Influence of Nanoparticle Shapes of Boehmite Alumina on the Thermal Performance of a Straight Microchannel Printed Circuit Heat Exchanger (original) (raw)
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An Experimental Study on Thermal Performance of Nano Fluids in Microchannel Heat Exchanger
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Nanomaterials
In this paper, two novel micro heat sinks (MHSs) were designed and subjected to thermal analysis using a numerical method. The fluid used was Boehmite alumina–water nanofluid (NFs) with high volume fractions (VOFs). Studies were conducted to determine the influence of a variety of nanoparticle (NP) shapes, such as platelet brick, blade, cylinder, and Os. The heatsink (HS) was made of copper, and the NFs entered it through the middle and exited via four outlets at the side of the HS. The finite element method was used to simulate the NFs flow and heat transfer in the HSs. For this purpose, Multi Physics COMSOL software was used. The maximum and middle values of HS temperature (T-MAX and T-Mid), thermal resistance (TH-R), heat transfer coefficient (h), FOM, etc., were studied for different NP shapes, and with Reynolds numbers (Re) of 300, 1000, and 1700, and VOFs of 0, 3, and 6%. One of the important outcomes of this work was the better thermal efficiency of the HS with rectangular fi...
Investigation on Heat Transfer Enhancement in Microchannel Using Al2O3/Water Nanofluids
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Nowadays, reducing heat generation in electronic devices while using microchannel cooling is used to solve this problem. Because the trend is globally marching toward the compact size, the component’s dimensions get smaller, but the warmth involved within the component increases. Studies of heat transfer rate are conducted to determine the effect of a fully heated microchannel conductor’s heat transfer performance. Experiments are performed using nanofluid Al2O3/water through a concentration percentage of 0.1% and 0.25% and deionized water through a microchannel conductor with 25 rectangular microchannel numbers with a dimension of ( 0.42 × 0.42 × 100 ) mm3. This present work deals with the effect of nanofluids and their concentration percentages. Finally, it concluded that better heat transfer performance was seen in nanofluids compared to deionized water. The reason is the high viscosity of nanofluid Al2O3/water due to these nanoparticles is deposited on the wall surface of the mi...
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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...
Numerical study of a crossflow heat exchanger to investigate thermal performance using nanofluids
8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING
In this study, conjugate heat transfer between solids and fluids has been analyzed for a cross flow rectangular shaped microchannel heat exchanger. Three different nanofluids have been used such as CuO-water, Al 2 O 3-water and Al 2 O 3-ethylene glycol to investigate the effect of changing nanoparticles volume fraction as well as, effect of changing the base fluid at constant temperature. Volume fraction has been varied from 0.5% to 4%. These nanofluids have been widely used in compact heat exchangers, micro reactors, automotive radiators etc. for their exhibition of larger thermosphysical properties than conventional fluids due to presence of nanosized particles in them which enhance heat transfer. It has been observed that changing the base fluid has had a much significant effect than changing the nanoparticle. Heat transfer coefficient, pressure drop and pumping power requirement have been investigated in terms of varying nanoparticles volume fraction and Reynolds number. In addition, different characteristics such as isotherms, channel wall temperature have been graphically shown.
Case Studies in Thermal Engineering, 2021
The effect of geometry and nanoparticles concentrations on the heat transfer and friction factor of the microchannel. • The conventional straight channel is compared with uniform wavy, dual wavy channel considering the equal volume. • The optimum channel is identified by using the Thermal Performance Factor considering the effect of heat transfer and pressure drop. • The heat transfer performance of all wavy channels was more than double compared to straight channel and increased with an increase in Reynolds number. • The base wall temperature reduced on average from 6 • C to 10 • C for a 100 to 900 increase in Reynolds number compared to the straight channel.
2011
The research presents an experimental study on the heat transfer and pressure drop characteristics of Al 2 O 3 -water nanofluids flowing through a microchannel heat sink (MCHS). The effects of Reynolds number and particle concentrations on the heat transfer and flow behavior are investigated. Comparison of the heat transfer coefficient obtained from water-cooled MCHS and nanofluids-cooled MCHS are also presented. MCHS with rectangular flow channel made from aluminum with dimension of 5x5 mm are used as the test section. Al 2 O 3 -water nanofluids with particle concentrations of 1.0, 2.0 and 3.0 wt.% are tested. Two electric heaters with each capacity of 50 W are used to supply heat to the test section. The experimental conditions are described as follows: 1) fluid temperature is setted at 15 o C and 2) Reynolds number ranging between 1500 and 3000. The results indicated that the heat transfer performance of MCHS increased with increasing Reynolds number as well as particle concentrations. Compared with pure water, the result indicated that heat transfer performances of nanofluid-cooled MCHS are higher than those of water by about 7 -15%. Finally, the pressure drop of nanofluids is close to the water.
International Journal of Heat and Mass Transfer, 2014
Nanofluid is a new engineering fluid which could improve the performance of heat exchanger. The aim of this paper is to study the effect of different particle shapes (cylindrical, bricks, blades, and platelets) on the overall heat transfer coefficient, heat transfer rate and entropy generation of shell and tube heat exchanger with different baffle angles and segmental baffle. Established correlations were used to determine the abovementioned parameters of the heat exchanger by using nanofluids. Cylindrical shape nanoparticles showed best performance in respect to overall heat transfer coefficient and heat transfer rate among the other shapes for different baffle angles along with segmental baffle. An enhancement of overall heat transfer coefficient for cylindrical shape particles with 20°baffle angle is found 12%, 19.9%, 28.23% and 17.85% higher than 30°, 40°, 50°baffle angles and segmental baffle, respectively in corresponding to 1 vol.% concentration of Boehmite alumina (c-AlOOH). Heat transfer rate is also found higher for cylindrical shape at 20°baffle angle than other baffle angles as well as segmental baffle. However, entropy generation decreases with the increase of volume concentration for all baffle angles and segmental baffle.
Heat Transfer and Numerical Analysis in Microchannel Heat Exchanger Using Nanofluids : A Review
Nanofluids are gaining lot of importance in thermal applications due to its excellent heat transfer characteristics. Micro-scale heat transfer devices are used on large scale in electronics industry which leads to the development of compact size heat exchanger with high heat transfer coefficient. Recent development in the field of nanotechnology involves the use of suspended nanoparticles in base fluids which leads to the improvement in the heat transfer coefficient of base fluids. This paper summarizes the articles published on enhancement of convective heat transfer in microchannel heat exchanger using nanofluids and effect of various thermophysical properties on heat transfer performance. Theoretical and experimental results for different geometries and effects on Nusselt number are reported in this paper. The results show outstanding increase in the importance of nanofluid application in microchannels. The effects of use of different nanofluids and their performance as compared to base fluids are shown.
Applied Thermal Engineering, 2021
The hydraulic and thermal performance of microchannel heat sink configurations for high performance electronic cooling applications is investigated by numerical modelling. Conjugate heat transfer simulations are obtained through the silicon walls and the fluid domain of a square base prism heat sink traversed by 50 parallel rectangular cooling ducts, under a 150 W/cm 2 constant heat flux input through the base. Al2O3 nanofluid coolant with a nanoparticle volume fraction ranging from 0 to 3% is supplied at 298 K, over the Reynolds number range 100 to 350, modelled as a single-phase homogeneous medium. Rectangular, twisted, and zigzag fins are inserted into the plain rectangular duct to enhance the heat transfer rate. The zigzag fin and 3% Al2O3 nanofluid provide the best thermal performance, with a 6.44 K lower average heated wall contact temperature, 60% higher Nusselt number, and 15% higher second law efficiency than without fins and plain water cooling. Twist in the microchannel fin unexpectedly reduced the microchannel pressure drop by 2% to 15% compared to a straight fin, possibly due to the more evenly distributed axial mass flux across the microchannel.