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 >

Amnart Boonloi¹, Withada Jedsadaratanachai^2,*

Frontiers in Heat and Mass Transfer, Vol.21, pp. 81-106, 2023, DOI:10.32604/fhmt.2023.041547 - 30 November 2023

Abstract Simulation of fluid-flow topology and thermal behavior in a round tube heat exchanger (RTHX) installed by three V-rib sets is reported. The expected phenomena for the rib installation are the generated vortex flow, impinging flow, greater fluid blending and thermal boundary layer disturbance (TBLD). These phenomena are key causes of the augmentation of heat transfer potentiality and thermal efficiency of the RTHX. Effects of rib height (b₁ = 0.05D – 0.25D and b₂ = 0.05D – 0.25D), rib pitch or rib spacing (P = D, 1.5D and 2D) and fluid directions (positive x (+x flow direction)… More > Graphic Abstract

Juanjuan Wang^*, Jiangping Nan, Yanan Wang

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.11, pp. 2761-2775, 2023, DOI:10.32604/fdmp.2023.021175 - 18 September 2023

Abstract The main objective of this study is the technical optimization of a Shell-and-Tube Heat Exchanger (STHE). In order to do so, a simulation model is introduced that takes into account the related gas-phase circulation. Then, simulation verification experiments are designed in order to validate the model. The results show that the temperature field undergoes strong variations in time when an inlet wind speed of 6 m/s is considered, while the heat transfer error reaches a minimum of 5.1%. For an inlet velocity of 9 m/s, the heat transfer drops to the lowest point, while the More >