Cooling performance of multi-nozzle spray with liquid nitrogen

Abstract

Spray cooling with liquid nitrogen has great advantages to achieve a cryogenic environment simulation system. The nozzle number, the mass flow rate and the gas velocity have crucial impacts on the cooling efficiency and the high-precision temperature control in the system. To gain insight into the multi-nozzle spray cooling performance, the small wind tunnel prototype with liquid nitrogen spray cooling was built, and the transient and steady-state cooling performance was experimentally studied. The results show that during the transient cooling process, the temperature is lower when the region is closer to the spray field. The temperature on the test plane near the spray has the biggest difference. After flowing through two elbow pipes, the high uniformity of the temperature distribution is obtained. The research of the steady state cooling shows that the average temperature gradually increases along the flow direction from the spray region, while the temperature uniformity is in the reverse order. And the small deviation among the data on the later three planes means a good temperature uniformity within the wind tunnel except the spray region. In addition, a lower gas velocity, a larger nozzle number and a higher injection pressure can enhance the cooling performance. However, the temperature uniformity becomes worse as the nozzle number increases. The results could provide theoretical guidelines for the engineering application of the cryogenic spray cooling.