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This paper presents a dynamic model of a transcritical air-conditioning system, specifically suited for multivariable controller design. The physically-based model retains sufficient detail to accurately predict system dynamic response while also being simple enough to be of value in determining appropriate control strategies. The control focus would be quasi-steady transitions between operating states by modulating flow rates of both air and refrigerant to meet changing constraints on capacity, efficiency, noise, etc. The model structure is highly modular, accommodating various system configurations and component types. The modeling results are programmed as a library of components for use in Simulink, a graphical programming package.

HEVs idle their engine during the stops to meet the cooling loads. However, idling reduces fuel economy and increases emissions and engine wear. The paper focuses on exploring alternative strategies for air conditioning the HEV during stop times. Simulation analyses are used to identify fundamental differences and new technology tradeoffs encountered in HEVs. An analysis of cooling loads on a car under typical weather and driving conditions is combined with efficiency estimates for an advanced a/c system to compare different cooling strategies in terms of fuel usage and overall system COP. Options considered include belt-and electrically-driven compressors, with thermal and electrical storage technologies. The results of this parametric analysis narrow the range of cooling strategies to be considered for detailed analysis and prototype testing.

Compressor rapid cycling has been shown to be capable of delivering the advantages of variable capacity control without the use of variable speed compressors. For automotive air conditioning systems, rapid cycling can be achieved by engaging and disengaging the clutch drive. However, rapid cycling results in oscillations in evaporator superheat which degrade system performance and may damage the compressor. This paper discusses the dynamics associated with compressor rapid cycling and possible system configurations and control strategies for modulating the expansion valve to regulate superheat during rapid cycling operation. These strategies include feedback control strategies such as thermostatic expansion valve (TXV), and PI control, as well as feedforward control strategies. The feedback control strategies regulate the average superheat temperature, but fail to eliminate the oscillations caused by rapid cycling.