DYNAMIC STUDY OF TWO - PHASE PIPE FLOW

Abstract

The present investigation pertains to dynamic study of two-phase tlow in pipes. Basically, it deals with the development of mathematical model for the prediction of pressure/temperature of the mixture in a pipe. It also describes the transient behaviour of variables for various changes in the input variables and thereby determine the most sensitive variable for the purpose of accurate monitoring and precise control. Using the basic principles of mass, momentum and heat transport and two-phase flow, material balance, energy balance, and momentum balance equations have been developed. The values of enthalpies, density have been incorporated in the model. The model developed is in the from of partial differential equations. These equations are solved by Lax-wendroff finite difference method. From the model, axial pressure in a horizontal pipe is calculated for a given set of operating variables as mentioned in chapter. 5 and compared with the axial pressures in a horizontal pipe due to Schwellnus and Shoukri (12). It is found that predicted values are approximately 5% higher than that of Schwellnus and Shoukri (12). The model developed is solved for transient response of void fraction of the gas, velocity of gas, velocity of liquid and temperature of the mixture. I'cmperature of the mixture has been found to be most sensitive variable since the time required to attain the steady-state value from the moment of disturbance is least than the other variables. This study is helpful in identification of the variables which should be closely monitored and controlled so that steady-state operation can be maintained even when a small change in operating variables takes place.