NUMERICAL SIMULATION AND EXPERIMENTAL VALIDATION OF INTERNAL HEAT EXCHANGER INFLUENCE IN CO{sub}2 TRANS-CRITICAL CYCLES UNDER REAL WORKING CONDITIONS FOR SMALL COOLING APPLICATIONS

摘要

The aim of this paper is to show the possibilities that CO{sub}2 offers for commercial refrigeration, considering a single stage trans-critical cycle using semi-hermetic reciprocating compressors under small cooling (HMBP) capacity systems. The present paper is a numerical and experimental comparative study of the whole refrigerating cycle in general, and reciprocating compressors in particular, considering a refrigerating system working with CO{sub}2 under a trans-critical refrigerating cycle. The present paper is focused on the influence of using internal heat exchanger (IHE) in order to improve the cycle performance under real working conditions. In order to validate the numerical results, a specific experimental unit specially designed and built to analyze trans-critical refrigerating equipments considering IHE has been built. Both numerical results and experimental data shows reasonable good agreement, while the comparative global values shows the improvement of cooling capacity and COP when IHE is considered in the CO{sub}2 trans-critical cycle under the same working conditions.