Análise experimental do desempenho energético de um refrigerador a compressão de vapor assistido por energia solar fotovoltaica para regiões sem eletrificação

Abstract

In the least assisted regions and without electrification, it became evident, during the Covid-19 pandemic, the absence of refrigeration systems for storing vaccines, medicines and food. To meet these demands, an alternative, in line with sustainable prerogatives, would be the use of a system consisting of a conventional vapor compression refrigerator operated by photovoltaic panels (PV-VCRS). The objective of this work was the experimental determination of the global coefficient of performance (COP) of a commercial refrigerator with a volume of 79 L associated with a photovoltaic panel with a power of 320 W and an efficiency of 19%. In addition to these components, the experimental bench had an MPPT charge controller, an AC- DC inverter with an efficiency of 88% and two electric batteries with unit loads of 45 Ah. To obtain the COP of the refrigerator, an electrical resistor was placed in the internal compartment. The resistor was supplied with electrical current by a variable voltage source, which provided a dissipated power of 30 W to 70 W. In addition to this internal heat generation rate, the energy input from the environment to the interior of the refrigerator was obtained with the help of heat transfer equations and correlations, for natural convection, radiation and thermal conduction. These correlations and the corresponding energy balance were supported with temperature values obtained by calibrated K-type thermocouples installed inside the refrigerator. A data acquisition system was used to record internal and ambient temperatures and compressor energy consumption. The results of the experimental tests revealed that the refrigeration capacity of the machine varied from 73.6 W to 136 W, for which the corresponding COP values associated with the refrigeration cycle varied from 1.08 to 1.52, while the values of the Overall COP ranged from 0.182 to 0.257. Thus, the energy performance, assessed by COP, was within the range found in the literature for common refrigerators. Therefore, through this investigation, PV-VCRS is confirmed as capable of meeting the demand presented, as long as there is good availability of solar radiation.