Burn rate (chemistry)

About: Burn rate (chemistry) is a research topic. Over the lifetime, 847 publications have been published within this topic receiving 8908 citations. The topic is also known as: Burning rate.

Methods Of Controlling An Internal Combustion Engine Including Multiple Fuels And Multiple Injectors

Abstract: A method for controlling the start of combustion and peak burn rate of an internal combustion engine system on a cycle-to-cycle basis including multiple direct fuel injectors, multiple indirect fuel injectors, and multiple liquid fuels. The actual start of combustion and actual peak burn rate are calculated using in-cylinder pressure or ionization. A predetermined start of combustion and a predetermined peak burn rate are selected. The start of combustion and peak burn rate control algorithm includes controlling a fuel ratio, an injection ratio, and a residual gas recirculation ratio. A predetermined fuel ratio, a predetermined injection ratio, and a predetermined residual gas recirculation are calculated by combining feed forward ratios and closed loop control ratios corresponding to the three ratios. The predetermined ratios are employed so that the system achieves the predetermined start of combustion and predetermined peak burn rate.

Analysis of compressed natural gas burn rate and flame propagation on a sub-compact vehicle engine

Abstract: In terms of sub-compact cars using alternative fuels, the vehicle characteristics are governed by the engine operation. The main focus of this paper was to evaluate a subcompact car engine on its performance and burn rate of gasoline and compressed natural gas (CNG) . A bi-fuel sequential system was used for this evaluation. Measurements of engine speed, torque and fuel were done on an eddy current dynamometer, while measurements of in-cylinder pressure, crank angle and spark were analyzed from results taken by a data acquisition system. The emissions readings were also compared using an emission analyzer. The results were analyzed for burn rate based on the first law of thermodynamics. A 3-dimensional computational fluid dynamics (CFD) model was done to estimate the flame speed. The comparison shows an average drop of 18.6% for the power, 7% for brake specific fuel consumption (BSFC) and the efficiency loss was 17.3%. Pressure analysis shows peak pressure dropped by 16%. The burn rate shows why CNG had a slower burning speed on the small engine. CFD predicted the flame propagation speed at 8.45 m/s. The engine speed of 4000 rpm at maximum brake torque produced the results nearest to those for gasoline. In conclusion, volumetric losses and CFD errors slightly reduce the accuracy of the results, but nevertheless an 8.45 m/s flame speed was estimated.

Improvements to RDX combustion modeling

Abstract: Many improvements have been made to models of RDX combustion in the past few years. The onedimensional model presented in this paper, models the solid, two-phase, and gas regions using complex kinetics and concentration and temperature dependent thermophysical properties. Calculated values agree well with experimentally determined burn rate, ap, melt layer thickness, surface temperature and species concentration profiles. When including laser-assisted burning in the model, a dark zone appeared similar to that seen experimentally. With the laser assisted case, the chemistry controlling the burn rate is significantly different from cases without the laser heat flux. Calculations show that the melt layer thickness is determined primarily by the liquid thermal conductivity and the surface temperature is controlled by the vapor pressure correlation. All other model predictions are relatively insensitive to these parameters. The weakest areas of the model remain the condensed phase decomposition and evaporation/condensation sub-model. Nomenclature A = area (cm) A = pre-exponential rate constant c = heat capacity (erg/g K) C = molar concentration (moles/cm-*) Ea = activation energy (cal/mole) H = molar enthalpy (erg/mole) h = specific enthalpy (erg/g) kk = number of gas phase species rh = mass flow rate (g/s) n = number of bubbles per volume 1 e 13 bubbles/cm^ p = pressure q = rate of progress variable (moles/cm s) rb = burn rate (cm/s) R = universal gas constant s = sticking factor T = temperature (K) u = gas velocity (cm/sec) V = diffusion velocity (cm/sec) W = average molecular weight (g/mole) W = molecular weight (g/mole) W = molar rate of production (moles/cm s) x = distance from 2-phase-gas interface (cm) X = mole fraction Y = mass fraction P = temperature exponent rate constant