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Dehumidification characteristics of direct expansion (DX) air conditioning (A/C) systems.

Number: pap. B2-019

Author(s) : CHAN M.

Summary

This paper discusses the re-evaporation phenomenon at finned surfaces of cooling coils in a direct expansion air conditioner (DX A/C) and how does it affect the indoor humidity. The study employed experimental results from a testing rig equipped in an environmental chamber. The experimental work included testing with different sensible heat ratio of constant cooling load. The focus was given to the change of indoor humidity and condensate collected at the cooling coils. Elevated indoor humidity was found with an increasing of moisture content. It is believed that it would cause thermal discomfort with high indoor humidity. This is a usual case in most domestic system using temperature as the only control parameter in DX A/C systems. The use of variable speed supply fans and compressors in A/C systems for controlling simultaneously indoor air temperature and humidity is now being used to deal with the problem. Simultaneous variations of both compressor and supply fan speed in a DX A/C system can help improve the control of indoor humidity. However, the associated control systems and hardware are both complicated and costly, often requiring a higher capital cost. The cost is almost doubled of the conventional one. This study suggests a low cost method improving the space humidity control of a DX A/C system. Based on experimental work done by the authors, high & low speed control algorithm results a good humidity control.

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Pages: 8 p.

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Details

  • Original title: Dehumidification characteristics of direct expansion (DX) air conditioning (A/C) systems.
  • Record ID : 30004937
  • Languages: English
  • Source: ACRA2010. Asian conference on refrigeration and air conditioning: Tokyo, Japan, June 7-9, 2010.
  • Publication date: 2010/06/07

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