Silva, R., Freitas, L., Reis, F., Munhato, M. et al., "Simulation of the Vehicle Air Conditioning System in a Dynamometer Test Bench," SAE Technical Paper 2013-36-0481, 2013, doi:10.4271/2013-36-0481.
The use of air conditioning systems in passenger cars in Brazil has increased significantly in the last decade. The installation rate increased from 47% in 2006 to about 80% in 2012. Especially for compressors with variable displacement, the measurement of the impact of this equipment on the engine performance and on the fuel consumption represents a challenge to be overcome. It must be considered that the environmental conditions present a great influence on the heat load to be removed from the passenger compartment. This paper describes the development of an experiment at an engine dynamometer bench to simulate the influence of the air conditioning system on the engine parameters. The combustion engine works with the compressor and all the others air conditioning system components assembled. The developed test allows the simulation of a large range of heat load on the evaporator module by controlling the air mass flow rate and air properties (temperature and humidity) at the air distributor inlet. A condenser module in the bench controls the condensation pressure by varying the air flow rate at the condenser. These two modules allowed making tests to define how the environmental conditions impact on the performance and on the fuel consumption by the air conditioning system at a steady state condition. As an example, the quantification of the condensation pressure influence on the fuel consumption in idle, partial and full load was performed. Also, the torque reduction on the engine shaft and its effect on the vehicle performance parameters were estimated for various heat loads.