Numerical study on flow and heat transfer characteristics of air-jet cooling system

Abstract

The present study aims to numerically analyze the cooling characteristics of the air-jet array in designing more efficient air-cooling system. Heat transfer and flow characteristics are also examined under different operating conditions and air-jet arrangements. The commercial CFD program (FLUENT V. 17) is used for the designed configuration where 10 specimens are cooled by the air-jet arrangement. From the result, it is found that the inner jet arrangement can make the cooling performance higher because of substantial interaction between them in the flow direction. When inner jets are installed for cooling, there is a fluid mixing zone before the specimen by short jet-to-jet distance, leading to a decrease in heat transfer. Also, the fluid mixing zones are concentrated near to the specimen because of similar flow rate between outer and inner jets. Therefore, we suggest the appropriate configuration showing the best cooling efficiency when considered the air temperature, the heat transfer coefficient, and the flow usage. The number of nozzles of inner jets is 44, but highvelocity jet is used for preventing flow mixing among the inner jets. Consequently, cooling with the outer jets effectively occurs around the specimen. This result would be helpful in determining the jet velocity and its configuration between inner and outer jets that are essential for multiple specimens cooling.