Common domestic refrigerator-freezer contains compartments for frozen and fresh food at corresponding average temperatures -18°C and 5°C respectively. Appliance equipped with sequential dual evaporator (SDE) refrigeration cycle with parallel evaporators, switching electro-valve and shared condenser and compressor has a strong theoretical potential for saving energy consumption versus system with evaporators in series. Improvement is mainly related to the possibility in increasing evaporation temperature during fresh food compartment operation. The present paper describes prototype of SDE refrigerator-freezer charged with R600a and equipped with variable speed compressor. To exploit main advantage of the SDE cycle experiments focus on the fresh food loop operation. Results at various compressor speeds are discussed and analyzed by the means of second law analysis in order to identify losses in each component in the loop. Major part of losses are observed in the compressor and in fresh food compartment evaporator, over 40% and 23% of available energy even at most favorable minimum compressor speed. The paper proposes modification of the fresh food compartment evaporator design by implementing slab with phase-change material which increases COP at maximum by 8% at 1600 RPM. However, results of numerical simulation also demonstrate that join change on the evaporator and condenser side brings COP improvements up to 50%.

Performance improvement of sequential dual evaporator refrigeration cycle in domestic refrigerator-freezer charged with R600A: prototype testing

JOPPOLO, CESARE MARIA;MOLINAROLI, LUCA;
2012-01-01

Abstract

Common domestic refrigerator-freezer contains compartments for frozen and fresh food at corresponding average temperatures -18°C and 5°C respectively. Appliance equipped with sequential dual evaporator (SDE) refrigeration cycle with parallel evaporators, switching electro-valve and shared condenser and compressor has a strong theoretical potential for saving energy consumption versus system with evaporators in series. Improvement is mainly related to the possibility in increasing evaporation temperature during fresh food compartment operation. The present paper describes prototype of SDE refrigerator-freezer charged with R600a and equipped with variable speed compressor. To exploit main advantage of the SDE cycle experiments focus on the fresh food loop operation. Results at various compressor speeds are discussed and analyzed by the means of second law analysis in order to identify losses in each component in the loop. Major part of losses are observed in the compressor and in fresh food compartment evaporator, over 40% and 23% of available energy even at most favorable minimum compressor speed. The paper proposes modification of the fresh food compartment evaporator design by implementing slab with phase-change material which increases COP at maximum by 8% at 1600 RPM. However, results of numerical simulation also demonstrate that join change on the evaporator and condenser side brings COP improvements up to 50%.
2012
9782913149908
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/665037
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