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Parameters affecting the performance of a dewpoint cooler consisting of a counterflow heat exchanger using water as refrigerant.

Author(s) : JANSSEN M., UGES P.

Summary

A dewpoint cooler is defined as an indirect evaporative cooler with a counterflow arrangement of the primary air to be cooled and the process air to be humidified and ventilated to the environment. Due to the counter flow arrangement the air exit temperature is not limited theoretically to the wet bulb temperature. The construction consists of polypropylene channel plates which guide the primary flow through its channels. The plates are covered with a hygroscopic foil and the return process flow is forced to flow between the plates, and is therefore in direct contact with the foils. Water is supplied to the foils via a distribution system. A number of such constructions have been build and experimentally investigated. The paper presents the experimental set-up with some results. A model has been developed based on simultaneous heat and mass transfer at the water film developed on the hygroscopic foil. The model is used for the evaluation of the experimental results and forms a theoretical base for maximum achievable performance. The model is subsequently used for optimising the heat exchanger geometry with respect to plate sizing, distances, etc. The prime parameters are here the exit temperature desired, the cooling capacity of the unit and the friction losses (pressure losses) within the unit. It is shown that the energy efficiency of the unit strongly depends on the design and that there is a trade off between minimum temperature achievable and energy efficiency. Finally some comparison with mechanical air conditioning systems is made with respect to the dependence of the capacity and efficiency of the ambient temperature and humidity. It is shown that even in moderate climates a dewpoint cooler can be effectively operated.

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Pages: 2010-2

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Details

  • Original title: Parameters affecting the performance of a dewpoint cooler consisting of a counterflow heat exchanger using water as refrigerant.
  • Record ID : 2010-1985
  • Languages: English
  • Source: 9th IIR-Gustav Lorentzen Conference on Natural Working Fluids (GL2010). Proceedings. Sydney, Australia, April 12-14, 2010.
  • Publication date: 2010/04/12

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