$A_1$	Area of the quadrilateral volume (${\mathrm{m}}^2$)
$A_{k_0}$	The area of $k_0$ material of the quadrilateral volume (${\mathrm{m}}^2$)
$A_{k_{\mathrm{c}}}$	The area of $k_c$ material of the quadrilateral volume (${\mathrm{m}}^2$)
$D_0$	Width of branching links ($\mathrm{m}$)
$D_1$	Width of the central link ($\mathrm{m}$)
$H_1$	Half-height of quadrilateral volume ($\mathrm{m}$)
$k_0$	Thermal conductivity of heat generation body ($\mathrm{W}/\mathrm{m}·\mathrm{K}$)
$k_c$	Thermal conductivity of high thermal conductivity channel ($\mathrm{W}/\mathrm{m}·\mathrm{K}$)
$L_1$	Base length of quadrilateral volume ($\mathrm{m}$)
$M_i$	Starting point of $i$th branching link (-)
$n$	Number of branches of the central high thermal conductivity material (-)
$q^{‴}$	Heat generation rate per unit volume (${\mathrm{W}/\mathrm{m}}^3$)
$T$	Temperature ($\mathrm{K}$)
$w_i$	Length of $i$th branching link ($\mathrm{m}$)
$F_{\mathrm{ST}}$	Complex function
$a_0$	Weighting coefficient
Greek symbols
$\alpha$	Porosity of thermal conductivity channel (-)
$\theta$	Angle defined in Figure 1 ($\mathrm{rad}$)
${\delta }_i$	Height of $i$th branching link ($\mathrm{m}$)
$\sigma$	Entropy generation rate ($\mathrm{W}/\mathrm{m}\text{·}\mathrm{K}$)
Superscript
$~$	Dimensionless
Subscripts
$i$	Counting index
$\mathrm{opt}$	Optimum
$\min$	Minimum
Abbreviations
HGB	Heat generation body
HTCC	High thermal conductivity channel
MTD	Maximum temperature difference
EGR	Entropy generation rate
MOO	Multi-objective optimization
PPC	Pumping power consumption