CONTROL OF HOUSEHOLD REFRIGERATORS PART II - ALTERNATE CONTROL APPROACHES FOR IMPROVING TEMPERATURE PERFORMANCE AND REDUCING ENERGY USE

In Part I it was shown that conventional control of household refriger ators is achieved by regulating the distribution of air in the freezer compartment to all other parts of the plant. In Part II three alterna tive approaches to the conventional control of a top-mount refrigerato r are presented: variable temperature bandwidths, uncoupled compressor and evaporator fan, and the combination of these two. These allowed t he plant to achieve near-ideal control with respect to improved temper ature performance in each compartment. Automatic airflow dampers were used with the dual controllers to independently regulate refrigerator compartment temperature. Plant performance was simulated using a model that computes the refrigerant and airflow systems behavior. Together, these alternate configurations and approaches define new control algo rithms that reveal the plant's optimal control model for improving per formance and energy usage relative to conventional controllers. Result s based on model simulations are dependent upon the model's accuracy a nd validity. However, the model validation studies cited here, though limited in scope, do show agreement between simulation and experimenta l data for the ambient temperatures and thermal load conditions consid ered. This suggests that these model results are reasonable, and repre sentative of actual plant behavior under these conditions and configur ations for a top-mount style refrigerator plant.