Numerical Simulations on Combustion and Heat Transfer in Porous Medium with Different Gyroid Triply Periodic Minimal Surfaces Structures

ABSTRACT

To investigate the influence of the porous medium with Triply Periodic Minimal Surfaces (TPMS) structures on lower concentration methane combustion. This study analyzed the flow field and heat transfer in the porous medium with three types, i.e. an axial gradual period type, a conical type and a uniform type, through the pore-scale simulation (PSS) approach. In cases of this study, the flashback equivalence ratio of the conical PMB is about 12.5% lower than that of the gradient PMB at the same inlet flow velocity, and the blow-off inlet flow velocity of the conical PMB is about 30% higher than that of the gradient PMB at the same equivalence ratio. Moreover, the flame shape is closely related to the local solid structure and flow velocity. The solid surfaces radiation heat transfer occurred mainly in regions with high solid temperature gradients. Additionally, the absolute value of the radiant heat flux is about 1/4 to 1/5 of the total heat flux, which reflects the proportion of thermal convection in the heat transfer on the solid surface. Convective heat transfer between solid and fluid occurred mainly in the areas of heat recuperation known as preheat zone, and higher inlet flow rates significantly increase the upstream convective heat transfer intensity.

KEYWORDS:

• Pore-scale simulation
• porous medium combustion
• triply periodic minimal surfaces
• solid surface radiation
• heat recuperation

Nomenclature

L	=	unite cell length
dpore	=	pore size
t	=	wall thickness of sheet-based TPMS structures
m	=	fitting constant
c	=	thickness control factor
p	=	static pressure
h	=	enthalpy [J/kmol]
k	=	thermal conductivity [W/m K]
T	=	temperature [K]
$\overrightarrow{J_i}$	=	diffusion flux
M	=	molecular mass
R	=	volume creation rate
Y	=	partial mass friction
$D_{i,m}$	=	mass diffusion coefficient
pop	=	local relative pressure field
Mw	=	molecular weight
$F_{kj}$	=	fraction of energy leaving k surface that is incident on surface j.
Ai	=	The facet area
A	=	total area of the surface
n	=	total number of the faces in the surface
Greek symbols	=
Ωi	=	region of i
Γf,in	=	fluid inlet
Γf,out	=	fluid outlet
Γf,side	=	fluid boundary
Γint	=	fluid and solid interface
ρ	=	density (kg/m3)
ω	=	period control factor
${\epsilon }_k$	=	emissivity
$\sigma$	=	Stefan-Boltzmann constant
$\phi$	=	porosity
${\alpha }_i$	=	the local value in the facet
Subscripts	=
i	=	component serial number
g	=	gas components
s	=	solid components
f	=	fluid components
in	=	inlet
out	=	outlet
w	=	burner wall

Acknowledgements

Financial supports from the National Natural Science Foundation of China (No. 52174214 & No. 51974303), Key R&D Program of Jiangsu Province (Grant No. BE2020645), the Fundamental Research Funds for the Central Universities (Grant No. 2020ZDPY0202, No. 2021GJZPY11 & No. 2021YCPY0207) are sincerely acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Financial supports from the National Natural Science Foundation of China (No. 52174214 & No. 51974303), the Fundamental Research Funds for the Central Universities (Grant No. 2020ZDPY0202, No. 2021GJZPY11 & No. 2021YCPY0207) are sincerely acknowledged.