Penelitian ini membandingkan sistem refrigerasi cascade yang menggunakan refrigeran R22 terhadap R290 pada sirkuit temperatur tinggi (high-stage) dengan memvariasikan bukaan katup ekspansi pada sirkuit temperatur rendah (low-stage). Variasi yang dilakukan adalah kondisi Normally Closed, 75% Normally Closed, dan 50% Normally Closed. Sirkuit pada temperatur rendah menggunakan refrigeran campuran R170/R744 (66.67/33.33) dalam % massa. Parameter yang dibandingkan adalah COP dan temperatur evaporasi pada sisi HS yang menggunakan R22 dengan HS menggunakan R290. Dari hasil pengujian dengan menggunakan refrigeran R290 pada sisi HS diperoleh COP tertinggi dan temperatur evaporasi terendah. Temperatur evaporasi terendah dicapai pada sisi low-stage -82.8°C dengan menggunakan R290 pada HS pada kondisi variasi XV Normally Closed pada tekanan suction 1 bar dan tekanan discharge 11.5 bar. Sedangkan COP terbesar diperoleh dengan skala COP 2.89 menggunakan R290 sebagai refrigeran HS pada variasi katup Normally Closed pada tekanan suction 1 bar dan tekanan discharge 11.5 bar dengan temperatur -16.4°C.

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This study compared a cascade refrigeration system that uses R22 to R290 in the high temperature circuit with a variations on the manual expansion valve in the low-stage. These variations were Normally Closed, 75% Normally Closed, and 50% Normally Closed. The system also uses new binary mixture of R170/R744 (66.67/33.33 in % mass) to perform in the low-stage circuit. The parameters that is being analized and collated from this study were COP and evaporating temperature of the high-stage circuit that uses R22 towards R290.

This experimentation indicates the high-stage circuit that uses R290 as a refrigerant has higher COP and lower evaporating temperature than using R22. Lowest evaporating temperature obtained in the low-stage was -82.8°C using R290 in the high-stage with a Normally Closed XV variation while the suction and discharge pressure are 1 bar and 11.5 bar. The highest COP was reached by 2.89 using R290 as the refrigerant in the highstage in a Normally Closed XV variation. The pressure of the suction and discharge were 1 bar and 11.5 bar with a temperature of -16.4°C.