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.

One-dimensional discrete combustion waves in periodical and random systems

Abstract: The authors consider propagation of burn wave along a one-dimensional system of point heat sources connected by inert heat-conducting elements for periodical and disordered systems. Dependence of burn rate of such systems on burn temperature is determined. It is shown that under certain conditions a steady-state combustion mode in periodical systems becomes unstable and it is replaced by oscillatory modes, which consistently lose stability in the form of doubling period bifurcations. It is established that the burn rate of disordered system is many times less than the burn rate of a periodical system at identical average parameters. Results of modeling are compared with experimental data on combustion of thermite systems.

Breeding a better stove : the use of computational fluid dynamics and genetic algorithms to optimise a wood burning stove for Eritrea

Abstract: Improved cooking stoves can bring significant benefits to women and children in rural African situations, due to reduced fuel consumption and improved indoor air quality. This investigation focuses on the use of Computational Fluid Dynamics (CFD) and Genetic Algorithms (GAs) to optimise a stove for Eritrea. Initial work focussed on developing a model of wood combustion in a fixed bed. An experimental investigation was carried out on regular wood cribs to determine the burn rate and temperature field above a wood fire. The experimental data was used to develop a numerical model using CFD software Fluent 6.2 and user-defined functions for the fixed bed of fuel. The model assumed that pyrolysis was limited by heat transfer through the fuel, and that char combustion was limited by oxygen diffusion to the fuel surface. Simulation results yielded a mean and maximum error of 16% and 42% respectively in fuel burn rate. In the second phase of the investigation, the numerical model of wood combustion was used as part of a larger CFD model to capture the behaviour of a complete stove. The model was compared with experimental data for rocket type stoves with different geometries. The model correctly identified the trends of fuel burn rate and heat transfer in the experimental data, though agreement with experimental values was poor and the model exhibited significant errors when altering stove height and diameter. In the final phase of the investigation, the stove model was used in conjunction with a genetic algorithm to optimise the stove shape. Two methods of genetic coding were investigated. The resulting stove is expected to half fuel consumption compared to the classic mogogo stove, though this remains to be experimentally verified.

Solid propellant burning rate during a pressure transient

Abstract: It is well known that the burning rate of a solid propellant during a rapid pressure excursion is not given by the steady state relation, r = apn, but instead is generally a function of the pressure change rate, the pressure magnitude change, and properties of the propellant. An approximate but explicit relation for the non-steady burning rate as a function of these parameters is derived and compared with other treatments. Use of a current model for composite propellant combustion is made (Krier, et al., 1968). Discussion of the applicability of such explicit equations to predict burning extinction as a function of the pressure decay rate is also included.

A Study of Field Burning Under Varying Environmental Conditions

Abstract: A field study on grass field burning was conducted in the Willamette Valley of Oregon during the summer of 1965. Approximately 230,000 acres of grass fields are burned in the valley during August and September. Serious air pollution problems result from this burning. The purposes of the study were to determine the effect of environmental variables on grass field burning and to determine if conditions exist when significant air pollution reduction can be achieved. The environmental variables investigated were time from harvest to burning, time of day, air temperature, relative humidity, soil and straw moisture, wind speed and direction, and fuel density. The dependent variables measured were particulate emission and size distribution, combustion temperature, burn rate, amount of ash, percent of organics in the particulate, and smoke appearance. The results were analyzed statistically to determine the significant variables and their relationship.