摘要:

A Multidimensional Performance Model of a Spark Ignition Engine Characterized by a Single Step Reaction to Equilibrium Abstract-A new multidimensional model of a spark ignition engine has been developed. The main features of this model are its two-dimensional computational scheme, the assumption of equilibrium conditions for the thermodynamical properties, and the automatic determination of the initial conditions.This approach enables the number of free parameters to be considerably reduced with respect to similar programs currently available, thus ensuring an overall increase in the reliability of the entire computational scheme.

ISSN:0010-2202    

DOI:10.1080/00102208608923845

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Cupola melting is primarily combustion/gasification of a coke bed containing a high inert of which some fraction melts continuously. The data base on such systems is sparse. So far base line experiments have been carried out without melting. In the present study, detailed experimental investigations were carried out on a 200 mm diameter cupola with and without melting of metal.The study of the distribution of temperature and the concentrations of the products of combustion at different points in the cupola in the two cases (i.e., with and without melting of metal) has revealed that the combustion (oxidation) as well as gasification (reduction) reactions are intensified right from the luyere level in the combustion zone. when melting of metal occurs on a thick coke bed and the superheated molten metal trickles down the bed. The carbon precipithick tation reaction is catalyzed by the solid cast-iron charge at elevated temperature in the melting zone and above it. The zone of negligible oxygen concentration (ZNO2) and the zone of maximum carbon dioxide (ZMCO2) and the zone of maximum temperature (ZMT) appear at lower heights, when the metal is melted and also the ZMCO2 and ZMT do not coincide as in the case of combustion of coke alone. The temperatures of gases at all the points in the regions above the melting zone and also in the ZMT are reduced. The temperature of gases at all the points in the regions below the melting zone are found to be higher. The melting rate and the molten metal temperature at the spout are observed to be a direct linear function of the combustion efficiency ratio (πc). the relative carbon saturation (RCS), and the temperature of the gases (Tg) at the periphery within the melting zone, just above the initial coke-bed height.

ISSN:0010-2202    

DOI:10.1080/00102208608923846

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The behavior of agglomerates o f boron particles, formed during the combustion of boron slurry fuels, was studied in the post-flame region of a Rat-flame burner. Agglomerates having initial diameters of 175-800 μmwere supported on a probe and placed in the hot gas environment. Measurements were made of the variation of agglomerate size with time. Quenched agglomerate surface morphology was studied using a scanning electron microscope. Burner operating conditions were varied to give fuel equivalence ratios in the range 0.3-0.7 and gas temperatures in the range 1690-1975 K at atmospheric pressure. Flame environments both with and without water vapor were considered. Observations of surface morphology of partiallyreacted slurry agglomerates suggest that the ignition and combustion process consists of the heat-up of a relatively porous agglomerate composed of individual boron particles covered with a solid oxide coating followed by oxide melting to form a liquid coating of low porosity. The oxide layer then gasifies. leaving an open, porous structure of reacting boron particles. Finally, the boron melts and transforms the agglomerate to a droplet. Measurements of ignition times and burning rates were interpreted in this framework for agglomerates formed from three different slurries. Burning rates computed from a diffusion-limited, equilibrium analysis were in reasonable agreement with measurements.

ISSN:0010-2202    

DOI:10.1080/00102208608923847

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The overall characteristics of high-intensity pulverized coal combustion have been predicted by a one-dimensional model. The mixing of the primary stream of pulverized coal and transport air with secondary combustion air was estimated by a growth angle of the primary jet. The coal particle burnout was strongly affected by the extent of devolatilization, which varies among coals. The extent of devolatilization as characterized by variation in a devolatilization coefficient was correlated with either proximate volatiles percentage or H/C mass ratio of the virgin coal. The resulting comparisons or predictions with measurements for eight coal types and three different combustors show that observed trends are generally predicted. The data used for these comparisons were obtained from a wide range of high-intensity combustion experiments. The proximate volatile matter in the virgin test coals ranged from 16 to 40 percent while the coal feed rate was varied from 12 to 290 kg/hr. Combustion air temperature varied from 297 to 1483 K while residence time ranged from 3 to 140 ms. Comparative results suggest that the predictive method can be useful in interpreting high intensity combustion test results.

ISSN:0010-2202    

DOI:10.1080/00102208608923848

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This work advances the area o f zone modeling by the development of a five-zone theoretical model with time-incrementing capabilities to predict the results of liquid pool methanol fires in a gas-tight enclosure. The model consists of a liquid pool fuel hed, a developed flame above the fuel bed, a plume on top of the flame, the enclosure walls, and an ambient gaseous medium between the enclosure walls and the flame-plume boundaries. It assumes a temperature dependent chemical equilibrium between the combustion products and evaporated fuel in the flame. It also dictates the energy feedback within each defined zone and predicts the temperatures (ambient gas. flame, and plume), the mass evaporation rate of the fuel, the total pressure. and the oxygen concentration within the enclosure. The early effects of oxygen concentration on a con-fined methanol fire are well established in this work through a comparison with an open methanol fire model. Initially the rising ambient gas temperature causes the mass evaporation rate of the fuel to increase. Eventually the dropping oxygen concenration reduces the mass evaporation rate through its influence on the mass air entrainment rate and the flame height. Tere is no evidence in the region of the maximum burning rate for the influence o f non-stoichiometric combustion.

ISSN:0010-2202    

DOI:10.1080/00102208608923849

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

An experimental study has heen conducted in a flow reactor on the oxidation of n-ocltane and iso-octane at 1080 K, one atmosphere pressure and equivalence ratio equal to one. It was found that (despite similar ratios of initial fuel decay) the conversion of the reaction intermediates to CO and COais much slower during the oxidation of iso-octane than n-octane. Iso-octane produced primarily iso-butylene and propylene as intermediate hydrocarbons whereas n-octane oxidation resulted primarily in the formation or ethne. Both the nature of the intermediates formed from each fuel and the relative rates of oxidation of the intermediates were shown to be related to the number of primary, secondary and tertiary H atoms present in the initial fuel. The basic chemistry revealed by the flow reactor experiments is suggestive of new insights into the chemical phenomena pertinent to knock in spark ignition engines.

ISSN:0010-2202    

DOI:10.1080/00102208608923850

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The influence of certain barium and cobalt salts was studied on the burning rate- pressure relationship or double-base propellants. Among barium salts, barium-β-resorcylate produced the best catalytic effect with significant plateau effect in the 35-70 kg/cm2pressure range, whereas among the cobalt salts the best results were obtained with cobalt stearatc in the low pressure range and with cobalt salicylate in the high pressure range. These salts were found to dccompose in the surface temperature range of double-base propellants. and propellants containing them decomposed at lower temperatures than the control.

ISSN:0010-2202    

DOI:10.1080/00102208608923851

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102208608923852

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor