Performance assessment of a transcritical CO₂ refrigeration system using MATLAB/Simulink: parametric analysis of operational control strategies
Abstract
This study presents a dynamic modeling approach using MATLAB/Simscape™ and Simulink® to evaluate the performance of an R744 transcritical CO₂ vapor-compression refrigeration cycle equipped with an internal heat exchanger (IHX). Unlike structural design optimization including IHX sizing, this study focuses on maximizing efficiency through the optimization of operational parameters such as superheat and pressure settings. Simulation scenarios included transient evaluations using Seoul’s annual outdoor temperature profiles, a parametric study varying superheat from 3 °C to 15 °C at a constant 35 °C ambient temperature, and an analysis of varying high- and low-side operating pressures. Results indicate that rising ambient temperatures increase refrigerant mass flow and cooling capacity, but significantly decrease the coefficient of performance (COP) due to a disproportionate increase in compressor power consumption. While higher superheat prevents liquid carryover, it reduces overall efficiency. Additionally, the optimal hot-side pressure for maximizing COP was found to be 10–12 MPa. Ultimately, this study demonstrates that system efficiency can be enhanced by 15–20% through operational parameter tuning alone, without hardware modifications.