Purpose

The widespread usage of magnetic nanoparticles (MNPs) requires their efficient synthesis during combustion process. This study aims to present a mathematical model for the oxidation of MNPs in a counter-flow non-premixed combustion system to produce MNPs, where the key sub-processes during the oxidation reaction are involved.

Design/methodology/approach

To accurately describe structure of flame and determine distributions of temperature and mass fractions of both reactants and products, equations of energy and mass conservations were solved based on the prevailing assumptions that three regions, i.e. preheating, reaction and oxidizer zones exist.

Findings

The numerical simulation was first validated against experimental data and characteristics of the combustion process are discussed. Eventually, the influences of crucial parameters such as reactant Lewis numbers, strain rate ratio, particle size, inert gas and thermophoretic force on structure of flame and combustion behavior were examined. The results show that maximum flame temperature can achieve 2,205 K. Replacing nitrogen with argon and helium as carrier gases can increase flame temperature by about 27% and 34%, respectively. Additionally, maximum absolute thermophoretic force was found at approximately 9.6 × 10–8 N.

Originality/value

To the best of authors’ knowledge, this is the first time to numerically model the preparation of MNPs in a counter-flow non-premixed combustion configuration, which can guide large-scale experimental work in a more effective way.

中文翻译：

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用于生物医学应用的逆流非预混燃烧生产磁性纳米颗粒的数学建模

目的

磁性纳米粒子 (MNP) 的广泛使用需要它们在燃烧过程中的有效合成。本研究旨在提出在逆流非预混燃烧系统中氧化 MNP 以产生 MNP 的数学模型，其中涉及氧化反应过程中的关键子过程。

设计/方法/方法

为了准确描述火焰的结构并确定反应物和产物的温度和质量分数的分布，基于三个区域，即预热区、反应区和氧化剂区存在的普遍假设，求解能量和质量守恒方程。

发现

数值模拟首先根据实验数据进行验证，并讨论了燃烧过程的特性。最后，研究了反应物路易斯数、应变率比、粒径、惰性气体和热泳力等关键参数对火焰结构和燃烧行为的影响。结果表明，最高火焰温度可以达到2205K。用氩气和氦气作为载气代替氮气可以分别使火焰温度提高约27%和34%。此外，发现最大绝对热泳力约为 9.6 × 10-8 N。

原创性/价值

据作者所知，这是第一次对逆流非预混燃烧配置中 MNP 的制备进行数值模拟，可以更有效地指导大规模实验工作。