PERFORMANCE CHARACTERISTICS OF DIVERGENCE MICRO-CHANNELS HEAT SINK USING NANOFLUIDS (original) (raw)

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.

Investigation of Thermal Properties of Microchannel Heat Sink with Nanofluid

2017

Advancement in micro and nano fabrication technologies eases to manufacture compact heat exchanger devices. The compact heat exchanger and heat transfer devices performance can drastically improved by using microchannel arrays along with use of nanofluids. The parametric analysis of semicircular microchannel heat sink with distilled water and different concentrations of Multiwalled carbon nanotubes is carried out theoretically along with experimentation. The theoretical design is carried out for Minimum thermal resistance, maximum heat transfer coefficient, minimum friction factor and pressure drop along with minimum entropy generation. The microchannels with 200 μm hydraulic diameters are prototyped on accurate wire cut EDM. The effect of heat fluxes and Reynolds number is observed on heat transfer coefficient and pressure drop in laminar region. The performance of IC system is achieved best under Reynolds number 550 to 750. The heat transfer enhancement is observed 39 % over pure ...

Numerical Modelling of Nanofluid Based Microchannel Heat Sink

Foundation of Computer Applications, 2019

The present paper describes the effect of heat transfer and fluid flow characteristics of rectangular microchannel under laminar flow conditions. Three dimensional model is created and simulated by applying suitable boundary conditions in the commercial CFD package ANSYS. Two microchannels with width 500 µm and 300 µm are considered for the present study. Water and nanofluid are chosen as working fluids. Two-phase mixture model is used for the modelling of microchannel working with nanofluid. Numerical model have been validated with the available experimental work in the literature. Then, the simulations were carried out for two different channels with nanofluid as working fluid. Heat transfer and flow characteristics of microchannels with nanofluid as working fluid have been obtained for different nanofluid volume concentrations. Finally, the comparison studies between water and nanofluid have been presented in order to understand the effective use of nanofluid as the heat transfer fluid.

Three-Dimensional Heat Transfer Analysis of Microchannel Heat Sink Using Nanofluid

2015

A numerical simulation of three dimensional heat transfers in a silicon based microchannel heat sink has been conducted using nanofluid (TiO2-H2O) by SIMPLE method. Model of microchannel consists of trapezoidal channel. Dimensions of trapezoidal microchannel are 10 mm length, 280 μm channel top width, 225 μm channel bottom width, 431 μm channel hypotenuse and 430 μm channel height. Influence of properties of nanofluid on the heat transfer is investigated. Different parameters like heat transfer coefficient, Nusselt number, heat flux, outlet temperature are studied for different pressure drop. Pumping power depends upon pressure difference. So power consumption can be optimized by this study. Result shows that heat transfer coefficient is high in comparison to the water as a coolant in microchannel heat sink. Because of boundary layer, variation of Nusselt number decreases along the flow direction.

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...

Effect of Nanofluids on Heat Transfer and Pressure Drop Characteristics of Diverging-Converging Minichannel heat sink

2019

Article history: Received 3 January 2019 Received in revised form 16 April 2019 Accepted 22 April 2019 Available online 26 April 2019 Combine effects of nanofluid and variable cross-section minichannel heat s ink has become a remarkable option for efficient cooling of thermal devices like miniature electronic devices and compact heat exchangers. In this paper, the single-phase numerical method was employed to study the effect of different nanofluids on heat transfer and pressure drop penalty in the Diverging-converging minichannel heat sink (DCMCHS). CFD analysis carried out using commercial ANSYS software employing the finite volume method. The nanofluids are prepared as stable nanoparticles of Al 2O3, Cu, and SiO2 and suspended in deionized water with concentrations of 0-0.8% volume. The DCMCHS subjected to a uniform heat flux of 45000 W/m2 and the fluid flow within the transition’s region with Reynolds number 2000 to 2300. The va l idations of numerical data conducted with result...

Thermal performance improvement in water nanofluid/GNP–SDBS in novel design of double-layer microchannel heat sink with sinusoidal cavities and rectangular ribs

Springer, 2019

In this numerical study, laminar flow of water nanofluid/GNP–SDBS (graphene nanoplatelet–sodium dodecylbenzene sulfonate) for 0–0.1% solid nanoparticles mass fraction was investigated for Reynolds numbers of 50–1000 in 3D space via finite volume method. In the newly proposed microchannel design, the cooling fluid is moving in countercurrent in the upper and lower layers of the microchannels, and there are cavities and sinusoidal routes on the solid walls of the microchannel, and the presence of rectangular ribs on the flow centerline along the fluid path enhances mixing for cooling fluid and creates better heat transfer for warm surfaces. The results of this study show that this special design of the microchannel can have a substantial increase in Nusselt number and heat transfer so that in the considered geometry by adding solid nanoparticles mass fraction it is possible to increase average Nusselt number for each Reynolds number by approximately 20%. Also, the mixing of the fluid because of formation of secondary flows has a strong effect on making the temperature distribution uniform in the cooling fluid and solid bed (wall) of the microchannel, especially in the lower layer. The upper layer of the microchannel always has a lower temperature due to indirect contact with heat flux compared with the lower layer. In this study, by increasing Reynolds number and mass fraction of solid nanoparticles the Nusselt number is increased and heat resistance of the lower wall of the microchannel is reduced. Based on the investigation of flow field and heat transfer, the use of the proposed design of the microchannel is recommended for Reynolds number less than 300.

Numerical Simulation of Nanofluids for Improved Cooling Efficiency in Microchannel Heat Sink

Applied Mechanics and Materials, 2014

Numerical simulation on 3-dimensional rectangular cross section of microchannel heat sink is conducted to investigate the effect of various type coolant consist of water and different type of nanofluids on the cooling performance of microchannel heat sink. FLUENT, a Computational Fluid Dynamic (CFD) is used as the solver of simulation. A rectangular microchannel with hydraulic diameter of 86um and length of 10mm under the boundary condition of constant heat flux and laminar flow with uniform inlet velocity with five sets of working fluid with different nanofluids. The defined model is validated with previous studies of numerical analysis. Results of present work show that using Diamond-H2O as cooling lead to higher efficiency of heat transfer in microchannel heat sink in comparison to others nanofluid and base fluid. Numerical results show that increasing the thermal conductivity of working fluid can enhanced heat transfer. Nusselt number follows the incremental in Reynolds number.