Nano Gözenekli Metal Organik Yapılarda Tane Boyutunun Difüzyon Hızına Etkisi
Nano Gözenekli Metal Organik Yapılarda Tane Boyutunun Difüzyon Hızına Etkisi
Dosyalar
Tarih
2014-02-18
Yazarlar
Kuzak, Fatih
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Institute of Science and Technology
Özet
Bu çalışmada hidrojenin ulaşım araçlarında yakıt olarak kullanılmasının önündeki en büyük engel olan depolanmasına çözüm olarak geliştirilen çok yüksek yüzey alanına sahip metal-organik kafeslerin, yeni geliştirilen nano gözenekli bir örneğinin farklı ortalama tane boyutuna sahip iki numunesinin hidrojen depolama özellikleri incelenmiştir. Hidrojenin, yeterli oranlarda depolanması oda sıcaklığında henüz mümkün olmadığından, malzemelerin hidrojen depolama testleri kriyojenik sıcaklıklarda gerçekleştirilmiştir. Birbirinden farklı 5 kriyojenik sıcaklıkta gerçekleştirilen hidrojen adsorpsiyon verilerinden yola çıkılarak hidrojenin bu malzemelerdeki adsorpsiyon ısısı hesaplanmıştır. Kinetik verilerden yola çıkılarak hidrojenin malzeme içerisinde difüzyonu ölçülmüştür. Difüzyon denklemi, Fick in ikinci yasasından yola çıkılarak gözenekli malzemelerin gerektirdiği uygun başlangıç ve sınır koşullarının yerleştirilmesiyle elde edilmiştir. Sonuç olarak, küçük ortalama tane boyutuna sahip olan numunenin, ortalama tane boyutu büyük olana göre hidrojeni daha hızlı depoladığı görülmüştür.
Hydrogen is a promising energy carrier for use in mobile applications, because of its high energy content. To solve the storage problem of hydrogen in vehicles a new kind of materials have been developed with high surface area, metal-organic frameworks. In this study, hydrogen adsorption properties of two samples of a nanoporous metal-organic material that they differ from each other by only average grain size, have been studied. Hydrogen adsorption by porous materials at room temperature, is very low. Therefore, the measurements have been performed at five different cryogenic temperatures, which allows a reliable determination of heat of adsorption of hydrogen. Diffusion equation has been obtained from Fick s second law, by employing appropriate initial and boundary conditions for porous materials. As a result, an unexpected difference in hydrogen uptake between the samples has been observed, and it is found that hydrogen diffusion is faster in the sample with small average grain size than the sample with large average grain size.
Hydrogen is a promising energy carrier for use in mobile applications, because of its high energy content. To solve the storage problem of hydrogen in vehicles a new kind of materials have been developed with high surface area, metal-organic frameworks. In this study, hydrogen adsorption properties of two samples of a nanoporous metal-organic material that they differ from each other by only average grain size, have been studied. Hydrogen adsorption by porous materials at room temperature, is very low. Therefore, the measurements have been performed at five different cryogenic temperatures, which allows a reliable determination of heat of adsorption of hydrogen. Diffusion equation has been obtained from Fick s second law, by employing appropriate initial and boundary conditions for porous materials. As a result, an unexpected difference in hydrogen uptake between the samples has been observed, and it is found that hydrogen diffusion is faster in the sample with small average grain size than the sample with large average grain size.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013
Anahtar kelimeler
hidrojen depolama,
adsorpsiyon,
gözenekli malzemeler,
metal organik kafesler,
yenilenebilir enerji,
hidrojen,
hydrogen storage,
physisorption,
chemisorption,
metal-organik frameworks,
porous materials,
renewable energy