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 >

Mohammed Yunus^*, Mohammad S. Alsoufi

Frontiers in Heat and Mass Transfer, Vol.12, pp. 1-8, 2019, DOI:10.5098/hmt.12.11

Abstract Swift cooling systems, improved microprocessor chips, processors’ performance and power usage have increased production of an enormous amount of heat and high operating temperatures due to excess heat flux density in the field of microelectronics. A rapid cooling of electronic circuits and heat dissipation for the same size of pipe with the present technology as nano size circuits critically generate high heat flux beyond 100 W/cm2 is currently the challenging task with which we are presented. Cooling in the form of heat transfer should be managed using both thermal conductivity (evaporation) and phase transition (condensation) between the two solid interfaces… More >

Yasushi Koito^a,*

Frontiers in Heat and Mass Transfer, Vol.13, pp. 1-6, 2019, DOI:10.5098/hmt.13.26

Abstract This paper describes extended numerical analyses on vapor pressure distribution in a centered-wick ultra-thin heat pipe. Analyses were conducted by using a three-dimensional model developed by the author. Numerical results were obtained changing design parameters and operating conditions of the heat pipe. Discussion was made on the heat transfer limit as well as the vapor pressure drop. Moreover, a simple method was also presented to evaluate the vapor pressure drop in the ultra-thin heat pipe. Calculated results with the simple method agreed in 10 % with the three-dimensional numerical results. More >

Randeep Singh^* , Masataka Mochizuki, Koichi Mashiko, Thang Nguyen^*

Frontiers in Heat and Mass Transfer, Vol.13, pp. 1-6, 2019, DOI:10.5098/hmt.13.24

Abstract In the present paper, data center energy conservation systems based on the heat pipe heat exchanger (HPHE) pre-cooler to downsize the chiller capacity and working time has analysed, designed and discussed. The proposed system utilizes thermal diode character of heat pipe to transfer waste heat from source (pre-cooler coolant) to ambient and have been analyzed as per metrological conditions in New York. HPHE Pre cooler with 118 heat pipes and designed for 30 °C ambient temperature has been designed to effectively dissipate 30 kW or more datacenter heat throughout the year. The payback period of the HPHE Pre cooler is… More >

Masataka Mochizuki^a,*,†, Thang Nguyen^b

Frontiers in Heat and Mass Transfer, Vol.13, pp. 1-6, 2019, DOI:10.5098/hmt.13.12

Abstract The cooling device for computers and electronics is getting smaller and thinner year after year, especially for the mobile handheld device such as smartphone which is the most popular gadget and widely use nowadays. It seems that in the current trend every 6-12 months a new model of smartphone is introduced and it was packed with faster processing processor, memories, and graphics, higher density battery, higher resolution for camera and video and so on. The drawback is the device getting hotter due to the increase of heat dissipation caused by faster computing. The traditional method of cooling by purely metal… More >

B. Orr^a,* , R. Singh^a, A. Akbarzadeh^b , M. Mochizuki^c

Frontiers in Heat and Mass Transfer, Vol.13, pp. 1-7, 2019, DOI:10.5098/hmt.13.8

Abstract Heat pipes that operate in the medium temperature range (550-700 K) are very rarely used in industry despite the potential demand of use. There is no consensus about suitable working fluids in this temperature range as research on possible working fluids is limited. One proposed working fluid is naphthalene. In this paper, a number of tests have been undertaken on both an individual naphthalene heat pipe and a naphthalene heat pipe heat exchanger. Unlike room temperature working fluids, medium temperature working fluids are solid at ambient temperature therefore they have unusual transient start up behaviour. Testing has indicated that these… More >

C. B. Sobhan^aG. P. Peterson^b,*

Frontiers in Heat and Mass Transfer, Vol.13, pp. 1-10, 2019, DOI:10.5098/hmt.13.5

Abstract Micro heat pipes have found applications in numerous types of systems where effective heat dissipation in a limited space is required. One relatively new design/fabrication methodology for parallel micro heat pipes with high performance is referred to as “wire-bonded” micro heat pipe arrays. The following review analyzes the principles of operation of these devices and investigates the recent developments in the technology, along with their fabrication and application. The results indicate that these micro heat pipe arrays present an attractive alternative for a number of interesting applications, including many that have yet to be explored.   More >

Hao Guo^a , Xianbing Ji^a,b,1 , Jinliang Xu^a,b

Frontiers in Heat and Mass Transfer, Vol.14, pp. 1-16, 2020, DOI:10.5098/hmt.14.14

Abstract With fast development of electronic devices, novel strategies of thermal management have been received great attention to dissipate high heat fluxes. As an efficient heat transfer device, loop heat pipe (LHP) provides ideal solution for such purpose. Even though LHP was invented nearly half-century ago, challenges still exist on its design, fabrication and operation. The objective of this paper is to present a thorough review on LHPs, paying more attention on the working principle, advantage and configuration. The review is performed in three aspects. First, the macroscopic operation characteristics such as start-up, temperature fluctuations and anti-gravity operation are described. Second,… 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 >

Yasushi Koito^*

Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-6, 2021, DOI:10.5098/hmt.16.8

Abstract Numerical analyses were conducted for an ultra-thin heat pipe in which a thin wick layer was placed on the bottom. The vapor temperature drop caused by vapor flow friction was discussed for two types of the ultra-thin heat pipes with small and large widths. The numerical results were compared with those obtained for an ultra-thin heat pipe with a centered-wick structure. It was confirmed that the vapor temperature drop was reduced effectively by increasing the width of the heat pipe. Therefore, a wider ultra-thin heat pipe, that is, an ultra-thin vapor chamber is a promising option for nextgeneration thermal management. More >