Open Access

ARTICLE

HEAT TRANSFER CHARCACTERISTICS IN A COPPER MICRO-EVAPORATOR AND FLOW PATTERN-BASED PREDICTION METHOD FOR FLOW BOILING IN MICROCHANNELS

by

a Heat and Mass Transfer Laboratory (LTCM), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
b Photovoltaic Technology Intellectual Property (Pty) Ltd, South Africa

* Corresponding Author: Email:

Frontiers in Heat and Mass Transfer 2012, 3(1), 1-14. https://doi.org/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 new flow pattern-based prediction method for flow boiling heat transfer coefficients in microchannels was developed based on the experimental results. The new prediction method also predicted published data for four other test sections accurately, capturing the trends versus vapor quality well.

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Keywords

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