Energy Efficient R744 A/C System Thanks to Torque Estimation 2005-01-2040
From 10 years, Valeo Climate Control leads R&D efforts to reduce green-house effect emissions due to automotive A/C systems. This paper deals with the development of an alternative A/C system using R744 refrigerant as the lowest Global Warming Potential refrigerant (GWP = 1) to replace existing R134a (GWP = 1300) technology.
The paper will show main aspects of the new technology developed for alternate refrigerant and then will focus on control strategy for the A/C system which is a key point for thermodynamic cycle efficiency using R744.
Firstly the R744 A/C system used for this study will be described, the concept of maximum COP high pressure linked to optimized R744 thermodynamic cycle will be explained, and the high pressure control strategy will be presented.
Secondly the control optimization for the gas cooler fan will also be explained in order to reduce the electrical consumption.
Finally the paper will present the compressor torque estimation during the A/C system operating modes. Key field test results will be shown in different running mode conditions and outside temperatures.