Flow rate prediction for an adiabatic capillary tube in a transcritical CO2 system: An analytic approach

Abstract

Transcritical nature of the CO2 refrigeration cycle makes the capillary tube behavior distinctly different compared with a conventional subcritical system. A novel closed-form analytical solution is proposed to simulate the flow characteristics of an adiabatic capillary tube. Such an analytical solution is being proposed, for the first time, for the transcritical-superheated-two phase region in a CO2-based transcritical heating-cooling system. Improved K value relations based on Gaussian function for CO2 are obtained employing MATLAB-based tools. Predictions by the proposed analytical model have been validated against carefully obtained test data and the observed agreement is fairly good. © The Author 2010. Published by Oxford University Press. All rights reserved.