VOLUME 10, NUMBER 3 HVAC&R RESEARCH JULY 2004 291 Detailed Experimental Validation of the Thermal and Fluid Dynamic Behavior of Hermetic Reciprocating Compressors Joaquim Rigola Gustavo Raush Carlos David Pérez-Segarra Asseni Oliva A detailed experimental analysis of the thermal and fluid dynamic behavior of hermetic recipro- cating compressors is presented. A hermetic compressor for household appliances has been experimentally tested. The fluid and solid thermal map evolution has been logged in several strategic points. The absolute instantaneous pressure has been determined in three specific zones: suction muffler, compression chamber, and cylinder head. The pV diagram inside the compressor chamber has also been experimentally obtained for the different working conditions studied without any previous hypothesis to determine the absolute pressure level. A complete description of the experimental equipment and its instrumentation is included. This experimen- tal approach has allowed validating a mathematical model developed for the numerical simula- tion of the thermal and fluid dynamic behavior of hermetic reciprocating compressors. Good agreement between the detailed numerical results and the experimental data has been obtained, allowing a better understanding of the thermal and fluid dynamic behavior of these compres- sors. INTRODUCTION Compressor performance design is defined by different parameters: mass flow rate or volu- metric efficiency, compression work or isentropic efficiency, mechanical and electrical efficien- cies, heat losses, COP, etc. To have a better understanding of the complex physical processes involved in this kind of unit, it is necessary not only to know these global values, but also their detachment and specific evolution under a wide range of different working conditions. Some of these meaningful parameters that define compressor behavior strongly depend on the overall heat transfer processes inside the compressor. Several authors have investigated the ther- mal analysis of compressor behavior. Liu and Zhou (1984) present a general correlation for instantaneous heat transfer to the cylinder wall and its influence in relation to the adiabatic com- pression chamber. Meyer (1987) analyzes heat transfer through the suction gas, which has adverse effects on compressor performance. Fagotti et al. (1994) and Cavallini et al. (1996) ana- lyze whole heat transfer modeling in hermetic reciprocating compressors and its influence in dif- ferent zones (the remnant fluid between the compressor shell and crankcase, suction muffler, the compression chamber, and discharge line). Other meaningful parameters that define compressor behavior are the compression work and its nondimensional ratio with isentropic work, i.e., isentropic efficiency. Both works (the com- pression work and the isentropic work) can also be split into four different compression parts: compression, discharge, expansion, and suction, with different contributions to isentropic effi- ciency (Pérez-Segarra et al. 2002). Several authors present different experimental investigations The authors are at the Heat and Mass Transfer Technological Centre (CTCC), Universitat Politècnica de Catalunya (UPC), Barcelona, Spain.