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ACRC Technical Report 136PDF


Title:A Theoretical Model for Predicting Adiabatic Short Tube
Author(s):Yin, J.M.
Subject(s):stationary air conditioning system analysis
mobile air conditioning systems
Abstract:A new theoretical model for predicting short tube orifice performance is presented. The new model can be used over wide parameter ranges, with subcooling from O°C to 50°C, inlet pressures as high as 35bar, and inlet quality from 0 to 0.98. The comparison of the model predictions to the nearly thousand experimental data for quality and subcooled inlet conditions, for tubes with and without screens and for different diameters and length, provided a comprehensive assessment of the model's accuracy. The model can predict the mass flow rate of with screen tubes within ±1O% by using nominal diameter, if the measured diameters were used, the deviations can be reduced further. For quality inlet and low subcooling inlet data, the present model is essentially the same as that for capillary tube case with metastable correction. For data with high subcooling, a new model is proposed based on the thermodynamic analysis that the flow can not be choked within the tube, but the experimental results shown that the flow is choked. The only way for refrigerant flow through the tube is choked just outside of the tube exit plane, and the choked pressure is the vaporization pressure, which is calculated from the corresponding saturation pressure and metastable correction.
Issue Date:1998-02
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center TR-136
Genre:Technical Report
Sponsor:Air Conditioning and Refrigeration Center Projects 69 and 78
Date Available in IDEALS:2009-05-18

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