A radiative heat transfer model for cylindrical enclosure in which the gas and temperature are axi-symmetrically distributed was developed using the zone method of analysis. A rigorous numerical integration scheme was devised to calculate various types of direct exchange areas between different zones. The radiative heat transfer between gas zones and that between gas zones and surface zones could therefore be computed accurately based upon distributions of gas temperature and absorption coefficient.
This radiation model was used to compute the radiative heat transfer in a diesel engine combustion chamber. Extensive soot data obtained via a sampling valve were used to calculate the gas absorption coefficient. An attempt was also made to allow for the radiation from the non-luminous gases, i.e. carbon dioxide and water vapour. Temperature distribution was obtained from a multi-zone combustion model. Results showed that the radiative heat transfer to the combustion chamber walls was negligible during the early stage of combustion, but represented a significant part of the total heat transfer when it reached its peak value. The results also showed the importance of radiative heat transfer between the various gas zones in the combustion chamber.