scholarly journals Thermal transfer of Nanofluids based on carbon nanotubes/glycerol and study of their rheological behavior

2019 ◽  
Vol 286 ◽  
pp. 08003 ◽  
Author(s):  
S. Lahlou ◽  
R. Sehaqui ◽  
N. Lahlou
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Heat Exchanger ◽  
Rheological Behavior ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Heat Transfer Fluids ◽  
Thermal Transfer ◽  
The Subject ◽  
Viscoplastic Models

In the field of heat transfer, the use of the properties of rheological behavior inherent to suspensions of nanoparticles in heat transfer fluids has been the subject of several years of work. Our study concerns the particular case of suspensions of multilayered carbon nanotubes (MNTCs) in glycerol. We highlight the effect of the mass fraction φ of (MNTCs) on the rheology of the solutions for 0.1% ≤ φ ≤1%, on the temperature [30-80°C] and the effect on a heat exchanger. The experimental results obtained are described by viscoplastic models for which the yield stress increases with φ. We then propose a law of polynomial evolution of the apparent viscosity as a function of the volume fraction for each value of the shear rate varying from 0s-1 to 100s-1.

scholarly journals Characterization of Local Nano-Heat Transfer Fluids for Solar Thermal Collection

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Kawira Millien
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Copper Nanoparticles ◽  
Energy Demand ◽  
Volume Fraction ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Solar Thermal ◽  
Heat Transfer Fluids

Performance of organic oils in solar thermal collection is limited due to their low thermal conductivity when they are compared to molten salt solutions. Extraction of organic oils from plants can be locally achieved. The purpose of this study was to investigate the effect of use of copper nanoparticles in some base local heat transfer fluids (HTFs). Addition of volume fraction of 1.2% of the copper nanoparticles to oil-based heat transfer fluids improved their thermal conductivity as deduced from the thermal heat they conducted from solar radiation. The oil-based copper nanofluids were obtained by preparation of a colloidal solution of the nanoparticles. Impurities were added to increase the boiling point of the nano-heat transfer fluids. Stabilizers were used to keep the particles suspended in the oil-based fluids. The power output of the oil-based copper nano-heat transfer fluids was in the range of 475.4 W to 1130 W. The heat capacity of the steam in the heat exchanger was 93.7% dry and had a thermal capacity of 5.71 × 103 kJ. The heat rate of flow of the oil-based copper nano-heat transfer fluids was an average of 72.7 Js−1·kg−1 to 89.1 Js−1·kg−1. The thermal efficiency for the oil-based copper nano-heat transfer fluids ranged from 0.85 to 0.91. The average solar thermal solar intensity was in the range 700 Wm−2 to 1180 Wm−2. The heat exchanger used in this study was operating at 4.15 × 103 kJ and a temperature of 500.0°C. The heat transfer fluids entered the exchanger at an average temperature of 381°C and exited at 96.3°C and their heat coefficient ranged between 290.1 Wm−2°C and 254.1 Wm−2°C. The average temperatures of operation ranged between 394.1°C and 219.7°C with respective temperature efficiencies ranging between 93.4% and 64.4%. It was established that utilization of copper nanoparticles to enhance heat transfer in oil-based local heat transfer fluids can mitigate energy demand for meeting the world’s increasing energy uses, especially for areas inaccessible due to poor land terrain.

scholarly journals Numerical and experimental investigation of alumina-based nanofluid effects on double-pipe heat exchanger thermal performances

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
A. Bendaraa ◽  
My. M. Charafi ◽  
A. Hasnaoui
Keyword(s):  
Heat Exchanger ◽  
Volume Fraction ◽  
Convective Heat Transfer Coefficient ◽  
Deionized Water ◽  
Comsol Multiphysics ◽  
Exchange Coefficient ◽  
The Subject ◽  
Double Pipe ◽  
Pipe Heat ◽  
Thermoelectric Power Plant

AbstractIn this study, we investigate the thermal behaviour of nanofluids in a double-pipe heat exchanger. It is about a counterflow configuration, designed to cool a lubrication unit of a thermoelectric power plant. The subject of this work is to evaluate the thermal performances of the exchanger by using a nanofluid based on alumina suspension comparing with deionized water. In order to evaluate the thermal performance of the studied configuration, we carried out numerical experiments in an application developed on COMSOL Multiphysics environment, these experiments are utilized to show the feasibility of this application. As result, we found that the nanofluid with an increase in its volume fraction leads to an increase in the overall exchange coefficient, the convective heat transfer coefficient, as well as the efficiency and the power of the exchanger. It is noted that an increase of 1% in volume fraction, can enhance the overall exchange coefficient, the power and the effectiveness of the exchanger by 17.62%, 1.473% and 10.80% respectively. Besides, it is noted that the increase in the concentration of nanofluids leads to a narrowing of the pinch points of the inlet and outlet temperatures, which means that nanofluids are more efficient in cooling temperatures than conventional fluids.

scholarly journals A sensitivity study on carbon nanotubes significance in Darcy–Forchheimer flow towards a rotating disk by response surface methodology

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anum Shafiq ◽  
Tabassum Naz Sindhu ◽  
Qasem M. Al-Mdallal
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Ethylene Glycol ◽  
Biot Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Rotating Disk ◽  
Sensitivity Study ◽  
Basic Fluid ◽  
Walled Cnts

AbstractThe current research explores incremental effect of thermal radiation on heat transfer improvement corresponds to Darcy–Forchheimer (DF) flow of carbon nanotubes along a stretched rotating surface using RSM. Casson carbon nanotubes’ constructed model in boundary layer flow is being investigated with implications of both single-walled CNTs and multi-walled CNTs. Water and Ethylene glycol are considered a basic fluid. The heat transfer rate is scrutinized via convective condition. Outcomes are observed and evaluated for both SWCNTs and MWCNTs. The Runge–Kutta Fehlberg technique of shooting is utilized to numerically solve transformed nonlinear ordinary differential system. The output parameters of interest are presumed to depend on governing input variables. In addition, sensitivity study is incorporated. It is noted that sensitivity of SFC via SWCNT-Water becomes higher by increasing values of permeability number. Additionaly, sensitivity of SFC via SWCNT-water towards the permeability number is higher than the solid volume fraction for medium and higher permeability levels. It is also noted that sensitivity of SFC (SWCNT-Ethylene-glycol) towards volume fraction is higher for increasing permeability as well as inertia coefficient. Additionally, the sensitivity of LNN towards the Solid volume fraction is higher than the radiation and Biot number for all levels of Biot number. The findings will provide initial direction for future device manufacturing.

A Brief Review on Thermal Behaviour of PANI as Additive in Heat Transfer Fluid

2021 ◽  
Vol 02 (01) ◽  
Author(s):  
A.G.N. Sofiah ◽  
◽  
M. Samykano ◽  
S. Shahabuddin ◽  
K. Kadirgama ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Conducting Polymers ◽  
Volume Fraction ◽  
Corrosion Property ◽  
Environmental Stability ◽  
Heat Transfer Fluid ◽  
Thermal Engineering ◽  
Engineering System ◽  
Heat Transfer Fluids

Since a decade ago, investigation on nanofluids has grown significantly owing to its enhanced thermal properties compared to conventional heat transfer fluids. This engineered nanofluid has been widely used in the thermal engineering system to improve their energy consumption by improving the thermal efficiency of the system. The addition of nano-size particles as additives dispersed in the base fluids proved to significantly either improve or diminish the behaviour of the base fluids. The behaviour of the base fluid highly depends on the properties of the additives material, such as morphology, size, and volume fraction. Among the variety of nanoparticles studied, the conducting polymers have been subject of high interest due to its high environmental stability, good electrical conductivity, antimicrobial, anti-corrosion property and significantly cheap compared to other nanoparticles. As such, the main objective of the present review is to provide an overview of the work performed on thermal properties performance of conducting polymers based nanofluids.

Thermal Performance of a Borehole Heat Exchanger Located in Guayaquil-Ecuador Using Novel Heat Transfer Fluids

2015 ◽  
Author(s):  
Guillermo Soriano ◽  
Diego Siguenza
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Phase Change Materials ◽  
Three Dimensional ◽  
Borehole Heat Exchanger ◽  
Element Analysis ◽  
Heat Transfer Fluids ◽  
Ground Source ◽  
Microencapsulated Phase Change Materials

An analysis of thermal performance of a vertical Borehole Heat Exchanger (BHE) from a close loop Ground Source Heat Pump (GSHP) located in Guayaquil-Ecuador is presented. The project aims to assess the influence of using novels heat transfer fluids such as nanofluids, slurries with microencapsulated phase change materials and a mixture of both. The BHEs sensitive evaluation is performed by a mathematical model in a finite element analysis by using computational tools; where, the piping array is studied in one dimension scenario meanwhile its surroundings grout and ground volumes are presented as a three dimensional scheme. Therefore, an optimized model design can be achieved which would allow to study the feasibility of GSHP in buildings and industries in Guayaquil-Ecuador.

Heat Transfer Effect of CNT and Ethylene Glycol Based Nano-Fluid in Twisted Tape Heat Exchanger with Balls

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
R. Saravanan ◽  
M. Karuppasamy ◽  
M. Chandrasekaran ◽  
V. Muthuraman
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Ethylene Glycol ◽  
Heat Exchangers ◽  
Twisted Tape ◽  
Heat Transfer Fluids ◽  
Nano Fluid ◽  
Carbon Nano Tubes ◽  
Heat Transfer Improvement ◽  
Nano Fluids

Heat transfer improvement is the main parameter in a heat exchanging equipment. Few methods to increase the coefficient of heat transfer is by creating the turbulence in heat exchanging elements and changing the heat transfer fluids. For current analysis of tube heat exchangers, tape inserts containing balls are implemented with nano-fluids in Carbon Nano Tubes (CNT) and ethylene glycol. 3D modelling and simulation of twisted tape heat exchanger with balls were carried out using Solidworks and ANSYS Workbench. Heat transfer rate, friction factor, temperature difference in the heat exchangers, Reynolds number and Nusselt number variations are assessed in this work.

Effect of CuO Nanoparticle Concentration on R134a/Lubricant Pool-Boiling Heat Transfer

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
M. A. Kedzierski
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Mass Fraction ◽  
Flat Surface ◽  
Volume Fraction ◽  
Nanoparticle Concentration ◽  
Transfer Enhancement ◽  
Fundamental Understanding ◽  
Determining Factor ◽  
Cuo Nanoparticle

This paper quantifies the influence of copper (II) oxide (CuO) nanoparticle concentration on the boiling performance of R134a/polyolester mixtures on a roughened horizontal flat surface. Nanofluids are liquids that contain dispersed nanosize particles. Two lubricant-based nanofluids (nanolubricants) were made with a synthetic polyolester and 30 nm diameter CuO particles to 1% and 0.5% volume fractions, respectively. As reported in a previous study for the 1% volume fraction nanolubricant, a 0.5% nanolubricant mass fraction with R134a resulted in a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) between 50% and 275%. The same study had shown that increasing the mass fraction of the 1% volume fraction nanolubricant resulted in smaller, but significant, boiling heat transfer enhancements. The present study shows that the use of a nanolubricant with half the concentration of CuO nanoparticles (0.5% by volume) resulted in either no improvement or boiling heat transfer degradations with respect to the R134a/polyolester mixtures without nanoparticles. Consequently, significant refrigerant/lubricant boiling heat transfer enhancements are possible with nanoparticles; however, the nanoparticle concentration is an important determining factor. Further research with nanolubricants and refrigerants is required to establish a fundamental understanding of the mechanisms that control nanofluid heat transfer.

scholarly journals Heat Transfer Improvement in MHD Natural Convection Flow of Graphite Oxide/Carbon Nanotubes-Methanol Based Casson Nanofluids Past a Horizontal Circular Cylinder

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1444
Author(s):  
Abdulkareem Saleh Hamarsheh ◽  
Firas A. Alwawi ◽  
Hamzeh T. Alkasasbeh ◽  
Ahmed M. Rashad ◽  
Ruwaidiah Idris
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Natural Convection ◽  
Graphite Oxide ◽  
Volume Fraction ◽  
Casson Fluid ◽  
Convection Flow ◽  
Local Skin ◽  
Casson Nanofluid ◽  
The Impact

This numerical investigation intends to present the impact of nanoparticles volume fraction, Casson, and magnetic force on natural convection in the boundary layer region of a horizontal cylinder in a Casson nanofluid under constant heat flux boundary conditions. Methanol is considered as a host Casson fluid. Graphite oxide (GO), single and multiple walls carbon nanotubes (SWCNTs and MWCNTs) nanoparticles have been incorporated to support the heat transfer performances of the host fluid. The Keller box technique is employed to solve the transformed governing equations. Our numerical findings were in an excellent agreement with the preceding literature. Graphical results of the effect of the relevant parameters on some physical quantities related to examine the behavior of Casson nanofluid flow were obtained, and they confirmed that an augmentation in Casson parameter results in a decline in local skin friction, velocity, or temperature, as well as leading to an increment in local Nusselt number. Furthermore, MWCNTs are the most efficient in improving the rate of heat transfer and velocity, and they possess the lowest temperature.

A Review of Micro Heat Exchanger Flow Physics, Fabrication Methods and Applications

2001 ◽  
Author(s):  
W. Jerry Bowman ◽  
Daniel Maynes
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Design Optimization ◽  
Heat Exchangers ◽  
Review Of The Literature ◽  
Fourth Section ◽  
The Third ◽  
Heat Exchanger Design ◽  
Micro Heat Exchanger ◽  
The Subject

Abstract A review of the literature in the area of micro heat exchangers is presented to provide a concise overview of the recent advances in this field of study. The review is divided into six sections. The first section reviews research focused on understanding friction and heat transfer in microchannels. The second section deals with heat exchanger design, optimization and comparison studies. The third section deals with fabrication methods used for constructing micro heat exchangers. The fourth section reviews applications of micro heat exchangers. The last two sections of the paper deal with miscellaneous topics and other reviews on the subject. The total review focuses on advances made after the early 1990’s.

Effect of convective boundary condition on unsteady flow of CNT-H2O nanofluid towards a stagnation-point on a shrinking/expanding flat sheet

2021 ◽  
pp. 095440892110546
Author(s):  
Sohita Rajput ◽  
Amit Kumar Pandey ◽  
Krishnendu Bhattacharyya ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Boundary Condition ◽  
Stagnation Point ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Convective Boundary Condition ◽  
Dual Solutions ◽  
Convective Boundary ◽  
Walled Carbon Nanotubes

A model study of unsteady stagnation-point flow of most important nanoparticles, that is, carbon nanotubes suspended nanofluid towards shrinking/expanding sheet with convective boundary condition is demonstrated. Two types of carbon nanotubes, namely, single-wall and multi-wall nanotubes are carefully considered. Numerical solutions of converted equations from governing equation of the problem are obtained and those are graphically presented. Similar to without carbon nanotubes case, dual and unique solutions in specific ranges of velocity ratio parameter are achieved. Analysis disclosures that the condition on range where dual solutions exist is unaltered with solid-volume fraction and type of carbon nanotubes. The surface drag-force and heat transfer rate from wall are larger for single-walled carbon nanotubes nanofluid than multi-walled carbon nanotubes nanofluid. An increment in the parameter related to convective boundary condition generates high rate of heat transfer. After stability analysis, it is identified that in case of dual solutions, upper branch is stable and lower branch is unstable, while unique solution is always stable.

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