Load-Predictive Temperature Control of an Air Conditioning and Refrigeration System

Abstract

In air conditioning and refrigeration (ACR) systems, the established industry method of capacity control is compressor ON/OFF cycling operations. This paper presents the design of load-predictive controller using compressor ON/OFF operations for temperature regulation with a target application of transport refrigeration systems. A dynamic ACR system model, which consists of a refrigerated cargo space, and a vapor compressor cycle (VCC) system, is developed. The validated VCC model is presented that captures compressor ON/OFF duty cycling dynamics. The dynamic cargo space model is described to accommodate varying conditions, such as door openings. The load-predictive controller tracks the pre-cool and predictive refrigeration load information which is generated based on the operating conditions in the next door-opening event, and decides to operate the VCC system with either normal ON/OFF control or pre-cool actions. Simulation results show that improved cargo space temperature regulation is obtained by implementing the load-predictive control strategy over the baseline industrial hysteretic control scheme in the coupled VCC/cargo space system.