SD-95-16-5 -- Application of Tandem System to High-Efficiency Refrigerator/Freezer PDF

The Tandem System, a new approach for using two evaporators in a refrigerator/freezer system, has been developed. The system configuration, with two evaporators connected in series and appropriate controls, takes advantage of the transient operation to save energy. This system was applied to a commercial 18 ft3 (509.7 L) unit and a high-efficiency sample unit in which the thick insulation and energy-saving valve were used. The daily energy consumption for both units were reduced by 18% as compared to the baseline unit. In addition, a new defrost method without using an electrical resistance heater was introduced, and the test was performed experimentally. This "internal defrost method," using the thermosiphon phenomenon between two evaporators, showed the potential of superior characteristics over the conventional approach. Taking advantage of control techniques, the Tandem System allowed independent temperature control for each compartment. Finally, a capability test showed that the Tandem System operated reliably at very different operating conditions.

KEYWORDS: year 1995, refrigerators, freezers, energy consumption, energy conservation, transient, operations, cyclic, heat flow, experiment, refrigeration, deicing, testing, thermosiphon, evaporators, properties, temperature control