Comparison of experimental and theoretical methods of obtaining the thermal properties of alumina/iron mono and hybrid nanofluids

2019 ◽  
Vol 292 ◽  
pp. 111377 ◽  
Author(s):  
Eric C. Okonkwo ◽  
Ifeoluwa Wole-Osho ◽  
Doga Kavaz ◽  
Muhammad Abid
Author(s):  
Jorge Silva-Yumi ◽  
Telmo Moreno Romero ◽  
Gabriela Chango Lescano

Nanofluids constitute an alternative for the most efficient use of energy as they allow generating or improving thermal properties among others of traditional fluids, they are defined as so-called base fluids, such as: water, ethylene glycol, oils, etc., which contain nanoparticles in suspension , such as: aluminum oxide, silicon oxide, titanium oxide, metal nanoparticles, carbon nanotubes, graphene, carbides, etc. Nanofluids can be synthesized by two methods, the nanoparticles can be obtained separately and then the nanofluid is prepared or both nanoparticles and the nanofluid can be prepared simultaneously, an important factor to consider in obtaining nanofluids is their stability. Stability can be achieved by physical treatment or chemical treatment using surfactants. There are many studies about nanofluids, however, most are obtained with synthetic nanoparticles, leaving the use of natural nanoparticles as a field to be explored, as well as other surfactants to improve their stability. Keywords: nanofluids, hybrid nanofluids, nanoparticles, nano refrigerant. Resumen Los nanofluidos constituyen una alternativa para el uso más eficiente de energía pues permiten generar o mejorar las propiedades térmicas entre otras de los fluidos tradicionales, son definidos como fluidos denominados base, como: agua, etilenglicol, aceites, etc., que contienen nanopartículas en suspensión, como: óxido de aluminio, óxido de silicio, óxido de titanio, nanopartículas metálicas, nanotubos de carbono, grafeno, carburos, etc. Los nanofluidos se pueden sintetizar por dos métodos, se pueden obtener las nanopartículas por separado y luego preparar el nanofluido o se puede preparar simultáneamente las nanopartículas y el nanofluido, un factor importante a considerar en la obtención de nanofluidos es su estabilidad. La estabilidad se puede lograr mediante tratamiento físico o tratamiento químico mediante la utilización de surfactantes. Existen muchos estudios acerca de nanofluidos sin embargo, la mayoría se obtienen con nanopartículas sintéticas, quedando el uso de nanopartículas naturales como un campo por explorar al igual que otros surfactantes para mejorar su estabilidad. Palabras Clave: nanofluidos, nonofluidos híbridos, nanoparticulas, nanorefrigerantes.


Author(s):  
Anwar Ilmar Ramadhan ◽  
Wan Hamzah Azmi ◽  
Rizalman Mamat

Background: Research has been focused on improving the thermal properties of single nanofluid components for recent of years. Therefore, hybrid nanofluids or composites have been developed to improve heat transfer performance. Stability and thermal conductivity of the Al2O3-TiO2-SiO2 nanoparticles suspended in the fluid base of water (W) and ethylene glycol (EG) mixture with volume ratio of 60:40. Methods: Experiments were tri-hybrid nanofluid stability was investigated for volume concentration of 0.5 ~ 3.0%, and temperature conditions from 30 to 70 °C for thermal conductivity measurements using a KD2 Pro Thermal Properties Analyzer. The experimental results show that the tri-hybrid nanofluid stability analysis was performed using a stable UVVis method for up to 30 days after preparation with 10 hour sonication time. Results: Comparison of data concentration ratios with sedimentation for single, hybrid, and tri-hybrid nanofluids yielding a stable tri-hybrid nanofluid with 80-90% value. Evaluation of zeta potential for tri-hybrid nanofluids yielded 63.72 mV in excellent stability classification. Sedimentation of this visual observation is influenced by the gravity of the movement of particles in the tube after 30 days. Conclusion: The highest thermal conductivity for tri-hybrid nanofluids was obtained at 3.0% and a maximum increase of up to 27% higher than that of the basic fluid (EG/W). Tri-hybrid nanofluids with a concentration of 0.5% gave the lowest effective thermal conductivity of 13.4% at 70 °C.


2022 ◽  
Vol 28 (2) ◽  
Author(s):  
Mohammed Elhoudi ◽  
Rachid Oukhrib ◽  
Christian A. Celaya ◽  
Daniel G. Araiza ◽  
Youness Abdellaoui ◽  
...  

Author(s):  
M. Y. Wong ◽  
C. Y. Tso ◽  
T. C. Ho

Abstract A thermal diode, a device to manipulate the heat flow in different directions, is useful in various thermal systems, such as solar thermal storage systems. It is noted that the performance of phase change thermal diodes shows the highest thermal rectification performances in the literature. The performances of the phase change thermal diode can be further improved by utilizing a working fluid with enhanced thermal properties. Since hybrid nanofluids are proven to have better thermal properties than the base fluid (i.e. water), in this study, a thermal diode using Al2O3-Cu/water hybrid nanofluid is fabricated and tested to investigate the feasibility of using hybrid nanofluid to enhance the performance of the thermal diode. The heat transfer and thermal rectification performances of the thermal diode using Al2O3-Cu/water hybrid nanofluid are compared experimentally, to a thermal diode using water. The effect of temperature on the heat transfer and thermal rectification performances of the thermal diode is also examined. The results indicate that the effective thermal conductivity in the forward direction and the diodicity of the thermal diode using Al2O3-Cu/water hybrid nanofluid are improved by 42.4% and 30.8%, respectively, compared to that of the thermal diode using water. The findings not only reveal a new direction for future research in enhancement of the thermal rectification performance of the phase change thermal diode but also provide an alternative research path for improving the performance of existing solar thermal storage systems.


1960 ◽  
Vol 23 ◽  
pp. 332-336 ◽  
Author(s):  
W WENDLANDT ◽  
J VANTASSEL ◽  
G ROBERTHORTON
Keyword(s):  

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