Flow characteristics of HFC-134a in an adiabatic helical capillary tube

Abstract

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.

In this paper, an attempt is made to model the refrigerants flow through helical adiabatic capillary tubes used in domestic refrigerators and small residential air conditioners. The present study, based on homogenous two-phase flow model, predicts the performance of the helical capillary tube under adiabatic flow conditions. The variation of different physical parameters like pressure, temperature, quality, void fraction, velocity, and entropy with the length of adiabatic capillary tube has been investigated. The effect of varying capillary tube diameter and the pitch on pressure variation along the length is carried out. The simulation results are validated with experimental findings of the previous researchers for straight capillary tube as the literature lacks experimental work on helical capillary tube. It is found that when subjected to similar conditions, the helical capillary tubes are shorter than their straight counterparts.