Experimental Study of Non-boiling Heat Transfer by High Flow Rate Nanofluids Spray

Abstract

Spray cooling has received interest as a technique to dissipate extremely high heat fluxes. Due to its high heat flux cooling capacity, temperature uniformity and acceptable cooling medium inventory, it continually finds new cooling applications from semiconductor to laser diode array, from high precision forging to space shuttle’s flash evaporator system. These applications are all concerning the phase change heat transfer. However, phase change happens in a relative high temperature which inevitably increases energy consumption and decreases life span of electronics. So the heat transfer research in non‐boiling spray cooling is worthwhile and urgent. Experimental investigation of non‐boiling spray cooling with low surface temperature and big flow rate was conducted. At the condition of room temperature and atmospheric pressure, water was used as working medium and water flow rate ranged from 0.58–0.95 L/min. It shows that the bigger the spray pressure, the better of the heat transfer performance. When the nozzle‐to‐surface distance is within a certain value, there exists an optimum position where the spray footprint is inscribed to the heated surface. TiO2‐water Nanofluids was used as cooling medium. The mass concentration of nanofluids was set to 0.1%, 0.5% and 1%, respectively. Heat transfer performance was found to be significantly enhanced and heat transfer coefficient was increased with the increased concentration.