Effect of Installation Conditions of Water Mist Nozzle on Thermal Radiation Attenuation Performance

Abstract

In this experimental study, the effect of installation conditions of a water mist nozzle on thermal radiation attenuation performance was investigated. Two types of nozzles (Small_nozzle and Large_nozzle) were used. Experiments were conducted under conditions in which the nozzle was installed near the heater and heat flux sensor (Position_NH and Position_NS, respectively), and water mist was discharged from one and two nozzles (Case_ID and Case_SD, respectively). To characterize the water mist spray, the water supply pressure and droplet size were measured, and visualization of the sprayed water mist was performed. The thermal radiation attenuation performance improved with an increase in the water flow rate, and Small_nozzle showed higher thermal radiation attenuation performance than Large_nozzle. Moreover, Case_SD showed lower thermal radiation attenuation performance than Case_ID_Sum (that is, the Sum of Case_ID & Position_NS and Case_ID & Position_NH) and the difference in thermal radiation attenuation performance between Case_SD and Case_ID_Sum at a higher water flow rate was more significant than that at a lower water flow rate. These might be attributed to the wide overlapping area of water mist discharged from two nozzles in Case_SD and at a higher water flow rate, narrowing the overall width of the water mist.