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Operation of large-scale heat pumps under fluctuating boundary conditions.

Number: 0937

Author(s) : MEESENBURG W., KRAMER K. R., CHRISTENSEN M. K., REINHOLDT P., POULSEN J. L., ELMEGAARD B.

Summary

Large-scale heat pumps are increasingly employed to provide district heating from ambient heat sources or industrial excess heat. Integration with fluctuating industrial or ambient heat sources poses a challenge to heat pumps as sudden changes in the heat source conditions may result in unstable operation conditions or even influence the compressor performance negatively. This is especially challenging for heat pumps operated with minimal superheating after the evaporator. While heat pumps integrated with fluctuating industrial processes, are often equipped with mixing tanks in the sink and source stream upstream of the heat pump, this is typically not the case for units supplying district heating. The aim of this study was to assess how plants not designed with such mixing tanks react to sudden changes in the sink and source conditions and which problems may occur. We focused on the analysis of the risk of liquid floodback, sudden condensation in the suction line and the analysis of the response of the pressure levels in the system. The study was conducted using a validated dynamic model of a one-stage ammonia heat pump with and without suction line heat exchanger. It was found that there is no risk of liquid floodback in both systems even for changes of the sink and source flow rate of up to 20 %/min and of the sink and source temperatures of up to 2 K/min. The amount of liquid that may condense in the suction line for the case without suction line heat exchanger is minimal. The pressure levels adapt quickly to the changed boundary conditions, an allowable gradient for changes in the pressure level could not be defined based on the results.

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Pages: 12

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Details

  • Original title: Operation of large-scale heat pumps under fluctuating boundary conditions.
  • Record ID : 30031476
  • Languages: English
  • Subject: Technology
  • Source: Proceedings of the 26th IIR International Congress of Refrigeration: Paris , France, August 21-25, 2023.
  • Publication date: 2023/08/21
  • DOI: http://dx.doi.org/10.18462/iir.icr.2023.0937

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