4771 - Heat Exchanger Dynamic Observer Design PDF

This paper presents the design of model-based nonlinear dynamic observers of an evaporator and a condenser for advanced control of air-conditioning and refrigeration systems. Control-oriented low-order models are derived for the evaporator and the condenser that are spatially distributed. Based on sensor measurements of the evaporating temperature, the nonlinear observer for the evaporator can be used to estimate the heat transfer rate and the length of the twophase section that cannot be measured directly in transient processes. Based on sensor measurements of the condensing temperature, the nonlinear observer for the condenser can be used to estimate the length of the two-phase section and the length of the subcooling section that cannot be measured directly. The simulation results and experimental testing are also presented. In air-conditioning and refrigeration applications, the nonlinear observers can be utilized to synthesize feedback linearization nonlinear control and provide accurate refrigerant charge inventory estimation and optimization for transient processes.

Units: SI