Inherent operational characteristics aided fuzzy logic controller for a variable speed direct expansion air conditioning system for simultaneous indoor air temperature and humidity control

• Published in: Energy and buildings 2018-01, Vol.158, p.558-568
• Main Authors: Yan, Huaxia, Xia, Yudong, Xu, Xiangguo, Deng, Shiming
• Format: Article
• Language: English
• Subjects: Direct expansion air conditioning; Fuzzy logic control; Humidity control; Inherent operational characteristics
• ISSN: 0378-7788
• DOI: 10.1016/j.enbuild.2017.10.013

•A FLC for a DX A/C system was developed for temperature and humidity control, which is simpler and cost less than MVC.•Controllability tests were conducted and acceptable results were observed.•Both indoor dry- and wet-bulb temperature can be controlled at their settings, with fluctuations no more than 0.35°C.•The operational characteristics for a DX A/C system was first directly used for control purpose. In small to medium sized buildings, direct expansion (DX) A/C systems are extensively used. Multi-variable controllers (MVCs) have been developed for variable speed (VS) DX A/C systems to control indoor air temperature and humidity simultaneously. Based on the previous extensive research work on the inherent operational characteristics of DX A/C systems, an alternative simpler approach was applied, by developing a fuzzy logic controller (FLC) for simultaneous indoor air temperature and humidity control, using a VS DX A/C system. In this paper, the developments of the FLC are presented. Firstly, a detailed description of the algorithm for the FLC is given. This is followed by detailing an experimental VS DX A/C system where the FLC was tested. Finally, the results of controllability tests for the FLC are reported. Controllability tests results demonstrated that the FLC developed can achieve the simultaneous control over indoor air temperature and humidity, with a reasonable control accuracy and sensitivity.