Concentration and temperature measurements by means of Raman spectroscopy in case of condensation with non-condensable gas

Abstract

Abstract Condensation in presence of non-condensable gas is safety relevant in case of loss-of-coolant accidents in pressurised water reactors. Non-condensable gas reduces the heat and mass transfer in the vapour phase, especially with low steam velocities. Insufficient heated emergency core cooling water can cause thermal shocks at the reactor pressure vessel for example. Within the scope of a research project supported by the Bundesministerium für Wirtschaft (BMWI) experiments have been performed to study the effect of non condensable gases on direct contact condensation at horizontal stratified steam/water flow. The paper presents the laser-optical measurement technique linear Raman spectroscopy for determination of concentration profiles in the vapour phase and temperature profiles in the liquid phase with high local resolution. The film theory, described in this paper, allows the approximation of these measured concentration profiles and therefore the calculation of local heat and mass transfer. If homogenous condensation occurs, the fog density in the vapour phase can also be estimated by means of Raman spectroscopy. Steady state and transient experiments are presented.