Experimental energy and exergy analyses of ship refrigeration system operated by frequency inverter at varying sea water temperatures


Yılmaz O. , Bayar H. , Başhan V., Yiğit K.

Journal Of The Brazilian Society Of Mechanical Sciences And Engineering, vol.44, no.4, pp.1-23, 2022 (Journal Indexed in SCI Expanded)

  • Publication Type: Article / Article
  • Volume: 44 Issue: 4
  • Publication Date: 2022
  • Doi Number: 10.1007/s40430-022-03439-5
  • Title of Journal : Journal Of The Brazilian Society Of Mechanical Sciences And Engineering
  • Page Numbers: pp.1-23

Abstract

Ship refrigeration compressors are sized to provide required capacity under extreme atmospheric and sea water temperatures,
as well as full load and pulldown rates. Refrigeration compressors usually operate at 50–60 Hz in on/of mode at partial load
in cold and temperate sea waters. The most efcient way to meet variable cooling demands is to change refrigerant mass
fow by adjusting compressor speed. This paper is based on experimental investigation of ship cold storage refrigeration
system on laboratory scale. Compressor is driven by inverter, and condenser is water-cooled type just like on ships. The
refrigeration compressor has a power range of 600–1000 W and a maximum power of 1500 W. The system’s refrigeration
capacity ranges from 500 to 1350 W, with a maximum capacity of 2000 W. Experimental results were subjected to energy
and exergy analyses. At 60 Hz, exergy efciencies of compressor, condenser, expansion valve, and cold storage are 37.9%,
91.1%, 86.2%, and 69.8%, at - 5 °C cold storage and 18 °C water temperatures. In the same order, they contributed 73.2%,
7.6%, 10.4%, and 7% to wasted power. When water temperature increased from 18 to 35 °C at - 5 °C storage temperature
and 50 Hz, coefcient of performance (COP) decreased by 55.2%. Despite compressor's thermodynamic irreversibility
decreasing, combined electrical–mechanical efciency deteriorated as frequency decreased. When compressor frequency
was reduced from 60 to 40 Hz at - 5 °C cold storage and 18 °C water temperatures, COP increased by 13.9%.