本研究主旨在探討LaNi5與La0.6Ce0.4Ni5儲氫合金罐體在循環吸放氫作用之下，不同粉末填充率以及罐體擺設方向對於罐壁應變變化的影響，並探討中空型與隔層型二種儲氫合金罐體結構設計對於罐體膨脹變形之影響。LaNi5 與La0.6Ce0.4Ni5兩款合金粉末之實驗條件分別為在3.2 MPa 及5 MPa 氫氣壓力下吸氫，真空狀態下放氫，於室溫下連續進行80次吸放氫循環，並利用掃瞄式電子顯微鏡觀察合金粉末在活化前以及實驗後的外觀型貌與尺寸變化。 實驗結果顯示，在吸放氫循環過程中，合金粉末吸氫膨脹會使罐體外壁產生明顯的應變值。在實驗過程中，合金粉末的粉碎化和緻密堆積現象是無可避免的，因此在垂直中空型罐體較低的區域會產生較大程度的應變累積。垂直中空型罐體在較高粉末填充率的條件下，每個吸放氫循環過程當中的吸氫應變與放氫應變之差值也相對的較大。罐體內增加隔層腔體的設計，可使合金粉末平均分配在罐體各層，以達到減少粉末緻密堆積及結塊的情形發生，所以粉碎化後的細化合金粉末在罐體中呈現鬆散的狀態，使得應變累積現象明顯減小。相較於垂直中空型罐體，將罐體放置於水平方向，也可以有效減少粉末堆積並降低應變累積到很小的程度，同時顯著改善其吸氫速率。總而言之，對於設計一個符合安全以及較高效率的儲氫合金罐體，增加一隔層腔體設計或將罐體水平放置，皆可滿足這個要求。 The purpose of this study is to investigate variations of wall strain in the hydride storage vessels of LaNi5 and La0.6Ce0.4Ni5 with different packing fractions and vessel placements during cyclic hydriding/dehydridng processes. Hollow and multi-chamber types of metal hydride storage vessels were employed for the expansion deformation analysis. The LaNi5 and La0.6Ce0.4Ni5 alloy powders were repeatedly hydrided with 3.2 MPa and 5 MPa hydrogen, respectively, and then dehydrided with vacuum at room temperature during the cyclic test. Morphologies of the LaNi5 and La0.6Ce0.4Ni5 powders before activation and after the cyclic test were examined using scanning electron microscopy. Experimental results showed that significant absorption strains in the vessel wall were induced by volume expansion of LaNi5 and La0.6Ce0.4Ni5 hydrides in vertical hollow vessels. A great extent of strain accumulation at a lower position in a vertical hollow vessel was attributed to the unavoidable pulverization and agglomeration of alloy powders. In a vertical hollow reaction vessel, a larger packing fraction resulted in a greater difference between the absorption and desorption strain during a hydriding/dehydriding cycle. Powder densification and agglomeration could be effectively lessened by a multi-chamber structure in a vertical reaction vessel resulting in a very small extent of strain accumulation. Placement of a hollow reaction vessel in a horizontal rather than vertical orientation could also effectively reduce the extent of powder agglomeration and strain accumulation to a minimum level and improve the hydriding reaction rate. In summary, for design of a hydride storage vessel with a greater reliability and efficiency, addition of a multi-chamber design inside the vessel and placement of the vessel in a horizontal orientation are favorable considerations.
