Critical heat flux of multinozzle spray cooling in a closed loop

Tiny nozzles are developed that are capable of creating swirling flow necessitated to generate a full cone spray. Eight miniature nozzles are embedded in a multinozzle plate used to generate a spray array for the cooling of high heat flux laser diodes. The target spray cooling area is a 1×2 cm² flat surface of a copper heater plate. A closed loop spray cooling test setup is established. FC-87, FC-72 and methanol are used as the working fluids. Critical heat flux (CHF) is investigated at various spray saturation temperatures and nozzle pressure drops (from 0.69 bar to 3.10 bar). It is demonstrated that the spray cooler can reach the CHF levels of 91.5 W/cm² with FC-87 and 490 W/cm² with methanol. A semiempirical correlation of CHF is presented using the present experimental data for the multinozzle spray cooling in the confined and closed system.