- Author
-
Tzeng, L.
|
Atreya, A.
- Title
- Theoretical Investigation of Piloted Ignition of Wood.
- Coporate
- Michigan State Univ., East Lansing, MI
- Sponsor
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
-
NIST GCR 91-595,
August 1991,
230 p.
- Distribution
- Available from National Technical Information Service
- Contract
- NIST-GRANT-60NANB8D0861
- Keywords
-
diffusion flames
|
equations
|
pilot ignition
|
premixed flames
|
wood
- Abstract
- A theoretical model for piloted ignition of a flame in the gas phase above a vaporizing or pyrolyzing solid has been developed. Using this model it has been found that (i) The postulated simplified governing equations adequately explain the pre-ignition flashes that are often observed experimentally; (ii) A rational criterion for positioning the pilot flame exists; (iii) The heat losses to the surface play an important role, indicating that the fuel evolution rate by itself is insufficient for predicting the onset of piloted ignition. In this investigation, a numerical integration scheme is developed that accounts for the often vastly different rates between chemical reaction and convection or diffusion processes in the equations of combustion theory. This new numerical scheme is found to be very efficient for the piloted ignition problem, which involves both pre-mixed and diffusion flames. Finally, a numerical model for piloted ignition of wood which includes transient solid-phase decomposition has been developed. It has been found that the activation energy for the combustion of the evolved fuel is 49 Kcal/mole.