A mathematical model has been developed to predict the performance of a helical capillary tube under adiabatic flow conditions. The proposed model can predict the length of the adiabatic helical capillary tube for a given mass flow rate or the mass flow rate through a given length of capillary tube. The effect of parameters like condensing pressure, degree of subcooling, pitch of helix and the coil diameter has been studied for the flow of refrigerant R-134a through the adiabatic helical capillary tube. A capillary tube selection chart has been developed, using the proposed model, to predict the mass flow rate of refrigerant R-134a through a capillary of size 1.07 mm diameter and 2 m length.

Units: SI