Chavannavar, Praveen Shivshankar (2005-08). Parametric examination of the destruction of availability due to combustion for a range of conditions and fuels. Master's Thesis. Thesis uri icon

abstract

  • A comprehensive second law analysis of combustion for a range of conditions and fuels was completed. Constant pressure, constant volume and constant temperature combustion processes were examined. The parameters studied were reactant temperature, reactant pressure, equivalence ratio and the fuels themselves. In addition, the contribution and relative significance of the various components (thermo-mechanical, reactive and diffusion) to the mixture availability was examined. Also, the effect of reactant mixture dissociation was incorporated into the combustion analysis. It was found that for similar initial conditions, constant pressure combustion and constant volume combustion exhibited similar trends. For constant temperature combustion, the trend is significantly different from the constant pressure and constant volume combustion, with almost the entire reactant availability being destroyed due to combustion at lower temperatures. Amongst the parameters examined, reactant mixture temperature had the most significant effect on the fraction of availability destroyed during combustion. The percentage availability destroyed reduced from 25 to 30% at 300 K to about 5% at 6000 K for constant pressure and constant volume combustion processes. The effect of the reactant mixture pressure on the fraction of availability destroyed was more modest. The values for the percentage availability destroyed for pressures ranging from 50 kPa to 5000 kPa were found to lie within a range of 5%. The effect of equivalence ratio on the fraction of reactant mixture availability destroyed was also documented. In general, it was found that the destruction of availability decreased with increasing equivalence ratios. This value, however, accounts for the availability due to fuel like species in the product mixture. Therefore, for practical applications, combustion of the stoichiometric mixture would be preferred over the rich equivalence ratios. It was found that the fraction of reactant availability destroyed increased with increasing complexity of the fuel??s molecular structure. In addition, it was shown that the diffusion availability terms is small and may be neglected, while the reactive availability and thermo-mechanical availability are more significant.
  • A comprehensive second law analysis of combustion for a range of conditions and fuels
    was completed. Constant pressure, constant volume and constant temperature combustion
    processes were examined. The parameters studied were reactant temperature, reactant
    pressure, equivalence ratio and the fuels themselves. In addition, the contribution and relative
    significance of the various components (thermo-mechanical, reactive and diffusion) to the
    mixture availability was examined. Also, the effect of reactant mixture dissociation was
    incorporated into the combustion analysis.
    It was found that for similar initial conditions, constant pressure combustion and constant
    volume combustion exhibited similar trends. For constant temperature combustion, the trend is
    significantly different from the constant pressure and constant volume combustion, with almost
    the entire reactant availability being destroyed due to combustion at lower temperatures.
    Amongst the parameters examined, reactant mixture temperature had the most
    significant effect on the fraction of availability destroyed during combustion. The percentage
    availability destroyed reduced from 25 to 30% at 300 K to about 5% at 6000 K for constant
    pressure and constant volume combustion processes.
    The effect of the reactant mixture pressure on the fraction of availability destroyed was
    more modest. The values for the percentage availability destroyed for pressures ranging from 50
    kPa to 5000 kPa were found to lie within a range of 5%.
    The effect of equivalence ratio on the fraction of reactant mixture availability destroyed
    was also documented. In general, it was found that the destruction of availability decreased with
    increasing equivalence ratios. This value, however, accounts for the availability due to fuel like
    species in the product mixture. Therefore, for practical applications, combustion of the
    stoichiometric mixture would be preferred over the rich equivalence ratios.
    It was found that the fraction of reactant availability destroyed increased with increasing
    complexity of the fuel??s molecular structure.
    In addition, it was shown that the diffusion availability terms is small and may be
    neglected, while the reactive availability and thermo-mechanical availability are more significant.

publication date

  • August 2005