The framework of theoretical method is two-fluid model coupled with reaction process. The k-ε model is used for gas phase, and the kinetic theory of granular flow is employed for solid phase. In the simulation, gasification process consists of three parts: pyrolysis, homogenous reaction, and heterogeneous reaction. In the first stage, biomass particles crack into carbon particles and volatile gases upon entering the reactor. Subsequently, the carbon particles and volatile gases react with oxygen, which includes both homogenous reaction and heterogeneous reaction. The effect of equivalence ratio (ER) is studied. It is found that all the products have same tendency with the increase of ER. H₂ and CH₄ change linearly with ER; CO and CO₂ change cubically with ER. This is because the mechanism of formation of CO and CO₂ is more complex than that of H₂ and CH₄. H₂ and CH₄ are consumed by O₂, so they tend to decrease with the increase of ER, whose value corresponds to the amount of O₂ fed. For CO and CO₂, however, things are more complicated: the extents at which CO and CO₂ decrease are converse. CO decreases significantly and then reaches a plateau and finally decreases again, while CO₂ decreases moderately at the beginning and then decreases sharply and finally becomes flat. The conclusion is that when oxygen concentration is low, increment of oxygen favors production of CO₂, and when oxygen concentration reaches a certain level, increment of oxygen favors production of CO, and when oxygen concentration continually increases, increment of oxygen favors production of CO₂ again.

Micro-channel heat sink (MCHS) has been extensively used in various electronic cooling fields. Double-layered MCHS, or DL-MCHS, is regarded as one effective technique for high-heat-flux transfer and is expected to meet the ever-increasing heat load requirement of future electronic device generations. In order to improve the cooling capacity, two new types of the MCHS, with a double-layered matrix structure (DL-M) and double-layered interlinked matrix structure (DL-IM) are proposed and investigated numerically. The two designs are compared with the traditional double-layered rectangular structure (DL-R) and the double-layered triangular structure (DL-T). Different properties of the heat sink are investigated to assess the overall heat transfer performance, for which coolant flow and heat transfer are both evaluated. The numerical results reveal that the periodical slot subchannel in the matrix has a significant effect on fluid flow for heat transfer. In comparison to the DL-R and the DL-T, the DL-M and DL-IM realize a much lower pressure drop and temperature rise at the base surface and also have higher Nusselt number and secondary flow intensity, therefore, manifesting better overall thermal performance. In the DL-M and DL-IM, the coolant flows along the periodical subchannel in one layer and is redirected into the second layer with vortices being induced. The vortices promote the coolant mixing and enhance the mass and heat transfer. These geometric design strategies can provide references for wide heat sink applications.