CONTROL OF HOUSEHOLD REFRIGERATORS PART I - MODELING TEMPERATURE CONTROL PERFORMANCE

Commercial household refrigerators use simple, cost-effective, tempera ture controllers to obtain acceptable control. A manually adjusted air flow damper regulates the freezer compartment temperature while a ther mostat controls operation of the compressor and evaporator fan to regu late refrigerator compartment temperature. Dual compartment temperatur e control can be achieved with automatic airflow dampers that function independently of the compressor and evaporator fan thermostat, result ing in improved temperature control quality and energy consumption. Un der dual control, freezer temperature is controlled by the thermostat while the damper controls refrigerator temperature by regulating airfl ow circulation. A simulation model is presented that analyzes a househ old refrigerator configured with a conventional thermostat and both ma nual and automatic dampers. The model provides a new paradigm for inve stigating refrigerator systems and temperature control performance rel ative to the extensive verification testing that is typically done by manufacturers. The effects of each type of control and damper configur ation are compared with respect to energy usage, control quality, and ambient temperature shift criteria. The results indicate that the appr opriate control configuration can have significant effects and can imp rove plant performance.