$r_0$	outer diameter of the micro pin fin (mm)	$Re$	Reynolds number
$r_i$	inner diameter of the micro pin fin (mm)	$Nu$	Nusselt number
H	height of micro pin fins channel (mm)	t	time (s)
n	number of micro pin fins	D	equivalent diameter (m)
L	length of micro pin fins channel (mm)	V	volumetric flow rate (mL/min)
W	width of micro pin fin channel (mm)	$T_{in}$	the inlet temperature (°C)
$S_1$	horizontal spacing of micro pin fins (mm)	$T_{out}$	the outlet temperature (°C)
$S_2$	longitudinal spacing of micro pin fins (mm)	$T_{surf}$	the bottom temperature (°C)
$∆P$	pressure drop between inlet and outlet of micro pin fins channel (kPa)	$T_i$ (i = 1, 2, 3)	measuring hole temperature of microchannel (°C)
P	heating power of DC power supply (W)	A	cross-sectional area (m2)
$S$	heat transfer area (m2)	$u$	velocity of fluid (m/s)
$h$	the average heat transfer coefficient (W/(m2⋅K))	Subscript
		0	benchmark
$Q_{loss}$	heat loss (kW/m2)	min	minimum
		max	maximum