This project starts with the idea to build a parametric 3D CFD study on gas venting in an immersion-cooled battery pack during a thermal runaway event. To reach the goal of the thesis we implemented first a simple 2D model in COMSOL Multiphysics 6.2, which is less accurate than the 3D one, but it is needed to verify that all the coupled physics work well. The tools used in the work are: laminar flow, Level Set for the oil-gas interface, heat transfer in solids and liquids, 2 ODEs to describe the total volume of gas trapped in the closed loop and the venting valve state, which is managed as a pressure threshold device with hysteresis.