Analysis of the variation mechanism in the main energetic parameters in a single-stage vapour compression plant

Based on a previously developed and validated steady-state model of a single-stage vapour compression plant, the present paper describes an in-depth study directed to examine the consequences of changes in the operating conditions in such a plant. These include modifications of condensing and evaporating temperatures and the total superheating degree at compressor suction, which are the main energy parameters in a refrigeration plant. The aim of this work is not to determine the final energy state when the operating conditions are modified, which could be achieved using the steady-state model, but to study the mechanism that explains the variation. The pursuit of this goal implies conducting a detailed analysis of the performance and influence of several intermediate variables, the evolution of which has a direct effect on the final cooling capacity, compression power and COP values. The results obtained show the significant influence of the suction pressure (through the specific suction volume) on the compression power and cooling capacity, while the condensing and evaporating temperatures have a similar influence on the COP.