OPTIMUM SPACING BETWEEN HORIZONTAL METAL HYDRIDE (MH) HYDROGEN STORAGE TANKS INTEGRATED WITH FUEL CELL POWER SYSTEM IN NATURAL CONVECTION

Mevcut araştırma doğal taşınımla ısıtılan metal hidrid tankların yakıt piline sağlaması gereken Hidrojen kapasitesini incelemektedir. Deşarj işleminde, tanklar arasındaki optimum aralığı tespit etmek için, farklı konfigürasyonlarda teorik ve sayısal analizler yapılmıştır. H/D=3, 5 ve 10 için analizler yapılmıştır. Bu üç konfigürasyon, H/D ve aralığa bağlı olarak, farklı sayıda tanktan meydana gelmektedir. Metal hidrid olarak AB5 tipi LaNi5 seçilmiştir. Analizlerde doğal taşınım ve MH in reaksiyon kinetikleri hesaba katılmıştır. Aralık, maksimum ısı transferini sağlayacak şekilde uygun bağıntılarla hesaplanmıştır. Sonuçlar, maksimum Nusselt değeri için tanklar arasında optimum bir aralık olduğunu göstermiştir. H/D nin artması veya Rayleigh sayısının azalması ile optimum aralık değeri artmaktadır. Ayrıca, Rayleigh sayısının artması ile optimum aralık %20 den fazla artmaktadır. Bu sonuçlar göstermiştir ki, optimum aralık denge MH denge basıncının ve H/D nin artması ile artacaktır

DOĞAL TAŞINIM ORTAMINDA YAKIT PİLİ GÜÇ SİSTEMİ İLE ENTEGRE YATAY METAL HİDRİD (MH) TANKLAR ARASINDAKİ OPTİMUM ARALIK

Present investigation examines the ability of metal hydride storage systems to supply hydrogen to a fuel cell, when the metal hydride tanks are heated by natural convection. To determine optimum spacing of horizontal MH tanks in desorption process, theoretical and numerical analysis is presented to compare different storage tank configurations. Three configurations are analyzed: storage cases with H/D=3, 5 and 10 (array height H, cylinder diameter D). Each of the three configuration had different number of cylinders in the array depending on the H/D and spacing between the cylinders. As MH alloys, AB5 type alloy (LaNi5) is selected. The analysis takes into account the effect of external natural convection heat transfer and reaction kinetics of MH. The spacing is calculated by maximizing the heat transfer by means of accurate correlations. The results of this study reveal that there exists a distance between the MH tanks for which the Nusselt number is maximum. By increasing H/D or decreasing the Rayleigh number, the optimal spacing will increase. Moreover by increasing Rayleigh numbers optimum spacing will increase more than 20%. These results show the optimum spacing in a given volume increase with the increasing equilibrium pressure and H/D ratio.

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