Analysis of flow pattern and heat transfer in direct contact condensation

Abstract

In direct contact condensation (DCC) phenomenon, whenever steam (vapor) is injected with very high velocity in sub-cooled water, the momentum and the energy of the steam is transferred to the surrounding liquid, leading to generation of flow pattern, turbulent in nature. The turbulent flow pattern enhances the heat transfer coefficient at the interface of steam jet and water (vapor-liquid interface) as well as at the immersed surfaces (solid-liquid interface). The flow and the temperature pattern in DCC system have been measured using hot film anemometer (HFA). The values of heat transfer coefficient at the vapor-liquid and solid-liquid interface were estimated using the CCA module of the HFA. The nozzle diameter (d₀) was varied in the range of 1-2 mm and the nozzle upstream pressure in the range of 0.3-0.35 MPa (corresponding velocities in the nozzle were 286-304 m/s). The time series of velocity and temperature at the interface were analyzed to get the rates of surface renewal. A comparison has been presented between the predicted and the experimental values of heat transfer coefficient.