Simulation of hydrogen production for mobile fuel cell applications via autothermal reforming of methane

This paper presents a simulation of catalytic autothermal reforming (ATR) of methane (CH4) for hydrogen (H2) production. ATR is essentially an oxidative steam reforming, which combines the exothermic partial oxidation (PO) with the endothermic steam reforming (SR) under thermally neutral conditions. A model is developed using HYSYS 2004.1 to simulate the conversion behavior of the reformer. The model covers all aspects of major chemical kinetics and heat and mass transfer phenomena in the reformer. The ATR and preferential oxidation (PrOx) processes is modeled using conversion reactor, while the water gas shift (WGS) process is modeled using equilibrium reactor within HYSYS environment. The conditions used for high CH4 conversion and high H2 yield are at air to fuel ratio of 2.5 and water to fuel ratio of 1.5. Under this condition, CH4 conversion of 100% and H2 yield of 44% on wet basis can be achieved and the system efficiency is about 87.7%

Integrated Micro Fuel Processor And Flow Delivery Infrastructure

Apparatus for transporting a fluid, atomizers, reactors, integrated fuel processing apparatus, combinations thereof, methods of atomizing reactants, methods of moving fluids, methods of reverse-flow in a reactor, and combinations thereof, are provided. One exemplary apparatus for transporting a fluid, among others, includes: a channel for receiving a fluid; a sensor for determining an internal condition of the fluid in the channel; and a channel actuator in communication with the sensor for changing a cross-sectional area of the channel based on the internal condition, wherein the change in cross-sectional area controls a parameter selected from a pressure and a fluid flow.Georgia Tech Research Corporatio

Policies and Motivations for the CO2 Valorization through the Sabatier Reaction Using Structured Catalysts. A Review of the Most Recent Advances

The current scenario where the effects of global warming are more and more evident, has motivated different initiatives for facing this, such as the creation of global policies with a clear environmental guideline. Within these policies, the control of Greenhouse Gase (GHG) emissions has been defined as mandatory, but for carrying out this, a smart strategy is proposed. This is the application of a circular economy model, which seeks to minimize the generation of waste and maximize the efficient use of resources. From this point of view, CO2 recycling is an alternative to reduce emissions to the atmosphere, and we need to look for new business models which valorization this compound which now must be considered as a renewable carbon source. This has renewed the interest in known processes for the chemical transformation of CO2 but that have not been applied at industrial level because they do not offer evident profitability. For example, the methane produced in the Sabatier reaction has a great potential for application, but this depends on the existence of a sustainable supply of hydrogen and a greater efficiency during the process that allows maximizing energy efficiency and thermal control to maximize the methane yield. Regarding energy efficiency and thermal control of the process, the use of structured reactors is an appropriate strategy. The evolution of new technologies, such as 3D printing, and the consolidation of knowledge in the structing of catalysts has enabled the use of these reactors to develop a wide range of possibilities in the field. In this sense, the present review presents a brief description of the main policies that have motivated the transition to a circular economy model and within this, to CO2 recycling. This allows understanding, why efforts are being focused on the development of different reactions for CO2 valorization. Special attention to the case of the Sabatier reaction and in the application of structured reactors for such process is paid

Challenges and progress on the modelling of entropy generation in porous media: a review

Depending upon the ultimate design, the use of porous media in thermal and chemical systems can provide significant operational advantages, including helping to maintain a uniform temperature distribution, increasing the heat transfer rate, controlling reaction rates, and improving heat flux absorption. For this reason, numerous experimental and numerical investigations have been performed on thermal and chemical systems that utilize various types of porous materials. Recently, previous thermal analyses of porous materials embedded in channels or cavities have been re-evaluated using a local thermal non-equilibrium (LTNE) modelling technique. Consequently, the second law analyses of these systems using the LTNE method have been a point of focus in a number of more recent investigations. This has resulted in a series of investigations in various porous systems, and comparisons of the results obtained from traditional local thermal equilibrium (LTE) and the more recent LTNE modelling approach. Moreover, the rapid development and deployment of micro-manufacturing techniques have resulted in an increase in manufacturing flexibility that has made the use of these materials much easier for many micro-thermal and chemical system applications, including emerging energy-related fields such as micro-reactors, micro-combustors, solar thermal collectors and many others. The result is a renewed interest in the thermal performance and the exergetic analysis of these porous thermochemical systems. This current investigation reviews the recent developments of the second law investigations and analyses in thermal and chemical problems in porous media. The effects of various parameters on the entropy generation in these systems are discussed, with particular attention given to the influence of local thermodynamic equilibrium and non-equilibrium upon the second law performance of these systems. This discussion is then followed by a review of the mathematical methods that have been used for simulations. Finally, conclusions and recommendations regarding the unexplored systems and the areas in the greatest need of further investigations are summarized

Catalytic Reforming of Higher Hydrocarbon Fuels to Hydrogen: Process Investigations with Regard to Auxiliary Power Units

This thesis discusses the investigation of the catalytic partial oxidation on rhodium-coated honeycomb catalysts with respect to the conversion of a model surrogate fuel and commercial diesel fuel into hydrogen for the use in auxiliary power units. Furthermore, the influence of simulated tail-gas recycling was investigated

Plasma assisted decomposition of methane and propane and cracking of liquid hexadecane

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityNon-thermal plasmas are considered to be very promising for the initiation of chemical reactions and a vast amount of experimental work has been dedicated to plasma assisted hydrocarbon conversion processes, which are reviewed in the fourth chapter of the thesis. However, current knowledge and experimental data available in the literature on plasma assisted liquid hydrocarbon cracking and gaseous hydrocarbon decomposition is very limited. The experimental methodology is introduced in the chapter that follows the literature review. It includes the scope and objectives section reflecting the information presented in the literature review and the rationale of this work. This is followed by a thorough description of the design and construction of the experimental plasma reformer and the precise experimental procedures, the set-up of hydrocarbon characterization equipment and the development of analytical methods. The methodology of uncertainty analysis is also described. In this work we performed experiments in attempt the cracking of liquid hexadecane into smaller liquid hydrocarbons, which was not successful. The conditions tested and the problems encountered are described in detail. In this project we performed a parametric study for methane and propane decomposition under a corona discharge for COx free hydrogen generation. For methane and propane a series of experiments were performed for a positive corona discharge at a fixed inter-electrode distance (15 mm) to study the effects of discharge power (range of 14 - 20 W and 19 – 35 W respectively) and residence time (60 - 240 s and 60 – 303 s respectively). A second series of experiments studied the effect of inter-electrode distance on hydrogen production, with distances of 15, 20, 25, 30 and 35 mm tested. The analysis of the results shows that both discharge power and residence time, have a positive influence on gaseous hydrocarbon conversion, hydrogen selectivity and energy conversion efficiency for methane and propane decomposition. Longer discharge gaps favour hydrogen production for methane and propane decomposition. A final series of experiments on corona polarity showed that a positive discharge was preferable for methane decomposition.Brunel School of Engineering and Desig

Advances in catalysis for fuel cells

Imperial Users onl

Autothermal non-catalytic reformation of jet fuel in a supercritical water medium

The non-catalytic reformation of jet fuel using supercritical water was studied in a specially designed 0.4-L Haynes Alloy 230 tubular reactor. Experiments were performed at a constant pressure of 24.1 MPa, a temperature of 770°C, and at a constant water-to fuel ratio of fifteen-to-one by mass with various space times and oxygen flow rates. The experiments were conducted with and without air flow so as to examine the effects of the concurrent partial oxidation on the overall reformation process. The reactor effluent gas consisted of hydrogen, nitrogen, carbon dioxide, carbon monoxide, methane and ethane. Increasing space time increases the extent of the carbon gasification reaction and the resultant hydrogen and carbon dioxide gaseous concentrations; however the carbon gasification percentage reaches a limit of about 70% after a space time of 75 seconds when no oxygen was present. It was also established that the addition of substoichiometric amounts of air, as an oxygen source, does not adversely affect the production of hydrogen gas under certain conditions while increasing carbon conversion and in-situ heat generation through partial oxidation. Carbon conversions of 86% to 94%, depending on the space time, were achieved with oxygen-to-carbon ratios of 0.4. In this thesis, the effects of space time and oxygen addition on the reformation of jet fuel are elucidated based on the experimental data --Abstract, page iii