Enhanced heat transfer characteristics of water based hybrid nanofluids with graphene nanoplatelets and multi walled carbon nanotubes

2021 ◽  
Author(s):  
T. Balaji ◽  
Sharan Rajendiran ◽  
C. Selvam ◽  
D. Mohan Lal
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Graphene Nanoplatelets ◽  
Heat Transfer Characteristics ◽  
Enhanced Heat Transfer ◽  
Transfer Characteristics ◽  
Water Based ◽  
Multi Walled Carbon Nanotubes ◽  
Hybrid Nanofluids ◽  
Walled Carbon Nanotubes

scholarly journals Thermophysical properties of nanofluids MWCNT (multi-walled carbon nanotubes) in water for emergency coolant from nuclear reactors

2021 ◽  
Vol 8 (3A) ◽  
Author(s):  
Alexandre Melo Oliveira ◽  
Amir Zacarias Mesquita ◽  
Enio Pedone Bandarra ◽  
Daniel Flórez Morales
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Thermophysical Properties ◽  
Nuclear Reactors ◽  
Energy Systems ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

To evaluate the synthesis and characterization of MWCNT (Multi-walled Carbon Nanotubes) with different degrees of functionalization in distilled water. The thermophysical properties (thermal conductivity and viscosity) of these nanofluids were measured at a temperature range (20-60°C) and concentrations (0.005-0.05%) by volume. Increases in thermal conductivity and viscosity were found 9.3% and 4.7%, respectively, at a volumetric concentration of 0.01% at a temperature of 30°C. The study of new fluids that improve the rate of removal of heat is fundamental to obtain greater efficiency of energy systems. Among the several factors that compromise the efficiency of the energy systems, we can highlight the thermophysical limitations of the conventional fluids, inhibiting in a very significant way some industrial applications. In this work we intend to improve the heat transfer characteristics of fluids commonly used by the addition of nanoparticles, made up of carbon nanotubes, in water which is the most used fluid for the cooling of nuclear reactors in operation today. It is intended to improve the heat transfer characteristics of fluids commonly used by the addition of nanoparticles, made of carbon nanotubes, through the addition of nanoparticles, made up of carbon nanotubes, in water which is the most used fluid for refrigeration of nuclear reactors currently in operation. In order to assess its benefits for the applicability and nuclear systems, ie primary coolant, safety systems, major accident mitigation strategies.

Forced Convection in a Microchannel Heat Sink Using Carbon Nanotubes for Heat Transfer Enhancement

2004 ◽  
Author(s):  
Blake E. Jakaboski ◽  
Yogendra Joshi ◽  
Michael Rightley
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Cross Section ◽  
Heat Sink ◽  
Infrared Camera ◽  
Open Loop ◽  
Microchannel Heat Sink ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Multi Walled Carbon Nanotubes

A new type of microchannel heat sink has been developed and evaluated in this study. The device consists of silicon microchannels on whose bottom surfaces multi-walled carbon nanotubes are grown. The objective of the study is to investigate the effect of carbon nanotubes on the heat transfer characteristics. The heat sink size is 15 mm × 15 mm × 0.675 mm. It contains two microchannel designs. One consists of eight channels of cross section 682 μm × 50 μm; the other has six channels of cross section 942 μm × 50 μm. The heat sink is incorporated in an open loop flow facility, with water as the coolant. Six different configurations are compared. Two have no nanotubes, two have closely spaced nanotube, while the last two designs have widely spaced nanotubes. The tests utilize an infrared camera as well as thermocouples placed in the flow for characterization. The heat transfer characteristics are compared for the different cases.

scholarly journals Thermal Efficiency, Heat Transfer, and Friction Factor Analyses of MWCNT + Fe3O4/Water Hybrid Nanofluids in a Solar Flat Plate Collector under Thermosyphon Condition

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 180 ◽  
Author(s):  
Bahaa Saleh ◽  
Lingala Syam Sundar
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Friction Factor ◽  
Thermal Efficiency ◽  
Volume Concentration ◽  
Multi Walled Carbon Nanotubes ◽  
Hybrid Nanofluids ◽  
Flat Plate Collector ◽  
Walled Carbon Nanotubes

The heat transfer, friction factor, and collector efficiency are estimated experimentally for multi-walled carbon nanotubes+Fe3O4 hybrid nanofluid flows in a solar flat plate collector under thermosyphon circulation. The combined technique of in-situ growth and chemical coprecipitation was utilized to synthesize the multi-walled carbon nanotubes+Fe3O4 hybrid nanoparticles. The experiments were carried out at volume flow rates from 0.1 to 0.75 L/min and various concentrations from 0.05% to 0.3%. The viscosity and thermal conductivity of the hybrid nanofluids were experimentally measured at different temperatures and concentrations. Due to the improved thermophysical properties of the hybrid nanofluids, the collector achieved better thermal efficiency. Results show that the maximum thermal conductivity and viscosity enhancements are 28.46% and 50.4% at 0.3% volume concentration and 60 °C compared to water data. The Nusselt number, heat transfer coefficient, and friction factor are augmented by 18.68%, 39.22%, and 18.91% at 0.3% volume concentration and 60 °C over water data at the maximum solar radiation. The collector thermal efficiency improved by 28.09% at 0.3 vol. % at 13:00 h daytime and a Reynolds number of 1413 over water data. Empirical correlations were developed for friction factor and Nusselt number.

Experimental Study on Heat Transfer of Multi-Walled Carbon Nanotubes/Water Nanofluids in Horizontal Microtubes

2016 ◽  
Author(s):  
Mehrdad Karimzadehkhouei ◽  
Abdolali Khalili Sadaghiani ◽  
Kürşat Şendur ◽  
M. Pınar Mengüç ◽  
Ali Koşar
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Considerable Effect ◽  
Outer Diameter ◽  
Heat Transfer Characteristics ◽  
Multi Walled Carbon Nanotube ◽  
Multi Walled Carbon Nanotubes ◽  
Study Heat Transfer ◽  
20 Nm ◽  
Walled Carbon Nanotubes

In this study, heat transfer characteristics of multi-walled carbon nanotube based nanofluids were investigated in horizontal microtubes with outer and inner diameters of ∼1067 and ∼889 μm, respectively. Carbon nanotubes (CNTs) with outer diameter of 10–20 nm and length of 1–2 micron as non-spherical nanoparticles were used for nanofluid preparation, where water was considered as basefluid. Nanofluid was characterized using the Scanning Electron Microscopy (SEM). According to obtained results, deposited CNTs have considerable effect on the convective heat transfer inside the microtube.

scholarly journals Conduction and convection heat transfer characteristics of water-based au nanofluids in a square cavity with differentially heated side walls subjected to constant temperatures

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 189-200 ◽  
Author(s):  
Primoz Ternik ◽  
Rebeka Rudolf
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Base Fluid ◽  
Volume Fraction ◽  
Heat Transfer Characteristics ◽  
Square Cavity ◽  
Onset Of Convection ◽  
Transfer Characteristics ◽  
Wide Range ◽  
Water Based

The present work deals with the natural convection in a square cavity filled with the water-based Au nanofluid. The cavity is heated on the vertical and cooled from the adjacent wall, while the other two horizontal walls are adiabatic. The governing differential equations have been solved by the standard finite volume method and the hydrodynamic and thermal fields were coupled together using the Boussinesq approximation. The main objective of this study is to investigate the influence of the nanoparticles? volume fraction on the heat transfer characteristics of Au nanofluids at the given base fluid?s (i.e. water) Rayleigh number. Accurate results are presented over a wide range of the base fluid Rayleigh number and the volume fraction of Au nanoparticles. It is shown that adding nanoparticles in a base fluid delays the onset of convection. Contrary to what is argued by many authors, we show by numerical simulations that the use of nanofluids can reduce the heat transfer rate instead of increasing it.

scholarly journals Temperature-Dependent Synergistic Effect of Multi-Walled Carbon Nanotubes and Graphene Nanoplatelets on the Tensile Quasi-Static and Fatigue Properties of Epoxy Nanocomposites

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 84
Author(s):  
Yi-Ming Jen ◽  
Hao-Huai Chang ◽  
Chien-Min Lu ◽  
Shin-Yu Liang
Keyword(s):  
Carbon Nanotubes ◽  
Fatigue Strength ◽  
Synergistic Effect ◽  
Polymer Nanocomposites ◽  
Graphene Nanoplatelets ◽  
Temperature Dependent ◽  
Epoxy Nanocomposites ◽  
Hybrid Fillers ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Even though the characteristics of polymer materials are sensitive to temperature, the mechanical properties of polymer nanocomposites have rarely been studied before, especially for the fatigue behavior of hybrid polymer nanocomposites. Hence, the tensile quasi-static and fatigue tests for the epoxy nanocomposites reinforced with multi-walled carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) were performed at different temperatures in the study to investigate the temperature-dependent synergistic effect of hybrid nano-fillers on the studied properties. The temperature and the filler ratio were the main variables considered in the experimental program. A synergistic index was employed to quantify and evaluate the synergistic effect of hybrid fillers on the studied properties. Experimental results show that both the monotonic and fatigue strength decrease with increasing temperature significantly. The nanocomposites with a MWCNT (multi-walled CNT): GNP ratio of 9:1 display higher monotonic modulus/strength and fatigue strength than those with other filler ratios. The tensile strengths of the nanocomposite specimens with a MWCNT:GNP ratio of 9:1 are 10.0, 5.5, 12.9, 23.4, and 58.9% higher than those of neat epoxy at −28, 2, 22, 52, and 82 °C, respectively. The endurance limits of the nanocomposites with this specific filler ratio are increased by 7.7, 26.7, 5.6, 30.6, and 42.4% from those of pristine epoxy under the identical temperature conditions, respectively. Furthermore, the synergistic effect for this optimal nanocomposite increases with temperature. The CNTs bridge the adjacent GNPs to constitute the 3-D network of nano-filler and prevent the agglomeration of GNPs, further improve the studied strength. Observing the fracture surfaces reveals that crack deflect effect and the bridging effect of nano-fillers are the main reinforcement mechanisms to improve the studied properties. The pullout of nano-fillers from polymer matrix at high temperatures reduces the monotonic and fatigue strengths. However, high temperature is beneficial to the synergistic effect of hybrid fillers because the nano-fillers dispersed in the softened matrix are easy to align toward the directions favorable to load transfer.

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