Two-phase flow characteristics and visualization of distributed confined array jet boiling

Confined array jet boiling can achieve high heat flux in a compact space and its flow resistance characteristics are critical to the design of cooling systems. The boiling images of distributed confined jet of HFE-7100 is recorded by a high-speed camera in this study. The effects of jet mass flux, jet height and surface structure of two-phase jet flow characteristics on micro-pin-finned surfaces are studied. A benefit from the distributed configuration of the jet array, in contrast to previous studies, is that the jet boiling pressure drop is independent of the heat flux, but only related to the jet mass flux. The effect of the surface structure on the pressure drop is negligible. Jet flow instability will be triggered by intermittently blockage of the jet inlet and outlet by large vapor masses in certain heated surfaces. Reducing the jet height can suppress two-phase flow instabilities while keeping the pressure drop almost constant and the CHF to slightly increase. The COP of distributed jet impingement boiling cooler proposed in this work can be up to 6 times higher than that of the conventional jet boiling cooler, and more than 2 times higher that of the microchannel heat sink.