Search results for "Combustion"

Transition Metal Compound Oxide Catalysts for Lowering the Light Off-Temperature of Particles from Diesel Exhaust

1993

Publisher Summary It has been realized that particle emissions from diesel engines are a severe environmental problem, which is difficult to solve by engine modifications alone. Even if the combustion occurs in a high excess of air, appreciable amounts of soot particles are found. Cracking processes, dehydrogenation, and polymerization play an important role in the formation of soot. To reduce soot fraction, several methods have been developed in the past, but most of them have fundamental disadvantages. Thus, a new procedure based on the catalytic burning of the soot in the exhaust gas is becoming important. This chapter describes the effect of several compound oxides. Further investigatio…

The mechanically activated combustion reaction in the Fe–Si system: in situ time-resolved synchrotron investigations

2002

Mechanical high-energy ball milling of Fe+2Si elemental powder mixtures was used to activate self sustaining combustion reaction in the case of iron disilicide synthesis. The reaction path as well as the influence of the microstructural parameters on phase transformation have been investigated in detail. Time-resolved X-ray diffraction (TRXRD) using the fast recording kinetics offered by the synchrotron radiation was coupled to an infrared camera in order to study the internal structure of the combustion wave. The crystallite size and the amount of mechanically induced phases play an important role during the combustion; the reaction path and the end product composition mainly depend on the…

Enhancement of self-sustaining reaction by mechanical activation: case of an FeSi system

1999

Mechanical high energy ball milling of an Fe2Si elemental powders mixture was used to activate a self sustaining combustion reaction or so-called self-propagating high-temperature synthesis (SHS) to form iron disilicide, a reaction for which the thermodynamic criterion is not favorable. A complete characterization of the milled powders before reaction was performed with energy dispersive X-ray spectrometry, specific surface measurements and X-ray diffraction profile analysis. Thermal and structural information describing the combustion front initiated by heating up a sample to 400°C in a Fe‐Si system is communicated. In order to isolate the phases involved in the gasless reaction, a time-re…

Gas sensing properties of Zn-doped p-type nickel ferrite

2012

Abstract The influence of zinc ion to the NiFe2O4 p-type semiconductor gas response characteristics is demonstrated. For characterization of gas sensor material, synthesized by sol–gel auto combustion method, X-ray diffraction (XRD), scanning electron microscopy (SEM), DC resistance and impedance spectroscopy (IS) measurements were employed. The response change of Zn doped nickel ferrite is related to the interruption of hole hopping between nickel ions. This was improved by change of conductivity type with temperature and gas exposure.

In situ synchrotron characterization of mechanically activated self-propagating high-temperature synthesis applied in Mo–Si system

1999

Abstract An original experiment was designed to monitor structural and thermal evolutions during the MASHS (Mechanically Activated Self-propagating High-temperature Synthesis) process in the Mo–Si system. Time-Resolved X-Ray Diffraction (TRXRD) coupled with an infrared imaging technique was performed to study, in situ, the formation of the α-MoSi2 phase in the combustion front. Despite a temporal resolution of 50 ms between two consecutive diffractograms, no intermediate phase was observed during the passage of the combustion front. The only reaction responsible for the self-sustentation is Mo+2Si→MoSi2 in the primary zone inside the combustion wave. The mechanical activation was found to i…

Development of net energy ratio and emission factor for quad-generation pathways

2014

Published version of an article in the journal: Energy Systems. Also available from the publisher at: http://dx.doi.org/10.1007/s12667-014-0126-4 The conversion of biomass to four different outputs via gasification is a renewable technology that could reduce the use of fossil fuels and greenhouse gas (GHG) emissions. This study investigates the energy aspects for a new concept of biomass based quad-generation plant producing power, heat, methanol and methane. Circulating fluidized bed gasifier and the gas technology institute (GTI) gasifier technologies are used for this quad-generation process. Two different biomass feedstocks are considered in this study. The net energy ratio for six diff…

Active Electric Control of Emissions from Swirling Combustion

2007

Ba0.5Sr0.5Co0.8Fe0.2O3-x electrocatalyst prepared by combustion-based methods: the role of the fuel type

2010

Spark ignition feedback control by means of combustion phase indicators on steady and transient operation

2014

In order to reduce fuel cost and CO2 emissions, modern spark ignition (SI) engines need to lower as much as possible fuel consumption. A crucial factor for efficiency improvement is represented by the combustion phase, which in an SI engine is controlled acting on the spark advance. This fundamental engine parameter is currently controlled in an open-loop by means of maps stored in the electronic control unit (ECU) memory: such kind of control, however, does not allow running the engine always at its best performance, since optimal combustion phase depends on many variables, like ambient conditions, fuel quality, engine aging, and wear, etc. A better choice would be represented by a closed-…

A Study on the Use of Combustion Phase Indicators for MBT Spark Timing on a Bi-Fuel Engine

2007

The performance of a spark ignition engine strongly depends on the phase of the combustion process with respect to piston motion, and hence on the spark advance; this fundamental parameter is actually controlled in open-loop by means of maps drawn up on the test bench and stored in the Electronic Control Unit (ECU). Bi-fuel engines (e.g. running either on gasoline or on natural gas) require a double mapping process in order to obtain a spark timing map for each of the fuels. This map based open-loop control however does not assure to run the engine always with the best spark timing, which can be influenced by many factors, like ambient condition of pressure, temperature and humidity, fuel p…