Modelling Adiabatic Capillary Tubes: A Critical Analysis

Rating Charts of R-22 Alternatives Flow through Adiabatic Capillary Tubes

Drop-in of R-22 alternatives in refrigeration and air conditioning systems requires a redesign of system components to improve system performance and reliability with the alternative refrigerants. The present paper aims at design adiabatic capillary tubes for R-22 alternatives such as R-417A, R-422D and R-438A. A theoretical model has been developed and validated with the available experimental...

Experimental Studies on Non-Adiabatic Flow of HFC-134a Through Capillary Tubes

Experimental Analysis of Capillary Tubes for CFC-12 and HFC-134a

This work presents experimental data for capillary tubes of the type commonly used as expansion devices in domestic appliances, employing CFC-12 and HFC-134a as working fluids. Capillary tubes of 0. 7, 0.8 and 1.0 millimeter internal diameter with lengths of 3 and 2 meters were tested. Condensing pressures of 18, 14, 11 and 9 bar, and subcooling ranging from 14 to 2 oc were chosen as the operat...

A Simulation for Predicting the Refrigerant Flow Characteristics Including Metastable Region in Non-Adiabatic Capillary Tubes

The capillary tube/suction line heat exchanger (SLHX) is widely used in small refrigeration systems. The refrigerant flowing in the SLHX experiences frictional and accelerational head losses, flashing, and heat transfer simultaneously. The simulation of refrigerant flow through SLHX is important since this will help engineers analyze and optimize the SLHX incorporated in a refrigeration system....

Effects of Bubbles on the Hydraulic Conductivity of Porous Materials – Theoretical Results

In a porous material, both the pressure drop across a bubble and its speed are nonlinear functions of the fluid velocity. Nonlinear dynamics of bubbles in turn affect the macroscopic hydraulic conductivity, and thus the fluid velocity. We treat a porous medium as a network of tubes and combine critical path analysis with pore-scale results to predict the effects of bubble dynamics on the macros...