Calculation of capillary tubes using dimensionless equations

Abstract
Five equations are presented for calculating the length of a capillary tube or the discharge of expanded refrigerant, and critical flow parameters at the tube’s outlet, such as pressure, vapour quality and speed. Coefficients for the equations determining the links between non-dimensional variables have been obtained by the regression analysis of polyvariant calculations on throttling of nine refrigerants. An example is given to illustrate the calculation process using an engineering calculator. The effect of boiling pressure on the tube length and refrigerant discharge is discussed.