Experiment of flow boiling heat transfer on micro-pin-finned chips with jet impingement

The experiment of flow boiling heat transfer on micro-pin-finned chips in FC-72 with jet impingement was conducted.The experimental conditions consisted of two different liquid subcooling degrees (25,35°C),three different cross flow velocities (V_c=0.5,1,1.5 m/s) and three different jet velocities (V_j=0,1,2 m/s).The dimensions of the silicon chips were 10 mm×10 mm×0.5 mm (length×width×thickness) on which two kinds of micro-pin-fins with the dimensions of 30 μm×120 μm,50 μm×120 μm (thickness×height) were fabricated by the dry etching technique. A smooth surface was also tested for comparison. The correlations for nucleate boiling curves and the maximum allowable heat flux curves were obtained. The results show that the heat transfer performance was improved with increasing liquid subcooling and flow velocity. All micro-pin-finned surfaces displayed a considerable heat transfer enhancement. The addition of jet impingement further enhanced the heat transfer at a high heat flux and increased the CHF. At a certain cross flow velocity, the enhancement was more significant as the jet velocity increased, especially for V_c=0.5 m/s, V_j=2 m/s. For the micro-pin-finned chips, the CHF increased by more than 93% while the subcooling was 35°C compared with V_c=0.5 m/s, V_j=0 m/s. As the cross velocity increased, the intensification degree of jet impingement decreased and the increase of CHF also decreased.