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Keywords:

  • Automobile Refrigerant;
  • Global Warming;
  • Flammable Hazards;
  • Dispersion;
  • Computational Fluid Dynamics CFD

Abstract

HFO-1234yf (Hydrofluoro-Olefin) is a new, low global warming refrigerant developed for automotive air-conditioning (A/C) systems [Nielsen et al., Chem Phys Lett 439 (2007), 18–22]. It was developed to replace R-134a, which is being phased out in the European Union because of its high global warming potential (IPCC, Intergovernmental Panel on Climate Change Fourth Assessment Report—Climate Change 2007: Synthesis Report, 2007). HFO-1234yf is highly energy efficient, exhibits low toxicity, and can be potentially used in direct expansion automotive A/C systems with minimal design modifications. Significant work has been previously 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 was also determined. This work enforces the benefit of using the inherently safer practice of minimization of refrigerant quantities. This article will review CFD modeling results for given refrigerant leak scenarios. © 2010 American Institute of Chemical Engineers Process Saf Prog, 2011