Effectiveness of MPCMS on Straight, Dimple-cavity & Rib-groove microchannel heat sinks – a comparative study

ABSTRACT

The novelty of microencapsulated phase change material slurry (MPCMS) in the microchannel is a proven technique for enhancing the heat transfer due to its combination of high latent heat transfer and surface area. In this experimental investigation, the paraffin is encapsulated with silica and titanium shells, and its thermal performance is compared with three different configurations like straight, dimple-cavity, and rib-groove microchannel heat sinks. The operating parameters are mass flow rate of 200–400 ml/min with Reynolds number (Re) 400–1350, heat flux of 10, 20, and 30 W/cm², and 1% and 2% of mass fraction (concentration of the MPCM in DI) with constant inlet sub-cooling 25°C. From the results, at Re. 780 and heat flux of 20 W/cm², the Nusselt number (Nu) shows an improved performance of 6.5% with Ti-1 in the straight channel configuration, when compared to plain DI. Further, Nu enhancement is up to 11.5% in the dimple-cavity and 26.9% in the rib-groove microchannel heat sinks under the same conditions. To clarify the effectiveness of MPCMS in three configurations, the measurement of COP is conducted. The results reveal that the heat transfer outweighs the required pumping power in all three configurations. Overall, the Rib-groove microchannel shows enhanced heat transfer of 131.6% than straight channel heat sinks and 47.85% higher than the dimple-cavity channel using Ti-1.

KEYWORDS:

• MPCM suspension
• Ribs-grooves
• cost of performance
• hydro-thermal performance

Disclosure statement

No potential conflict of interest was reported by the authors.

Nomenclature

Ti-1	=	Paraffin encapsulated with Titanium shell with a concentration of 1% in DI
Ti-2	=	Paraffin encapsulated with Titanium shell with a concentration of 2% in DI
Si-1	=	Paraffin encapsulated with Silica shell with a concentration of 1% in DI
Si-2	=	Paraffin encapsulated with silica shell with a concentration of 2% in DI
MPCM	=	Microencapsulated Phase Change material
Ab	=	Base area of heat sink (m2)
P	=	Pumping power (W)
∆P	=	Pressure drop (N/m2)
L	=	Length of microchannel heat sink (m)
W	=	Width of the channel(m)
Dh	=	Hydraulic diameter(m)
$q_{\mathit{eff}}$	=	Effective heat flux (W/m2)
N	=	No. of channel

Greek symbols

µ	=	dynamic viscosity (kg/m.s)
${\rho }_s$Density of slurry (kg/m3)	=

Abbreviation

Nu	=	Nusselt number
Re	=	Reynolds number
COP	=	Cost of performance
DI	=	De-ionized water