Transient operation characteristics and control method in combined air-conditioning systems

Abstract

This study examines, using actual driving and simulations, transient operation characteristics and control methods for a combined system. It consists of both single-stage compression-type and single-effect absorption-type refrigerators and is driven by the shaft power and waste heat from a gas engine. Given the complicated nature of the system, determining the unsteady-state performance and control characteristics of the entire system is difficult. Hence, it must be equipped with an adequate control system to maintain acceptable system performance. Our results reveal that this system is controlled, as predicted, under unsteady-state conditions by using a novel control method. The unsteady-state simulation model is validated by comparing the driving results with the simulated results. Thus, gas-engine-driven combined air-conditioning systems possess a response time similar to absorption-type refrigerators. This indicates that the transient response of the entire system is governed by the absorption-type refrigerator, although the cooling capacity of the absorption-type refrigerator is only 13% of the entire cooling capacity. Therefore, when designing the control system of the combined system, the fact that the entire combined system is mainly governed by the absorption-type refrigerator should be considered despite its low cooling capacity.