Adiabatic flow characteristics of R-600a inside a helically coiled capillary tube

This paper presents an experimental investigation of a helically coiled capillary tube with an adiabatic flow of R-600a. The details of experimental facility for testing a capillary tube with different inlet sub-cooling degree and varying pressure are discussed. The effect of coil diameter, capillary length, capillary tube diameter, sub-cooling degree and inlet pressure on mass flow rate are described. The degree of sub-cooling at the inlet of both straight and helical capillary tube is varied from 3 to 15 °C. The experimental results confirm that, the mass flow rate in the straight capillary tube is 1.5-16 percent higher than the coiled capillary tube. A non-dimensional correlation to predict the mass flow rate through a straight and helical coiled capillary tube has been developed with a good agreement of ±20 percent of measured mass flow rate.