Onset of nucleate boiling and critical heat flux with boiling water in microchannel

Abstract

This paper focuses on experimental determination of onset of nucleate boiling (ONB) and critical heat flux (CHF) at the microscales, and comparison of these with available correlations. The working fluid is deionised water and microchannel of four different hydraulic diameters: 65, 70, 107 and 125 μm, have been tested. Effect of hydraulic diameter (65-125 μm), mass flux (60-1410 kg/m2s) and heat flux (0-910 kW/m2) on ONB and CHF has been studied in detail. The heat flux for onset of nucleate boiling increases with hydraulic diameter and mass flux. The critical heat flux tends to increase with a decrease in hydraulic diameter and with increasing mass flux. The effect of surface roughness on CHF has also been tested to a limited extent; no clear change in the CHF value was observed upon changing the surface roughness by an order of magnitude. The empirical correlations tested in this study predict the experimental data to varying extent. These results may help better determine the lower and upper limits of heat flux while designing heat sink for electronic cooling.