Detailed thermodynamic characterization of hermetic reciprocating compressors C.D. Pe ´rez-Segarra * , J. Rigola, M. So `ria, A. Oliva Centre Tecnolo `gic de Transfere `ncia de Calor (CTTC), Lab. de Termote `cnia i Energe `tica. Universitat Polite `cnica de Catalunya (UPC), ETSEIT, Colom 11, 08222 Terrassa, Spain Received 17 February 2004; received in revised form 21 September 2004; accepted 22 September 2004 Available online 8 January 2005 Abstract The aim of this paper is the detailed analysis of different well-known thermodynamic efficiencies usually used to characterize hermetic compressors. Attention is focussed on the volumetric efficiency, the isentropic efficiency, and the combined mechanical–electrical efficiency. A procedure is presented to detach these efficiencies into their main components (physical sub-processes) to get deeper insight on the overall behavior. The volumetric efficiency is split into partial efficiencies related to pressure drop and heat transfer effects, supercharging effects, superdischarging effects, leakages, etc. The isentropic efficiency is detached using two different points of view: the work associated to the individual sub-processes (compression, discharge, expansion, suction), and the work associated to the underpressures, overpressures, and between the inlet and outlet mean compressor pressures. Finally, the combined mechanical– electrical efficiency is related to the heat transfer losses/gains, and to the exergy transfers and exergy destroyed. Even though some of the concepts introduced in the paper can be applied to different kinds of compressors, the discussion is specially focussed on hermetic reciprocating compressors. An advanced simulation model developed by the authors has been used to generate data to illustrate the possibilities of the detailed thermodynamic characterization proposed. The criteria developed are useful tools for comparison purposes, to characterize compressors, and to assist designers during the optimization process. q 2004 Elsevier Ltd and IIR. All rights reserved. Keywords: Survey; Reciprocating compressor; Hermetic compressor; Efficiency; Volumetric efficiency; Modelling Caracte ´risation thermodynamique des compresseurs a ` piston herme ´tiques Mots cle ´s : Enque ˆte ; Compresseur a ` piston ; Compresseur herme ´tique ; Efficacite ´ ; Rendement volume ´trique ; Mode ´lisation 1. Introduction A vapor compression refrigeration system is basically composed by an evaporator, a compressor, a condenser, and an expansion device. The system is designed to extract some amount of energy in the evaporator, and deliver this energy 0140-7007/$35.00 q 2004 Elsevier Ltd and IIR. All rights reserved. doi:10.1016/j.ijrefrig.2004.09.014 International Journal of Refrigeration 28 (2005) 579–593 www.elsevier.com/locate/ijrefrig * Corresponding author. Tel.: C34 93 7398192; fax: C34 93 7398101. E-mail address: labtie@labtie.mmt.upc.es (C.D. Pe ´rez- Segarra).