Efficiency of Cascade Refrigeration Cycle Using C3H8, N2O, and N2

Abstract

This article presents a new natural gas liquefaction cycle that utilizes propane (C3H8), nitrogen monoxide (N2O), and nitrogen gas (N2) cycles. A liquefaction cycle with staged compression was designed and simulated using HYSYS software for improving cycle efficiency. This included a cascade cycle with a three-stage compression consisting of a C3H8, an N2O, and an N2 cycle. The new C3H8, N2O, and N2 liquefaction cycle is compared to the optimized cascade cycle using propane, ethylene, and methane. The compressor work, specific energy, and coefficient of performance (COP) of the cascade cycles were compared and analyzed. The COP of the new cascade cycle that utilizes three-stage compression process 3 is 25% higher than that of basic single-stage process 1. Also, the new liquefaction cycle requires less specific power for the same amount of liquefied natural gas (LNG) produced by optimized cascade cycle. For example, the specific power and COP of the new cascade cycle are respectively up to 16% less and 14% higher than those of the optimized cascade cycle under the same conditions of feed gas composition and liquefaction rate.