Characteristics of the heat release in three-dimensional, highly porous reactors under engine-like conditions in comparison with free diesel injection conditions

Abstract

An innovative engine concept with fuel injection and combustion in a three-dimensional porous combustion reactor allows realization of very clean and efficient combustion. In this paper the combustion process as realized in a free-volume combustion chamber and in porous combustion reactors was analysed under diesel-engine-like conditions. A special combustion chamber allows simulations of engine conditions corresponding to the moment when diesel injection begins (the initial conditions). There are characteristic features (modes) of a heat release process that was defined in a two-dimensional and three-dimensional field of the initial pressure and temperature. The characteristic modes of the heat release process in a free-volume chamber were analysed and compared with the process occurring in highly porous three-dimensional combustion reactors. These combustion modes depend on the reactor parameters, especially on its heat capacity, pore structure and density. The combustion in the reactor occurs at a reduced temperature; however, a qualitative similarity of the heat release process to that in a free-volume combustion chamber was proven. Furthermore, a limitation of the reaction rate at high initial temperatures and pressures was recognized in the case of porous reactors. This indicates the applicability of this combustion technology to internal-combustion engines even at high loads and has the favourable effect of a lower combustion noise.