Metal hidrür reaktörlerin mikro ölçekte modellenmesi
Küçük Resim Yok
Tarih
2023
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Niğde Ömer Halisdemir Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu tezin temel amacı, metal hidrür reaktörlerde mikro ölçekte bir matematiksel modelin geliştirilmesidir. Bu model, metal hidrür reaktörlerde hidrojen depolama malzemelerinin termal iletkenliklerini iyileştirmek ve depolama yeteneklerini artıran, kinetiğini açıklayan bir modelin oluşturulması, simülasyonu ve doğrulanmasından oluşmuştur. İlk olarak, hidrojen depolama malzemesi olarak kullanılan LaNi5 tozlarının bakır kaplama kalınlıkları 0,8-1,4 µm aralığında Digimat yazılımı yardımıyla oluşturulmuş ve davranışını simüle etmek için COMSOL'da üç boyutlu bir model oluşturulmuştur. Daha sonra LaNi5 tozlarına %1, %5, %10 ve %20 oranlarda genişletilmiş grafit (ENG) eklenerek Digimat yazılımı yardımı ile geometrik yapı oluşturulmuş ve COMSOL yardımıyla çözülmüştür. Geliştirilen mikro modeller, hidrojeni şarj eden metal alaşımının kütle korunumu, gözenekli ortamda Darcy akışı ve hidrojen şarj işlemleri için ekzotermik reaksiyonla ısı üretimi dikkate alınarak formüle edilmiş, sayısal olarak çözülmüş ve deneysel olarak doğrulanmıştır. Bakır kaplama kalınlığı 1,2 µm ve ENG katkı oranı %5 olarak optimize edilmiş olup hidrojen depolama malzemesinin termal iletkenliği %350 civarında artırılmıştır. Depolama işlemleri sonucunda LaNi5 tozlarının tamamen H2 ile bağlandığı da gözlemlenmiştir.
The main objective of this thesis is to develop a mathematical model at a micro scale for metal hydride reactors. This model consists of the creation, simulation, and validation of a model that improves the thermal conductivity of hydrogen storage materials in metal hydride reactors and enhances their storage capabilities, describing their kinetics. Initially, the copper coating thicknesses of LaNi5 powders used as hydrogen storage material were created using Digimat software in the range of 0.8-1.4 µm, and a three dimensional model was established in COMSOL to simulate their behavior. Subsequently, geometric structures were formed by adding expanded graphite (ENG) to LaNi5 powders at ratios of 1%, 5%, 10%, and 20% using Digimat software, and these structures were solved with the help of COMSOL. The developed micro models, considering the mass conservation of the metal alloy absorbing hydrogen, Darcy flow in a porous medium, and exothermic heat production during hydrogen absorption processes, were formulated, numerically solved, and experimentally verified. The copper coating thickness was optimized at 1.2 µm, and the ENG contribution ratio was optimized at 5%, resulting in approximately a 350% increase in the thermal conductivity of the hydrogen storage material. It was also observed that LaNi5 powders were fully bonded with H2 after the storage processes.
The main objective of this thesis is to develop a mathematical model at a micro scale for metal hydride reactors. This model consists of the creation, simulation, and validation of a model that improves the thermal conductivity of hydrogen storage materials in metal hydride reactors and enhances their storage capabilities, describing their kinetics. Initially, the copper coating thicknesses of LaNi5 powders used as hydrogen storage material were created using Digimat software in the range of 0.8-1.4 µm, and a three dimensional model was established in COMSOL to simulate their behavior. Subsequently, geometric structures were formed by adding expanded graphite (ENG) to LaNi5 powders at ratios of 1%, 5%, 10%, and 20% using Digimat software, and these structures were solved with the help of COMSOL. The developed micro models, considering the mass conservation of the metal alloy absorbing hydrogen, Darcy flow in a porous medium, and exothermic heat production during hydrogen absorption processes, were formulated, numerically solved, and experimentally verified. The copper coating thickness was optimized at 1.2 µm, and the ENG contribution ratio was optimized at 5%, resulting in approximately a 350% increase in the thermal conductivity of the hydrogen storage material. It was also observed that LaNi5 powders were fully bonded with H2 after the storage processes.
Açıklama
Fen Bilimleri Enstitüsü, Makine Mühendisliği Ana Bilim Dalı
Anahtar Kelimeler
Makine Mühendisliği, Mechanical Engineering
