John W. Sheffield

An outlook of hydrogen as an automotive fuel

Abstract The characteristics of the use of hydrogen as an internal combustion engine fuel, of the metal hydrides for hydrogen storage and of hydrogen fuel feed systems for the cases of hydrogen as a primary fuel and as supplemental fuel. The results clearly establish that supplemental hydrogen in the gasoline-air mixture can (1) expand the range of combustibility of the fuel-air mixture and hence more lean, (2) increase the effective efficiency of the engine and (3) reduce toxic emissions.

An Economic Analysis of Three Hydrogen Liquefaction Systems

Abstract Solar-hydrogen energy systems have received some attention in recent years as viable alternatives to the present fossil-fuel based energy systems. This paper presents an economic analysis of three hydrogen liquefaction systems with an associated cost comparison. The analysis takes into account the energy cost, operation and maintenance, and fixed charges on capital investment. Electrical requirements of the compressors or energy cost of a liquefier are prodemoninantly functions of the liquefier efficiency and are less dependent on the production rate required. Liquefaction costs in a large-scale liquid hydrogen plant depend primarily on the energy costs. Operation and maintenance costs, on the other hand, constitute; (1) plant payroll, (2) consumable supplies and equipment, (3) outside support services, and (4) miscellaneous costs. Finally, capital investment in a liquefaction system depends, to a great extent, upon the production rate, the types of liquefaction cycles utilized, and the location of the plant. The analysis showed that the cost of liquefying hydrogen is lowest for an optimized large-scale type liquid hydrogen plant and is highest for a simple conceptual liquid hydrogen plant. The liquefaction cost was also shown to reach a value of

Experimental investigation of thermal conductance of finned tube contacts

0.63/kg for the optimized large-scale type plant at a production rate of 30,000 kg/h when the cost of electricity is

Analysis and Optimization of Thermal Stratification and Self-Pressurization Effects in Liquid Hydrogen Storage Systems—Part 1: Model Development

0.04/(kW h).

Hydrogen and fresh water production from sea water

Abstract An experimental study was conducted to investigate the contact conductance of plate finned tubes. The basic theory of thermal contact conductance supports the use of measurable parameters including interference, fin spacing, fin thickness, tube hardness, and tube diameter as prediction parameters. Thirty-one coils were tested in a vacuum chamber. A correlation was developed that predicts the thermal contact conductance. The heat transfer results of the experimental study are presented.

Assessment of Hydrogen Energy for Sustainable Development

This paper reports on analyses and optimization studies of problemes associated with liquid hydrogen thermal stratification and self-pressurization in cryogenic vessels. Three different pressure rise models were employed to calculate the self-pressurization and boil-off rates. These are a homogenous model, a surface-evaporation model, and a thermal stratification model. The first two uodels are based on the assumption that no temperature gradients exist in the tank, while the third one takes the temperature distribution into account. Employing the thermal stratification model, temperature gradients and their effect on the pressure rise rates in liquid hydrogen tank are analyzed

Analytical and Experimental Investigation of Melting Heat Transfer

Abstract A review of hydrogen production as a source of energy was made. Electrolysis was found to be the major technique of hydrogen production from sea water. A potential difficulty with this process is the chlorine and oxygen that are evolved at the anode. A new concept for hydrogen production from sea water by an electrochemical method was investigated. In this concept fresh water and hydrogen are produced simultaneously. The electric cell consists of a set of electrodes with each electrode suspended between two plastic membranes (cations and anions). Hydrogen is evolved from the cation compartment and chlorine gas from the anion compartment. Cost estimation and evaluation of the process were made.

Thermal contact conductance of a phase-mixed coating layer by transitional buffering interface

Preface. Energy Security through Hydrogen J.W. Sheffield.- 21st Centurys Energy: Hydrogen Energy System T.N. Veziroglu.- Energy Policy is Technology Politics - The Hydrogen Energy Case C.J. Winter.- Hydrogen from Renewables N. Lymberopoulos.- Hydrogen Fuelling Sustainability of Energy Systems, Regional Integration and Development: The Sahara Wind Project K. Benhamou.- Pathway for Hydrogen in Urban Transit System T.K. Bose et al.- Energy Transitions in Transportation: Is It a Technology or a Policy Driven Process? R. Macario.- Prospects for Hydrogen as a Military Fuel K. D. Pointon, J.B. Lakeman.- The US Military and Hydrogen in Missouri S.Tupper.- Fuel Cells for Clean Power Generation: Status and Perspectives F. Barbir.-Performance of Single-Chamber Solid Oxide Fuel Cells I. Kellogg et al.- Hydrogen Production from Solar Energy I.E. Ture.- Chemical Synthesis of Mixed-Oxide Powders for Solid Oxide Fuel Cell (SOFC) Electrolyte and Electrodes C. Oncel, M.A. Gulgun.- Solar Hydrogen Production in Algeria: Perspectives and Applications S. Labed.- Bio-Hydrogen Production by Anaerobic Biological Fermentation of Agriculture Waste M. Al-Alawi.- Hydrogen Energy System for Sustainable Development N.H. Afgan, M.G. Carvalho.-Renewable Energy in Armenia: State of The Art and Development Strategies (Hydropower) S. Gevorgyan, V. Sargsyan.- Renewable Energy in Armenia: State of The Art and Development Strategies (Wind, Solar And Hydrogen Energy) S. Gevorgyan,and V. Sargsyan.- Thermodynamic Efficiency Analysis of a Hydrogen Production System Fuelled with Hydrocarbon Fuels for Fuel Cell Applications A. Ersoz et al.-Development of Ecologically Friendly Technology for Gasification of Municipal Solid Wastes M. Slenkin, G. Geletukha.- Prospects for Sustainable Development of Ukrainian Energy Sector O. Udovyk.- The Latest Activities of International Ecoenergy Academy on Renewable Energy Development in Azerbaijan F.G. Aliyev, F.F. Aliyev.- The Hydride Systemsand Peculiarities of Hydrogen Solubility in These Structures S. Y. Zaginaichenko et al.- Author Index. Subject Index.

Analysis and Optimization of Thermal Stratification and Self-Pressurization Effects in Liquid Hydrogen Storage Systems—Part 2: Model Results and Conclusions

A computational model is presented for the prediction of the heat transfer between a heat-transfer fluid (HTF) and a phase change material (PCM) of a latent heat storage unit. Two models of flow, hydrodynamically fully developed and developing, of the HTF were proposed in this study. A two-dimensiona l enthalpy method was used for the computation of the phase change heat transfer in the PCM. A fully implicit finite-difference scheme was utilized for the calculation of convective heat transfer in the HTF. The unknown time-dependent boundary condition between the HTF and the PCM was found iteratively. The predictions were substantiated by their fair agreement with experimental data. Factors affecting the heat-transfer rates between the HTF and the PCM were studied numerically for both the hydrodynamically fully developed and developing flows. It was found that the Nusselt number is significantly increased by the developing temperature profiles. The developing velocity profiles also increased the Nusselt number. However, the influence on Nusselt number due to the developing velocity profiles was less significant than that due to the developing temperature profiles. Other factors affecting the Nusselt number are discussed.

Second law analysis of active magnetic regenerative hydrogen liquefiers

The thermal contact conductances of metallic joints having phase-mixed coating layers applied by a novel transitional buffering interface technique was investigated. This study is restricted to relatively low contact pressure and to microhardness (P/H) ratios, 10~ < PlH < 6 x 10~, where very little data exist. These results are extremely useful for some applications such as electrical contacts in spacecraft. The purposes of this work were 1) to conduct an experimental study to examine four different coating materials, two pure materials, and two phase-mixed materials; and 2) to develop a theoretical model for a phase-mixed coating layer to predict the thermal contact conductance under the first-load cycle. The theoretical model included both the thermal and mechanical (microhardness) aspects of the contact problem. An extensive experimental program was carried out employing four different coating materials, as well as a broad range of surface roughness and microhardness. In order to obtain more robust coatings than conventional methods with better endurance, an adhesion test was conducted to investigate the adhesive strength of transitional buffering interface (TBI) coating layers.