Browsing by Author "An, Qing"

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Citation Count: 0
The effect of initial temperature and oxygen ratio on air-methane catalytic combustion in a helical microchannel using molecular dynamics approach
(Elsevier, 2024) An, Qing; Salahshour, Soheıl; Alizadeh, As'ad; Al-Rubaye, Ameer H.; Jasim, Dheyaa J.; Tang, Miao; Sabetvand, Rozbeh
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 heli- cal microchannel. The LAMMPS package was used to conduct this investigation. This study exam- ines how simulated structures function during burning in excess oxygen (EO) and oxygen defi- ciency (OD). Furthermore, palladium was used as a catalyst with an atomic ratio of 4 %. The find- ings 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 angstrom/ps and 1617 K to 0.45 angstrom/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 %, respec- tively. 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 angstrom/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.
Citation Count: 0
The pool boiling heat transfer of ammonia/Fe 3 O 4 nano-refrigerant in the presence of external magnetic field and heat flux: A molecular dynamics approach
(Pergamon-elsevier Science Ltd, 2024) An, Qing; Salahshour, Soheıl; Alizadeh, As 'ad; Kamoon, Saeed S.; AL-Yasiri, Mortatha; Zhang, Mengyan; Hekmatifar, M.
Pool boiling is distinguished by its capacity to eliminate excessive heat fluxes (HFs) at low temperatures. In recent decades, the optimal design of flooded evaporators elevated the significance of pool boiling HT with refrigerant to conserve natural resources and energy. The industry highly regards this process on account of its superior heat transfer (HT) coefficient in comparison to other HT mechanisms. Among the types of boiling, pool boiling has a special place due to its ability to remove HFs at low temperatures. This study was the first to investigate the boiling characteristics of the ammonia/Fe 3 O 4 nano -refrigerant in a copper (Cu) nanochannel (NC) through molecular dynamics (MD) simulations. The primary goal was to investigate the effect of external HF (EHF) and external magnetic field amplitude (EMFA) on nanostructures ' atomic behavior (AB) and thermal behavior (TB). The research findings indicate that increasing the applied EHF led to increased particle movement and the HT rate. By changing the EHF, boiling behavior in the nano -refrigerant may also be seen. Maximum (Max) velocity (Vel.) increased to 8.970 & Aring;/ps when the EHF increases to 0.5 W/m 2 . Atomic collisions and particle mobility both increase when the EHF increases. Therefore, the maximum temperature value increases to 359.46 K. When the EMFA applied to the nano -refrigerant reaches to 0.5 T, the maximum values of the parameters, such as the Temp. and the velocity, reach to 410.07 K, and 11.802 & Aring;/ps, respectively.