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Characterization of magnesium ferrite nanofluids for heat transfer applications
Materials Today: Proceedings xxx (xxxx) xxx
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Characterization of magnesium ferrite nanofluids for heat transfer applications K. Ajith a, I.V. Muthuvijayan Enoch b, A. Brusly Solomon a,⇑, Archana Sumohan Pillai b a Micro and Nano Heat Transfer Lab, Centre for Research in Material Science and Thermal Management, Department of Mechanical Engineering, Karunya Institute of Technology and Sciences, Coimbatore, India b Department of Chemistry & Department of NanoScience, Karunya Institute of Technology and Sciences, Coimbatore, India
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Article history: Received 18 August 2019 Accepted 5 September 2019 Available online xxxx Keywords: Thermal conductivity Surface tension Viscosity Nanoparticles Ferrofluid Volume fraction
a b s t r a c t This study intends to examine the suitability of magnesium ferrite nanofluid for heat transfer applications by measuring the thermophysical properties. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) are used to determine the surface morphology and size of magnesium ferrite nanoparticle. The ferrofluid is prepared by dispersing MgFe2O4 nanoparticles of size 80 nm in the Deionized water. The thermal conductivity, viscosity and surface tension of MgFe2O4 ferrofluid were investigated for five different volume fractions 0.01, 0.05, 0.10, 0.15, and 0.20, respectively. The hydrothermal synthesis method is employed for the preparation of magnesium ferrite nanoparticles. The outcome of the study indicates that thermal conductivity and viscosity of the ferrofluid is improved proportionally with intensification in volume fraction. Also noticed that the surface tension is decreased with the increasing volume fraction. The maximum enhancement of thermal conductivity and viscosity is 9.88% and 49% at the highest volume fraction of 0.20. The percentage of decrease in surface tension of the ferrofluid is observed as 45.8% at 0.20 volume fraction. The surface tension of ferrofluid decreases in connection with the rise in temperature from 293 to 333 K. Ó 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the First International Conference on Recent Advances in Materials and Manufacturing 2019.
1. Introduction Energy resource utilization is one of the most vital issues in the world. Hydrocarbon fuels, nuclear energy, and sustainable energy resources are the three primary energy sources in use today. The increased consumption of hydrocarbon fuels results in depletion of the ozone layer, climate change, and global warming. Renewable energy resources are the appropriate energy sources because they can be produced repeatedly from itself without causing any harm to the living world [1]. Energy from the sun is one among the essential eco-friendly energy sources due to non-polluting behaviour; it is a reliable source of electricity; it is long-running and requires low maintenance. Solar water heating systems utilize the heat generated from the solar irradiations and transfer this heat energy to the working fluid, consequently its temperature increases, and this fluid can be used for domestic purposes. Indirect water heating systems employ free convection heat transfer, in ⇑ Corresponding author. E-mail address: [email protected] (A. Brusly Solomon).
which thermal energy is transmitted from the solar collector to working fluids then transferred to the domestic supply with the aid of the heat exchanger. Therefore, the thermophysical property of the working fluid plays a significant role in thermal energy transmission. The thermal conductivity of working fluids, which is used for thermal energy transfer is low, and this leads to low heat absorption and low heat transfer efficiency [2]. The thermal conductivity of base thermal fluid can be enhanced by dispersing high thermal conductivity metals or metal oxides into the traditional fluids; as a result, the thermal conductivity of the base fluid increases. The size of the dispersed particle is a crucial factor; if the size of the diluted particles is less than100 nanometer, it alters the thermal properties of the base fluid and called nanofluid. There is numerous literature which delivers the data about the alteration in heat transfer properties of the conventional base fluid such as water, kerosene, ethylene glycol, etc. when mixed with nanoparticles like ceramic, metal, metal oxide, carbon nanotubes, etc. [3]. The maximum augmentation in thermal conductivity is reported as 100% when multiwalled carbon nanotube is used in nanofluid [4]. Metal oxide, like CuO, also enhanced the thermal conductivity
https://doi.org/10.1016/j.matpr.2019.09.014 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the First International Conference on Recent Advances in Materials and Manufacturing 2019.
Please cite this article as: K. Ajith, I. V. Muthuvijayan Enoch, A. Brusly Solomon et al., Characterization of magnesium ferrite nanofluids for heat transfer applications, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.014
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K. Ajith et al. / Materials Today: Proceedings xxx (xxxx) xxx
of water by 75% [5]. Researchers are trying to augment the thermal conductivity of conventional fluids to its extreme by the use of ferrofluids with the application of a magnetic field. John Philip et al. [6] examined the importance of the magnetic field on kerosenebased Fe3O4 nanofluid. The magnetic induction of 0–500 G was applied and tested for the volume percentage from 0.031 to 6.3%. It was concluded that the presence of the magnetic field and a surge in the volume percentage of magnetic nanoparticle makes a historic enhancement on thermal conductivity of 300% at 82 Gauss. Wei Yu et al. [7] studied the use of Fe2O4/kerosene nanofluid by varying the temperature from 10 to 60 °C and ranged the particle concentration from 0.1 to 1%. The results reveal that the rise in the particle concentration and temperature improves the nanofluid thermal conductivity. The maximum enhancement was 34% at maximum particle concentration. Gui et al. [8] found that the magnetic nanoparticle concentration has a substantial effect on the rate of thermal energy transfer of the ferrofluid and is more at higher particle concentration. Studies were carried out for different levels of ferrotec EMG series-water based ferrofluid and determined that magnetic field strength and the heat transfer rate is inversely related. Decrease of heat transfer rate was observed with the increase of magnetic field strength because of the particle attraction to the channel wall when the magnetic flux is applied. Amani et al. [9] analysed the viscosity of manganese ferrite/ water ferrofluid by the application of different magnetic flux density, and the results obtained were related with the conclusions arrived in the nonattendance of magnetic flux. Volume concentration for this study was varied from 0.25% to 3%. Results showed that change in measured thermal property is directly proportional to the concentration of the particle and magnetic field. The study also concluded that viscosity of ferrofluid decreased with a rise in temperature. Arana et al. [10] prepared nickel ferrite ferrofluid by mixing nickel ferrite nanoparticle and kerosene as the base fluid for finding the consequence of magnetic flux density on the thermal property of the ferrofluid. The outcomes of the experimental study show that thermal conductivity improvement of the nickel ferrite ferrofluid is 170% in the existence of magnetic flux. Results indicate that thermal diffusivity of the ferrofluid is increased up to 70 times more than the base fluid kerosene without particle. Shahsavar et al. [11] studied the heat transfer properties of hybrid nanofluids comprising Fe3O4 magnetic nanoparticles and carbon nanotubes with water as the base fluid. The results indicate that the Fe3O4 particle concentration or CNT concentration has an impact on the variation of thermal properties. Also found, increasing particle concentration amplified the viscosity and thermal conductivity of the ferrofluid. Karimi et al. [12] used two different nanomaterials such as Fe3O4 and CoFe2O4, for preparing the water-based nanofluid. The volume fraction of ferrofluid is varied from 0 to 4.8% by dispersing these two different nanomaterials in
deionized water. At highest volume fraction such as 4.8%, the thermal conductivity of Fe3O4 and CoFe2O4 nanofluid is maximum. By the application of the magnetic flux density from 0 to 500 G, the thermal conductivity of both Ferrofluids (Fe3O4 and CoFe2O4) increased significantly. The maximum thermal conductivity augmentation is obtained at the lower magnetic field around 200 Gauss and is 196% for Fe3O4 nanofluid and 148% for CoFe2O4 nanofluid at volume fraction 4.8%. From the above short review of literature, it was noticed that the thermal properties of water, kerosene, and water/ethylene glycol are measured and used as base fluids. Also, thermal features of fluids containing nanoparticles such as Fe3O4, CoFe2O4, FeC, magnetic nanodiamond-cobalt oxide hybrid nanoparticles, maghemite nanoparticle, MnFe2O4 nanoparticle, ferrotec EMG series nanoparticles, and Nickel ferrite nanoparticles are measured. The results indicate that the thermal properties of the base fluid can be reformed using magnetic nanoparticle along with the application of a magnetic field. Moreover, the use of MgFe2O4 in heat transfer application is found to be rare, and the particle possesses high magnetic properties, the same is prepared using hydrothermal method and characterized. 2. Experimental procedure 2.1. Synthesis of MgFe2O4 nanoparticle, preparation, and characterization of ferrofluid Magnesium ferrite nanoparticle with chemical formula MgFe2O4 was prepared using the hydrothermal method, which is synthesized from the mixtures of metal nitrate hydrate solution. The raw material used for the synthesis of nanomaterial were analytical grade Iron (III) Nitrate nonahydrate, and Magnesium Nitrate hexahydrate was used as raw material and which are purchased from Sigma-Aldrich, which is 99.95% pure. The mixture comprising of Iron nitrate solution of 25 ml with molarity 0.4, magnesium nitrate solution of 25 ml with molarity 0.2 and 35 ml distilled water was prepared. After the mixing process, 0.05 molarity of glycerol was added to the mixture and this blend was heated at 150 °C for 18 h using autoclave reactor. After precipitation, it was filtered using Whatman filter paper and washed with deionized water. Then the filtered material was dehydrated at 70 °C for 3 h in a vacuum. Finally, the products were dried to obtain magnesium ferrite nanoparticle. SEM and TEM image of the synthesized magnesium ferrite nanoparticle are illustrated in Fig. 1(a) and (b) respectively. MgFe2O4 nanoparticles were suspended into the deionized water for preparing the magnetic nanofluid. The size and shape of magnesium ferrite nanoparticle synthesized by the hydrothermal method is 80 nm and is spherical, which is used for the preparation of magnetic nanofluid. A Hielscher UP400S ultrasonic mixer was
Fig. 1. (a) SEM image; (b) TEM image of the synthesized MgFe2O4 nanoparticle.
Please cite this article as: K. Ajith, I. V. Muthuvijayan Enoch, A. Brusly Solomon et al., Characterization of magnesium ferrite nanofluids for heat transfer applications, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.014
K. Ajith et al. / Materials Today: Proceedings xxx (xxxx) xxx
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used for the preparation nanofluid. The mixer was configured with 60% pulse time and 65% amplitude. The process took 20 min for 100 ml samples. After initial sonication, sodium dodecyl sulfate was added into the nanofluid as a surfactant for better stability. Following the addition of SDS, the mixture was sonicated for 10 min [13]. The thermal conductivity of magnesium ferrite ferrofluids is measured by KD2 pro. Brookfield DV-E viscometer is employed for measuring the viscosity of MgFe2O4 ferrofluid. The surface tension of prepared nanofluid is measured by the use of SITA portable surface tension Meter Dyno Tester. All thermal properties are observed between the volume fractions from 0.01 to 0.20.
fraction is increased, there is a proportionate intensification of viscosity. The viscosity augmented by 10% at 0.01 vol fraction of nanofluid and increased by 49% for 0.20 vol fraction compared to the viscosity of DI-water. Addition of nanoparticle into the base fluid forms large bunches of nanoparticles due to Van der Waals forces which lead to deterring of the fluid layer movement over the other layer, thereby increasing the viscosity. When the volume fraction is increased, the size of the formed nanoclusters also increases, and hence, there is a proportionate increase in viscosity [9].
3. Result and discussion
The surface tension of the base fluid calculated is 73.2 mN/m at 303 K. By the addition of magnesium ferrite nanoparticle, the surface tension of the prepared ferrofluid is lessened. The variation of surface tension concerning volume fraction is illustrated in Fig. 3 (a). The surface tension is decreased significantly with the change in volume fraction from 0.01 to 0.20. The percentage of decrease of surface tension is 3.08% at a volume fraction of 0.01 and 45.8% at a volume fraction of 0.20. Surface tension is a vital thermal property for heat transfer in heat pipes, which is a heat transfer device used for electronics cooling. The reduced surface tension of the working fluid enhances the capillary effect in the heat pipe and leads to better circulation of working fluid from condenser to evaporator and leading to the better thermal performance of the heat pipe. Fig. 3(b) shows the change in surface tension of the ferrofluid at various concentration concerning the temperature. It is observed that surface tension of the ferrofluid decreases with the surge in temperature from 20 to 60 °C By increasing the temperature the liquid molecules move to higher kinetic energy and hence coherent
3.1. Volume fraction effect on the thermal conductivity and viscosity of MgFe2O4 ferrofluid The impact of the intensification in MgFe2O4 particle concentration on the thermal conductivity of magnesium ferrite ferrofluid is shown in Fig. 2(a). It is found that the thermal conductivity of the Deionized water is 0.597 W/mK at 298 K. The thermal conductivity of the prepared ferrofluid is measured at different particle concentration in the range of 0.01–0.20. The thermal conductivity of the ferrofluid is improved by 5.19%, 6.86%, 7.53%, 8.04, and 9.88% respectively for the concentrations 0.01,0.05,0.10, 0.15 and 0.2 when compared to water. Thermal conductivity of MgFe2O4 nanoparticle is high and leads to the enhancement of thermal conductivity of prepared ferrofluid. The relation between viscosity of the MgFe2O4 ferrofluid and the magnetic nanoparticle volume fraction is shown in Fig. 2. (b). It is found that when the volume
3.2. The surface tension of MgFe2O4 ferrofluid at various volume fraction and temperature
Fig. 2. Result of change in volume fraction on a) Thermal conductivity; b) Viscosity of magnesium ferrite nanofluid.
Fig. 3. The surface tension of magnesium ferrite nanofluid at a) various volume fraction; b) various temperature.
Please cite this article as: K. Ajith, I. V. Muthuvijayan Enoch, A. Brusly Solomon et al., Characterization of magnesium ferrite nanofluids for heat transfer applications, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.014
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Fig. 4. Comparison of theoretical and measured a) Thermal conductivity; b) Relative viscosity of ferrofluids.
forces between the liquid molecules and the surface tension is reduced [14]. 3.3. Validation of experimental data with theoretical models The measured and theoretical thermal conductivity of nanofluids is compared and presented in Fig. 4(a). The theoretical correlations developed by Timofeeva [15] and Sundar [16] are considered for comparison. It is observed that the measured and theoretical thermal conductivity of MgFe2O4/water ferrofluid is comparable. However, Timofeeva model is deviating from the measurements. Fig. 4(b) shows the analogy between the relative viscosity observed and those computed by Einstein [17], Batchelor [18], Brinkman [19], and Sundar [16] model. The observation is that Brinkman and Batchelor correlation approximately predicts with 96% confidence level up to 0.10 vol fraction beyond that it deviates largely. Finally, the enhancement in thermophysical properties suggests that this ferrofluid is suitable for heat transfer applications. 4. Conclusion The experimental investigation is carried out for finding the suitability of magnesium ferrite nanofluid for heat transfer application by measuring the heat transfer properties of the ferrofluid. The hydrothermal method is used to synthesize MgFe2O4 nanoparticles. The volume fraction is changed from 0.01 to 0.20 and which improves the thermal conductivity and viscosity of the ferrofluid. At ambient temperature, the improvement in thermal conductivity was observed 9.88% and 49% enrichment in viscosity at 0.20 vol fraction. The surface tension of the prepared ferrofluid shows an inverse response for the surge in volume fraction. The percentage of decrease in the surface tension at volume fraction 0.20 is 45.8% and surface tension of the ferrofluid decreases with increase in temperature. The above results show that the magnesium ferrite/water nanofluid is suitable for the heat transfer application, such as heat pipes. Acknowledgments The authors would like to thank DST – SERB, India. (DST/SERB/ YSS/2015/001084) for the financial support for this research work.
References [1] A. Hussain, S.M. Arif, M. Aslam, Emerging renewable and sustainable energy technologies: state of the art, Renew. Sustain. Energy Rev. 71 (December 2016) (2017) 12–28. [2] A.H. Elsheikh, S.W. Sharshir, M.E. Mostafa, F.A. Essa, M.K. Ahmed Ali, Applications of nanofluids in solar energy: a review of recent advances, Renew. Sustain. Energy Rev. 82 (October 2017) (2018) 3483–3502. [3] N. Sezer, M.A. Atieh, M. Koç, A comprehensive review on synthesis, stability, thermophysical properties, and characterization of nanofluids, Powder Technol. 344 (2019) 404–431. [4] J. Ponmozhi et al., Thermodynamic and transport properties of CNT - water based Nanofluids, J. Nano Res. 11 (2010) 101–106. [5] B. Chitra, K.S. Kumar, Heat transfer enhancement using single base and double base nanofluids, J. Mol. Liq. 221 (2016) 1128–1132. [6] J. Philip, P.D. Shima, B. Raj, Enhancement of thermal conductivity in magnetite based nanofluid due to chainlike structures, Appl. Phys. Lett. 91 (20) (2007) 2005–2008. [7] W. Yu, H. Xie, L. Chen, Y. Li, Enhancement of thermal conductivity of kerosenebased Fe3O4 nanofluids prepared via phase-transfer method, Colloids Surf., A 355 (1-3) (2010) 109–113, https://doi.org/10.1016/j.colsurfa.2009.11.044. [8] S. Akilu et al., Investigation on viscosity of Fe3O4 nanofluid under magnetic field, J. Magn. Magn. Mater. 598 (November) (2017) 66–77. [9] M. Amani, P. Amani, A. Kasaeian, O. Mahian, F. Kasaeian, S. Wongwises, Experimental study on viscosity of spinel-type manganese ferrite nanofluid in attendance of magnetic field, J. Magn. Magn. Mater. 428 (November 2016) (2017) 457–463. [10] M. Arana, P.G. Bercoff, S.E. Jacobo, Thermomagnetic characterization of organic-based ferrofluids prepared with Ni ferrite nanoparticles, Mater. Sci. Eng., B 215 (2017) 1–8. [11] A. Shahsavar, M. Bahiraei, Experimental investigation and modeling of thermal conductivity and viscosity for non-Newtonian hybrid nanofluid containing coated CNT/Fe3O4 nanoparticles, Powder Technol. 318 (2017) 441–450. [12] A. Karimi, S.S.S. Afghahi, H. Shariatmadar, M. Ashjaee, Experimental investigation on thermal conductivity of MFe2O4 (M = Fe and Co) magnetic nanofluids under influence of magnetic field, Thermochim. Acta 598 (September 2015) (2014) 59–67. [13] J.C. Joubert, M. Sharifpur, A.B. Solomon, J.P. Meyer, Enhancement in heat transfer of a ferrofluid in a differentially heated square cavity through the use of permanent magnets, J. Magn. Magn. Mater. 443 (2017) 149–158. _ L. Lugo, S.M.S. Murshed, Current trends in [14] P. Estellé, D. Cabaleiro, G. Zyła, surface tension and wetting behavior of nanofluids, Renew. Sustain. Energy Rev. 94 (November 2017) (2018) 931–944. [15] E.V. Timofeeva, Thermal conductivity and particle agglomeration in alumina nanofluids: experiment and theory, Phys. Rev. E: Stat. Nonlinear Soft Matter Phys. 76 (6) (2007) 28–39. [16] L. Syam Sundar, M.K. Singh, A.C.M. Sousa, Investigation of thermal conductivity and viscosity of Fe3O4 nanofluid for heat transfer applications, Int. Commun. Heat Mass Transf. 44 (2013) 7–14. [17] A. Einstein, Investigation on the Brownian movements, 1956. [18] G.K. Batchelor, The effect of Brownian motion on the bulk stress in a suspension of spherical particles, J. Fluid Mech. 83 (1977) 97–117. [19] H.C. Brinkman, The viscosity of concentrated suspensions and solutions, J. Chem. Phys. 20 (4) (1952) 571.
Please cite this article as: K. Ajith, I. V. Muthuvijayan Enoch, A. Brusly Solomon et al., Characterization of magnesium ferrite nanofluids for heat transfer applications, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.014
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Characterization of magnesium ferrite nanofluids for heat transfer applications K. Ajith a, I.V. Muthuvijayan Enoch b, A. Brusly Solomon a,⇑, Archana Sumohan Pillai b a Micro and Nano Heat Transfer Lab, Centre for Research in Material Science and Thermal Management, Department of Mechanical Engineering, Karunya Institute of Technology and Sciences, Coimbatore, India b Department of Chemistry & Department of NanoScience, Karunya Institute of Technology and Sciences, Coimbatore, India
a r t i c l e
i n f o
Article history: Received 18 August 2019 Accepted 5 September 2019 Available online xxxx Keywords: Thermal conductivity Surface tension Viscosity Nanoparticles Ferrofluid Volume fraction
a b s t r a c t This study intends to examine the suitability of magnesium ferrite nanofluid for heat transfer applications by measuring the thermophysical properties. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) are used to determine the surface morphology and size of magnesium ferrite nanoparticle. The ferrofluid is prepared by dispersing MgFe2O4 nanoparticles of size 80 nm in the Deionized water. The thermal conductivity, viscosity and surface tension of MgFe2O4 ferrofluid were investigated for five different volume fractions 0.01, 0.05, 0.10, 0.15, and 0.20, respectively. The hydrothermal synthesis method is employed for the preparation of magnesium ferrite nanoparticles. The outcome of the study indicates that thermal conductivity and viscosity of the ferrofluid is improved proportionally with intensification in volume fraction. Also noticed that the surface tension is decreased with the increasing volume fraction. The maximum enhancement of thermal conductivity and viscosity is 9.88% and 49% at the highest volume fraction of 0.20. The percentage of decrease in surface tension of the ferrofluid is observed as 45.8% at 0.20 volume fraction. The surface tension of ferrofluid decreases in connection with the rise in temperature from 293 to 333 K. Ó 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the First International Conference on Recent Advances in Materials and Manufacturing 2019.
1. Introduction Energy resource utilization is one of the most vital issues in the world. Hydrocarbon fuels, nuclear energy, and sustainable energy resources are the three primary energy sources in use today. The increased consumption of hydrocarbon fuels results in depletion of the ozone layer, climate change, and global warming. Renewable energy resources are the appropriate energy sources because they can be produced repeatedly from itself without causing any harm to the living world [1]. Energy from the sun is one among the essential eco-friendly energy sources due to non-polluting behaviour; it is a reliable source of electricity; it is long-running and requires low maintenance. Solar water heating systems utilize the heat generated from the solar irradiations and transfer this heat energy to the working fluid, consequently its temperature increases, and this fluid can be used for domestic purposes. Indirect water heating systems employ free convection heat transfer, in ⇑ Corresponding author. E-mail address: [email protected] (A. Brusly Solomon).
which thermal energy is transmitted from the solar collector to working fluids then transferred to the domestic supply with the aid of the heat exchanger. Therefore, the thermophysical property of the working fluid plays a significant role in thermal energy transmission. The thermal conductivity of working fluids, which is used for thermal energy transfer is low, and this leads to low heat absorption and low heat transfer efficiency [2]. The thermal conductivity of base thermal fluid can be enhanced by dispersing high thermal conductivity metals or metal oxides into the traditional fluids; as a result, the thermal conductivity of the base fluid increases. The size of the dispersed particle is a crucial factor; if the size of the diluted particles is less than100 nanometer, it alters the thermal properties of the base fluid and called nanofluid. There is numerous literature which delivers the data about the alteration in heat transfer properties of the conventional base fluid such as water, kerosene, ethylene glycol, etc. when mixed with nanoparticles like ceramic, metal, metal oxide, carbon nanotubes, etc. [3]. The maximum augmentation in thermal conductivity is reported as 100% when multiwalled carbon nanotube is used in nanofluid [4]. Metal oxide, like CuO, also enhanced the thermal conductivity
https://doi.org/10.1016/j.matpr.2019.09.014 2214-7853/Ó 2019 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the First International Conference on Recent Advances in Materials and Manufacturing 2019.
Please cite this article as: K. Ajith, I. V. Muthuvijayan Enoch, A. Brusly Solomon et al., Characterization of magnesium ferrite nanofluids for heat transfer applications, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.014
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K. Ajith et al. / Materials Today: Proceedings xxx (xxxx) xxx
of water by 75% [5]. Researchers are trying to augment the thermal conductivity of conventional fluids to its extreme by the use of ferrofluids with the application of a magnetic field. John Philip et al. [6] examined the importance of the magnetic field on kerosenebased Fe3O4 nanofluid. The magnetic induction of 0–500 G was applied and tested for the volume percentage from 0.031 to 6.3%. It was concluded that the presence of the magnetic field and a surge in the volume percentage of magnetic nanoparticle makes a historic enhancement on thermal conductivity of 300% at 82 Gauss. Wei Yu et al. [7] studied the use of Fe2O4/kerosene nanofluid by varying the temperature from 10 to 60 °C and ranged the particle concentration from 0.1 to 1%. The results reveal that the rise in the particle concentration and temperature improves the nanofluid thermal conductivity. The maximum enhancement was 34% at maximum particle concentration. Gui et al. [8] found that the magnetic nanoparticle concentration has a substantial effect on the rate of thermal energy transfer of the ferrofluid and is more at higher particle concentration. Studies were carried out for different levels of ferrotec EMG series-water based ferrofluid and determined that magnetic field strength and the heat transfer rate is inversely related. Decrease of heat transfer rate was observed with the increase of magnetic field strength because of the particle attraction to the channel wall when the magnetic flux is applied. Amani et al. [9] analysed the viscosity of manganese ferrite/ water ferrofluid by the application of different magnetic flux density, and the results obtained were related with the conclusions arrived in the nonattendance of magnetic flux. Volume concentration for this study was varied from 0.25% to 3%. Results showed that change in measured thermal property is directly proportional to the concentration of the particle and magnetic field. The study also concluded that viscosity of ferrofluid decreased with a rise in temperature. Arana et al. [10] prepared nickel ferrite ferrofluid by mixing nickel ferrite nanoparticle and kerosene as the base fluid for finding the consequence of magnetic flux density on the thermal property of the ferrofluid. The outcomes of the experimental study show that thermal conductivity improvement of the nickel ferrite ferrofluid is 170% in the existence of magnetic flux. Results indicate that thermal diffusivity of the ferrofluid is increased up to 70 times more than the base fluid kerosene without particle. Shahsavar et al. [11] studied the heat transfer properties of hybrid nanofluids comprising Fe3O4 magnetic nanoparticles and carbon nanotubes with water as the base fluid. The results indicate that the Fe3O4 particle concentration or CNT concentration has an impact on the variation of thermal properties. Also found, increasing particle concentration amplified the viscosity and thermal conductivity of the ferrofluid. Karimi et al. [12] used two different nanomaterials such as Fe3O4 and CoFe2O4, for preparing the water-based nanofluid. The volume fraction of ferrofluid is varied from 0 to 4.8% by dispersing these two different nanomaterials in
deionized water. At highest volume fraction such as 4.8%, the thermal conductivity of Fe3O4 and CoFe2O4 nanofluid is maximum. By the application of the magnetic flux density from 0 to 500 G, the thermal conductivity of both Ferrofluids (Fe3O4 and CoFe2O4) increased significantly. The maximum thermal conductivity augmentation is obtained at the lower magnetic field around 200 Gauss and is 196% for Fe3O4 nanofluid and 148% for CoFe2O4 nanofluid at volume fraction 4.8%. From the above short review of literature, it was noticed that the thermal properties of water, kerosene, and water/ethylene glycol are measured and used as base fluids. Also, thermal features of fluids containing nanoparticles such as Fe3O4, CoFe2O4, FeC, magnetic nanodiamond-cobalt oxide hybrid nanoparticles, maghemite nanoparticle, MnFe2O4 nanoparticle, ferrotec EMG series nanoparticles, and Nickel ferrite nanoparticles are measured. The results indicate that the thermal properties of the base fluid can be reformed using magnetic nanoparticle along with the application of a magnetic field. Moreover, the use of MgFe2O4 in heat transfer application is found to be rare, and the particle possesses high magnetic properties, the same is prepared using hydrothermal method and characterized. 2. Experimental procedure 2.1. Synthesis of MgFe2O4 nanoparticle, preparation, and characterization of ferrofluid Magnesium ferrite nanoparticle with chemical formula MgFe2O4 was prepared using the hydrothermal method, which is synthesized from the mixtures of metal nitrate hydrate solution. The raw material used for the synthesis of nanomaterial were analytical grade Iron (III) Nitrate nonahydrate, and Magnesium Nitrate hexahydrate was used as raw material and which are purchased from Sigma-Aldrich, which is 99.95% pure. The mixture comprising of Iron nitrate solution of 25 ml with molarity 0.4, magnesium nitrate solution of 25 ml with molarity 0.2 and 35 ml distilled water was prepared. After the mixing process, 0.05 molarity of glycerol was added to the mixture and this blend was heated at 150 °C for 18 h using autoclave reactor. After precipitation, it was filtered using Whatman filter paper and washed with deionized water. Then the filtered material was dehydrated at 70 °C for 3 h in a vacuum. Finally, the products were dried to obtain magnesium ferrite nanoparticle. SEM and TEM image of the synthesized magnesium ferrite nanoparticle are illustrated in Fig. 1(a) and (b) respectively. MgFe2O4 nanoparticles were suspended into the deionized water for preparing the magnetic nanofluid. The size and shape of magnesium ferrite nanoparticle synthesized by the hydrothermal method is 80 nm and is spherical, which is used for the preparation of magnetic nanofluid. A Hielscher UP400S ultrasonic mixer was
Fig. 1. (a) SEM image; (b) TEM image of the synthesized MgFe2O4 nanoparticle.
Please cite this article as: K. Ajith, I. V. Muthuvijayan Enoch, A. Brusly Solomon et al., Characterization of magnesium ferrite nanofluids for heat transfer applications, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.014
K. Ajith et al. / Materials Today: Proceedings xxx (xxxx) xxx
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used for the preparation nanofluid. The mixer was configured with 60% pulse time and 65% amplitude. The process took 20 min for 100 ml samples. After initial sonication, sodium dodecyl sulfate was added into the nanofluid as a surfactant for better stability. Following the addition of SDS, the mixture was sonicated for 10 min [13]. The thermal conductivity of magnesium ferrite ferrofluids is measured by KD2 pro. Brookfield DV-E viscometer is employed for measuring the viscosity of MgFe2O4 ferrofluid. The surface tension of prepared nanofluid is measured by the use of SITA portable surface tension Meter Dyno Tester. All thermal properties are observed between the volume fractions from 0.01 to 0.20.
fraction is increased, there is a proportionate intensification of viscosity. The viscosity augmented by 10% at 0.01 vol fraction of nanofluid and increased by 49% for 0.20 vol fraction compared to the viscosity of DI-water. Addition of nanoparticle into the base fluid forms large bunches of nanoparticles due to Van der Waals forces which lead to deterring of the fluid layer movement over the other layer, thereby increasing the viscosity. When the volume fraction is increased, the size of the formed nanoclusters also increases, and hence, there is a proportionate increase in viscosity [9].
3. Result and discussion
The surface tension of the base fluid calculated is 73.2 mN/m at 303 K. By the addition of magnesium ferrite nanoparticle, the surface tension of the prepared ferrofluid is lessened. The variation of surface tension concerning volume fraction is illustrated in Fig. 3 (a). The surface tension is decreased significantly with the change in volume fraction from 0.01 to 0.20. The percentage of decrease of surface tension is 3.08% at a volume fraction of 0.01 and 45.8% at a volume fraction of 0.20. Surface tension is a vital thermal property for heat transfer in heat pipes, which is a heat transfer device used for electronics cooling. The reduced surface tension of the working fluid enhances the capillary effect in the heat pipe and leads to better circulation of working fluid from condenser to evaporator and leading to the better thermal performance of the heat pipe. Fig. 3(b) shows the change in surface tension of the ferrofluid at various concentration concerning the temperature. It is observed that surface tension of the ferrofluid decreases with the surge in temperature from 20 to 60 °C By increasing the temperature the liquid molecules move to higher kinetic energy and hence coherent
3.1. Volume fraction effect on the thermal conductivity and viscosity of MgFe2O4 ferrofluid The impact of the intensification in MgFe2O4 particle concentration on the thermal conductivity of magnesium ferrite ferrofluid is shown in Fig. 2(a). It is found that the thermal conductivity of the Deionized water is 0.597 W/mK at 298 K. The thermal conductivity of the prepared ferrofluid is measured at different particle concentration in the range of 0.01–0.20. The thermal conductivity of the ferrofluid is improved by 5.19%, 6.86%, 7.53%, 8.04, and 9.88% respectively for the concentrations 0.01,0.05,0.10, 0.15 and 0.2 when compared to water. Thermal conductivity of MgFe2O4 nanoparticle is high and leads to the enhancement of thermal conductivity of prepared ferrofluid. The relation between viscosity of the MgFe2O4 ferrofluid and the magnetic nanoparticle volume fraction is shown in Fig. 2. (b). It is found that when the volume
3.2. The surface tension of MgFe2O4 ferrofluid at various volume fraction and temperature
Fig. 2. Result of change in volume fraction on a) Thermal conductivity; b) Viscosity of magnesium ferrite nanofluid.
Fig. 3. The surface tension of magnesium ferrite nanofluid at a) various volume fraction; b) various temperature.
Please cite this article as: K. Ajith, I. V. Muthuvijayan Enoch, A. Brusly Solomon et al., Characterization of magnesium ferrite nanofluids for heat transfer applications, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.014
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Fig. 4. Comparison of theoretical and measured a) Thermal conductivity; b) Relative viscosity of ferrofluids.
forces between the liquid molecules and the surface tension is reduced [14]. 3.3. Validation of experimental data with theoretical models The measured and theoretical thermal conductivity of nanofluids is compared and presented in Fig. 4(a). The theoretical correlations developed by Timofeeva [15] and Sundar [16] are considered for comparison. It is observed that the measured and theoretical thermal conductivity of MgFe2O4/water ferrofluid is comparable. However, Timofeeva model is deviating from the measurements. Fig. 4(b) shows the analogy between the relative viscosity observed and those computed by Einstein [17], Batchelor [18], Brinkman [19], and Sundar [16] model. The observation is that Brinkman and Batchelor correlation approximately predicts with 96% confidence level up to 0.10 vol fraction beyond that it deviates largely. Finally, the enhancement in thermophysical properties suggests that this ferrofluid is suitable for heat transfer applications. 4. Conclusion The experimental investigation is carried out for finding the suitability of magnesium ferrite nanofluid for heat transfer application by measuring the heat transfer properties of the ferrofluid. The hydrothermal method is used to synthesize MgFe2O4 nanoparticles. The volume fraction is changed from 0.01 to 0.20 and which improves the thermal conductivity and viscosity of the ferrofluid. At ambient temperature, the improvement in thermal conductivity was observed 9.88% and 49% enrichment in viscosity at 0.20 vol fraction. The surface tension of the prepared ferrofluid shows an inverse response for the surge in volume fraction. The percentage of decrease in the surface tension at volume fraction 0.20 is 45.8% and surface tension of the ferrofluid decreases with increase in temperature. The above results show that the magnesium ferrite/water nanofluid is suitable for the heat transfer application, such as heat pipes. Acknowledgments The authors would like to thank DST – SERB, India. (DST/SERB/ YSS/2015/001084) for the financial support for this research work.
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Please cite this article as: K. Ajith, I. V. Muthuvijayan Enoch, A. Brusly Solomon et al., Characterization of magnesium ferrite nanofluids for heat transfer applications, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.09.014