Experimental investigation of nozzle submergence depth on steam cavity thermal characteristics in direct contact condensation

Abstract

Direct contact condensation has found wide applications in an industrial sector because of its enormous mass and heat transfer capabilities. In the current experimental investigation, effect of submergence depth has been analyzed on the thermal characteristics of steam plume issuing into water tank from two geometrically different steam spray nozzles i.e. converging–diverging (CD) nozzle and straight pipe (SP) nozzle. The steam cavity images were taken using high-speed camera which were processed by MATLAB image-processing tool for the measurement of steam-water interfacial area. It was observed that axial temperature distribution rises with the increase in submergence depth while for radial temperature distributions reverse was found to be true. Additionally, the temperatures at nozzle exit were noted to be independent of submergence depth. The heat transfer coefficient decreases as the steam pressure, water temperature and submergence depth is increased for both the nozzles and found in range of 1.661–2.91 MW/m2·K and 1.472–1.989 MW/m2·K for the CD and SP nozzle, respectively. Moreover, the effect of submergence depth was found to be almost negligible at the higher submergence depth values.