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Somchai Wongwises - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of rheological properties and thermal conductivity of SiO_2–P25 TiO_2 hybrid Nanofluids
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Zalán István Várady, István Endre Lukács, János Molnár, Ida Anna Balczár, Somchai Wongwises, Imre Miklós SzilágyiAbstract:Over many years, great efforts have been made to develop new fluids for heat transfer applications. In this paper, the thermal conductivity (TC) and viscosity of SiO_2–P25 TiO_2 (SiO_2–P25) hybrid Nanofluids were investigated for different nanoparticle volume concentrations (0.5, 1.0 and 1.5 vol%) at five various temperatures (20, 30, 40, 50 and 60 °C). The mixture ratio (SiO_2:P25) in all prepared hybrid Nanofluids was 1:1. Besides, pure SiO_2, P25 Nanofluids were prepared with the same concentrations for comparison with the hybrid Nanofluids. The base fluid used for the preparation of Nanofluids was a mixture of deionized water and ethylene glycol at a ratio of 5:1. Before preparing the Nanofluids, the nanoparticles were analyzed with energy-dispersive X-ray analysis, scanning electron microscope, X-ray powder diffraction, and Fourier transform infrared spectroscopy. The zeta potentials of the prepared Nanofluids except SiO_2 Nanofluids were above 30 mV. These Nanofluids were visually observed for stability in many days. The TC enhancement of the hybrid Nanofluid was higher than the pure Nanofluid. In particular, with 1.0 vol% concentration, the maximum enhancement of SiO_2, P25 and SiO_2–P25 Nanofluids were 7.5%, 9.9% and 10.5%, respectively. The rheology of the Nanofluids was Newtonian. The viscosity increment of SiO_2, P25 and hybrid Nanofluids were 19%, 32% and 24% with 0.5 vol% concentration. A new correlation was developed for the TC and dynamic viscosity of SiO_2–P25 hybrid Nanofluid.
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effect of thermophysical properties models on the predicting of the convective heat transfer coefficient for low concentration Nanofluid
International Communications in Heat and Mass Transfer, 2008Co-Authors: Weerapun Duangthongsuk, Somchai WongwisesAbstract:Abstract The term of Nanofluid refers to a solid–liquid mixture with a continuous phase which is a nanometer sized nanoparticle dispersed in conventional base fluids. In order to study the heat transfer behavior of the Nanofluids, precise values of thermal and physical properties such as specific heat, viscosity and thermal conductivity of the Nanofluids are required. There are a few well-known correlations for predicting the thermal and physical properties of Nanofluids which are often cited by researchers to calculate the convective heat transfer behaviors of the Nanofluids. Each researcher has used different models of the thermophysical properties in their works. This article aims to summarize the various models for predicting the thermophysical properties of Nanofluids which have been commonly cited by a number of researchers and use them to calculate the experimental convective heat transfer coefficient of the Nanofluid flowing in a double-tube counter flow heat exchanger. The effects of these models on the predicted value of the convective heat transfer of Nanofluid with low nanoparticle concentration are discussed in detail.
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effect of thermophysical properties models on the predicting of the convective heat transfer coefficient for low concentration Nanofluid
International Communications in Heat and Mass Transfer, 2008Co-Authors: Weerapun Duangthongsuk, Somchai WongwisesAbstract:Abstract The term of Nanofluid refers to a solid–liquid mixture with a continuous phase which is a nanometer sized nanoparticle dispersed in conventional base fluids. In order to study the heat transfer behavior of the Nanofluids, precise values of thermal and physical properties such as specific heat, viscosity and thermal conductivity of the Nanofluids are required. There are a few well-known correlations for predicting the thermal and physical properties of Nanofluids which are often cited by researchers to calculate the convective heat transfer behaviors of the Nanofluids. Each researcher has used different models of the thermophysical properties in their works. This article aims to summarize the various models for predicting the thermophysical properties of Nanofluids which have been commonly cited by a number of researchers and use them to calculate the experimental convective heat transfer coefficient of the Nanofluid flowing in a double-tube counter flow heat exchanger. The effects of these models on the predicted value of the convective heat transfer of Nanofluid with low nanoparticle concentration are discussed in detail.
Zhengguo Zhang - One of the best experts on this subject based on the ideXlab platform.
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preparation and photo thermal conversion performance of modified graphene ionic liquid Nanofluids with excellent dispersion stability
Solar Energy Materials and Solar Cells, 2017Co-Authors: Jian Liu, Leilei Chen, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract Dispersion stability has been long considered as a critical issue for applying Nanofluids in various fields, especially for the applications at elevated temperatures. Herein a novel route is explored to improve the dispersion stability of graphene (GE)/ionic liquid (IL) Nanofluids for use as working fluids in medium- and high-temperature direct absorption solar collectors (DASCs), which involves modifying GE according to the molecular structure of the IL. Specifically, GE was modified using the reagents and process for synthesizing [HMIM]BF 4 , followed by dispersing the modified GE (MGE) into [HMIM]BF 4. It is verified that the molecular chains similar to [HMIM]BF 4 have been grafted on the nanosheets of GE, and the MGE/[HMIM]BF 4 Nanofluids exhibit much better dispersion stability than the one containing the unmodified GE, even at elevated temperatures. Moreover, the temperature profiles of the Nanofluids containing MGE and GE were obtained both from the experimental measurement and the theoretical prediction using a one-dimensional transient heat transfer model. It is shown that the experimental data are in good agreement with the numerical ones for the MGE Nanofluids, while a large deviation between them is found for the one containing the unmodified GE. And the MGE Nanofluid shows enhanced receiver efficiency as compared to the GE one due to its much improved dispersion stability. Further, the transient model was used to predict the performance of the MGE Nanofluid based DASCs under high solar concentrations. And by integrating the MGE concentration and the receiver height into a parameter, namely optical thickness, the optimization of the MGE Nanofluid based DASC was carried out varying solar concentration, MGE concentration, Nanofluid height and exposure time. It is revealed that the photo-thermal conversion performance of Nanofluids greatly depends on its dispersion stability at elevated temperatures, and the MGE/[HMIM]BF 4 Nanofluids possess excellent dispersion stability and show great potentials for use as the working fluids in DASCs. This work sheds light on effective routes for improving dispersion stability of Nanofluids as well as numerical investigations on Nanofluid based DASCs.
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Preparation and photo-thermal conversion performance of modified graphene/ionic liquid Nanofluids with excellent dispersion stability
Solar Energy Materials and Solar Cells, 2017Co-Authors: Jian Liu, Leilei Chen, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract Dispersion stability has been long considered as a critical issue for applying Nanofluids in various fields, especially for the applications at elevated temperatures. Herein a novel route is explored to improve the dispersion stability of graphene (GE)/ionic liquid (IL) Nanofluids for use as working fluids in medium- and high-temperature direct absorption solar collectors (DASCs), which involves modifying GE according to the molecular structure of the IL. Specifically, GE was modified using the reagents and process for synthesizing [HMIM]BF 4 , followed by dispersing the modified GE (MGE) into [HMIM]BF 4. It is verified that the molecular chains similar to [HMIM]BF 4 have been grafted on the nanosheets of GE, and the MGE/[HMIM]BF 4 Nanofluids exhibit much better dispersion stability than the one containing the unmodified GE, even at elevated temperatures. Moreover, the temperature profiles of the Nanofluids containing MGE and GE were obtained both from the experimental measurement and the theoretical prediction using a one-dimensional transient heat transfer model. It is shown that the experimental data are in good agreement with the numerical ones for the MGE Nanofluids, while a large deviation between them is found for the one containing the unmodified GE. And the MGE Nanofluid shows enhanced receiver efficiency as compared to the GE one due to its much improved dispersion stability. Further, the transient model was used to predict the performance of the MGE Nanofluid based DASCs under high solar concentrations. And by integrating the MGE concentration and the receiver height into a parameter, namely optical thickness, the optimization of the MGE Nanofluid based DASC was carried out varying solar concentration, MGE concentration, Nanofluid height and exposure time. It is revealed that the photo-thermal conversion performance of Nanofluids greatly depends on its dispersion stability at elevated temperatures, and the MGE/[HMIM]BF 4 Nanofluids possess excellent dispersion stability and show great potentials for use as the working fluids in DASCs. This work sheds light on effective routes for improving dispersion stability of Nanofluids as well as numerical investigations on Nanofluid based DASCs.
A. Venu Vinod - One of the best experts on this subject based on the ideXlab platform.
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Heat transfer enhancement using non-Newtonian Nanofluids in a shell and helical coil heat exchanger
Experimental Thermal and Fluid Science, 2018Co-Authors: B. Anil Kumar Naik, A. Venu VinodAbstract:Abstract The current investigation examines heat transfer using three different non-Newtonian Nanofluids comprising of Fe 2 O 3 , Al 2 O 3 and CuO nanoparticles in aqueous carboxymethyl cellulose (CMC) base fluid. The studies were carried out to determine enhancement in heat transfer compared to base fluid (aqueous CMC solution) in a shell and helical coil heat exchanger. Non-Newtonian Nanofluids containing nanoparticles in the concentration range of 0.2–1.0 wt% were prepared. Nanofluid and water were used on shell side and tube side respectively. The thermal analysis was carried out to determine overall heat transfer coefficient and shell-side Nusselt number, at different conditions such as flow rate of cold water (0.5–5 lpm), shell side fluid (Nanofluid) temperature (40–60 °C) and stirrer speeds (500–1500 rpm). The results show that the Nusselt number increases with increasing Nanofluid concentration, shell side fluid temperature, Dean number (flow rate of coil-side water), and stirrer speeds. It was found that the CuO/CMC-based Nanofluid showed better heat transfer than the other two types of fluid (Fe 2 O 3 and Al 2 O 3 ). The heat transfer performance of non-Newtonian Nanofluids was significantly enhanced at higher Nanofluid concentrations, shell-side temperatures, stirrer speeds and Dean numbers.
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Heat transfer intensification in a shell and helical coil heat exchanger using water-based Nanofluids
Chemical Engineering and Processing: Process Intensification, 2016Co-Authors: Tangellapalli Srinivas, A. Venu VinodAbstract:Abstract Nanofluids have been reported to be capable of heat transfer intensification. Performance of an agitated shell and helical coil heat exchanger has been experimentally investigated using three water based Nanofluids (Al 2 O 3 , CuO and TiO 2 ). The studies were carried out at different concentrations of Nanofluid, Nanofluid temperatures, stirrer speeds and coil-side fluid flow rates. Nanofluids of three concentrations 0.3, 0.6, 1, 1.5 and 2% by weight have been prepared for this purpose. Cetyltrimethyl ammonium bromide (CTAB) was used as stabilizer. Nanofluid was used as heating medium (shell-side) and water was used as coil-side fluid. It was found that heat transfer rate increases with increase in Nanofluid concentration. Higher values of Nanofluid concentration, stirrer speed and shell-side fluid temperature resulted in greater effectiveness of heat exchanger. A maximum increase of 30.37%, 32.7% and 26.8% in effectiveness of heat exchanger was observed for Al 2 O 3 , CuO and TiO 2 /water Nanofluids respectively, when compared to water, indicating intensification of heat transfer.
Mohd Faizul Mohd Sabri - One of the best experts on this subject based on the ideXlab platform.
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Performance evaluation of a shell and tube heat exchanger operated with oxide based Nanofluids
Heat and Mass Transfer, 2016Co-Authors: I.m. Shahrul, I.m. Mahbubul, Rahman Saidur, S. S. Khaleduzzaman, Mohd Faizul Mohd SabriAbstract:This study is about the performance evaluation of a shell and tube heat exchanger operated with Nanofluid. Thermal conductivity, viscosity, and density of the Nanofluids were increased, but the specific heat of the Nanofluids was decreased with increasing the concentrations of the particles. The convective heat transfer coefficient was found to be 2–15 % higher than that of water at 50 kg/min of both side fluid. Nevertheless, energy effectiveness has improved about 23–52 % for the above-mentioned Nanofluids. As, energy effectiveness (ɛ) is strongly depends on the density and specific heat of the operating fluids therefore, maximum ɛ has obtained for ZnO–W Nanofluid and lowest found for SiO_2–W Nanofluid.
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a comparative review on the specific heat of Nanofluids for energy perspective
Renewable & Sustainable Energy Reviews, 2014Co-Authors: I.m. Shahrul, R Saidur, I.m. Mahbubul, S. S. Khaleduzzaman, Mohd Faizul Mohd SabriAbstract:Abstract Nanofluid is one of the novel inventions of science. Nanofluid can be used for energy savings by increasing the heat transfer performance of the heat recovery systems, which are generally struggling to overcome the present challenging issues such as global warming, greenhouse effect, climate change, and fuel crisis. Specific heat capacity is necessary to analyze energy and exergy performances. This paper extant different characteristic of specific heat capacity of Nanofluids containing preparation and measuring methods, effects of volume fraction, temperature, types and sizes of nanoparticles and base fluids. Additionally a compilation has been done on available theoretical correlation related to specific heat of Nanofluid. Based on existing experimental and theoretical results, Nanofluid specific heat falls with the enhancement of volume concentration of nanoparticle though there are some inconsistencies among outcomes. Moreover, specific heat of the Nanofluids are generally increased after adding dispersant in the mixtures. However, many contradictory results about the effects of temperatures on specific heat of Nanofluids found in the literatures. Therefore, this review will help the researchers and related peoples to get enough information to select a Nanofluid based on specific heat for their practical applications.
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effectiveness study of a shell and tube heat exchanger operated with Nanofluids at different mass flow rates
Numerical Heat Transfer Part A-applications, 2014Co-Authors: I.m. Shahrul, Mohd Faizul Mohd Sabri, I.m. Mahbubul, Rahman Saidur, S. S. Khaleduzzaman, Mustafizur RahmanAbstract:Several challenging issues, such as global warming, greenhouse effect, fuel security, and the high price of energy, motivate people to think about energy savings. Energy can be saved by effectively using available materials and facilities. Heat exchangers play a significant part in the field of energy conservation, conversion, and recovery. Nanofluids can be used in the heat exchangers to reduce global energy losses. Thermal performance of a shell and tube heat exchanger operated with Nanofluids has been analytically investigated at different mass flow rates and compared with water as the base fluid. Suspensions of ZnO, CuO, Fe3O4, TiO2, and Al2O3 nanoparticles in water (W) at 0.03 volumetric fractions have been considered. It is found that, for a certain mass flow rate (50 kg/min) of tube side and shell side fluid, the highest heat transfer coefficient (h) belongs to Al2O3-WNanofluid and the lowest to CuO-W Nanofluid. However, maximum energy effectiveness (ϵ) improvement took place by 43% for ZnO-W nanof...
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investigating the heat transfer performance and thermophysical properties of Nanofluids in a circular micro channel
International Communications in Heat and Mass Transfer, 2013Co-Authors: M R Sohel, R Saidur, Mohd Faizul Mohd Sabri, M Kamalisarvestani, Mohamad Fathi Mohamad Elias, Ali IjamAbstract:Abstract In this paper, the thermal performance of a circular shaped copper microchannel heat sink using three types of Nanofluids is discussed analytically. Al2O3–Water, TiO2–water and CuO–water Nanofluids were used in this analysis and the comparative thermal performance of these three Nanofluids is also discussed. The hydraulic diameter of the circular channel is 400 μm and the total block dimension is 10 mm × 10 mm × 4 mm. A steady, laminar and incompressible flow with constant heat flux is assumed in the circular channel. The analyses are done at various volume fractions ranging from 0.5 vol.% to 4 vol.% and at a constant inlet velocity of 1.5 m/s. The results showed that the thermal performance can be increased significantly by using CuO–water Nanofluid as a coolant for cooling of electronic heat sink when Al2O3–water and TiO2–water Nanofluids showed less improvement. Compared to pure water, the highest improvement (13.15%) in the heat flux occurred for 4 vol.% CuO–water Nanofluid when Al2O3–water and TiO2–water Nanofluids showed 6.80% and 6.20% improvements respectively. This improvement in heat flux is calculated without considering the additional required pumping power due to the increased viscosity of Nanofluids. Therefore, CuO–water Nanofluid can be recommended to obtain maximum heat transfer performance in a circular microchannel heat sink.
Jian Liu - One of the best experts on this subject based on the ideXlab platform.
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preparation and photo thermal conversion performance of modified graphene ionic liquid Nanofluids with excellent dispersion stability
Solar Energy Materials and Solar Cells, 2017Co-Authors: Jian Liu, Leilei Chen, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract Dispersion stability has been long considered as a critical issue for applying Nanofluids in various fields, especially for the applications at elevated temperatures. Herein a novel route is explored to improve the dispersion stability of graphene (GE)/ionic liquid (IL) Nanofluids for use as working fluids in medium- and high-temperature direct absorption solar collectors (DASCs), which involves modifying GE according to the molecular structure of the IL. Specifically, GE was modified using the reagents and process for synthesizing [HMIM]BF 4 , followed by dispersing the modified GE (MGE) into [HMIM]BF 4. It is verified that the molecular chains similar to [HMIM]BF 4 have been grafted on the nanosheets of GE, and the MGE/[HMIM]BF 4 Nanofluids exhibit much better dispersion stability than the one containing the unmodified GE, even at elevated temperatures. Moreover, the temperature profiles of the Nanofluids containing MGE and GE were obtained both from the experimental measurement and the theoretical prediction using a one-dimensional transient heat transfer model. It is shown that the experimental data are in good agreement with the numerical ones for the MGE Nanofluids, while a large deviation between them is found for the one containing the unmodified GE. And the MGE Nanofluid shows enhanced receiver efficiency as compared to the GE one due to its much improved dispersion stability. Further, the transient model was used to predict the performance of the MGE Nanofluid based DASCs under high solar concentrations. And by integrating the MGE concentration and the receiver height into a parameter, namely optical thickness, the optimization of the MGE Nanofluid based DASC was carried out varying solar concentration, MGE concentration, Nanofluid height and exposure time. It is revealed that the photo-thermal conversion performance of Nanofluids greatly depends on its dispersion stability at elevated temperatures, and the MGE/[HMIM]BF 4 Nanofluids possess excellent dispersion stability and show great potentials for use as the working fluids in DASCs. This work sheds light on effective routes for improving dispersion stability of Nanofluids as well as numerical investigations on Nanofluid based DASCs.
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Preparation and photo-thermal conversion performance of modified graphene/ionic liquid Nanofluids with excellent dispersion stability
Solar Energy Materials and Solar Cells, 2017Co-Authors: Jian Liu, Leilei Chen, Xiaoming Fang, Zhengguo ZhangAbstract:Abstract Dispersion stability has been long considered as a critical issue for applying Nanofluids in various fields, especially for the applications at elevated temperatures. Herein a novel route is explored to improve the dispersion stability of graphene (GE)/ionic liquid (IL) Nanofluids for use as working fluids in medium- and high-temperature direct absorption solar collectors (DASCs), which involves modifying GE according to the molecular structure of the IL. Specifically, GE was modified using the reagents and process for synthesizing [HMIM]BF 4 , followed by dispersing the modified GE (MGE) into [HMIM]BF 4. It is verified that the molecular chains similar to [HMIM]BF 4 have been grafted on the nanosheets of GE, and the MGE/[HMIM]BF 4 Nanofluids exhibit much better dispersion stability than the one containing the unmodified GE, even at elevated temperatures. Moreover, the temperature profiles of the Nanofluids containing MGE and GE were obtained both from the experimental measurement and the theoretical prediction using a one-dimensional transient heat transfer model. It is shown that the experimental data are in good agreement with the numerical ones for the MGE Nanofluids, while a large deviation between them is found for the one containing the unmodified GE. And the MGE Nanofluid shows enhanced receiver efficiency as compared to the GE one due to its much improved dispersion stability. Further, the transient model was used to predict the performance of the MGE Nanofluid based DASCs under high solar concentrations. And by integrating the MGE concentration and the receiver height into a parameter, namely optical thickness, the optimization of the MGE Nanofluid based DASC was carried out varying solar concentration, MGE concentration, Nanofluid height and exposure time. It is revealed that the photo-thermal conversion performance of Nanofluids greatly depends on its dispersion stability at elevated temperatures, and the MGE/[HMIM]BF 4 Nanofluids possess excellent dispersion stability and show great potentials for use as the working fluids in DASCs. This work sheds light on effective routes for improving dispersion stability of Nanofluids as well as numerical investigations on Nanofluid based DASCs.
