tube-in-tube (HCTT) heat exchangers are widely applied to the process technology because of their compactness and higher heat transfer efficiency. HCTT heat exchangers play an important role in liquified natural gas (LNG) use and cold energy recovery. The heat transfer characteristics, pressure distribution, and degree of vaporization of LNG in HCTT heat exchangers are numerically investigated. By comparing the simulation results of the computational model with existing experimental results, the effectiveness of the computational model is verified. The numerical simulation results show the vapor volume fraction of the HCTT heat exchanger is related… More >

Yangyiming Rong¹, Weitao Su¹, Shuai Wang², Bowen Du¹, Jianjian Wei², Shaozhi Zhang^2,*

Frontiers in Heat and Mass Transfer, Vol.22, No.4, pp. 1209-1229, 2024, DOI:10.32604/fhmt.2024.052415 - 30 August 2024

Abstract Finned-tube heat exchanger (FTHE) is often used as an evaporator in commercial products of separated heat pipe (SHP). The working conditions of FTHE in gravity-assisted SHP are significantly different from those working in refrigerators and air conditioners. Although FTHE is widely used in commercial products of SHP, previous research on its characteristics is very limited. In this paper, a mathematical model for a SHP with FTHE as the evaporator and plate heat exchanger as the condenser is established and verified with experiments. Parametric analyses are carried out to investigate the influences of evaporator design parameters:… More >

Abdul Sattar Laghari¹, Mohammad Waqas Chandio¹, Laveet Kumar^2,*, Mamdouh El Haj Assad³

Energy Engineering, Vol.121, No.8, pp. 2023-2038, 2024, DOI:10.32604/ee.2024.051082 - 19 July 2024

Abstract The selection of working fluid significantly impacts the geothermal ORC’s Efficiency. Using a mixture as a working fluid is a strategy to improve the output of geothermal ORC. In the current study, modelling and thermodynamic analysis of ORC, using geothermal as a heat source, is carried out at fixed operating conditions. The model is simulated in the Engineering Equation Solver (EES). An environment-friendly mixture of fluids, i.e., R245fa/R600a, with a suitable mole fraction, is used as the operating fluid. The mixture provided the most convenient results compared to the pure working fluid under fixed operating More >

Kun Yan¹, Yunyu Wang², Jun Yan^3,*

CMES-Computer Modeling in Engineering & Sciences, Vol.140, No.2, pp. 1949-1974, 2024, DOI:10.32604/cmes.2024.048877 - 20 May 2024

Abstract Topology optimization of thermal-fluid coupling problems has received widespread attention. This article proposes a novel topology optimization method for laminar two-fluid heat exchanger design. The proposed method utilizes an artificial density field to create two permeability interpolation functions that exhibit opposing trends, ensuring separation between the two fluid domains. Additionally, a Gaussian function is employed to construct an interpolation function for the thermal conductivity coefficient. Furthermore, a computational program has been developed on the OpenFOAM platform for the topology optimization of two-fluid heat exchangers. This program leverages parallel computing, significantly reducing the time required for More >

Abeer H. Falih^*, Basima Salman Khalaf, Basim Freegah

Frontiers in Heat and Mass Transfer, Vol.22, No.2, pp. 597-613, 2024, DOI:10.32604/fhmt.2024.049812 - 20 May 2024

Abstract In this study, the primary objective was to enhance the hydrothermal performance of a dimpled tube by addressing areas with low heat transfer compared to other regions. To accomplish this, a comprehensive numerical investigation was conducted using ANSYS Fluent 2022 R1 software, focusing on different diameters of dimples along the pipe’s length and the distribution of dimples in both in-line and staggered arrangements. The simulations utilized the finite element method to address turbulent flow within the tube by solving partial differential equations, encompassing Re numbers spanning from 3000 to 8000. The study specifically examined single-phase… More > Graphic Abstract

Fawziea M. Hussien¹, Atheer S. Hassoon^2,*, Ghaidaa M. Ahmed¹

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 175-191, 2024, DOI:10.32604/fhmt.2023.047177 - 21 March 2024

Abstract A heat exchanger’s performance depends heavily on the operating fluid’s transfer of heat capacity and thermal conductivity. Adding nanoparticles of high thermal conductivity materials is a significant way to enhance the heat transfer fluid's thermal conductivity. This research used engine oil containing alumina (Al₂O₃) nanoparticles and copper oxide (CuO) to test whether or not the heat exchanger’s efficiency could be improved. To establish the most effective elements for heat transfer enhancement, the heat exchangers thermal performance was tested at 0.05% and 0.1% concentrations for Al₂O₃ and CuO nanoparticles. The simulation results showed that the percentage increase… More >

Fayi Yan^*, Xuejian Pei, He Lu, Shuzhen Zong

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 287-304, 2024, DOI:10.32604/fhmt.2023.045038 - 21 March 2024

Abstract As compact and efficient heat exchange equipment, helically coiled tube-in-tube heat exchangers (HCTT heat exchangers) are widely used in many industrial processes. However, the thermal-hydraulic research of liquefied natural gas (LNG) as the working fluid in HCTT heat exchangers is rarely reported. In this paper, the characteristics of HCTT heat exchangers, in which LNG flows in the inner tube and ethylene glycol-water solution flows in the outer tube, are studied by numerical simulations. The influences of heat transfer characteristics and pressure drops of the HCTT heat transfers are studied by changing the initial flow velocity,… More >

Ali Jaber Abdulhamed^*, Aws Al-Akam, Wisam J. Khudhayer, Ali Sabri Allw

Energy Engineering, Vol.121, No.2, pp. 273-290, 2024, DOI:10.32604/ee.2023.045583 - 25 January 2024

Abstract Heat augmentation techniques play a vital role in the heating and cooling processes in industries, including solar collectors and many applications that utilize heat exchangers. Several studies are based on inserting fillers inside the tubes to enhance heat transfer. This investigation considered the effects of twisted tapes with large holes on a tubular heat exchanger’s (HX) heat transmission, pressure drop, and thermal boosting factor. In the experimental section, counter-swirl flow generators used twisted tapes with pairs of 1.0 cm-diameter holes and changes in porosity (R_p) at 1.30% and 2.70%. In the experiments, air was utilized as… More >