Critical Mass Flow Rate and Pressure Distribution through Horizontal Adiabatic Capillary Tubes for the Flow of R-134A

Abstract

Although numerical methods such as drift flux model or separated flow model are known as alternatives for experimental methods to predict critical mass flow rate through capillary tubes, they are time consuming and may not be suitable to an engineer’s need. As a result, in this paper two general correlations are developed by using drift flux model to predict critical mass flow rate and critical pressure distribution through capillary tubes. Critical mass flow rate and pressure distribution for nearly 500 operational conditions for the flow of R-134a, with inlet pressure varying from 800 to 1500 kPa and inlet subcold temperature of 0 ≤ sub T ≤ 10°C flowing through capillary tubes with length varying from 1 to 2 m and inner diameter of 0.5 ≤ D ≤ 1.5 mm were evaluated. Using developed data from drift flux model and dimensionless analysis, two general correlations were developed to predict critical mass flow rate and critical pressure distribution through capillary tubes.