The R134a refrigerant is often used in small-scale VCRS, and has been used to cool electronic chips. Schmidt and Notohardjono [1] used R-134a as a coolant, and adopted a DC spiral compressor to
remove 525 W of heat at an evaporation temperature of 15–35 C while keeping the COP of the VCRS at 2–3. The system was applied to the server device IBM S/390 G4 CMOS. The average temperature
of the CPU was maintained at approximately 40 C, but the weight of VCRS was as heavy as 27 kg. Heydari [19] also used R-134a as the coolant for VCRS with reciprocating compressors, reducing the temperature of an electronic chip from 86 to 20 C and achieving a COP of 3 for the VCRS. Phelan et al. [20] developed a microVCRS with high-power micro-electro-mechanical components. Although this system could remove 300 W of heat at an evaporation temperature of 5 C, it was applied to a general commercialuse spiral compressor. Trutassanawin et al. [21] also used R-134a to establish a cooling system with a cooling ability at 268 W, COP of 2.8–4.7, evaporation resistance at 0.6–0.77 C/W, heat resistance of 0.04–0.18 C/W, and isentropic efficiency at 25–60%. In 2008, Sathe et al. [22] examined the performance of a rotary compressor using R-134a as the working coolant for electronics cooling. The estimated cooling capacity and COP varied from 163 to 489 W and 2.1 to 7.4, respectively.