A Reactive Molecular Dynamics Investigation of Nanoparticle Interactions in Hydrocarbon Combustion

Figures & data

Table 1. Simulation details.

NVT ensemble simulations			NVE ensemble simulations
Particle	Gas	$T$ (K)	Particle	Gas	$T_{\mathrm{p}\mathrm{a}\mathrm{r}\mathrm{t}\mathrm{i}\mathrm{c}\mathrm{l}\mathrm{e}}$ (K)	$T_{\mathrm{g}\mathrm{a}\mathrm{s}}$ (K)
AlNP or FeNP	O2	300	AlNP	n-C7H16/O2	500	1000
FeNP	n-C7H16/O2	1800	AlNP or FeNP	n-C7H16/O2	500	2000
–	n-C7H16/O2	1800 & 2800	AlNP or FeNP	n-C7H16/O2	1000	1000
			–	n-C7H16/O2	–	1000

Figure 1. Initial domain configurations for (a)–(b) NVT simulations and (c) NVE simulations. CPK coloring is used to distinguish different chemical elements: Fe atoms are in orange; C atoms are in gray; O atoms are in red; H atoms are in white colour.

Figure 2. Time evolution of consumed O₂ (number of molecules) and Potential Energy (PE) during AlNP and FeNP oxidation without hydrocarbon fuel using QEq and QTPIE charge equilibration methods.

Figure 3. Reactant consumption in the presence and absence of nanoparticles using QEq and QTPIE methods. AlNP and FeNP simulations are conducted at $T=1800$ K; gas-only simulations were performed at $T=2800$ K. The number fraction of each molecule corresponds to their number in each timeframe divided by the respective initial number.

Table 2. Atomic charges of AlNP and FeNP computed with the QEq and QTPIE method at the beginning and end of the simulated time for a nanoparticle-oxygen system without hydrocarbon fuel. Charges are given in multiples of electron charge.

		AlNP/O2 system						FeNP/O2 system
		QEq method			QTPIE method			QEq method			QTPIE method
Time	Element	Ave.	Min.	Max.	Ave.	Min.	Max.	Ave.	Min.	Max.	Ave.	Min.	Max.
0 ps	O gas phase	−0.08	−0.23	−0.02	0.0	−0.01	0.0	−0.06	−0.18	0.01	0.0	−0.04	0.02
	NP atoms	0.06	−0.03	0.23	0.0	0.0	0.0	0.03	0.0	0.12	0.0	0.0	0.01
500 ps	O gas phase	−0.23	−0.23	−0.23	0.01	0.0	0.06	−0.16	−0.16	−0.16	0.02	0.0	0.06
	O absorbed	−0.98	−1.31	−0.21	−0.2	−0.97	0.13	−0.53	−0.88	−0.21	−0.26	−0.67	0.04
	NP atoms	0.7	−0.08	1.29	0.08	−0.15	1.02	0.25	−0.03	0.56	0.08	−0.05	0.48

Figure 4. Dissociation reaction of n-heptane molecules at a FeNP surface. The n-C₇H₁₆ dissociation is initiated by dehydrogenation. Colours indicate the atomic charges.

Figure 5. Temperature evolution for various systems comprising FeNP and AlNP.

Figure 6. Potential energy and n-heptane/oxygen consumption for systems containing AlNP and FeNP. Results are presented for cases with initial nanoparticle and gas temperatures equal to 1000 K. The number fraction of each molecule corresponds to their number in each timeframe divided by the respective initial number.

Figure 7. Dominant intermediate species for the systems with AlNP (left) and FeNP (right). Results are presented for cases with initial nanoparticle and gas temperatures equal to 1000 K.