Temperature pull-down of a retrofitted wine refrigerator cabinet cooled by a caloric system emulator.

The present study analyzes the time-dependent thermal behavior of a retrofitted wine refrigerator cabinet operated by a caloric system emulator. The presence of a full load of wine bottles enabled the assessment of the thermal stratification inside the cabinet. Further experimental tests have been performed to quantify the overall thermal conductance of the cabinet walls and the thermal conductance of the glass door. A detailed mathematical model was developed to predict the temperature pull down in the refrigerated compartment, considering the interaction between the cabinet air and the wine bottles. In addition to the air and bottle temperatures, a good agreement (lower than 15% relative error) was observed for the cooling capacity. The numerical simulations revealed that the cabinet door was responsible for approximately 60% of the thermal load (even though it corresponded to approximately 20% of the cabinet external area).

Influence of Heat Exchanger Design on the Thermal Performance of a Domestic Wine Cooler Driven by a Magnetic Refrigeration System.

Conventional and not-in-kind refrigerators require heat exchangers for their operation. Yet, most magnetic cooling studies do not take full account of those components despite their importance in defining the cooling capacity and temperature span. To investigate the influence of heat exchanger design parameters on the performance of magnetic refrigerators, a model was developed to integrate the heat exchangers, regenerators and thermal reservoirs. The results were compared with data generated in an apparatus that emulates the conditions of the thermal fluid supplied by the regenerators to a cold heat exchanger positioned inside the cabinet of a retrofitted 130-liter wine cooler. Six tube-fin heat exchangers were evaluated to identify the most suitable geometry (number of tube rows and fin density) for the compact magnetic refrigerator. Numerical simulations described the influence of the heat exchanger on the regenerator performance in terms of the liquid stream effectiveness. For a temperature span of 20°C between the external environment and the refrigerated compartment, the best heat exchanger/fan assembly resulted in a cooling capacity reduction of 37\% and a temperature span increase of 32\%, in comparison with an idealized system. The expected system coefficient of performance (COP) and second-law efficiency were 1.8\% and 13\%, respectively.