Thermodynamic analysis of two types of compressors applied to household heat pump water heaters.

The use of heat pumps for domestic water heating has increased over recent years and thus, as regulations are becoming increasingly restrictive, the compressor design must be improved for this application. The main issues in the development of compressors for this application are the requirements of low power consumption and high pressure ratios, due to the high condensing temperatures and the low evaporation temperatures, which are typical of cold climates. The efficiency of a heat pump is affected by the adopted vapor compression technology, but few comparative studies of these technologies are available in literature. This paper reports a comparative study of the two most common compression technologies applied to heat pumps for domestic water heating: the reciprocating and rolling piston compressors. Results from losses inventory are used to identify the main source of inefficiencies of each technology for this application.