Coolant Filling Simulation Model in 1D with GT-Suite : A Study on Scania's Electric Truck's Battery Cooling Circuit

Abstract: Driven by the goal of decreasing emissions and pollutants towards a more sustainable future, the automotive industry is undergoing a rapid transition towards battery-powered electric vehicles. This shift to sustainable transport is fast-paced, and new technical solutions are being offered on a regular basis to fulfil the future needs for electric vehicles, including battery-electric trucks. This continuously necessitates a fast development of the battery-electric truck, along with the cooling system. To validate the cooling system, Scania's preferred approaches are testing and 3D simulations. However, these approaches are time-consuming and cannot match the pace of the design or the development. This thesis addresses the implementation of using 1D Simulations (GT-Suite) to carry out coolant filling simulations as a more efficient approach by studying the filling of the battery cooling system in an electric truck and, later, validating the results obtained with a test rig. In this thesis, different cases were defined, each adding more complexity to the circuit, and the parameters studied were the filling times and the location of air traps. Finally, a case with a closed circuit and running a coolant pump was developed to study the possibilities of devising quicker deaeration techniques for the circuit. The work completed in this thesis may be used as an example of how filling simulations can be performed with GT-Suite. This thesis is a good starting point, exploring a vast potential in using 1D Simulations to simulate the coolant-air interaction in a cooling system. Nonetheless, the findings revealed that GT-Suite v2020 and v2021 lack a robust model to properly simulate the interaction of coolant and air in certain sections of the circuit. In addition, the simulation model failed to obtain a steady-state solution in some cases resulting in discrepancies between the results from the test rig and the simulations. In conclusion, it was found that 1D simulations are not an ideal way forward when individual components of the cooling circuit are being considered, for example, the cooling plates, but are much quicker and seem to be a promising method to get an overview on a system level.