Utilizing the inverse Marangoni convection to facilitate extremely-low-flow-rate intermittent spray cooling for large-area systems

摘要

An economical approach is required for solving the portability and maintenance problems of a spray cooling system for facilities stationed in remote areas. To reduce liquid consumption and decrease the number of nozzles required for large-area cooling, we propose the use of a self-rewetting fluid coupled with an intermittent spray that induces a surface-tension-driven flow to extend film evaporation. With an extremely low flow rate of 0.325 ml s(-1), the working fluid can be effectively pulled toward a hot region through the inverse Marangoni convection, which promotes thermal uniformity and postpones dryout. Consequently, the cooling rate is considerably improved and the temperature fluctuation over time is reduced. Because of the extremely low liquid consumption, strong film evaporation and intensive nucleation, as opposed to impingement momentum, play major roles in cooling. Although multiple-nozzle configurations outperform single-nozzle configurations at high input power, the performance differentiation between double and quadruple nozzles is small, and excellent cooling can be achieved with a nozzle density as low as 0.10 cm(-2). By using double or quadruple nozzles in the short-spray mode, the highest heat flux of 7.4 W cm(-2) can be achieved with a temperature fluctuation of +/- 0.5 degrees C and spatial deviation smaller than 4%.