Experimental investigation of pressure drop and heat transfer performance of amino acid-functionalized MWCNT in the circular tube
12 Apr 2016-Journal of Thermal Analysis and Calorimetry (Springer Netherlands)-Vol. 124, Iss: 1, pp 205-214
TL;DR: In this paper, an experimental study was conducted to clarify the forced convective heat transfer coefficient and pressure drop of water-based nanofluid including multi-walled carbon nanotubes (MWCNT) flowing through a horizontal circular tube.
Abstract: In this research, an experimental study was conducted to clarify the forced convective heat transfer coefficient and pressure drop of water-based nanofluid including multi-walled carbon nanotubes (MWCNT) flowing through a horizontal circular tube. In order to prepare a stable colloidal suspension in aqueous media, two methods of non-covalent and covalent functionalizations were used by gum Arabic (GA) and arginine (Arg), respectively. Both nanofluids of MWCNT-GA/water and MWCNT-Arg/water were prepared at concentrations of 0.1 and 0.2 mass%, and they were investigated in a laminar regime (Re = 800–2000) at constant heat flux. A significant increase in the convective heat transfer coefficient with the addition of the Arg-functionalized MWCNT was the main achievement. Also, the convective heat transfer coefficient increased with increasing the nanofluid concentration and Reynolds number. Note that the thermal performance of MWCNT-Arg/water nanofluid is better than MWCNT-GA/water nanofluid. In addition, the low mass concentration of MWCNT had an insignificant effect on the pressure drop enhancement. Performance index results also showed that both prepared nanofluids are appropriate alternative for heat transfer equipment.
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TL;DR: In this article, two design methods and feed-forward neural network were provided to model the thermal conductivity of hybrid nanofluid and two data estimation methods with experimental data showed that both methods are accurate for predicting data.
Abstract: In the present study, measurement and optimization of the thermal conductivity of a hybrid nanofluid are carried out. SiO2 nanoparticles with average diameter of 20–30 nm and multi-walled carbon nanotube (MWCNT), with internal and external diameter of 2–6 and 5–20 nm, respectively, were dispersed in ethylene glycol and made the hybrid SiO2–MWCNT (85:15)–ethylene glycol nanofluid. The thermal conductivity of nanofluids in volume fractions of 0.05–1.95 % at temperatures between 30 and 50 °C is measured experimentally. The results indicated that thermal conductivity ratio (TCR) of hybrid nanofluids increases nonlinearly with increasing temperature and concentration. Thus, the greatest increase in TCR at a concentration of 1.94 % and a temperature of 50 °C was 22.2 %. Studying the cost of production and the suspension of hybrid nanofluid and nanofluid containing SiO2 and MWCNT particles illustrated that using the hybrid nanofluid could be the most optimal one in terms of cost and percentage of TCR. In order to model the thermal conductivity of hybrid nanofluid, two design methods and feed-forward neural network were provided. R
2 value of new methods and artificial neural network (ANN) was obtained 0.9864 and 0.9981, respectively. Comparing these two data estimation methods with experimental data showed that both methods are accurate for predicting data. But ANN has much less error than the correlation outputs.
144 citations
TL;DR: In this paper, the effect of attack angle of triangular ribs, by using finite volume method, has been numerically studied in a two-dimensional microchannel, where cooling fluid is water/Ag nanofluid with volume fractions of 0-4% of nanoparticles, and nanoparticle diameters are 25, 50 and 75.
Abstract: In the present study, the effect of attack angle of triangular ribs, by using finite volume method, has been numerically studied in a two-dimensional microchannel. The cooling fluid is water/Ag nanofluid with volume fractions of 0–4% of nanoparticles, and nanoparticle diameters are 25, 50 and 75 nm. The nanofluid flow has been considered as laminar with Reynolds numbers of 5, 100 and 500. Also, the attack angles have been studied at the range of 30°–60°. In this study, the effects of variations in attack angles on triangular ribs, volume fraction of nanoparticles, nanoparticles diameter and Reynolds number have been investigated. The results indicate that using nanoparticles with smaller diameter improves heat transfer rate. Moreover, it is shown that the friction coefficient and pumping power are almost independent of nanoparticle diameter. However, increasing Reynolds number, pumping power enhancement becomes more important by increasing the volume fraction of nanoparticles. In low Reynolds numbers, the influence of ribs is approximately insignificant on the streamlines; it is very effective in high Reynolds numbers. The existence of rib on the direction of fluid motion causes asymmetrical velocity profile in the top section of the rib. Using triangular rib with higher attack angle can improve heat transfer significantly due to the high-velocity gradients and better mixing of fluid flow.
129 citations
TL;DR: In this article, the effects of temperature and volume fraction on thermal conductivity of SWCNT-Al2O3/EG hybrid nanofluid are investigated, and an experimental correlation and a neural network are presented and for thermal conductivities of the nanoprocessor in terms of volume fraction and temperature.
Abstract: In the present paper, the effects of temperature and volume fraction on thermal conductivity of SWCNT–Al2O3/EG hybrid nanofluid are investigated. Single-walled carbon nanotube with outer diameter of 1–2 nm and aluminum oxide nanoparticles with mean diameter of 20 nm with the ratio of 30 and 70%, respectively, were dispersed in the base fluid. The measurements were conducted on samples with volume fractions of 0.04, 0.08, 0.15, 0.3, 0.5, 0.8, 1.5 and 2.5. In order to investigate the effects of temperature on thermal conductivity of the nanofluid, this characteristic was measured in five different temperatures of 30, 35, 40, 45 and 50 °C. The results indicate that enhancement of nanoparticles’ thickness in low volume fractions and at any temperature causes a considerable increment in thermal conductivity of the nanofluid. In this study, the highest enhancement of thermal conductivity was 41.2% which was achieved at the temperature of 50 °C and volume fraction of 2.5%. Based on the experimental data, an experimental correlation and a neural network are presented and for thermal conductivity of the nanofluid in terms of volume fraction and temperature. Comparing outputs of the experimental correlation and the designed artificial neural network with experimental data, the maximum error values for the experimental correlation and the artificial neural network were, respectively, 2.6 and 1.94% which indicate the excellent accuracy of both methods in prediction of thermal conductivity.
125 citations
TL;DR: In this paper, the authors present a comprehensive and up-to-date review of carbon nanotubes (CNTs) being applied in various heat transfer (convective and boiling) and mass transfer systems such as heat exchangers and separators.
Abstract: The pursuit of superior working fluids for heat and mass transfer systems in the industry is on the rise, inspired by not only to maximize revenue but also to accommodate heat dissipation or chemical separation under extreme conditions The addition of a small amount of nanoparticle, a product called nanofluid, has been initiated over the last decade In particular, researchers have employed carbon nanotubes (CNTs) into conventional fluids as their preferred nanoparticles due to the merits of having a remarkable thermal conductivity compared to other nanoparticles Here, we present a comprehensive and up to date review of this incredible fluid being applied in various heat transfer (convective and boiling) and mass transfer systems such as heat exchangers and separators Other critical parameters associated with the practicality of the CNT nanofluids such as pumping power and efficiency are also discussed We surveyed a remarkable range of results of some of the heat and mass transfer studies that strongly depend on the inherent CNT nanofluid characteristics and operating conditions such as CNT treatment, size, concentration, Reynolds number, and so on A major conclusion that can be drawn from this review is the significantly higher heat transfer coefficient at lower pressure drop or pumping power of the CNT nanofluid compared to other nanofluids, which implied better thermal performance of the heat transfer system Besides that, the concentration of CNT is the influential factor to achieve optimum boiling heat transfer while the mass transfer performance of the CNT nanofluid is moderately good against other nanofluids Additionally, CNT treatment using covalent functionalization is crucial for the overall stability and performance of the CNT nanofluid However, several issues that inhibit their widespread use such as possible corrosion-erosion in systems, lack of risk assessments, and high cost of CNT nanofluid must be thoroughly addressed in future studies
91 citations
TL;DR: In this paper, the effects of Al2O3/water nanofluid on the hydrodynamics and convective heat transfer of a counter flow double-tube heat exchanger were investigated.
Abstract: Double-tube heat exchanger is primarily adapted to high-temperature, high-pressure applications due to their relatively small diameters. An experimental study performed to investigate the effects of Al2O3/water nanofluid on the hydrodynamics and convective heat transfer of a counter flow double-tube heat exchanger. The nanofluid was used as hot fluid and passed through the inner tube of the heat exchanger considering fully developed turbulent flow regime. Experiments were conducted at the nanofluid flow rates of 7, 9, and 11 L min−1, nanofluid inlet temperatures of 45, 55, and 65 °C, and dilute nanoparticle concentrations of 0.05 and 0.15 vol%. Local convective heat transfer coefficient in double-tube heat exchanger has been measured experimentally for the first time. Results showed that nanofluids had higher Nusselt number than pure water. Also, the Nusselt number increased by increasing particles volume fraction, flow rate as well as temperature of nanofluid. However, increasing the convective heat transfer coefficient of the nanofluids was not sensible with increasing the concentration. In addition, the ratio of the heat transfer coefficient of nanofluid to that of the base fluid decreased by increasing Reynolds number. Adding γ-Al2O3 nanoparticles to the base fluid increased the friction factor. In this study, the greatest enhancement in the heat transfer coefficient and the friction factor obtained at 0.15 vol% concentration of nanoparticles which were 23 and 25 %, respectively.
77 citations
References
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TL;DR: In this article, an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat-transfer fluids, which are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluid, and they represent the best hope for enhancing heat transfer.
Abstract: Low thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids that are required in many industrial applications. In this paper we propose that an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat transfer fluids. The resulting {open_quotes}nanofluids{close_quotes} are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluids, and they represent the best hope for enhancement of heat transfer. The results of a theoretical study of the thermal conductivity of nanofluids with copper nanophase materials are presented, the potential benefits of the fluids are estimated, and it is shown that one of the benefits of nanofluids will be dramatic reductions in heat exchanger pumping power.
4,634 citations
"Experimental investigation of press..." refers background in this paper
...Xuan and Li [12] studied convective heat transfer of the nanofluid Cu/water flowing through a copper tube under con-...
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TL;DR: In this article, the authors used a Brookfield rotating viscometer to measure the viscosities of the dispersed fluids with γ-alumina (Al2O3) and titanium dioxide (TiO2) particles at a 10% volume concentration.
Abstract: Turbulent friction and heat transfer behaviors of dispersed fluids (i.e., uttrafine metallic oxide particles suspended in water) in a circular pipe were investigated experimentally. Viscosity measurements were also conducted using a Brookfield rotating viscometer. Two different metallic oxide particles, γ-alumina (Al2O3) and titanium dioxide (TiO2), with mean diameters of 13 and 27 nm, respectively, were used as suspended particles. The Reynolds and Prandtl numbers varied in the ranges l04-I05 and 6.5-12.3, respectively. The viscosities of the dispersed fluids with γ-Al2O3 and TiO2 particles at a 10% volume concentration were approximately 200 and 3 times greater than that of water, respectively. These viscosity results were significantly larger than the predictions from the classical theory of suspension rheology. Darcy friction factors for the dispersed fluids of the volume concentration ranging from 1% to 3% coincided well with Kays' correlation for turbulent flow of a single-phase fluid. The Nusselt n...
3,730 citations
"Experimental investigation of press..." refers background in this paper
...Pak and Cho [11] conducted an experimental study on convective heat transfer of the nanofluids Al2O3/water and TiO2/water in turbulent flow under constant heat flux boundary conditions....
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...Nanofluid viscosity is calculated by Brinkman equation [38]. lnf ¼ lbf 1 uð Þ2:5 ð3Þ Density and specific heat capacity are calculated by Cho and Pak equations [11]....
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TL;DR: In this paper, an expression for the viscosity of solutions and suspensions of finite concentration is derived by considering the effect of the addition of one solute-molecule to an existing solution, which is considered as a continuous medium.
Abstract: An expression for the viscosity of solutions and suspensions of finite concentration is derived by considering the effect of the addition of one solute‐molecule to an existing solution, which is considered as a continuous medium.
3,724 citations
"Experimental investigation of press..." refers methods in this paper
...Nanofluid viscosity is calculated by Brinkman equation [38]....
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Book•
01 Jan 1971
TL;DR: In this paper, the authors present basic concepts and analysis of experimental data for basic electrical measurements and sensors, including Displacement and Area Measurements, Pressure Measurement, Flow Measurement and Temperature Measurement.
Abstract: 1 Introduction 2 Basic Concepts 3 Analysis of Experimental Data 4 Basic Electrical Measurements and Sensing Devices 5 Displacement and Area Measurements 6 Pressure Measurement 7 Flow Measurement 8 The Measurement of Temperature 9 Thermal and Transport-Property Measurements 10 Force, Torque, and Strain Measurements 11 Motion and Vibration Measurement 12 Thermal and Nuclear-Radiation Measurements 13 Air-Pollution Sampling and Measurement 14 Data Acquisition and Processing 15 Report Writing and Presentations 16 Design of Experiments Appendix A-Conversion Factors and Material Properties Appendix B-Digital Imaging Systems
2,943 citations
"Experimental investigation of press..." refers methods in this paper
...Using Holman equation [39], experimental error is calculated as follows:...
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TL;DR: In this paper, the authors studied the heat transfer behavior of aqueous suspensions of multi-walled carbon nanotubes (CNT nanofluids) flowing through a horizontal tube.
1,334 citations
"Experimental investigation of press..." refers background in this paper
...[44] reported a significant increase in the convective heat transfer coefficient (about 375 %) at mass concentration of 0....
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