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Numerical investigation of convective heat transfer of single wall carbon nanotube nanofluid laminar flow inside a circular tube

Saeed Farqad Rasheed, Jasim Marwah A., Mahmood Natheer B., Jaffar Zahraa M.

Archives of Thermodynamics

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2021

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Vol. 42, no 2

103--119

EN

This study presents the behavior of a single wall carbon nanotube (SWCNT)/water nanofluid for convective laminar flow inside a straight circular pipe heated by a constant heat flux. Five volume fractions of SWCNT were used to investigate their effect on the heat transfer coefficient, Nusselt number, temperature distribution and velocity field in comparison with pure water flow. One model for each property was tested to calculate the effective thermal conductivity, effective dynamic viscosity, and effective specific heat of the SWCNT/water mixture. The models were extracted from experimental data of a previous work. The outcomes indicate that the rheological behavior of SWCNT introduces a special effect on the SWCNT/water properties, which vary with SWCNT volume fraction. The results show an improvement in the heat transfer coefficient with increasing volume fraction of nanoparticles. The velocity of SWCNT/water nanofluid increased by adding SWCNT nanoparticles, and the maximum increase was registered at 0.05% SWCNT volume fraction. The mixture temperature is increased with the axial distance of the pipe but a reduction in temperature distribution is observed with the increasing SWCNT volume fraction, which reflects the effect of thermophysical properties of the mixture.

2

Analysis of selected aspects of a tank gassing-up process on board liquefied petroleum gas carrier. Part I

Wieczorek Agnieszka

Archives of Thermodynamics

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2021

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Vol. 42, no 2

43--58

EN

The paper is a thermodynamics analysis of the removal of any inert gas from the tank using the vapors of any liquefied petroleum gas cargo (called cargo tank gassing-up operation). For this purpose, a thermodynamic model was created which considers two boundary cases of this process. The first is a ‘piston pushing’ of inert gas using liquefied petroleum gas vapour. The second case is complete mixing of both gases and removal the mixture from the tank to the atmosphere until desired concentration or amount of liquefied petroleum gas cargo in the tank is reached. Calculations make it possible to determine the amount of a gas used to complete the operation and its loss incurred as a result of total mixing of both gases.

3

Nonlocal critical velocities of fluid conveying clamped-pinned Single-Walled Carbon Nanotubes subjected to axial magnetic field

Rao C. K., Rao L. B.

Engineering Transactions

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2017

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Vol. 65, iss. 2

319--333

EN

The problem of stability of fluid conveying carbon nanotubes clamped at one end and pinned at the other end and subjected to an axial magnetic field is investigated in this paper. Non-local continuum mechanics formulation is utilized to derive the governing fourth-order partial differential equations, which takes into consideration the small length scale effects and the axial magnetic field. Galerkin’s technique is used to find the solution of the governing equation for the case of clamped-pinned boundary. Closed-form expressions for the critical flow velocity above which the system becomes unstable, of the fluid conveying carbon nanotubes, are obtained and numerical results for different values of axial magnetic field parameter are presented in this paper for use in industrial dynamic design of such devices. The results obtained from these simple and approximate expressions are compared with those existing in literature, wherever available and an excellent agreement is found between them. Along with extensive results on critical velocities new and interesting results are also reported for varying values of nonlocal length parameter. From the results presented in this paper, it is observed that the non-local length parameter along with axial magnetic field parameter are having considerable influence on the critical velocities of the fluid conveying nanotubes.

4

Application of generalized differential quadrature method to nonlinear bending analysis of a single SWCNT over a bundle of nanotubes

Fereidoon A., Babaee A. M., Rostamiyan Y.

Archives of Mechanics

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2012

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Vol. 64, nr 4

347-366

EN

The deformation of an individual single walled carbon nanotube (SWCNT) over a bundle of nanotubes has been studied using the generalized differential quadrature (GDQ) method. The effects of length, diameter, and minimum value of Lennard–Jones experimental potential have been considered in the governing equation which is derived based on the GDQ and the issues related to the implementation of the boundary and compatibility conditions were addressed. The explanation of reliability and flexibility of the GDQ is done by solving several selected examples which are evaluated by comparing them with existing exact or approximate solutions which were previously generated by finite element approach.

5

Reversible electron charge transfer in single-wall carbon nanotubes

Costa S., Bachmatiuk A., Borowiak-Palen E.

Polish Journal of Chemical Technology

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2008

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Vol. 10, nr 2

1-4

EN

Single-wall carbon nanotubes (SWCNT) have proved to be very special materials due to their unique electronic properties. Over the last years many scientists have dedicated their research to the study of the these materials as an electronic system. Amphoteric doping effects (n-type and p-type), which can be reversed, became a very popular way of manipulating the optic and electronic properties of carbon nanotubes. In the particular case of SWCNT, the most common and widely used procedure, which changes their properties, is acid treatment applied as a purification procedure. The effect of the addition of this kind of the dopant has been widely studied but not fully understood so far. Here, we present a study, of two kinds of SWCNT, produced within different techniques: (i) chemical vapors deposition and (ii) laser ablation. The main difference between the two types is the diameter distribution of the obtained materials, which is broad in the first technique and narrow in the second. After the acid treatment it is possible to observe a diameter sensitive doping effect on both samples. Resonance Raman spectroscopy, optical absorption spectroscopy (OAS) in UV/Vis/NIR and the Fourier transform middle-infrared (FTIR) spectroscopy have been applied for the characterization of the samples.