CFD MODELLING OF BOILING FLOW

Abstract

The two phase liquid-vapour flow is an important part of heating process. In order to improve the safety it is essential to understand the mechanisms governing this flow and the mechanism governing the formation of vapour bubbles at the Critical Heat Flux. There are Previous researches exists about nucleation and heat transfer at normally achievable temperatures and pressures. The main purpose of this project is to develop an effective heat transfer model for calculating heat transfer coefficient. The setup used for this study is taken from the ALAM et. al. (2008) literature in order to simulate. A single heating rod is immersed in a vertical tank. Inlet water pressure and heat flux rate can be varied in this setup and the effects of these variations on nucleation can be observed.CFD code FLUENT 6.3 is used for simulation purpose. . Simulations have been carried out in 2D Heating System using a transient Eulerian-Eulerian model. In our simulation a NUCLEATE BOILING MODEL is incorporated by using USER DIFINED FUNCTION facility in FLUENT. PODOWSKY model is incorporated with the help of UDF facility. Pressure based EULARIAN multiphase model has been-selected. Simulated results are obtained for 2D geometry by using pure water as a heating media. The material of heating rod is chosen as STAINLESS-STEEL. The simulated results are obtain for heat transfer coefficient, bubble frequency, bubble departure diameter, nucleation site density, wall flux, evaporative heat flux, quenching heat flux etc for heating surface. These simulated results are validated with previously obtain experimental data's