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Modeling and energy performance evaluation of a double effect gas driven air conditioning system using ammonia/water absorption and desiccant evaporative cooling.

Number: pap. n. 70

Author(s) : SCOCCIA R., MOTTA M.

Summary

In this paper a gas driven air conditioning system, worked out coupling two sorption cycles, is presented. The system integrates an absorption heat pump and a low temperature driven desiccant evaporative cooling air handling unit (DEC). The result is a new double effect gas driven air-conditioning for primary air treatment. The coupling is created through two hydronic loops: one between the heat source of the heat pump and the DEC, and the other between the latter and the heat pump heat sink. In the summer operation mode (hot and humid season), the heat pump has two useful effects: delivers the heating power (condenser/absorber side) needed to remove the water adsorbed by the desiccant wheel and provides the cooling power needed at the supply air flow (evaporator side). In winter operation mode, the hydraulic connection between the DEC and the heat pump is inverted, and the latter is used to heat the supply air, recovering energy from the indoor exhaust air. For this application an ammonia/water absorption heat pump has been selected; after a compatibility analysis on the temperature levels of the selected DEC system. The system design is based on a commercial heat pump (nominal heating power 41.6 kW) and it has led to a DEC air handling unit with a nominal air flow rate of 5’000 m3/h. In order to assess the energy performance of the new gas driven air-conditioning concept, models of the two subsystems have been developed and implemented in MATLAB. Furthermore in order to find the best energy performance of the system an optimization algorithm has been used for set the control signals. A simulation campaign aiming at the assessment, for several outdoor conditions, of the ratio between the net supply air energy exchange and the non-renewable primary energy used by the system (PER) has been carried out. The results highlighted that the average PER (conversion factor delivered electricity to non-renewable primary energy: 2.18 kWhPE/kWhel) is around 1.4 for hot and humid conditions and around 2.1 for cold and dry conditions. It is concluded that the presented gas driven air conditioning system is characterized by low electrical and primary energy consumptions and that is suitable for mild temperate/continental climate. Moreover, the novel system concept could turn to be particularly suitable in areas where the natural gas is cheap and/or the conversion factor from electric to primary energy is low.

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Pages: 10 p.

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Details

  • Original title: Modeling and energy performance evaluation of a double effect gas driven air conditioning system using ammonia/water absorption and desiccant evaporative cooling.
  • Record ID : 30014352
  • 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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