Combustion ratio

In order to provide further insight into the post-combustion ratio and the heat transfer efficiency, the factors that affect the PCR and HTE will be delineated. The factors that affect the PCR and HTE will be discussed separately with the understanding that a complex relationship may exist between the two parameters. The factors that affect the PCR are shown in Table 4, and Fig. 3 demonstrates the primary conditions for postcombustion. The PCR should be kept relatively high, since the fuel consumption decreases with an increase in the PCR at the same HTE (Aukrust, 1993). However, as mentioned, high PCR may lead to problems due to increases in ... 

Constituents Oxidant Combustible Ratio Specific Gravity, g/cc Specific Impulse, sec Remarks... 

In the pilot plant, strong radial gas concentration profiles, up to a factor 3 higher concentrations near the wall compared to the centre, have been measured. These profiles are obtained during gasification conditions (d50 °C, and X=0.30). However, measured CO profiles are found to be flat under certain process conditions. In case of only primary air, the CO profiles are flat On the other hand secondary air and combustion process conditions yield important radial CO gradients. This indicates that the shape of the radial CO profile is related to the oxygen to combustibles ratio. 

The optimum air-fuel ratio can be expressed as the stoichiometric or theoretical combustion ratio. This is the mixture in which fuel will be burned completely. In other words, all the carbon will be converted to carbon dioxide, all hydrogen converted to water, and all sulfur converted to sulfur dioxide. If there are unburned components in the exhaust gas, such as C, H2, or CO, the combustion process is incomplete. Carbon monoxide is produced if there is insufficient oxygen to oxidize the fuel fully. Nitrogen... 

Solvent vapors cannot bum if the amount of air in the mixture is above or below the correct combustion ratio. If the amount of oxygen in the mixture is too small to support combustion due to a surplus of the fuel vapors, it is at the upper explosive limit (DEL) of the mixture. When the volume of the fuel in the mixture is too low to support combustion due to a lack of burnable vapors, it is at the lower explosive limit (LEE) of the mixture. It is necessary to ensure that these vapor-air mixtures are always below LEE or above UEE ratios. 

Combustion Ratio Combustion reaction stoichiometric ratio of component i, [moles of CO2 formed/moles of component i combusted]... 

Chemical, convective, and radiative heats of combustion (ratio of the summation of the heat release rate to the summation of the release rate of material vapors) (Table 53.9) ... 

Table 17.2. Stoichiometric combustion ratios for organic compounds in pure oxygen and dry air Oxidant Stoichiometric combustion ratios for a fuel C31 p,S ...

If these are approximately the same in the liquid and vapor phase cases, then explosion behavior will be similar. This requirement for proper oxygen to combustible ratio explains why partial evaporation of oxygen from a sample may result in apparent higher sensitivity. 

F. Schoor, F. Norman, R. Vandermeiren, J. Berghmans, E. Buick, Flammability limits, limiting O2 concentration and minimum inert gas/combustible ratio of H2/CO/N2/Air mixture. Int. J. Hydrogen Energy 4(4), 2069-2075 (2009)... 

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