One-Dimensional Numerical Investigation of a Cylindrical Micro Combustor

In this paper, a one-dimensional numerical approach is used to study the effect of various parameters such as micro combustor diameter, mass flow rate and external convection heat transfer coefficient on the temperature and species mass fraction profiles. A premixed mixture of H2-Air with a multi-step chemistry (9 species and 19 reactions) is used and thermal conductivity of the mixture is considered as a function of species thermal conductivity and temperature by using a set of new relations. The transient gas phase energy and species conservation equations result in an Advection-Diffusion-Reaction system (A-D-R) that leads to two stiff systems of PDEs, which can not be solved by conventional Computational Fluid Dynamics (CFD) methods. In the present work, Strang splitting method, which is suitable for nonlinear stiff system of PDEs, is used. The results show that both convection heat transfer coefficient and micro combustor diameter have a significant effect on the combustion and heat transfer rates in the micro scales. Also, increasing the convective heat transfer coefficient and decreasing the diameter and inlet mixture velocity, decreases the temperature and active radicals along the micro combustor.