Thermal management of mini channel slotted fin heat sink using TiO₂-H₂O blend of anatase and rutile nanoparticles: experimental and numerical study

ABSTRACT

High processing demand has started high heat generation problems inside compact electronic components. In this work, firstly the thermal performance was investigated experimentally for the mini channel having slots on straight rectangular fin heat sink. Slots were made which reinitialize the thermal boundary layer at each slot position. This effect makes the flow again in a developing state and helps in a better mixing of the flow inside the channel due to the presence of vortexes because of slots, which overall results in better heat transfer. The thermal performance of the slotted fin heat sink was compared to the straight rectangular fin heat sink. Secondly, TiO₂-pure water (0.005% and 0.01%) which was the blend of Anatase and Rutile crystalline-shaped nanoparticles were used both numerically and experimentally. The base temperature was reduced 8.2% using pure water at 1LPM when compared with the straight rectangular fin heat sink reported in the literature. The lowest base temperature recorded for the slotted fin heat sink was found to be 40.25°C using TiO₂-pure water (0.01%) nanofluids at 1 LPM. The reduction in base temperature observed for TiO₂ -H₂O (0.005%) and TiO₂-pure water (0.01%) was 8.8% and 11%, respectively, as compared to pure water. Experimental results were numerically validated with good agreement.

KEYWORDS:

• Mini channel
• slotted fin heat sink
• TiO2-pure water
• Rutile and Anatase mixture
• Thermal management

Disclosure statement

No potential conflict of interest was reported by the authors.

Nomenclature

w_s	=	heat sink width in mm
l_s	=	heat sink length in mm
l_f	=	fin length in mm
t_f	=	Fin thickness in mm
S_t	=	Thickness of slot in mm
h_b	=	Heat sink base height in mm
h_f	=	Fin height in mm
h	=	height of nozzle from base in mm
H	=	collective height in mm
l_c	=	Chip length in mm
t_c	=	Chip thickness in mm
l_t	=	Overall length in mm
f_s	=	spacing between fins in mm
C_nf	=	Specific heat for nanofluids in kJ/kgK
C_np	=	Specific heat for nanoparticles in kJ/kgK
C_bf	=	Specific heat of base fluid in kJ/kgK
$K_{\mathrm{\_}nf}$	=	Nanofluids thermal conductivity in W/mK
$K{\mathrm{\_}}_{np}$	=	Nanoparticles Thermal conductivity in W/mK
$K_{\mathrm{\_}bf}$	=	Base fluid Thermal conductivity in W/mK
L.M.T.D	=	Log of mean temperature difference in 0C
L.P.M	=	Liters per minute
ṁ	=	Mass flow rate in kg/s
Q	=	Heat transfer rate in W
Q	=	Volumetric flow rate in LPM
R_th	=	Thermal resistance in 0C/W
T_b	=	Temperature at base in 0C
T_i	=	Inlet Temperature in 0C
T_o	=	Outlet Temperature in 0C
W_np	=	Nanoparticles weight fraction
W_bf	=	Base fluid weight fraction
∅	=	Volume fraction
p_bf	=	Base fluid density in kg/m3
p_np	=	Nanoparticles density in kg/m3
p_nf	=	Nanofluids density in kg/m3
$\mu \mathrm{\_}nf$	=	Dynamic viscosity of nanofluids in kg/ms
$\mu \mathrm{\_}bf$	=	Dynamic viscosity of base fluid in kg/ms
$\rho \mathrm{\_}m$	=	Density of mixture in kg/m3
V_m	=	Velocity of mixture in m/s
$\mu$ _m	=	mixture viscosity in kg/ms
Re_P	=	Reynolds number for primary phase
K_t	=	Thermal conductivity for turbulent phase in W/mK
H_K	=	Enthalpy for K-phase in kJ/kg
K_m	=	Thermal conductivity for k-phase in W/mK
$\phi$_np	=	nanoparticle volumetric concentration
$\phi$_k	=	volumetric concentration for k-phase
${\stackrel{\text{scriptscriptstylerightharpoonup}}{V}}_p$	=	velocity for secondary phase in m/s
${\stackrel{\text{scriptscriptstylerightharpoonup}}{V}}_f$	=	velocity for primary phase in m/s
${\stackrel{\text{scriptscriptstylerightharpoonup}}{V}}_{dr,k}$	=	drift velocity for k-phase in m/s