FUZZY LOGIC LIQUID LEVEL CONTROL

Chiller operating efficiency is optimized by controlling the system to maintain the condenser liquid refrigerant level at a value which will minimize or prevent gas bypass to the evaporator. This is accomplished by sensing the level of liquid refrigerant in the condensor and incorporating fuzzy logic to properly position a multi-position valve which can variably restrict the flow of this liquid into the evaporator, according to this sensed parameter. The fuzzy logic utilizes as inputs both the level error from a set point level and the rate of change of the sensed level. Each of these inputs are combined by fuzzy logic techniques to provide the required output signal to control the opening and closing of the valve.