Open Access Publications
Permanent URI for this collection
Open access publications by faculty, postdocs, and graduate students in the Department of Mechanical Engineering.
Browse
Browsing Open Access Publications by Author "Aryal, Utsav Raj"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item 3D Computational Model for an Electrochemical Gas Separation and Inerting System(Journal of The Electrochemical Society, 2022-04-25) Aryal, Utsav Raj; Aziz, Majid; Prasad, Ajay K.Aircraft fuel tank inerting is employed to reduce the flammability of the fuel vapor in the ullage (air volume above the fuel) by restricting its oxygen concentration to a safe value—12% for commercial aircraft and 9% for military aircraft. Inerting is typically accomplished by displacing oxygen in the ullage with an inert gas like nitrogen. Electrochemical gas separation and inerting system (EGSIS) is an on-board method to generate and supply nitrogen-enriched air (NEA) to the fuel tank. EGSIS combines a polymer electrolyte membrane (PEM) electrolyzer anode which dissociates water to evolve oxygen, and a PEM fuel cell cathode which reduces oxygen from atmospheric air to produce NEA at its outlet. This paper represents the first attempt to model and simulate EGSIS using a three-dimensional, steady state, isothermal model. Various EGSIS performance indicators such as current density, reactant concentration distribution, and polarization curves are studied as a function of operating conditions and design parameters. The results from the computational model are validated against our previous experimental results for various operating conditions. The simulation results reveal the effects of temperature, reactant flowrates, and material property optimization on EGSIS performance. Different operating strategies are explored with the goal of improving system performance.Item Electrochemical gas separation and inerting system(Journal of Power Sources, 2021-05-15) Aryal, Utsav Raj; Chouhan, Ashish; Darling, Robert; Yang, Zhiwei; Perry, Mike L.; Prasad, Ajay K.Following the TWA 800 flight disaster in 1996 which was attributed to an explosion in the fuel tank, inerting of the ullage (air volume above the fuel in the tank) has gained prominence. Fuel tank inerting is the process of reducing the flammability of the ullage by supplying it with an inert gas like nitrogen. Current inerting techniques are expensive, consume large amounts of energy, and fail prematurely. Here, we propose a novel in-flight electrochemical gas separation and inerting system (EGSIS) to produce and supply nitrogen-enriched air (NEA). EGSIS combines a polymer electrolyte membrane (PEM) fuel cell cathode with a PEM electrolyzer anode to generate humidified NEA as the cathode output which can be dehumidified and supplied directly to the fuel tank. The required rate of NEA varies during a typical flight and a major advantage of EGSIS is that the rate of NEA generation can be conveniently controlled by varying the voltage applied to the system. Here, we report on the performance of a single-cell EGSIS apparatus and evaluate its suitability for aircraft fuel tank inerting.Item Optimization of an Electrochemical Gas Separation and Inerting System(Journal of The Electrochemical Society, 2022-06-17) Prasad, Ajay K.; Aryal, Utsav RajAircraft fuel tank inerting is typically accomplished by supplying nitrogen enriched air (NEA) into the ullage (volume of air above the fuel level in the tank). We have developed a novel on-board electrochemical gas separation and inerting system (EGSIS) to generate NEA for fuel tank inerting. EGSIS is an electrically powered system that functionally combines a proton exchange membrane (PEM) fuel cell cathode with an electrolyzer anode. Water management is important in such a PEM-based system because proton transfer requires proper hydration of the membrane. Extremes of both dryout and flooding conditions should be avoided for optimal EGSIS performance. Previous single-cell EGSIS experiments revealed that supplying liquid water at the anode will maintain sufficient membrane hydration even when the system is operated under dry cathode conditions. However, it was difficult to avoid flooding at low cathode air stoichiometries when parallel flow field channels were employed. Here, we implement various strategies to optimize EGSIS performance such as using serpentine and interdigitated flow field channels, as well as a double-layer gas diffusion layer with graded hydrophobicity to mitigate flooding and improve water management. We also present a theoretical analysis of various stack configurations for a practical EGSIS module.