Experimental study on flow patterns of direct contact condensation between steam jet and subcooled water flow in rectangular channel

To fundamentally understand the details of steam-water interface, visual investigation is conducted in a rectangular channel with rectangular nozzles. The flow fields of DCC are filmed when the steam pressure, subcooled water pressure and subcooled water temperature at the device inlet get 0.1-0.45 MPa, 0.1-0.4 MPa, and 30°C respectively. Moreover, a condensation regime map based on the inlet parameters is achieved. The result indicates that the process of DCC in a rectangular channel can be divided into five regions: steam region, subcooled water region, mixture layer, backflow region and homogenous bubble region. The interface between steam region and mixture layer is clearly observed. Under various inlet steam and water conditions , the flow patterns of DCC can be characterized as bubble flow, interface oscillation, tail oscillation, stable jet and divergent jet. The temperature distribution on the bottom wall is obtained, and the average heat transfer coefficient of stable jet is found to be within the range of 5.2-9.0 MW · m^-2 · °C^-1.