A direct expansion based enhanced dehumidification air conditioning system for improved year-round indoor humidity control in hot and humid climates

Once a conventional On-Off controlled single evaporator direct expansion (DX) air conditioning (A/C) system is installed, it has to be operated at different seasonal cooling load situations, and hence would have a hard time in trying to maintain the desired indoor thermal environment at all times, unless complicated and costly supplementary measures to provide variable dehumidification capacity are provided. Therefore, a novel standalone enhanced dehumidification A/C (EDAC) system was proposed based on multi-evaporator air conditioning technology. This paper reports an experimental study on the developments of such an EDAC system and the control strategy for operating the EDAC system for achieving improved year-round indoor humidity level. Firstly, the detailed configurations of the EDAC system and the control strategy are presented. Secondly, a detailed description on the setup of a prototype experimental EDAC system, and on instrumentation and experimental cases is reported. This is followed by presenting the experimental results and related discussions. The experimental results show that the use of the EDAC system and the control strategy was able to achieve year-round improved indoor humidity control, while still maintaining the required indoor air temperature control in hot and humid climates, at a higher energy efficiency, as compared to a conventional On-Off controlled single evaporator DX A/C system.