Studies Of The Storage By Adsorption Of Hydrogen On The Activated Carbon During Charge And Discharge

Condradiction between energy consumption and supply emerged to be one of the most important factors affecting the world economy and peace. One aspect is the increasement in energy demand in step with the development of economy, and the other is the insufficient energy supply due to the limit of the energy source, searching for alternative fuels is therefore urgently needed. Hydrogen is one of most promising for its advantage of zero emission, and environment friendly and resourceful, however, the lack of efficient storage method is a bottleneck of the utilizing. Since 1980's, the study of adsorption hydrogen on carbon-based materials has always been concerned. Due to it has low specific weight and can reach very high specific surface area with reasonable cost.Because of poor heat conductivity of the adsorbent bed, adsorption heat makes process of charge and discharge non-isothermal during the adsorption and desorption and accordingly lessen actual hydrogen quantity comparing with the isothermal process. Therefore, analyzing the characteristic of charge and discharge, analyzing the influence of adsorption heat on performance of adsorbent bed are crucial.Based on the above ideas, according to volumetric method, a setup for dynamic adsorption test of hydrogen was established, The volume of adsorption vessel is 540 ml, and about 205g activated carbon SAC-01 with specific surface area 1800 m2/g was used. At ambient temperature, the charge and discharge tests of the storage vessel were undertook at the pressure 10.5 MPa, 8 MPa, 6 MPa, 4 MPa, and the thermal resulted from effect adsorption heat and the performance of the storage system were investigated. Results show that the quick charge at pressure from 0.1 to 10.5 MPa resulted in a maximum temperature rise of 27 K, and the processes of the quick discharge under 10.5 MPa brought about a maximum temperature drop of 25 K. Conclusions were drawn that measures can be taken to weaken the effect of the adsorption heat on the performances of the storage system.ANSYS is employed to simulate temperature distribution within the storage vessel in the process of quick charge and discharge. Considering the actual charge and discharge process, a relatively simple adiabatic model for charge and discharge is also established and numerically solved. For a adsorption cylinder about 540 ml, comparing with the experimental results shows the accuracy of simulation.To overcome the detrimental impact of adsorption during discharge, a method of heat management for storage system is presented. That is, we may weaken the temperature fluctuation of adsorption bed by introducing an outer heat source during discharge. For example, we may use the exhaust of engine (about 180℃) to heat the adsorption bed when discharge.