Abstract

Direct-contact condensation of vapour containing the inert gas on a spray of subcooled liquid exists in a number of technical applications. For example, it may be found in the nuclear industry (e.g. pressurized jet under normal operating conditions, in safety analyses) or in the chemical industry (e.g. mixing-type heat exchanger, degasser, sea water desalting). The problem is also essential to modelling and analysis of some fundamental phenomena of two phase flow, such as condensation in power engineering condenser of steam power plant as well as a new concept of negative CO2 power plant, where separation of carbon dioxide from the mixture of steam and inert gas takes place in the spray ejector condenser (SEC) followed by the centrifugal separation in the cyclone. The phenomenon of direct-condensation heat transfer is primarily characterized by the appropriate transport of heat and mass through a moving vapour-liquid interface. Furthermore, using a spray ejector condenser (SEC) with separators can be considered as an alternative method to increase the efficiency of separation process. The present survey attempts to investigate the effect of different initial velocity of mixture and droplet on their temperature as well as the effect of diameter of throat on temperature of droplet and mixture. For the ejector design, the study focuses on the ejector nozzle, pre-mixing chamber, the mixing section and the diffuser. Flow properties and ejector geometry are considered using the thermodynamic equations, conservation equations and other assumptions established based on literature. Comparisons with experimental data show a good consistency with experimental results. Results show that increasing the value of initial velocity of mixture of steam (Um0) not only results in increasing the temperature of droplet, but also leads to rise the temperature of mixture of steam at the length of throat. Moreover, the lowest value for temperature of droplet and mixture of steam is when the drop is moving in stagnant environment (() = 0).

Authors (3)