Experimental and Numerical Analysis of Micro-Scale Heat Transfer using Carbon based Nanofluid in Microchannel for Enhanced Thermal Performance (original) (raw)
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Jurnal Teknologi, 2016
The microchannel heat sink (MCHS) has been established as an effective heat removal system in electronic chip packaging. With increasing power demand, research has advanced beyond the conventional coolants of air and water towards nanofluids with their enhanced heat transfer capabilities. This research had been carried out on the optimization of the thermal and hydrodynamic performance of a rectangular microchannel heat sink (MCHS) cooled with carbon nanotube (CNT) nanofluid, a coolant that has recently been discovered with improved thermal conductivity. Unlike the common nanofluids with spherical particles, nanotubes generally come in cylindrical structure characterized with different aspect ratios. A volume concentration of 0.1% of the CNT nanofluid is used here; the nanotubes have an average diameter and length of 9.2 nm and 1.5 mm respectively. The nanofluid has a density of 1800 kg/m3 with carbon purity 90% by weight having lignin as the surfactant. The approach used for the op...
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Concerns over the exponential increase in the heat produced per unit area in electronic chips have driven advanced research into the nanofluid capability as a coolant. Generally reported for its improved thermal conductivity in particular at higher concentrations, different types of surfactant normally added used to stabilize the nanofluid have reported different thermal resistance to heat flow. This paper reports an analysis of the thermal performance of a nanofuid-cooled microchannel heat sink (MCHS) with 0.1% volume fraction of CNT nanofluid utilizing two different surfactants; Lignin (N2) and sodium polycarboxylate (N3) as stabilizers. Multi-objective particle swarm optimization (MOPSO) algorithm was utilized to simultaneously minimize the thermal resistance and pumping power by optimizing the design parameters; the wall width and channel aspect ratios. Optimization outcomes showed that the thermal resistance of CNT nanofluids is lower than water by 1% at 20°C. Nanofluid with N3 has a significantly higher pressure drop than water, up to 47%. CNT nanofluid with N3 performed poorly due to the high viscosity which consequently results both in higher thermal resistance and pressure drop. Since a surfactant alters the properties of nanofluid, it could improve or deteriorate the performance of a MCHS overall and must not be taken lightly as a MCHS is expected to operate for a long time.
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The high heat flux dissipation rate is necessary for recent heat transfer equipment and electronics cooling systems. The highest heat transfer coefficient is achieved by integration of micro areal channels along with nanofluids. In this research we have done theoretical calculations with experimental analysis of straight microchannel with circular section with distilled water and carbon nanotubes nanofluid. The geometrical parameters are optimized in theoretical investigations and experimental analysis is carried out. The Reynolds number which is function of mass flow and heater input wattage is varied to investigate effect on heat transfer coefficient. The Reynolds number is varied from 450-750. The nanofluids containing carbon nanotubes in concentrated solution are varied from 0.01 to 0.1 % of distilled water for experimental analysis and we get enhanced performance results with less pressure rise in this concentration of nanofluid. The nanofluids are prepared with two steps metho...
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International Journal of Heat and Technology
This paper presents an experimental comparative thermal analysis of Multi Walled Carbon Nano Tubes (MWCNT) in rectangular minichannels. 0.01% volume concentration of MWCNT nanoparticles were suspended in water as base fluid to obtain MWCNT-water nanofluid. MWCNT nanoparticles do not readily get mix well with water, hence functionalization of these particles is carried out. Scanning Electron Microscopy (SEM) analysis is done for the functionalized MWCNT nanofluid. For 0.25lpm (liter per minute), 0.5lpm and 0.75lpm flow rates variation in Nusselt number (Nu), Convective heat transfer coefficient (h), friction factor, pressure drop and pumping power for MWCNT-water nanofluid is compared with water. For all the flow rates considered in present investigation, an increase in all the thermal performance parameters is observed. For 0.5lpm flow rate of nanofluid, the % enhancement in Convective heat transfer coefficient and actual heat transfer rate is 15.48 and 91.21 which is maximum compared to other flow rates considered in the present investigation.
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International Communications in Heat and Mass Transfer, 2013
In this paper, the thermal performance of a circular shaped copper microchannel heat sink using three types of nanofluids is discussed analytically. Al 2 O 3-Water, TiO 2-water and CuO-water nanofluids were used in this analysis and the comparative thermal performance of these three nanofluids is also discussed. The hydraulic diameter of the circular channel is 400 μm and the total block dimension is 10 mm×10 mm× 4 mm. A steady, laminar and incompressible flow with constant heat flux is assumed in the circular channel. The analyses are done at various volume fractions ranging from 0.5 vol.% to 4 vol.% and at a constant inlet velocity of 1.5 m/s. The results showed that the thermal performance can be increased significantly by using CuO-water nanofluid as a coolant for cooling of electronic heat sink when Al 2 O 3-water and TiO 2-water nanofluids showed less improvement. Compared to pure water, the highest improvement (13.15%) in the heat flux occurred for 4 vol.% CuO-water nanofluid when Al 2 O 3-water and TiO 2-water nanofluids showed 6.80% and 6.20% improvements respectively. This improvement in heat flux is calculated without considering the additional required pumping power due to the increased viscosity of nanofluids. Therefore, CuO-water nanofluid can be recommended to obtain maximum heat transfer performance in a circular microchannel heat sink.