Absfmcf-Energy efficiency of refrigeratinn systems has gradually been improved with help of control schemes utilizing the mom flexible components. This paper proposes an appmach in line with this Wnd, where a suboptimal condenser pressure is found in order in minimize the energy consumption. The objective is to give an idea of how this optimization scheme works as well as to show what amount of energy it is possible to s v e . A steady state model of a simple refrigeration system will be used as a basis for the optimization.

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A supermarket refrigeration system is a hybrid system with switched nonlinear dynamics and discrete-valued input variables such as opening/closing of valves and start/stop of compressors. Practical and simulation studies have shown that the use of distributed hysteresis controllers to operate the valves leads to synchronization, meaning that the opening and closing actions of the valves coincide. Consequently, the compressor periodically has to work hard resulting in low efficiency, inferior control performance and a high wear on the compressor. In this paper we propose two control schemes of low complexity for desynchronizing the valve operations while improving performance. Simulation results indicate the potential increase in efficiency and reduction in wear comparing with traditional control schemes.