Simulation And Optimization Of Adsorptive Hydrogen Storage System For Vehicular Application

The economic development of the20th Century was driven by oil based energy. As peak oil approaching, the oil economy, however, will come to the end without a doubt. New energy based economy, therefore, is proposed by worldwide economists and politicians. For many years, oil depended automobile industry is being criticized by the community, no mention the criticisms it received because of the environment pollution issues. Hence, some alternative fuels for motive power are concerned and studied, among which hydrogen is supposed to be a potential fuel to deliver energy. Hydrogen vehicle is one of the promising options for automobile industry to come out from the dilemma it faces.Many affords have been paid for the commercialization of hydrogen vehicles including both fuel cell vehicle and hydrogen internal combustion engine vehicle, while the absence of a qualified on-board hydrogen storage system is still one of the primary bottlenecks. Cryo-adsorptive hydrogen storage is one of a few solutions which can partly fulfill the DOE (United States department of energy) targets. Therefore, system analyzes are necessary for designing and optimizing adsorptive hydrogen storage system.In this paper we present a lumped parameter model for adsorptive hydrogen storage system by simply employing general mass balance and energy balance equations resulted from the fundamental thermodynamic conservations. A modified Dubinin-Astakhov (D-A) isotherm and a variational isosteric heat of adsorption are adopted in the lumped parameter model to improve validity for whole charge-discharge cycle. The lumped parameter model is implemented in MATLAB/SIMULINK platform. The model is well validated by experiments with different cooling conditions, which conducted by IRH (institute of hydrogen research, university of Quebec at Trois-Rivieres).First, the lumped model is applied in simulation of the charge and discharge cycle for two sets tests based on normal temperature water cooling hydrogen storage system. Several parameters are calibrated and validated by comparing the simulation results and experimental data. Good agreements are observed between simulation pressure and experimental pressure. The concept of thermal averaging temperature is used to fill the gap between the multi-scale models, such as OD model of MATLAB/SIMULINK and2D model of COMSOL. We also obtain good agreements between simulation temperature and thermal averaging temperature. Thus, the lumped parameter model can well predict pressure and temperature variation during hydrogen storage process. On this basis, parametric studies are carried out to analyze the validity of variational heat of adsorption, the practicality of heat transfer coefficient and the effect of hydrogen storage pressure.Then the lumped parameter model is used in simulation of charge process of cryo-adsorptive hydrogen storage system. Nearly7times hydrogen storage capacity under the same hydrogen storage pressure is observed from the simulation results when compared with normal temperature water cooling hydrogen storage system. Subsequently, the influences of charge flow rate, charge flow temperature, porosity of adsorbent bed as well as storage pressure on the performance of hydrogen storage system are discussed and analyzed. A minimal charge flow rate of200SLPM (standard liter per minute) and a minimal tank capacity of150L are necessary to fulfill DOE targets for onboard hydrogen storage systems for light-Duty vehicles.Finally, a simulation platform is developed for performing efficiently system analysis on onboard hydrogen storage system. The simulation platform is then applied in the performance predicting and optimization of the onboard hydrogen storage system. Hydrogen storage temperature, charge flow temperature and effective hydrogen storage capacity are discussed and analyzed.