Doctoral Dissertations


"Hydrogen is an energy carrier that can be produced from a variety of sources, offering one of the viable solutions to the increasing demands for clean and sustainable energy. Compared to the conventional fuels, hydrogen has distinct properties that need to be properly accounted for during its safer storage and delivery as well as more efficient and cleaner utilization. The broader objective of this study is to contribute to the scientific knowledge necessary to overcome key technical barriers to the widespread implementation of hydrogen in transportation applications. Specifically, lower flammability limit of hydrogen is first measured with an enhanced experimental setup and then supported with a theoretical analysis in order to provide safety guidelines for hazardous conditions. Small and large hydrogen releases are computationally investigated under different conditions corresponding to potential accidental release scenarios. This involves quantifying the relative roles of buoyancy, diffusion and momentum during hydrogen transient mixing in air and the associated flammable zones in a simple geometry. The numerical predictions are extended to a practical geometry in which high pressure unsteady hydrogen leaks occur due to a catastrophic failure of a storage tank in a typical mobile hydrogen unit. Additionally, the combustion, performance and emission characteristics of a hydrogen-powered internal combustion engine are simulated by incorporating fuel-specific sub-models into a quasi-dimensional model, which is subsequently validated against independent data and utilized to quantify the effect of exhaust gas recirculation on emissions of oxides of nitrogen. Such reasonably fast and accurate predictive tools are essential to effectively design and optimize hydrogen engines for higher efficiency and near-zero emissions in the automotive industry"--Abstract, page iii.


Köylü, Ümit Ö. (Ümit Özgür)

Committee Member(s)

Akin, Elvan
Hosder, Serhat
Homan, Kelly
Sheffield, John W.


Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering


United States. Defense Logistics Agency
National University Transportation Center


Missouri University of Science and Technology

Publication Date

Summer 2010

Journal article titles appearing in thesis/dissertation

  • Experimental study and theoretical analysis on lower flammability limit of hydrogen in air
  • Detailed simulations of the transient mixing, leakage and flammability of hydrogen in air in simple geometries
  • High-pressure hydrogen leak from a storage tank
  • Computational modeling, validation, and utilization for predicting the performance, combustion and emission characteristics of hydrogen IC engines


xvi, 148 pages

Note about bibliography

Includes bibliographical references (pages 139-145).


© 2010 Shravan Kumar Vudumu, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Hydrogen as fuel -- Safety measures
Hydrogen as fuel
Internal combustion engines -- Fuel systems

Thesis Number

T 9657

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