Design and Construction of a Mobile Air Conditioning Test Facility for Transient Studies

Compared to other air-conditioning and refrigeration systems, mobile air-conditioning systems are unique in the respect that they operate almost entirely under transient conditions. The major operating transients include: (i) changes in compressor speed due to variations in vehicle engine speed, (ii) changes in condenser air flow due to ram-air effects at the front of the vehicle, (iii) changes in the passenger compartment air temperature during a pulldown mode, and (iv) cycling of the compressor clutch to prevent evaporator frosting. A versatile experimental facility has been developed to permit testing of mobile alc systems under a wide variety of both transient and steady-state operating conditions. The facility serves as a flexible test bed for the development and validation of transient system models, advanced mobile alc control techniques, and on-board diagnostic tools for mobile applications. The air- and refrigerant-side loops of the facility are thoroughly instrumented and can accommodate the stock or prototype components of nearly any mobile alc system. The facility makes extensive use of controlled system-input devices which allow the researcher to simulate the majority of the transient operating conditions encountered by mobile alc systems in field usage. Transient demonstration tests show that the facility is an excellent tool for conducting modeling, control, and diagnostic studies. Steadystate validation tests show that the evaporator- and condenser-side energy balances are in need of improvement. Sources of error have been identified, and an appropriate plan of corrective action has been established.Air Conditioning and Refrigeration Project 5