Enhanced heat spray cooling with a moving nozzle

Experimental studies were performed to understand the thermal performance of the heat spray cooling with a moving nozzle. The test-rig included an open loop system with a stepping motor for the nozzle movement along the rectangular surfaces. Both the flat and structured surfaces were employed. The experimental results revealed that both the nozzle to surface distance and the nozzle moving speed have an influence on the temperature distribution. The temperature variance was smaller at the lower flow rate than at the higher flow rate. For the structured surface, the temperature variance was lower for the shorter fins. At the low heat flux, a higher heat transfer coefficient was observed on the flat surface than on the enhanced surfaces. This is because of the thin water film on the flat surface as compared to the thick water film on the enhanced surfaces due to the capillary action. However, at the high heat flux, the enhanced surfaces showed a higher heat transfer coefficient than the flat surface due to the higher evaporation rate from the water film induced by the increased area of the fins.