Fuzzy logic control of the compressor speed and electronic expansion valve in a chiller

Recently, energy conservation and reduction of the global warming effect become one of the most important subject in the worldwide. Greenhouse gas emission and global warming are increasing indirectly because of the fact that inefficient using of the refrigeration system. Refrigeration system?s energy consumption is steadily increasing in overall energy consumption, since their using has been increasing. Refrigeration systems have full of energy conservation that is having minimum energy consumption while satisfying the user?s needs. Energy consumption of the refrigeration system can be optimized by capacity modulation methods. These methods allow us to match the compressor refrigeration capacity to the cooling load at any time. Although there are many ways to achieve capacity modulation, variable speed capacity modulation is the most efficient method.In this thesis, variable speed capacity modulation method has been studied. The primary aim of this study is to setup a fuzzy logic controller to regulate speed of the scroll compressor used in 5 kW capacity chiller system by using PWM inverter. In addition to this, effect of the expansion valves like thermostatic and electronic on variable speed refrigeration system has been studied. The experimental setup had been designed to operate at fixed speed. During the study, to ensure variable speed, PWM inverter was added and fuzzy logic algorithm was implemented on the experimental setup. Thus ensure more energy efficient system and to apply new control techniques to the refrigeration systems has been studied by this research. As a result, variable speed compressor showed 17.2 percent COP increase according to the on-off controlled fixed speed system by using fuzzy logic control.