Thermodynamic evaluation of two portable cooler running with reciprocating and mini-rotary compressors

Abstract

Small-capacity refrigeration has got an increasing attention of the consumermarket. In addition to the efficiency of electric equipment, the demand forcompactness has also become a relevant requirement. Among thealternatives available to cool down small cabinets, mechanical vaporcompression refrigeration remains prominent due to its satisfactoryperformance when compared to other cooling technologies. Compressorindustries have invested in the development of compact and efficientproducts, exploring different compression principles for small-capacityapplications, as is the case of mini-rotary compressors. In this context, theobjective of the present work is to assess the thermodynamic performanceof a 38-liter portable vapor compression refrigeration system running withtwo different compressors designed for small-capacity applications: minirotaryand reciprocating. Experimental tests were carried out at threedifferent ambient temperatures (16, 25 and 32 °C) in order to obtain the keyperformance parameters for each compressor (e.g., power consumption,cooling capacity, internal air temperature, and the condensing andevaporating temperatures). Finally, thermodynamic analyses wereconducted to account for the internal and external irreversibilities by meansof second law efficiencies, allowing for a comparison of the systemperformance running with both compressors in the same thermodynamicgrounds. Albeit a refrigeration (second law) efficiency by 25% higher wasobserved for the reciprocating compressor, it provided a smaller coolingcapacity and, therefore, led to a higher pull-down time.