Energy and Exergy Viability Analysis of Nanofluids As A Coolant for Microchannel Heat Sink (original) (raw)
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Transdisciplinary Journal of Engineering & Science
Energy is one of the primary foundations supporting evolutionary changes. Heat transfer is improved by increasing the surface area density and/or changing the base fluid characteristics. Because of its small size and improved heat transfer properties, nanofluid cooled microchannel heat sinks (MCHS) have lately become a popular choice for electronics and thermal applications. The influence of employing nanofluids for cooling a chip was investigated experimentally in this work to evaluate the heat transfer characteristics. The investigations were carried out in order to confirm the influence of nanofluid concentration and wall temperature upon thermal-hydraulic properties of the microchannel heat sink. In present study, Al2O3 water nanofluid was employed, with 0.1, 0.2, 0.3, 0.4, and 0.5% nanoparticle volume fractions, mass flow rate (MFL) 2, 5, and 8 m/s at 25, 30 and 35oC inlet tempreture. The resulting experimental findings was verified from results obtained by other researchers, w...
Optimization of nanofluid-cooled microchannel heat sink
Thermal Science, 2013
The optimization of a nanofluid-cooled rectangular microchannel heat sink is reported. Two nanofluids with volume fraction of 1 %, 3 %, 5 %, 7 % and 9 % are employed to enhance the overall performance of the system. An optimization scheme is applied consisting of a systematic thermal resistance model as an analysis method and the elitist non-dominated sorting genetic algorithm (NSGA-II). The optimized results showed that the increase in the particles volume fraction results in a decrease in the total thermal resistance and an increase in the pumping power. For volume fractions of 1 %, 3 %, 5 %, 7 % and 9 %, the thermal resistances were 0.072, 0.07151, 0.07075, 0.07024 and 0.070 [ o K W -1 ] for the SiC-H 2 O while, they were 0.0705, 0.0697, 0.0694, 0.0692 and 0.069 [ o K W -1 ] for the TiO 2 -H 2 O. The associated pumping power were 0.633, 0.638, 0.704, 0.757 and 0.807 [W] for the SiC-H 2 O while they were 0. 645, 0.675, 0.724, 0.755 and 0.798 [W] for the TiO 2 -H 2 O. In addition, for the same operating conditions, the nanofluid-cooled system outperformed the water-cooled system in terms of the total thermal resistance (0.069 and 0.11 for nanofluid-cooled and water-cooled systems, respectively). Based on the results observed in this study, nanofluids should be considered as the future coolant for electronic devices cooling systems.
An Experimental Study on Thermal Performance of Nano Fluids in Microchannel Heat Exchanger
The enhancement of heat transfer performance in heat exchanger is achieved by reducing the size of the hydraulic diameter or by using a working fluid that has a better thermal conductivity compared to conventional working fluids. The application of a small hydraulic diameter can be found in the microchannel heat exchanger (MCHE). The design and the testing of the MCHE were done in this research. The MCHE was tested with several working fluids, such as the distilled water, the Al 2 O 3 -water nanofluids at 1%, 3% and 5% volume concentration, and the SnO 2 -water nanofluids at 1% volume concentration. The temperature of inlet and outlet were set at 50 o C and 25 o C, respectively. The variations of flow rate at the inlet were applied from 100 ml/min up to 300 ml/min. The addition of nanoparticle in the base fluid was proven to improve the heat transfer of the MCHE, the 5% Al 2 O 3 -water and 1% SnO 2 -water nanofluids are able to absorb the heat 9% and 12% higher than the base fluid. The overall heat transfer coefficient of MCHE with 5% Al 2 O 3 -water and 1% SnO 2 -water nanofluids were 13% and 14% higher than the base fluid.
Performance Analysis of Electronics Cooling using Nanofluids in Microchannel Heat Sink
International Journal of Engineering and Technology, 2016
Performance analysis of thermal enhancement for cooled microchannel heat sink (MCHS) using nanofluidsmathematical formulation was investigated and presented in this paper. Heat transfer capability in terms of thermal conductivity, heat transfer coefficient, thermal resistance, heat flux and required pumping power were evaluated on the effectiveness of copper oxide (CuO), silicon dioxide (SiO 2) and titanium dioxide (TiO 2) with water as a base fluid. The results showed that thermal performance augmented by 12.2% in thermal conductivity at particle volume fraction of 4% to CuO-water nanofluid, 11.8% for SiO 2-water and 10.0% for TiO 2-water. The maximum heat transfer coefficient enhances of 12.4% for CuO, SiO 2 is 8.22% and 7.4% for TiO 2 with the same inlet velocity of 3 m/s. The addition of nanoparticle concentration significantly enhances the heat transfer, but elevates the expenses of higher required pumping power to increase the pressure drop. The maximum enhancement of heat flux in CuOwater was found to be 2575 kW/m 2 , 2501 kW/m 2 for SiO 2-water and 2485 kW/m 2 for TiO 2-water nanofluid at 4% of volume fraction. The pressure drop is increased with the mass flow rate of 1021 kg/m3 for CuO-water at 0.5% of volume fraction and 47925 Pa to 54314 Pa pressure drop at 4% of volume fraction. The CuO-water pumping power was found to be the highest at 4% of volume fraction with 102.3 W at 3 m/s inlet velocity compared to SiO 2 and TiO 2 also increased the pumping power of 75.0 W to 90.6 W with increasing volume fraction and pressure drop. The positive thermal results implied that CuOnanofluid is a potential candidate for future applications in MCHS.Further analysis is recommended to be done with various Reynolds number, pumping power and flow rate of nanoparticles to obtain better heat transfer performance of cooling fluids.
Analysis of thermal characteristics of nanofluid Enriched Microchannel Heat Sink
2016
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...
Study of microchannel heat sink performance with expanded microchannels and nanofluids
2016
In this paper a microchannel heat sink with expanded microchannels and nanofluids is numerically investigated. The object of this paper is to study and improve the cooling performance of microchannel heat sink. Both the geometrical parameters and working fluids were studied and a comparison was made between them. Expanded microchannels (sudden expanded and diverging) were used instead of straight microchannels, also micro pin fins with square and triangular shapes were used for heat transfer enhancement. Sudden expanded microchannels were studied with different expansion ratios and expansion lengths. Three types of nanofluids (Cu-water, Al 2 O 3-water and Diamond-water) with volume concentration (1 – 5) % were studied as working fluids and their effects on overall performance of heat sink were compared with pure water. The results obtained shows that the overall performance of microchannel heat sink increased with increasing the expansion ratio or decreasing the expansion length. For the same expansion ratio the sudden expanded microchannels gives higher modification compared with diverging microchannels. Also using of nanofluids lead to enhance the heat transfer and the improvement got by geometric parameters such as using of expanded microchannels or fins is much larger than that obtained by using nanofluids for the same heat sink.
International Journal of Thermal Sciences, 2014
The energy efficiency of geothermal heat exchanger (GHE) systems can be significantly impacted by the thermal performance of heat transfer fluid inside. In the present study, nanofluid (CuO/water) was experimentally used in the GHE to investigate its thermal performance as circuit fluid. The main part of experimental system consisted of a 0.8 m  0.5 m  0.58 m box, two double U-tubes, thermocouples and thermal resistors. A three-dimensional discrete phase model was built to simulate the flow process. By using nanofluid, the heat transfer rate and pumping power consumption of the GHE system increased by 39.84% and 16.75%. Moreover, the heat load-to-pumping power ratio had an enhancement of 20.2%. Furthermore, the previous literature showed that the nanofluids, which had a significant effect on the heat transfer of other types of heat exchangers, had an insignificant effect (less than 5%) on the energy efficiency of GHEs. The simulation result showed that the special structure of traditional GHEs may be the main reason for the lower possibility of collision between nanoparticles and the insignificant effect of nanofluid on its heat transfer enhancement. Therefore, the length of every straight tube segment should be restricted to achieve the better thermal performance of GHEs using nanofluids as heat transfer fluid.
In this paper the performance of a counter flow microchannel heat exchanger (CFMCHE) is numerically investigated with a nanofluid as a cooling medium. Two types of nanofluids are used Cu-water and Al 2 O 3-water. From the results obtained it's found that thermal performance of CFMCHE increased with using the nanofluids as cooling medium with no extra increase in pressure drop due to the ultra fine solid particles and low volume fraction concentrations. The nan-ofluids (Cu-water and Al 2 O 3-water) volume fractions were in the range 1% to 5%. It's also found that nanofluid-cooled CFMCHE could absorb more heat than water-cooled CFMCHE when the flow rate was low. For high flow rates the heat transfer was dominated by the volume flow rate and nanoparticles did not contribute to the extra heat absorption. Also the performance of CFMCHE can be increased considerably by using nanofluids with higher thermal conductivities.