Energy-saving-oriented control strategy for vapor compression refrigeration cycle systems

Abstract

Aiming at the disadvantage of system efficiency, a novel control strategy of maximizing energy saving while meeting the cooling demand for vapor compression refrigeration cycle (VCC) is presented. The VCC system is a core element in heating, ventilating, and air-conditioning (HVAC) system, and its coefficient of performance (COP), a measure of system efficiency for VCC system, is strongly influenced by the evaporator superheat and the pressure difference between evaporator and condenser, and the relationships between them are nonlinear thermodynamic coupling characteristics. In order to maximize the coefficient of performance (COP) which depends on operating conditions, in the meantime, meet the changing demands of cooling capacity, an analysis on the measured relationship between the setting value of stable superheat degree and cooling load is firstly carried out in this paper, then a model predictive control (MPC) based controller is developed for tracking the calculated setting curve of superheat and pressure difference based on model identified from experimental data. During the proposed control strategy, an optimization problem is solved which produces the maximal effect on the system performance. The effectiveness of the control performance is validated on the experimental rig.