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Non-condensable gases at low concentrations in a high-temperature heat pump operating with R-1336mzz(Z).

Number: 2314

Author(s) : BRENDEL L. P. M., LÜCHINGER N., ARPAGAUS C., BERTSCH S. S.

Summary

R-1336mzz(Z) is a hydrofluoroolefin (HFO) refrigerant with a high critical temperature of 171.4 °C and therefore has prospects for application in high-temperature heat pumps (HTHP). The refrigerant has a saturation pressure below ambient at room temperature, causing concern about non-condensable gases (NCGs) like ambient air coming into the system during servicing or due to sub-atmospheric pressures in the heat pump. This study experimentally tests for negative effects of growing levels of air in the system using a HTHP with an internal heat exchanger (IHX), suction gas accumulator, and liquid receiver. Tests are conducted with air pressures of 5, 15.3, 25.6, 51.2 and 282 mbar before charging refrigerant resembling air mass fractions between 0.004% and 0.2%. Characteristic data (i.e., COP, pressures, discharge temperature) was collected at two different operating conditions for all five NCG levels. No negative effect of the NCG was found in the performance tests. Additional dew point temperature measurements also showed results within the measurement uncertainty as if no NCGs were in the system. An increase of the resting pressure was measurable and is in line with the expected effects of NCGs in a vapor compression system. It is concluded that the maximum tested level of NCGs tested was insufficient to alter the overall system performance.

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  • Original title: Non-condensable gases at low concentrations in a high-temperature heat pump operating with R-1336mzz(Z).
  • Record ID : 30033182
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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