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Multiphase Flow its Application in Water Management and Harvesting in Fuel Cells
Date Issued
01-01-2019
Author(s)
Thomas, Tibin M.
Indian Institute of Technology, Madras
Vedarajan, Raman
Ganguly, Ranjan
Abstract
Increased emission of carbon dioxide into the atmosphere from the fossil fuel-powered automobiles and power plants is one of the major sources of global warming. Using renewable and clean sources of energy as a fuel can control this. Among the other available alternatives, fuel cells have emerged as a promising source of clean energy due to their high efficiency, low/zero emission rate, modular design, and portability. Besides, fuel cells are capable of producing water as a by-product, making them an attractive option for potable water. Recent trends in the global automotive market show a strong trend of gravitating toward hydrogen fuel cell-powered automotive from the existing battery-operated automotive in the coming years. Owing to the high power density characteristics, polymer electrolyte membrane (PEMFC) fuel cell has been considered to be the most attractive one as the primary power source in fuel cell vehicle. Attaining slug-free drainage of water from the gas diffusion layers (GDLs) in PEMFC is one of the key challenges in their commercialization. Water management of hydrogen fuel cell can be optimized by extensive analysis of two-phase heat transfer phenomena like condensation and evaporation happening across GDL of the fuel cell. Excessive accumulation of water droplet on the GDL reduces the overall efficiency of the fuel cell. Thus, water removal from GDL is very important. Studies have shown that the quality of the water from a PEMFC meets the standard health requirements for drinking, indicating the importance of harvesting water from fuel cell exhausts as a sustainable drinking water source. The challenge in such water harvesting lies in achieving high condensation rate with minimum cooling energy penalty. This chapter reviews the fuel cell in general with a focus on multiphase phenomena and its use in water management in the GDL of fuel cells and harvesting drinking water from fuel cell exhaust. The background fundamentals are provided, and the state of art is discussed. Finally, the future perspective of water management and harvesting in fuel cells is provided in a larger backdrop of global energy–water nexus.