مطالعه پارامتري و بهينه سازي فرايند جذب در مخزن هيدريد فلزي جهت ذخيره هيدروژن

Hydrogen, recognized for its high energy mass density, presents a viable alternative to fossil fuels. However, the optimal and safe storage of hydrogen remains a significant challenge due to its low volumetric energy density. Traditional hydrogen storage methods, including pressurized tanks and sub-cooled liquid storage, exhibit drawbacks such as high operational costs and safety concerns. Conversely, emerging techniques like silicate microspheres and carbon nanotubes are inadequate alternatives due to their low efficiency. Among the innovative storage methods, the use of metal hydride tanks offers considerable advantages. This approach involves a tank containing a metallic alloy that serves as a porous medium. The alloy possesses the ability to absorb hydrogen while releasing heat. Consequently, the process is characterized by two phases: hydrogen absorption occurs with heat rejection, while hydrogen release is facilitated by heat absorption. This duality underscores the critical importance of thermal management within these tanks. The safety and convenience of charging and discharging hydrogen represent significant benefits of this method. Nonetheless, the substantial weight of these tanks has pro‎mp‎ted engineers to seek solutions aimed at enhancing their performance. This thesis provides a comprehensive introduction to these reservoirs and reviews existing research. It further discusses the numerical simulation of the reservoir by analyzing the governing equations related to the hydrogen absorption process within the metal hydride tank. Following validation and grid independence, the model investigates the influence of eight distinct parameters on the tankʹs performance. These parameters include the heat transfer coefficient of the coolant, ambient temperature, inlet pressure, porosity coefficient of the metal, permeability of the metal, heat transfer coefficient of the metal, reaction activation energy, and reaction rate constants. The results showed that among these 8 parameters, the increase of some of them, such as the heat transfer coefficient of the cooling fluid or the ambient temperature, leads to an increase in the density of hydrogen absorption and at the same time, a decrease in the temperature peak during absorption, which Both are positive effects. while the increase of some other parameters such as hydrogen input pressure, metal permeability, reaction activation energy and reaction rate constant; It only leads to an increase in the absorbed density, but it raises the temperature peak. It was also found that the metal conductivity heat transfer coefficient has no significant effect on the performance of the tank. Further, considering the importance of environmental conditions on tank performance, optimizing the tank to achieve the best environmental conditions such as ambient temperature, inlet pressure, and heat transfer coefficient of cooling fluid displacement; was paid With the aim of achieving the maximum reduction of the temperature peak of the control variables in the form of the heat transfer coefficient of the cooling fluid equal to 14.1 W/m^2.K, the ambient temperature equal to 283 K and the inlet pressure of 18.96 pascal were obtained. If the goal is the greatest increase in hydrogen absorption density; The heat of the cooling fluid is equal to 10.3 W/m^2.K, the ambient temperature is equal to 295.4 K and the inlet pressure is 19.7 Pascal.

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