Dispersion Modeling of Leaks of Low GWP Refrigerant HFO-1234yf in An Automobile Garage

HFO-1234yf is a new low global warming refrigerant developed for automotive air conditioning systems. It was developed to replace HFC-134a which is being phased out in the European Union due to high global warming potential. HFO-1234yf is highly energy efficient, exhibits low toxicity, and can potentially be used in direct expansion automotive a/c systems with minimal design modifications. Significant work has previously been completed to confirm the mild flammability characteristics of HFO-1234yf. To understand the impact of accidental releases of HFO-1234yf into a garage environment, Computational Fluid Dynamics (CFD) modeling was used to simulate releases of HFO-1234yf under various a/c line rupture scenarios. In particular, releases were simulated using a leak source in a calm open area, a room with no forced ventilation and the same space but impinging on a flat plate. The refrigerant concentration was determined as function of distance (x,y and z directions) from the leak point during leak event. The size and shape of the portion of the refrigerant plume above the lower flammability limit (LFL) was also determined. The work enforces the benefit of using the inherently safer practice of minimization of refrigerant quantities. This paper will review CFD modeling results for given refrigerant leak scenarios.