CFD simulation and experimental study of calcium carbide heat transfer under natural convection and radiation heat transfer

ABSTRACT

Few studies on the heat transfer of calcium carbide (CA) under natural convection exist currently. Studying the radiative heat transfer of CA is of significant importance for its waste heat utilization. Therefore, this paper, based on CFD simulations, investigates the heat transfer processes of CA under natural convection and radiative heat transfer. Additionally, on-site experiments are conducted to measure the temperature of CA. The results indicate that considering radiation, the maximum discrepancy between simulation and experimentation is 11.9%, while without considering radiation, the maximum discrepancy increases to 85%. Based on the temperature variations on the surface of CA and changes in cooling rates, it is inferred that waste heat recovery should occur within the first three hours after the CA is taken out of the furnace. Within the initial six hours, the convective and radiative heat transfer amounts are 17.1 kW•h and 155.67 kW•h, respectively, with the latter constituting 90.11% of the total heat exchange. Therefore, adopting a radiation-based approach is recommended for the recovery of waste heat from CA. Finally, employing data regression analysis, a functional relationship between the natural convection-radiation coupled heat transfer coefficient and time is derived.

KEYWORDS:

• Calcium carbide
• CFD simulation
• natural convection, radiation
• solidification

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Nomenclature

d	=	hydraulic length，m
F	=	shape factor
c	=	specific heat，J/kg*K
$\mathit{g}$	=	acceleration of gravity，m/s2
h	=	convection heat transfer coefficient，W/m2·K
$\bar{\mathrm{h}}$	=	coupling heat transfer coefficient, W/(m2·K)
P	=	pressure，Pa
Q	=	heat exchange, J
t	=	time，s
T	=	temperature，K
u	=	velocity in x-direction，m/s
w	=	velocity in z-direction，m/s
x	=	x-direction，m
z	=	z-direction，m
Greek symbols	=
$\mathit{\epsilon }$	=	emissivity of the surface
$\mathit{\rho }$	=	density，kg/m3
$\mathit{\alpha }$	=	thermal diffusivity，m2/s
$\mathit{\beta }$	=	volumetric thermal expansion coefficient，K−1
$\mathit{\mu }$	=	dynamic viscosity，N*s/m2
$\mathit{\sigma }$	=	Stefan-Boltzmann constant，W/(m2·K4)
$\mathit{\lambda }$	=	thermal conductivity，W/m·K
Subscripts	=
air	=	air
cap	=	pot of calcium carbide
L	=	length
r	=	reference
ra	=	radiation
ca	=	calcium carbide
f	=	fluid
s	=	solid
Dimensionless parameters	=
$\mathit{Nu}$	=	Nusselt number

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.

Notes on contributors

Ping Tao

Ping Tao, male, with a master’s degree.

Xichao Di

Xichao Di, male, with a master’s degree.

Meihui Zhou

Meihui Zhou, female, with a master’s degree.

Jianqiu Zhou

Jianqiu Zhou, male, professor at Nanjing Tech University.