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Decarbonizing steam generation with high temperature heat pumps: refrigerant selection and flowsheet evaluation.

Number: 0059

Author(s) : HÖGES C., VENZIK V., VERING C., MULLER D.

Summary

High temperature heat pumps have a high potential to reduce carbon emissions in industrial processes by replacing conventional heating systems for low-pressure steam generation. However, heat pump performance is sensitive to the selected refrigerant, flow sheet, and operating conditions complicating the design process. Thus, we conduct a refrigerant selection and evaluate five flow sheets for a low-pressure steam application, which heats liquid water from 80°C at 1.5 bar to 120°C steam. First, refrigerants are screened to identify suitable low-GWP (<150) refrigerants. We find 15 alternative refrigerants. Second, the performance of the selected refrigerants is evaluated in five flow sheets, including two vapor injection and a parallel-compression configurations. R717 outperforms all other solutions concerning cycle efficiency and heating capacity for all investigated cycles. However, R717 leads to high compressor discharge temperatures limiting the applicability with compressor lubricant. Here, lubricant-free technologies such as turbo compressors are promising. Besides R717, the investigation shows further solutions with high efficiencies. Most promising refrigerants, however, have a double bond in their molecule structure, reducing their chemical stability. Furthermore, the cycle configuration using vapor injection in combination with an internal heat exchanger yields the highest cycle efficiencies. Compared to the simple flow sheet, more than 20% of improvements are possible.

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Pages: 12 p.

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Details

  • Original title: Decarbonizing steam generation with high temperature heat pumps: refrigerant selection and flowsheet evaluation.
  • Record ID : 30031077
  • Languages: English
  • Source: 14th IEA Heat Pump Conference 2023, Chicago, Illinois.
  • Publication date: 2023/05/15

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