Thermal Conductivity of Nanoparticle - Fluid Mixture

Wang, Xinwei; Xu, Xianfan; Choi, Seok Jin

doi:10.2514/2.6486

Cited by 2,062 publications

(861 citation statements)

References 24 publications

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“…In contrast to pH 4 and 7, f-Cu 2+ was nondetect at pH 11 both via direct measurements and modeling. Hydrolysis of Cu 2+ occurs at alkaline pH so it exists mostly as Cu(OH) 4 2− , Cu(OH) + , Cu(OH) 2 , and Cu(OH) 3 − . In general, Kocide had higher amounts of dissolved and suspended Cu than nano-Cu and nano-CuO at pH 7 on Cu mass basis.…”

Section: Speciationmentioning

confidence: 99%

Influence of Extracellular Polymeric Substances on the Long-Term Fate, Dissolution, and Speciation of Copper-Based Nanoparticles

Adeleye

Conway

Pérez

et al. 2014

Environ. Sci. Technol.

209

216

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ABSTRACT:The influence of phytoplankton-derived soluble extracellular polymeric substances (EPS), pH, and ionic strength (IS) on the dissolution, speciation, and stability of nano-CuO, nano-Cu, and Kocide (a micron sized Cu(OH) 2 -based fungicide) was investigated over 90 days. EPS improved the stability of commercial copper-based nanoparticles (CBNPs) in most conditions, in addition to influencing their dissolution. The dissolution rate was pH 4 ≫ pH 7 > pH 11. The presence of EPS correlated with higher dissolved Cu at pH 7 and 11, and lower dissolved Cu at pH 4. More dissolution was observed at higher IS (NaCl) due to complexation with Cl − . Dissolution of nano-CuO at pH 7 increased from 0.93% after 90 days (without EPS) to 2.01% (with 5 mg-C EPS/L) at 10 mM IS. Nano-CuO dissolved even more (2.42%) when IS was increased to 100 mM NaCl (with EPS). The ratio of freeCu 2+ /total dissolved Cu decreased in the presence of EPS, or as pH and/or IS increased. On a Cu mass basis, Kocide had the highest dissolved and suspended Cu at pH 7. However, dissolution of nano-Cu resulted in a higher fraction of free Cu 2+ , which may make nano-Cu more toxic to pelagic organisms. ■ INTRODUCTIONGlobal production of copper-based nanoparticles (CBNPs) was estimated at ∼200 t/yr in 2010, and is increasing. 1 CBNPs have found use in cosmetics, pigments, paints and coatings, electronics, and pesticides. 2−4 These applications may lead to direct exposure of CBNPs to the environment due to normal use, product wear-and-tear, and/or end-of-life disposal. 1 Toxicity of CBNPs and composites to organisms has been demonstrated. 2,5−8 It is therefore important to understand the long-term fate and transformations of these materials in aquatic systems in order to predict exposure to at-risk organisms.Stability and dissolution of engineered nanoparticles (ENPs) depend on ionic strength (IS), pH, and natural organic material (NOM). 9−12 Rapid aggregation of nano-Cu was reported in freshwater by Griffitt et al. 5 The authors also found that less than 0.1% of the nano-Cu dissolved in 48 h in the freshwater media used (pH 8.2). 98% dissolution of nano-Cu was however reported at pH 6 in "uterine-fluid" after a week, 13 demonstrating the importance of pH and media composition on CBNPs' dissolution. Mudunkotuwa and co-workers 14 reported increased dissolution of aged and new CBNPs in the presence of organic acids. Similarly, Worthington et al. 15 showed that the chitosan improved stability and dissolution of nano-Cu. To our knowledge, no studies have previously investigated the effects of naturally occurring NOM such as extracellular polymeric substances (EPS) on the stability and dissolution of CBNPs. EPS are synthesized by microorganisms, which are abundant in natural aquatic systems. EPS are mainly composed of polysaccharides, proteins, nucleic acids, and other polymers; and their composition may vary spatially and temporally even within the same species. 16 EPS may interact with ENPs, thus affecting their fate and transformation. 17 Additional...

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Section: Speciationmentioning

confidence: 99%

Influence of Extracellular Polymeric Substances on the Long-Term Fate, Dissolution, and Speciation of Copper-Based Nanoparticles

Adeleye

Conway

Pérez

et al. 2014

Environ. Sci. Technol.

209

216

View full text Add to dashboard Cite

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“…6 and 7 show a comparison between the practical measurement of dynamic viscosity with that obtained from the empirical relation of Einstain, 1956 model [14], Brinkman, 1952 model [15], Wang et al model [16] and Batchel model [17]. Figs.…”

Section: Measurement Of the Nanofluid Thermal Propertiesmentioning

confidence: 99%

“…Lee et al [2], observed enhancement of thermal conductivity of nanofluids using CuO and Al2O3 nanoparticles with water and ethylene glycol compared to base fluids. The thermal conductivities of nanofluids with CuO and Al2O3 nanoparticles have been determined experimentally using steady -state parallel -plate technique by Wang et al [3], for different base fluids such as water, ethylene glycol and engine oil. The thermal conductivity of these nanofluids is increased with increasing volume fraction of the nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Experimental Analysis of Heat Transfer Enhancement and Flow with Cu, TiO2 Ethylene Glycol Distilled Water Nanofluid in Spiral Coil Heat

Sultan

2017

Tikrit j. eng. sci.

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Nanofluid ethylene glycol enhancement metallic nano metallic A R T I C L E I N F O A B S T R A C TThis experimental investigation was performed to improve heat transfer in the heat exchanger (tube of shell and helically coiled (using nanoparticles for turbulent parallel flow and counter flow of distilled water (Dw) and ethylene glycol (EG) fluids. Six types of nanofluids have been used namely: copper -distilled water, copper -distilled water and ethylene glycol, copper -ethylene glycol, titanium oxide -distilled water, titanium oxide -distilled water and ethylene glycol, titanium oxide -ethylene glycol with 0.5%,1%,2%,3% and 5% volume concentration as well as the range of Reynolds number are 4000 -15000. The experimental results reveal that an increase in coefficient of heat transfer of 50.2 % to Cu -Dw, 41.5% to Cu -( EG + Dw ), 32.12 % for Cu -EG , 36.5% for TiO2 -Dw, 30.2 % to TiO2 -( EG + Dw) and 25.5%, to TiO2 -EG . The strong nanoconvection currents and good mixing caused by the presence of Cu and TiO2 nanoparticles. The metal nanofluids give more improvement than oxide nanofluids. The shear stress of nanofluids increases with concentration of nanoparticles in the case of parallel and counter flow. The effect of flow direction is insignificant on coefficient of overall heat transfer and the nanofluids behave as the Newtonian fluid for 0.5%,1%,2%,3% and 5%. Good assent between the practical data and analytical prediction to nanofluids friction factor which means the nanofluid endure pump power with no penalty. This study reveals that the thermal performance from nanofluid Cu -Dw is higher than Cu -(EG + Dw) and Cu -EG due to higher thermal conductivity for the copper and distilled water compared with ethylene glycol.

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“…The length of crystallizer tank is 25 cm. Before starting the performance, the prepared magnesium sulfate solution was kept at a constant and maintained initial temperature at 60 ˚C with the help of heating tank in crystallizer consisting heater and stirrer in which the constant temperature is maintained by control system consisting of thermocouple 12 . The magnesium sulfate solution was kept in inner tank of crystallizer and the cold fluid flows through annular space between inner tank and jacket.…”

Section: Thermocouplesmentioning

confidence: 99%

Influence of Nanofluid on the Performance of Crystallization

2014

Chem Sci Trans

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Nanofluids, the fluid suspensions of nanomaterials , have shown many interesting properties, and the distinctive feature offer unprecedented potential for many applications. Nanofluids which are known as new generation of thermal fluids have particular feature which are affected on their behavior. Present paper focuses on behavior of nanofluids in crystallization. The objectives of this paper are to visualize the effect of nanofluid in crystallization operation as compared to convectional fluids i.e water (DW). Results are presented in terms of heat transfer coefficient. For 1% nanofluid heat transfer coefficient is 255.645 w/m 2o K and 264.438 w/m 2o K for 3% nanofluids which enhance significantly the crystallization performance. The use of CuO nanofluids in crystallizer increases the yield of crystallizer. The percentage increase in yield for 1% nanofluids is 4.4% and for 3% nanofluids percentage increase in yield was 5.5%. The nanoparticles used in the experiment was 98.5% pure copper oxide, with an average particle size of 32 nm synthesized by using chemical precipitation method. The nanofluid was prepared by mixing nanoparticles with de-ionized water to prepare experimental concentration of 1% and 3%. The magnesium sulfate solution to be crystallizing is prepared in lab and the average percentage increases heat transfer coefficients for 1% nano-Fluid was found to be 13.1% and 22.31 for 3% nanofluids.

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Thermal Conductivity of Nanoparticle - Fluid Mixture

Cited by 2,062 publications

References 24 publications

Influence of Extracellular Polymeric Substances on the Long-Term Fate, Dissolution, and Speciation of Copper-Based Nanoparticles

Influence of Extracellular Polymeric Substances on the Long-Term Fate, Dissolution, and Speciation of Copper-Based Nanoparticles

Experimental Analysis of Heat Transfer Enhancement and Flow with Cu, TiO2 Ethylene Glycol Distilled Water Nanofluid in Spiral Coil Heat

Influence of Nanofluid on the Performance of Crystallization

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