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Analyses of different defrost methods in air to water industrial CO2 heat pumps.

Number: 0009

Author(s) : KRISTOFERSSON J., DELETRE P. J. E., RASMUSSEN L., KRISTOFFERSEN J. W., CHRISTENSEN K. G.

Summary

Carbon dioxide (CO2) or R744 is a nontoxic, natural and future proof refrigerant with a low global warming potential (GWP) of 1, making it well-suited for large air-to-water heat pumps in district heating systems. Efficiency is a crucial element in the operation of heat pumps, and it's important to keep it as high as possible. Ice build-up on the evaporator surface reduces the efficiency of the system by lowering the suction temperature and needs to be removed. A traditional method of removing ice for CO2 heat pumps is manly by electrical heating rods which decreases the efficiency of the heat pump during defrost. This study investigates and evaluates alternative methods for defrosting the evaporator in order to find the method with the lowest reduction in overall efficiency. Six alternative defrosting methods were analysed for the heat pump for two running conditions i.e., where the compressors were not controlled during defrost, and also where they were speed controlled to maintaining the same heating capacity as before during defrost.

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Pages: 11

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Details

  • Original title: Analyses of different defrost methods in air to water industrial CO2 heat pumps.
  • Record ID : 30030968
  • Languages: English
  • Subject: Technology
  • Source: 10th IIR Conference on Ammonia and CO2 Refrigeration Technologies.
  • Publication date: 2023/04/27
  • DOI: http://dx.doi.org/10.18462/iir.nh3-co2.2023.0009

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