Jet impingement in a crossflow configuration: Convective boiling and local heat transfer characteristics

Highlights: • Impingement jet is applied to flow boiling for improved heat transfer. • Local heat transfer is measured using micro-fabricated RTD sensors. • The jet blowing ratio affects significantly the boiling performance of ONB and CHF. • An optimal jet blowing ratio is obtained for enhancing boiling heat transfer. - Abstract: Flow boiling accompanied impingement jet was highly desired to enhance convective heat transfer. The secondary jet impingement system was designed to get enhanced heat transfer performance. The fluidic behavior was analyzed through visualization, and the local heat transfer was evaluated using an array of resistance temperature detector (RTD) sensors. The dielectric fluid FC-72 was used as coolant, and flowed through the rectangular channel with flow rate of Re = 6000 and saturated condition. We confirmed that the jet blowing ratio significantly influenced to the fluidic structure and local heat transfer distributions. Reinforced convective motion by jet flow removed bubbles on the heating surface, and increased local heat transfer coefficient by 59% with decreased wall superheat by 11% at the jet blowing ratio of 1:5. Whereas more intensified convective flow could delay onset of nucleate boiling (ONB) by disturbing thermal boundary layer at the jet blowing ratio of 1:10. Critical heat flux (CHF) increased quasi-linearly by increasing of the jet blowing ratio leading to the reinforcement of total fluidic momentum. Based on the results of the various jet blowing ratios and consequent local/overall heat transfer data, we conclude that the jet blowing ratio of 1:5 is an optimized condition for enhancing heat transfer coefficient at a given exit quality in the tested blowing ratios