The effect of initial temperature and oxygen ratio on air-methane catalytic combustion in a helical microchannel using molecular dynamics approach

In industrial environments where combustion (Com.) is widely carried out, such as steam power plants, gas turbines, etc., the most common way to express the amount of oxygen consumption is its excess percentage in addition to the stoichiometric ratio, and the nearness of a catalyst causes combustion to happen at a high ratio. There are different influential factors in catalytic combustion, such as initial temperature (IT). The current study uses the molecular dynamics (MD) method to examine how the IT and oxygen ratio affect air-methane catalytic combustion in a helical microchannel. The LAMMPS package was used to conduct this investigation. This study examines how simulated structures function during burning in excess oxygen (EO) and oxygen deficiency (OD). Furthermore, palladium was used as a catalyst with an atomic ratio of 4 %. The findings show that raising the IT may enhance its atomic behavior (AB) and thermal performance (TP). The maximum velocity (MV) and maximum temperature (MT) increased from 0.26 Å/ps and 1617 K to 0.45 Å/ps and 1891 K in EO as IT increased from 300 to 700 K. By accelerating the particle velocity, it is anticipated that the catalytic combustion process would proceed more quickly. As a result, after increasing the IT to 700 K, the heat flux (HF), thermal conductivity (TC), and combustion efficiency (CE) increase to 2101 W/m2, 1.23 W/m. K, and 93 %, respectively. On the other hand, the results show that increasing IT affects combustion performance in the presence of OD. In the presence of OD, the MV and CE converge to 0.38 Å/ps and 94 % at 700 K. Therefore. It can be concluded that the atomic ratio of oxygen and the IT can significantly affect combustion process

Changes in mechanical properties of copper-silver matrix welded by the iron blade by increasing initial pressure: A molecular dynamics approach

Atomic investigation of many common phenomena can be included as interesting achievements. Using these achievements makes it possible to design promising structures for various actual applications. The current research describes the mechanical performance of Ag and Cu samples after welding at various initial pressures. For this purpose, the Molecular Dynamics (MD) approach is used via the LAMMPS package. Technically, MD simulations are done in 2 main steps. Firstly, the atomic stability of welded Ag-Cu samples is described at various initial conditions (initial pressure). Then, tension test settings are implemented in equilibrated systems. The MD outputs indicate that the physical stability of the welded samples was altered by changing the initial pressure between 1 and 10 bar. Simulation results predict that the mechanical resistance of atomic samples decreases by enlarging the initial pressure. Numerically, the ultimate strength of the Ag-Cu matrixes decreases from 1.424 MPa to 1.241 MPa by increasing the initial pressure from 1 bar to 10 bar, respectively. This mechanical performance arises from atomic disorder created inside samples. So, it is expected that initial condition changes affect the atomic evolution of welded metallic samples, and this phenomenon should be considered in the design of mechanical structures in industrial cases