Search results for "Combustion"

Energy Conversion: Solid Oxide Fuel Cells: First-Principles Modeling of Elementary Processes

2013

Fuel cells are electrochemical devices that directly transform the chemical free energy of combustion (e.g., H2 + O2 and CHx + O2) into electrical energy. The avoidance of a thermal detour guarantees high theoretical efficiency. As far as the temperature regimes are concerned, we distinguish between high temperature ceramic fuel cells, intermediate-temperature fuel cells, and low temperature (i.e., only slightly above room temperature) fuel cells. The high temperature fuel cells are usually based on oxide components (ternary transition metal oxides as cathodes, Ni or Cu cermets as anodes, and acceptor-doped zirconia or ceria as electrolytes). The high temperature necessary for ion conductio…

Influence of Chlorine, Sulphur and Water Vapor on High Temperature Corrosion of Fe, Cr, Ni Alloys for Waste Incinerators

2006

The behavior of three different materials with respect to their Fe, Cr, Ni contents have been studied between 450°C and 700°C, in waste incinerators combustion conditions, where it occurs a main influence of chlorine, sulfur and water vapor. This works analyzes the behavior of these materials which depends on their capability to form melted compounds and on the nature of these melted phases. Also as the corrosion mechanism is influenced by the presence or missing of any corrosive species, the study focalizes on the specific influence of SO2 and alkaline chorine. Effect of additive ashes on the corrosion behavior of tested materials is also studied. The mechanism of corrosion in waste incine…

Low temperature catalytic combustion of propane over Pt-based catalyst with inverse opal microstructure in microchannel reactor

2007

A novel Pt-based catalyst with highly regular, periodic inverse opal microstructure was fabricated in a microchannel reactor, and catalytic testing revealed excellent conversion and stable activity for propane combustion at low temperatures.

Mechanical Activation as a New Method for SHS

2006

The use of mechanical activation (the elemental powder mixture is milled for a short time at given frequency and impact energy) as a precursor to self-propagating high-temperature synthesis (SHS) results in the formation of nanostructured porous materials. The mechanical activation step was found necessary (i) to modify the thermal parameters of the combustion front (i.e. combustion front velocity, thermal heating rate…) in the cases of Mo-Si, Fe-Al, Ni-Si (ii) to initiate a combustion front in the case of systems having a low exothermicity. Nevertheless, the control of the mechanically activated mixture characteristics and, the understanding of the mechanical activation role on the SHS par…

Conservative averaging method for solving some nonlinear heat transfer problems related to combustion

2020

A Comprehensive Model for the Auto-Ignition Prediction in Spark Ignition Engines Fueled With Mixtures of Gasoline and Methane-Based Fuel

2018

The introduction of natural gas (NG) in the road transport market is proceeding through bifuel vehicles, which, endowed of a double-injection system, can run either with gasoline or with NG. A third possibility is the simultaneous combustion of NG and gasoline, called double-fuel (DF) combustion: the addition of methane to gasoline allows to run the engine with stoichiometric air even at full load, without knocking phenomena, increasing engine efficiency of about 26% and cutting pollutant emissions by 90%. The introduction of DF combustion into series production vehicles requires, however, proper engine calibration (i.e., determination of DF injection and spark timing maps), a process which…

Catalytic performances of Co3O4/CeO2 and Co3O4/CeO2-ZrO2Composite oxides for methane combustion: influence of catalyst pretreatment temperature and o…

2007

Abstract The influence of catalyst pre-treatment temperature (650 and 750 °C) and oxygen concentration ( λ  = 8 and 1) on the light-off temperature of methane combustion has been investigated over two composite oxides, Co 3 O 4 /CeO 2 and Co 3 O 4 /CeO 2 –ZrO 2 containing 30 wt.% of Co 3 O 4 . The catalytic materials prepared by the co-precipitation method were calcined at 650 °C for 5 h (fresh samples); a portion of them was further treated at 750 °C for 7 h, in a furnace in static air (aged samples). Tests of methane combustion were carried out on fresh and aged catalysts at two different WHSV values (12 000 and 60 000 mL g −1  h −1 ). The catalytic performance of Co 3 O 4 /CeO 2 and Co 3…

Vacuum arc deposition of protective layers on glass and polymer substrates

2001

Abstract Vacuum arc deposition allows one to deposit various coatings on insulating and temperature-sensitive substrates (like polymers). An advantage of the vacuum arc deposition technique is the low substrate temperature during the deposition process. A vacuum arc deposition apparatus for the coating of large-area substrates has been developed. Ti, TiN, TiO 2 and diamond-like single and multilayer coatings have been deposited on plastic and glass substrates. The vacuum arc technology permits formation of multilayer colour filters of high uniformity on substrates with dimensions up to 2000×1400 mm 2 . The microstructure, chemical composition and optical properties of the deposited coatings…

A Simulation Study Assessing the Viability of Shifting the Location of Peak In-Cylinder Pressure in Motored Experiments

2020

Hybrid powertrains utilize an engine to benefit from the power density of the liquid fuel to extend the range of the vehicle. On the other hand, the electric machine is used for; transient operation, for very low loads and where legislation prohibits any gaseous and particulate emissions. Consequently, the operating points of an engine nowadays shifted from its conventional, broad range of speed and load to a narrower operating range of high thermal efficiency. This requires a departure from conventional engine architecture, meaning that analytical models used to predict the behavior of the engines early in the design cycle are no longer always applicable. Friction models are an example of …

Semi-continuous feeding and gasification of alfalfa and wheat straw pellets in a lab-scale fluidized bed reactor

2015

Abstract Small scale air-blown fluidized bed gasification of alfalfa and wheat straw pellets were conducted for semi-continuous solid feeding and range of operating conditions varied due to the modifications in equivalence ratio (ER) (0.20–0.35) achieved both by varying solid and air input. Alfalfa pellets displayed an improvement in several gasification variables such as gas lower heating value (∼4.1 MJ/Nm3), specific gas yield (1.66 Nm3/kg), cold gas efficiency (∼42%) and carbon conversion efficiency (∼72%) as ER maximized to 0.35 which was found optimum for this feedstock for the present course of experiments. Gasification parameters of wheat straw pellets on the other hand were characte…