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Experimental based numerical investigation of microchannel condenser integrated freezers

Dinçer, Seren
The recent developments in the production techniques enable the use of mini/micro channel heat exchangers in household refrigerators. This led refrigeration companies to evaluate the impact of the use of microchannel heat exchangers theoretically and experimentally in household refrigerator units. This study aims to implement the microchannel condenser in a frost-free freezer as a replacement of macro scale coil type condenser. Microchannel condenser used in this study has 0.846 mm hydraulic diameter. Energy consumption and cooling performance of both condensers are compared at 25 ambient temperature. R600a is used as a refrigerant in both systems. Variable capacity compressor is also used to investigate the effect of compressor speed on both types of condensers used in the system. Additionally, fan motor which cools the condensers is selected as variable speed and the effect of condenser fan speed is also investigated. With the microchannel condenser, 83% volume decrease is achieved with about 1% increase in energy consumption compared to a coil condenser for a cycle providing the same cabinet internal temperatures. A numerical model for an accurate predesign is developed to simulate overall vapor compression cycle under steady state conditions. The model includes finned and tube evaporator, variable capacity compressor, capillary tube and microchannel condenser models. The model predicts the energy consumption of the product with 2% difference.