MODELING FLOW CHARACTERISTICS OF CAPILLARY TUBES FOR SYSTEM SIMULATION: EXTENSION TO THE SUPERHEATED REGIME

摘要

Capillary tubes are widely used in refrigeration and air-conditioning appliances. The existed capillary tube models concentrate on the subcool or low-quality inlet state. To simulate the dynamic process of actual plants, superheated flow should be involved in capillary tube model. In this work, an adiabatic capillary tube model including superheated regime is developed. Based on the model, the characteristics of high-quality and superheated flow when refrigerants CFC12, HFC134a and HC600a flow through capillary tube are analyzed. It is found that refrigerant mass flow rate does not always decrease with increase of refrigerant quality at capillary inlet. In addition, theoretical analyses of existed two-phase viscosity models are done and McAdams model is proved to be a good one, which is consistent with the experimental results.