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EDITORIAL

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 >

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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 >

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ARTICLE

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 >

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REVIEW

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 >

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Jiwon Yu^a , Seok-Won Kang^a, Saeil Jeon^b, Debjyoti Banerjee^a,*
Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-9, 2012, DOI:10.5098/hmt.v3.1.3004
Abstract Experiments were performed to study the forced convective heat transfer of de-ionized water (DI water) and aqueous nanofluids in a microchannel and temperature measurements were obtained using an array of nanosensors (i.e., thin film thermocouples or “TFT”). Heat flux values were calculated from the experimental measurements for temperature recorded by the TFT array. The experiments were performed for the different test fluids where the flow rate, mass concentration (of silica nanoparticles ~10-30 nm diameter) in the colloidal suspension and the wall temperature profile (as well as applied heat flux values) were varied parametrically.
Anomalous enhancement of the convective heat… More >

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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 >

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Sira Saisorn^a,b, Somchai Wongwises^b,c,*
Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-15, 2012, DOI:10.5098/hmt.v3.1.3006
Abstract A summary of recent research on flow boiling in micro-channels is provided in this article. This review aims to survey and identify new findings arising in this important area, which may contribute to optimum design and process control of high performance miniature devices comprising extremely small channels. Several criteria for defining a micro-channel are presented at first and the recent works on micro-scale flow boiling are subsequently described into two parts including flow visualization and two-phase heat transfer. The results obtained from a number of p revious studies show that the flow behaviours and heat transfer mechanisms in micro-channels deviate… More >

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Sira Saisorn^a,b, Somchai Wongwises^b,c,∗
Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-7, 2012, DOI:10.5098/hmt.v3.1.3007
Abstract Two-phase pressure drop during flow boiling has been studied for several decades. Obviously, the publications available on micro-channels are relatively small compared with those for ordinarily sized channels. Although the use of micro-channels yields several advantages, the pressure drop taking p lace in these extremely small channels is higher than that in the ordinarily sized channels because of the increased wall friction. The knowledge of the two-phase pressure drop characteristics in addition to heat transfer phenomena is essential to the design and evaluation of the micro-systems. In this paper, recent research on the flow boiling pressure drop in micro-scale channels… More >

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REVIEW

P. K. Das^*, S. Chakraborty, S. Bhaduri
Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-17, 2012, DOI:10.5098/hmt.v3.1.3008
Abstract A state of the art review of critical heat flux during flow boiling through mini and microchannels has been provided based on the open literature. This review mainly examines three aspects, namely the experimental investigations, the available correlations and the state of prediction using those correlations and finally the proposed physical mechanisms as well as the theoretical models. Before discussing the specific literature on microchannels, a brief overview of critical heat flux for pool and flow boiling is provided. The review has been concluded with a summary of the available information on this topic and the need for future research. More >

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