Automotive HVAC loop characterization, optimization and assessment in GT-SUITE

In order to reduce CO2 emissions of the transportation sector, all over the world, but specially in the European Union, environmental legislation has become more and more stringent, so that electrification seems to be the future of transports. For this reason, during the last decade, OEMs started offering more Battery Electric Vehicles (BEV) to their customers. However, the spread of this kind of vehicles on the market is still slow, mainly due to the range anxiety, the fear that the battery capacity is not enough. That is why, other than the improvement of battery technologies, OEMs work on the optimization of all vehicle’s sub-systems, so that their impact on the driving range is reduced. Under this point of view, the HVAC (Heating, Ventilation and Air Conditioning) is probably the most critical system for two reasons: first because it requires a lot of energy, specially to heat up the cabin during winter days, but also because it can be integrated in the larger cooling system of the vehicle, therefore contributing to improve the whole vehicle efficiency. In this context, CAE (Computer Aided Engineering) tools are extremely important to design the best system, reducing costs and time. The goal of this thesis is to develop a methodology for the modelling of a thermal system in GT-SUITE, one of the most widespread platforms for 1D modelling in automotive industry, own by the American company Gamma Technologies LLC. The work has been carried out in GammaTech Engineering S.r.l., the consulting firm of Gamma Technologies, in collaboration with Stellantis. The developed methodology is applied to model two versions of the HVAC system of a Stellantis’ BEV: a “Base” circuit only capable of cooling mode and a “Heat Pump” circuit capable of both cooling and heating modes. For each version, compressor and all the heat exchangers are calibrated and validated by simulating datasheet experimental conditions, and pipes are modelled starting from CAD by using GEM3D (a pre-processor within GT-SUITE). Then, the circuit is built, and the optimal refrigerant mass is evaluated by the charge determination procedure. By focusing on the “Heat Pump” circuit, both cooling and heating simulations are performed, to compare GT-SUITE methodology with the current Stellantis’ one.