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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

FLOW BOILING IN MICROCHANNELS WITH HFE-7100: EXPERIMENTAL RESULTS AND COMPARISION WITH CORRELATIONS

Get access (open in a dialog) DOI: 10.1615/IHTC16.mpf.020879
pages 6649-6656

Abstract

An experimental investigation of flow boiling heat transfer in a copper multi-microchannel heat sink with a hydraulic diameter of 0.46 mm is described in this paper. The heat sink consisted of 25 rectangular microchannels, which were 0.7 mm wide, 0.35 mm deep and 25 mm long. The separating wall thickness between the channels was 0.1 mm and the width of the heat sink was 20 mm giving a base area of 500 mm2. HFE-7100 was chosen as the test fluid due to its environmentally friendly nature and high dielectric strength. It was also considered a suitable choice for cooling electronic components that require working surface temperature between 80 °C to 125 °C. A high-speed, high-resolution camera was used to capture the flow patterns during the experiments. All experiments were performed at a system pressure of 1 bar, inlet sub-cooling temperature of 5 K, mass flux ranging from 50 to 250 kg/m2 s and a heat flux range of 43.96−335.29 kW/m2. Four flow patterns were observed namely bubbly, slug, churn and annular flow. It was found that the local heat transfer coefficient increases with increasing heat flux and decreases slightly with increasing vapour quality, while there is a negligible effect of mass flux. The experimental results were compared with a number of existing heat transfer correlations that were proposed for macro and micro scale with some correlations showing good agreement. Similar comparisons with pressure drop correlations were also included.