Mathematical Model of Fluid flow through the Thermostatic Expansion Valve

摘要

As it has been mentioned the aim of this paper is to represent an accurate mathematical model of the thermostatic expansion valve for mass flow rate and valve movement. It should be noted that due to flashing and interacting between the evaporator pressure and the thermobulb pressure, using an orifice equation to simulate the expansion valve is a rough approximation. The orifice equation to predict the mass flow rate through the expansion valve can not predict the effect of flashing and sub-cooling on the mass flow rate. The effect of flashing is to decrease the mass flow rate where the sub-cooling the liquid, increases the mass flow rate through the valve. Thus a new relation based on this factor is introduced for mass flow rate through the valve and an equation also is obtained for the valve movement.