Zhengyuan Pei¹, Yasushi Koito^2,*

Frontiers in Heat and Mass Transfer, Vol.22, No.5, pp. 1381-1397, 2024, DOI:10.32604/fhmt.2024.056624 - 30 October 2024

Abstract Extended experiments were conducted on the oscillation characteristics of merged liquid slugs in a horizontally oriented polymer pulsating heat pipe (PHP). The PHP’s serpentine channel comprised 14 parallel channels with a width of 1.3 and a height of 1.1 . The evaporator and condenser sections were 25 and 50 long, respectively, and the adiabatic section in between was 75 mm long. Using a plastic 3D printer and semi-transparent filament made from acrylonitrile butadiene styrene, the serpentine channel was printed directly onto a thin polycarbonate sheet to form the PHP. The PHP was charged with hydrofluoroether-7100.… More >

Mahyar Kargaran^*, Hamid Reza Goshayeshi, Ali Reza Alizadeh Jajarm

Frontiers in Heat and Mass Transfer, Vol.22, No.5, pp. 1461-1476, 2024, DOI:10.32604/fhmt.2024.056284 - 30 October 2024

Abstract Solar energy is a valuable renewable energy source, and photovoltaic (PV) systems are a practical approach to harnessing this energy. Nevertheless, low energy efficiency is considered a major setback of the system. Moreover, high cell temperature and reflection of solar irradiance from the panel are considered chief culprits in this regard. Employing pulsating heat pipes (PHPs) is an innovative and useful approach to improving solar panel performance. This study presents the results of the power performance of a PV panel attached to a newly designed spiral pulsating heat pipe, while graphene oxide nanofluid with three 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 >

Kenta Hashimoto¹, Guohui Sun¹, Yasushi Koito^2,*

Frontiers in Heat and Mass Transfer, Vol.22, No.3, pp. 687-702, 2024, DOI:10.32604/fhmt.2024.052928 - 11 July 2024

Abstract Centered or striped wick structures have been used to develop ultrathin heat pipes. Differing from traditional heat pipes, the centered or striped wick structures leave noncontact container surfaces with the wick structure. In this study, experiments and numerical analyses were conducted to investigate the influence of these noncontact surfaces. In the experiments, a strip-shaped wick structure was placed vertically, the top was sandwiched between wider rods and the bottom was immersed in a working fluid. The rod width was greater than the wick width; thus, noncontact surfaces were left between the rod and the wick… More >

Yasushi Koito^1,*, Akira Fukushima²

Frontiers in Heat and Mass Transfer, Vol.22, No.3, pp. 869-887, 2024, DOI:10.32604/fhmt.2024.050910 - 11 July 2024

Abstract Thermal and fluid-flow characteristics were numerically analyzed for ultra-thin heat pipes. Many studies have been conducted for ultra-thin heat pipes with a centered wick structure, but this study focused on separated wick structures to increase the evaporation/condensation surface areas within the heat pipe and to reduce the concentration of heat flux within the wick structure. A mathematical heat-pipe model was made in the three-dimensional coordinate system, and the model consisted of three regions: a vapor channel, liquid-wick, and container wall regions. The conservation equations for mass, momentum, and energy were solved numerically with boundary conditions… More >

Randeep Singh^1,*, Tomoki Oridate², Tien Nguyen²

Frontiers in Heat and Mass Transfer, Vol.22, No.3, pp. 703-717, 2024, DOI:10.32604/fhmt.2024.050744 - 11 July 2024

Abstract Electrification of vehicles intensifies their cooling demands due to the requirements of maintaining electronics/electrical systems below their maximum temperature threshold. In this paper, passive cooling approaches based on heat pipes have been considered for the thermal management of electric vehicle (EV) traction systems including battery, inverter, and motor. For the battery, a heat pipe base plate is used to provide high heat removal (180 W per module) and better thermal uniformity (<5°C) for the battery modules in a pack while downsizing the liquid cold plate system. In the case of Inverter, two phase cooling system… More > Graphic Abstract

Bin Xiao^*

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 35-48, 2024, DOI:10.32604/fhmt.2024.048039 - 21 March 2024

Abstract Experiments were conducted in this study to examine the thermal performance of a thermosyphon, made from Inconel alloy 625, could recover waste heat from automobile exhaust using a limited amount of fluid. The thermosyphon has an outer diameter of 27 mm, a thickness of 2.6 mm, and an overall length of 483 mm. The study involved directing exhaust gas onto the evaporator. This length includes a 180-mm evaporator, a 70-mm adiabatic section, a 223-mm condenser, and a 97-mm finned exchanger. The study examined the thermal performance of the thermosyphon under exhaust flow rates ranging from… More >

Nobuhito Nagasato¹, Zhengyuan Pei¹, Yasushi Koito^2,*

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 49-63, 2024, DOI:10.32604/fhmt.2024.047502 - 21 March 2024

Abstract Visualization experiments were conducted to clarify the operational characteristics of a polymer pulsating heat pipe (PHP). Hydrofluoroether (HFE)-7100 was used as a working fluid, and its filling ratio was 50% of the entire PHP channel. A semi-transparent PHP was fabricated using a transparent polycarbonate sheet and a plastic 3D printer, and the movements of liquid slugs and vapor plugs of the working fluid were captured with a high-speed camera. The video images were then analyzed to obtain the flow patterns in the PHP. The heat transfer characteristics of the PHP were discussed based on the… More >

Chen Gao¹, Kai Sun¹, QingZhi Hou^2,3, KeWei Song^1,2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.4, pp. 1-3, 2023, DOI:10.32604/icces.2023.08905

Abstract As the fossil energy is increasingly exhausted and air pollution becomes more and more serious, blade electric vehicles equipped with rechargeable lithium-ion battery turns into the major developing direction of new energy automobile [1-3]. Lithium-ion batteries have the advantages of high energy density, light weight, and no pollution, and thereby are widely used in electric vehicles [4,5]. However, the working performance and service life of lithium-ion batteries are greatly affected by temperature [6]. Excessive high and low temperature will reduce the charge and discharge capacity of lithium-ion batteries, shorten their service life, and even lead… More >

Yasushi Koito^1,*, Shoma Hitotsuya², Takamitsu Takayama², Kenta Hashimoto²

Frontiers in Heat and Mass Transfer, Vol.21, pp. 33-46, 2023, DOI:10.32604/fhmt.2023.041829 - 30 November 2023

Abstract An ultra-thin flattened heat pipe has been developed with a centered wick structure. This structure is essential to make the heat pipe thinner. However, the centered wick structure reduces the evaporation and condensation surface areas of the wick structure because it is sandwiched between heat pipe walls. In this study, because detailed discussion has not been made, heat transfer experiments were conducted for the wick structure sandwiched between two solid walls. This study focused on the evaporation heat transfer characteristics from the sandwiched wick structure. The experiments were conducted with three wick structures, that is,… More >