Amit Agrawal^a,*, V.S. Duryodhan^a, S. G. Singh^b

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-7, 2012, DOI:10.5098/hmt.v3.1.3005

Abstract An experimental study of flow boiling through diverging microchannels has been carried out in this work, with the aim of exploring reduction in flow instabilities during boiling in diverging microchannels. Effect of mass flux, heat flux and divergence angle on two phase pressure drop has been studied using deionized water as the working fluid. The experiments are carried out on three test sections with divergence angle of 4, 8 and 12 deg with nearly constant hydraulic diameter (146, 154 and 157 µm respectively), for inlet mass flux and heat flux range of 117 - 1197 kg/m² -s and 2.5 to… More >

Yaohua Zhang^a,*, Yoshio Utaka^b

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-12, 2012, DOI:10.5098/hmt.v3.1.3003

Abstract This paper reviews recent research on microlayer formed by confined vapor bubbles during boiling in mini/microchannels. Experimental measurements, simulations and theoretical studies are described and compared. As a reference to clarify the mechanism for the formation of a microlayer, Taylor flow (i.e. elongated bubble flow in mini/micro circular tubes under adiabatic conditions and at Re << 1) and elongated bubble flow at high velocity, with consideration of the influence of inertia, are also reviewed. Compared to the steady adiabatic conditions, one of the distinct points for the boiling condition is that the bubble grows exponentially due to rapid evaporation of… More >

Etienne Costa-Patry^a, Jonathan Olivier^b, John R. Thome^a,∗

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-14, 2012, DOI:10.5098/hmt.v3.1.3002

Abstract This article presents new experimental results for two-phase flow boiling of R-134a, R-1234ze(E) and R-245fa in a micro-evaporator. The test section was made of copper and composed of 52 microchannels 163μm wide and 1560μm high with the channels separated by 178μm wide fins. The channels were 13.2mm long. There were 35 local heaters and temperature measurements arranged in a 5×7 array as a pseudo-CPU. The total pressure drops of the test section were below 20kPa in all cases. The wall heat transfer coefficients were generally above 10’000W/m²K and a function of the heat flux, vapor quality and mass flux. A… More >

Tomio Okawa^*,†

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-8, 2012, DOI:10.5098/hmt.v3.1.3001

Abstract The present article summarizes the studies on the thermalhydraulic condition under which the onset of nucleate boiling (ONB) is triggered in subcooled flow boiling. Available correlations and experimental data show that the ONB is tended to be delayed in mini and microchannels. It is known that the ONB condition is significantly dependent on the surface condition even in conventional-sized channels. Accumulation of ONB data accompanied by the information on the surface condition is therefore considered of importance to elucidate the mechanisms of boiling incipience in microchannels. Discussion is also made for the bubble dynamics observed in mini and microchannels. It… More >

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-3, 2012, DOI:10.5098/hmt.v3.1.1001

Abstract This article has no abstract. More >

Soumei Baba^a,*, Nobuo Ohtani^a, Osamu Kawanami^b, Koichi Inoue^c, Haruhiko Ohta^a

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-8, 2012, DOI:10.5098/hmt.v3.4.3002

Abstract Effects of tube orientation on flow boiling heat transfer coefficients were investigated for FC72 flowing in single mini-tubes with tube diameters of 0.13 and 0.51 mm to define boundaries on a dominant force regime map. For the tube diameter of 0.51 mm, when mass velocity and vapor quality was varied, heat transfer coefficients were influenced by tube orientation at Froude number Fr < 4, while the effect of tube orientation on heat transfer coefficients disappears at Fr > 4. The results indicated that the boundary between the body force dominated and the inertia dominated regimes was given by Fr ≈… More >

Mohamed S. El-Genk^a,b,c,∗, Amir F. Ali^a,c

Frontiers in Heat and Mass Transfer, Vol.3, No.4, pp. 1-14, 2012, DOI:10.5098/hmt.v3.4.3001

Abstract Advanced spreaders for cooling a 10 x 10 mm underlying computer chip with a central hot spot (CHS) could remove > 85 W of dissipated thermal power at junctions’ temperature < 100o C. The spreaders comprise a 1.6 - 3.2 mm thick Cu substrate and an 80-μm thick micro-porous copper (MPC) surface cooled by saturation nucleate boiling of PF-5060 dielectric liquid. Investigated are the effects of varying the heat flux at the chip’s 1 and 4 mm² CHS and the impedance of thermal interface material (TIM) between the Cu substrate and underlying chip. Results confirmed the effectiveness of the MPC… More >

Wei Zhong¹, Zhenfang Xin², Lihua Wang^1,*, Haiping Liu²

CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.2, pp. 1427-1453, 2024, DOI:10.32604/cmes.2023.031271

Abstract Flash boiling atomization (FBA) is a promising approach for enhancing spray atomization, which can generate a fine and more evenly distributed spray by increasing the fuel injection temperature or reducing the ambient pressure. However, when the outlet speed of the nozzle exceeds 400 m/s, investigating high-speed flash boiling atomization (HFBA) becomes quite challenging. This difficulty arises from the involvement of many complex physical processes and the requirement for a very fine mesh in numerical simulations. In this study, an HFBA model for gasoline direct injection (GDI) is established. This model incorporates primary and secondary atomization, as well as vaporization and… More >

A. Zoubir^a , R. Agounoun^a,*, I. Kadiri^b, K. Sbai^a , M. Rahmoune^a

Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-6, 2016, DOI:10.5098/hmt.7.35

Abstract Boiling heat transfer process is important because it is a way to increase the flux density transmitted at low temperature differences. To quantify the thermal exchanges, we performed an experimental study of the nitrogen pool boiling, in transient conditions, on a horizontal brass ribbon for a fixed flux density. The results show that there is no break between the monophasic convection zone and the nucleated boiling region. In the nucleated boiling zone, the temperature variations are very small. We also note that the overheating required to trigger boiling increases with the time delay after the activation of nucleation sites. More >

Zihuan Ma¹, Xiang Ma¹, Chengyu Hu¹, Jinjia Wei^1,2,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.26, No.2, pp. 1-1, 2023, DOI:10.32604/icces.2023.08963

Abstract Flow boiling in microchannel heat sinks is considered as a promising cooling solution for electronic components. Higher heat flux can be effectively dissipated by the utilization of the latent heat of vaporization. However, most of the current studies on flow boiling in microchannels are mainly experimental investigations and two-dimensional numerical studies. In this paper, the Volume of Fluid (VOF) model combined with the Lee evaporation-condensation phase change model is used to simulate the flow boiling of HFE7100 in horizontal microchannels by three-dimensional conjugate numerical simulation. The numerical simulation results are compared with the experimental results [1], showing an excellent agreement.… More >