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Application of a hybrid control of expansion valves to a domestic heat pump and a walk-in cooler refrigeration system.

Author(s) : BACH C. K., GROLL E. A., BRAUN J. E., et al.

Type of article: Article

Summary

Hybrid refrigerant flow control, as proposed by Kim et al. (2008), employs a primary expansion valve that provides most of the pressure drop between the condensing and evaporation pressures, while small secondary balancing valves in the distributor lines to the circuits of the evaporator adjust the refrigerant flow to provide equal circuit exit superheats. In this article, experimental results for the application of the hybrid control of expansion valves to a 3-ton (10.6-kW) R404A walk-in cooler refrigeration system and a 5-ton (17.6-kW) domestic heat pump are presented. For the walk-in cooler refrigeration, initial data was taken using the inbuilt thermostatic expansion valve. Baseline data with an electronic expansion valve was taken for both systems to determine the best possible performance without using individual circuit flow control. After that, secondary balancing valves were inserted into the distributor lines to complete the hybrid control scheme. The tests were repeated to determine the achievable performance improvement. Frost build up tests at high indoor room humidity were conducted with all control schemes to determine the influence of the control scheme on frost distribution and system performance. To determine the influence of a fixed and repeatable airside maldistribution, additional tests with partially blocked evaporator coils were conducted for both units with the electronic expansion valve and hybrid control scheme.

Details

  • Original title: Application of a hybrid control of expansion valves to a domestic heat pump and a walk-in cooler refrigeration system.
  • Record ID : 30010561
  • Languages: English
  • Source: HVAC&R Research - vol. 19 - n. 7
  • Publication date: 2013/10
  • DOI: http://dx.doi.org/10.1080/10789669.2013.822251

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