High efficiency air conditioning model based analysis for the automotive sector

• Development of a two-level model based procedure for the A/C system in automotive sector.
• Analysis of the system with R1234yf as working fluid.
• Investigation of off design condition.
• Assessment of components design influence: evaporator, condenser, orifice.
• Introduction and study of a liquid cooled condenser (compared with the actual air cooled one).

The air conditioning (A/C) system of the cabin is one of the most energy consuming auxiliaries in a vehicle and its optimization is a technological option suitable for achieving fuel consumption reduction in automotive sector.Hence, in this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, expansion valve and evaporator. The model considers off-design behavior of components, being this system often at partial load operating conditions.Therefore, considering fixed orifice as expansion device, performance of the whole system has been evaluated and an optimization of the components was derived. Their design influence has been assessed and, moreover, the opportunity to have an A/C condenser cooled by a liquid circuit in place of external air is discussed, considering the opportunity to integrate it into the main engine cooling system. The performances outlined using R1234yf showed a 22% reduction of compressor shaft power with respect to the air cooled condenser case and significant COP increase.