梯度填充膨胀石墨的金属氢化物反应器吸氢过程数值分析
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摘要
为了研究金属氢化物床层中膨胀石墨(Expanded natural graphite,ENG)的填充方式对反应器性能的影响,建立了镁基金属氢化物(MgH_2)反应器的二维多物理场耦合模型并采用COMSOL Multiphysics V5.3软件求解。所研究反应器内装填了MgH_2与ENG混合制作的复合压片。分别研究了在金属氢化物床层中不同ENG含量以及ENG梯度填充对吸氢反应的影响,证明了ENG梯度填充方式的优越性。计算结果表明:随着反应床ENG含量的增加,床层温度下降速率加快,吸氢反应速率得到提升;与ENG均匀填充方式相比,沿着床层热流密度增大方向增加ENG含量的梯度填充方式可以使反应床温度分布更均匀,强化换热效果更好,反应器的单位质量蓄热功率更高。
In order to investigate the effects of the filling method of expanded natural graphite(ENG) in the reaction bed on the metal hydride reactor performance, a two-dimensional multi-physics model for the reactor filled with pelletized magnesium hydride-graphite composites was established. This model was solved using the software COMSOL Multiphysics V5.3. The effects of different ENG contents and ENG graded filling in the reaction bed on the hydrogen absorption process were studied respectively, and the superiority of the ENG graded filling method was verified. The results show that with the increase of ENG content in the reaction bed, the temperature drop rate of the reaction bed accelerates and the hydrogen absorption rate increases. Compared with the uniform filling method, the ENG graded filling method with the ENG content increasing along the direction in which the heat flux increases can contribute to more uniform temperature distribution in the reactor bed, and show better heat transfer enhancement effect and higher gravimetric heat storage rate of the reactor.
In order to investigate the effects of the filling method of expanded natural graphite(ENG) in the reaction bed on the metal hydride reactor performance, a two-dimensional multi-physics model for the reactor filled with pelletized magnesium hydride-graphite composites was established. This model was solved using the software COMSOL Multiphysics V5.3. The effects of different ENG contents and ENG graded filling in the reaction bed on the hydrogen absorption process were studied respectively, and the superiority of the ENG graded filling method was verified. The results show that with the increase of ENG content in the reaction bed, the temperature drop rate of the reaction bed accelerates and the hydrogen absorption rate increases. Compared with the uniform filling method, the ENG graded filling method with the ENG content increasing along the direction in which the heat flux increases can contribute to more uniform temperature distribution in the reactor bed, and show better heat transfer enhancement effect and higher gravimetric heat storage rate of the reactor.
引文
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[2]鲍泽威,吴震,NYALLANG N S,等.金属氢化物高温蓄热技术的研究进展[J].化工进展,2012,31(8):1665-1670.
[3]AFZAL M,MANE R,SHARMA P.Heat transfer techniques in metal hydride hydrogen storage:a review[J].International Journal of Hydrogen Energy,2017,42(52):30661-30682.
[4]SANCHEZ A R,KLEIN H P,GROLL M.Expanded graphite as heat transfer matrix in metal hydride beds[J].International Journal of Hydrogen Energy,2003,28(5):515-527.
[5]CHAISE A,DE RANGO P,MARTY P,et al.Enhancement of hydrogen sorption in magnesium hydride using expanded natural graphite[J].International Journal of Hydrogen Energy,2009,34(20):8589-8596.
[6]POHLMANN C,R?NTZSCH L,KALINICHENKA S,et al.Magnesium alloy-graphite composites with tailored heat conduction properties for hydrogen storage applications[J].International Journal of Hydrogen Energy,2010,35(23):12829-12836.
[7]HERBRIG K,R?NTZSCH L,POHLMANN C,et al.Hydrogen storage systems based on hydride-graphite composites:computer simulation and experimental validation[J].International Journal of Hydrogen Energy,2013,38(17):7026-7036.
[8]CHAISE A,DE RANGO P,MARTY P,et al.Experimental and numerical study of a magnesium hydride tank[J].International Journal of Hydrogen Energy,2010,35(12):6311-6322.
[9]CHAISE A,MARTY P,DE RANGO P,et al.A simple criterion for estimating the effect of pressure gradients during hydrogen absorption in a hydride reactor[J].International Journal of Heat and Mass Transfer,2009,52(19/20):4564-4572.
[10]DE RANGO P,MARTY P,FRUCHART D.Hydrogen storage systems based on magnesium hydride:from laboratory tests to fuel cell integration[J].Applied Physics A,2016,122(2):126.
[11]BAO Z W,YANG F S,WU Z,et al.Optimal design of metal hydride reactors based on CFD-Taguchi combined method[J].Energy Conversion and Management,2013,65:322-330.