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

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 flow patterns and temperature distributions… More >

Brenton S. Taft^a,*, Kevin W. Irick^b

Frontiers in Heat and Mass Transfer, Vol.12, pp. 1-7, 2019, DOI:10.5098/hmt.12.24

Abstract On September 7th, 2017 the U.S. Air Force Research Laboratory launched the second Advanced Structurally Embedded Thermal Spreader (ASETSII) flight experiment to space on Orbital Test Vehicle 5. The ASETS-II experiment is made of three low-mass, low-cost oscillating heat pipes (OHPs) and an electronics/experiment control box. The three primary science objectives of the experiment are to measure the initial on-orbit thermal performance, to measure long duration thermal performance, and to assess any lifetime degradation. The three OHPs on ASETS-II are of varying configuration (center heating with single- and double-sided cooling) and working fluids (butane and R-134a) in order to isolate… More >

Roshan Devidas Bhagat^a,*, Samir J. Deshmukh^b

Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-16, 2021, DOI:10.5098/hmt.16.23

Abstract Numerical analysis of passive two phase fluid flow in a 3D Closed Loop Pulsating Heat Pipe (CLPHP) with turns in evaporator and condenser section is carried out. Water is used as working fluid. The volume of fluid model (VOF) is used to simulate passive two-phase fluid flow in a Closed Loop Pulsating Heat Pipe. Filling ratio (FR) of is kept in the range of 60 to 70%. The evaporator temperature is set in the range of 353 K. The condenser temperature is set in the range of 298 K. The contours of volume fraction water, wall temperature and contours of… More >

Felix Schily^a,∗, Wolfgang Polifke^a

Frontiers in Heat and Mass Transfer, Vol.17, pp. 1-15, 2021, DOI:10.5098/hmt.17.16

Abstract A simple open-loop pulsating heat pipe model is proposed, which allows to analytically determine the start-up behavior by a linear stability analysis. Two distinct types of instability can occur in such a pulsating heat pipe: oscillatory and non-oscillatory. This paper demonstrates that for bubbles consisting of non-condensible gas, large temperature gradients along the wall are required to achieve start-up, whereas start-up is fairly easy to achieve when there is only a single working medium that forms bubbles from its vapor. The study also finds that surface tension as such only influences start-up indirectly, while contact angle hysteresis dampens out any… More >

Xuehui Wang¹, Edward Wright¹, Zeyu Liu¹, Neng Gao^2,*, Ying Li³

Energy Engineering, Vol.119, No.2, pp. 801-814, 2022, DOI:10.32604/ee.2022.018241

Abstract The pulsating heat pipe is a very promising heat dissipation device to address the challenge of higher heat-flux electronic chips, as it is characterised by excellent heat transfer ability and flexibility for miniaturisation. To boost the application of PHP, reliable heat transfer performance evaluation models are especially important. In this paper, a heat transfer correlation was firstly proposed for closed PHP with various working fluids (water, ethanol, methanol, R123, acetone) based on collected experimental data. Dimensional analysis was used to group the parameters. It was shown that the average absolute deviation (AAD) and correlation coefficient (r) of the correlation were… More >