Development of an Experimental Facility to Evaluate the Performance of Air-Cooled Automotive and Household Refrigerator Condensers Utilizing Ozone-Safe Refrigerants

摘要

Chlorofluorocarbons or CFC's have long been the refrigerants of choice in vaporcompression . refrigeration systems, including mobile air conditioning andhousehold refrigerator/freezer applications. Due to enviromental concernsregarding ozone layer depletion and global warming, international agreementshave been legislated that will gradually reduce and eventually eliminate theserefrigerants. Although alternative, ozone-safe refrigerants have been developed,their effect on the performance of air-cooled condensers must?? still be evaluatedso that industry may more effectively design air conditioning and refrigerationsystem components in the future. A full condenser test apparatus has beendesigned and constructed to allow experimental determination of the heattransfer and friction characteristics of air-cooled condensers utilizingalternative refrigerants. Baseline testing has recently been conducted using CFC-12 and simulating a wide range of air-side and refrigerant-side conditions at thecondenser inlet. Separate experiments were included either single phase or twophase refrigerant flow through the condenser. Modified Wilson Plot procedureshave been implemented to evaluate the air-side heat transfer resistances and todevelop a Colburn j-factor correlation for an automotive condenser with two rowsof staggered, wavy finned tubes. The correlation agrees fairly well with otherempirical correlations appearing in the literature for the same type of condensergeometry. Additional expected trends in the experimental data were observed;however, existing uncertainties in temperature and pressure measurementsrequire that refinements be made to the system in the near future.