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Development of a carbon-ammonia adsorption gas-fired domestic heat pump.

Number: pap. n. 83

Author(s) : METCALF S., RIVERO PACHO A., CRITOPH R.

Summary

An air source gas-fired heat pump system intended to replace conventional condensing boilers is under development. The adsorption cycle uses ammonia refrigerant and activated carbon adsorbent in four generators with heat recovery and has a nominal heat output of 7 kW. Predicted annual average COP based on gross calorific value is 1.35 in a UK application with low temperature radiators. The prototype was first tested in May 2011. Whilst the machine functioned as a heat pump and delivered hot water at up to 60°C, internal leakage in water diverting valves and ammonia check valves meant that the efficiency was unacceptably low. Additionally, heat transfer in the adsorption generators was poorer than predicted which resulted in a heat output of only 3 kW. Modifications were made to existing off-the-shelf ammonia check valves and bespoke water valves employing ceramic discs in a polymeric shell were developed. These were installed on the machine, together with larger generators in order to increase the heat output. The system achieved a heat output of 4.3-5 kW and a COP of 1.13-1.2.When coupled with a gas burner this equates to a COP of 1-1.06 based on gross calorific value of gas. The lower than predicted performance is attributed to ammonia check valve leakage & blockage, heat loss, and poor water flow distribution within the adsorption generators.

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Pages: 9 p.

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Details

  • Original title: Development of a carbon-ammonia adsorption gas-fired domestic heat pump.
  • Record ID : 30014360
  • Languages: English
  • Source: International sorption heat pump conference (ISHPC2014), College Park, United States, March 31-April 2, 2014.
  • Publication date: 2014/03/02

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