COMPRESSOR PERFORMANCE ANALYSES OF REFRIGERANTS (R22 and R407C) WITH VARIOUS LUBRICANTS IN A HEAT PUMP

摘要

System performance in heat pumps depends upon several factors: refrigerant and lubricant choice, type of compressor, type of heat exchangers, expansion devices etc. Depending upon these factors, system performance can change significantly, as much as 30% or more. An important question in analyzing system performance is determining which part of the system is responsible for changes in performance: is it due to the compressor, the system components (heat transfer, or refrigerant mass flow rate, etc.) or combined effects of both? In this study, we have examined system performance of a duct-free split heat-pump unit (2.5 kW) with a rotary compressor, designed for R-22/mineral oil and tested with R-407C and various POE oils. System performance (capacity and energy efficiency for both cooling and heating modes) showed significant variations among the different lubricants tested. As a first step to understand such behavior, we analyzed compressor performance with the various lubricants under the same ambient conditions. Based on a polytropic analysis, we concluded that the compressor performance is not responsible for the observed large variations in system performance.