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Article
Publication date: 22 November 2018

Esmaeil Jalali and Arash Karimipour

In this paper, the forced convection heat transfer of the nanofluid composed of water and AL2O3 nanoparticles is simulated in a two-dimensional horizontal microchannel by…

Abstract

Purpose

In this paper, the forced convection heat transfer of the nanofluid composed of water and AL2O3 nanoparticles is simulated in a two-dimensional horizontal microchannel by injecting the lower wall. The upper wall of the microchannel is 303 K at temperature TH. On the lower wall of the microchannel, there are three holes for flow injection. Other parts of the wall are insulated. In this paper, the effect of parameters such as Reynolds number, slip coefficient and volume fraction of nanoparticles is investigated.

Design/methodology/approach

The boundary condition of the slip velocity is considered on the upper and lower walls of the microchannel. In this work, the flow of nanofluid in the microchannel is considered to be slow, permanent and Newtonian. In the present study, the effect of injection through the microchannel wall on the slip velocity is examined for the first time.

Findings

The results are also presented as velocity profiles and Nusselt number diagrams. It was found that the Nusselt number increases with increasing the amount of slip coefficient of velocity and the weight percentage of solid nanoparticles. The rate of this increase is higher in the high values of the Reynolds number.

Originality/value

A novel paper concerned the simulation of cross-flow injection effects on the slip velocity and temperature domain of a nanofluid flow inside a microchannel.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 26 September 2019

Zhe Tian, Ali Abdollahi, Mahmoud Shariati, Atefeh Amindoust, Hossein Arasteh, Arash Karimipour, Marjan Goodarzi and Quang-Vu Bach

This paper aims to study the fluid flow and heat transfer through a spiral double-pipe heat exchanger. Nowadays using spiral double-pipe heat exchangers has become popular…

Abstract

Purpose

This paper aims to study the fluid flow and heat transfer through a spiral double-pipe heat exchanger. Nowadays using spiral double-pipe heat exchangers has become popular in different industrial segments due to its complex and spiral structure, which causes an enhancement in heat transfer.

Design/methodology/approach

In these heat exchangers, by converting the fluid motion to the secondary motion, the heat transfer coefficient is greater than that of the straight double-pipe heat exchangers and cause increased heat transfer between fluids.

Findings

The present study, by using the Fluent software and nanofluid heat transfer simulation in a spiral double-tube heat exchanger, investigates the effects of operating parameters including fluid inlet velocity, volume fraction of nanoparticles, type of nanoparticles and fluid inlet temperature on heat transfer efficiency.

Originality/value

After presenting the results derived from the fluid numerical simulation and finding the optimal performance conditions using a genetic algorithm, it was found that water–Al2O3 and water–SiO2 nanofluids are the best choices for the Reynolds numbers ranging from 10,551 to 17,220 and 17,220 to 31,910, respectively.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 13 December 2019

Huawei Wu, Peyman Torkian, Amir Zarei, Iman Moradi, Arash Karimipour and Masoud Afrand

This paper aims to investigate atoms type and channel roughness effects on fluid behavior in nanochannel.

Abstract

Purpose

This paper aims to investigate atoms type and channel roughness effects on fluid behavior in nanochannel.

Design/methodology/approach

The results of mechanical properties of these structures are reported in this work by using molecular dynamics method.

Findings

The results show that nanochannel roughness is a limiting factor in flowing fluid in nanochannel. Moreover, fluids with less atomic weight have more free movement in ideal and non-ideal nanochannels.

Originality/value

For the study of mechanical properties of fluid/nanochannel system, the authors calculated parameters such as potential energy, density, temperature and velocity profiles of simulated fluids.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 10 December 2019

Yeping Peng, Ghasem Bahrami, Hossein Khodadadi, Alireza Karimi, Ahmad Soleimani, Arash Karimipour and Sara Rostami

The purpose of this study is simulation of of polymer electrolyte membrane fuel cell. Proton-exchange membrane fuel cells are promising power sources for use in power…

Abstract

Purpose

The purpose of this study is simulation of of polymer electrolyte membrane fuel cell. Proton-exchange membrane fuel cells are promising power sources for use in power plants and vehicles. These fuel cells provide a high level of energy efficiency at low temperature without any pollution. The convection inside the cell plays a key role in the electrochemical reactions and the performance of the cell. Accordingly, the transport processes in these cells have been investigated thoroughly in previous studies that also carried out functional modeling.

Design/methodology/approach

A multi-phase model was used to study the limitations of the reactions and their impact on the performance of the cell. The governing equations (conservation of mass, momentum and particle transport) were solved by computational fluid dynamics (CFD) (ANSYS fluent) using appropriate source terms. The two-phase flow in the fuel cell was simulated three-dimensionally under steady-state conditions. The flow of water inside the cell was also simulated at high-current density.

Findings

The simulation results suggested that the porosity of the gas diffusion layer (GDL) is one of the most important design parameters with a significant impact on the current density limitation and, consequently, on the cell performance.

Originality/value

This study was mainly focused on the two-phase analysis of the steady flow in the fuel cell and on investigating the impacts of a two-phase flow on the performance of the cell and also on the flow in the GDL, the membrane and the catalyst layer using the CFD.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 4 December 2018

Marjan Goodarzi, Saeed Javid, Ali Sajadifar, Mehdi Nojoomizadeh, Seyed Hossein Motaharipour, Quang-Vu Bach and Arash Karimipour

With respect to two new subjects, i.e. nanofluids and microchannels, in heat transfer systems and modern techniques used for building them, this paper aims to study on…

Abstract

Purpose

With respect to two new subjects, i.e. nanofluids and microchannels, in heat transfer systems and modern techniques used for building them, this paper aims to study on effect of using aluminum oxide nanoparticles in non-Newtonian fluid of aqueous solution of carboxy-methyl cellulose in microtube and through application of different slip coefficients to achieve various qualities on surface of microtube.

Design/methodology/approach

Simultaneously, the effect of presence of nanoparticles and phenomenon of slip and temperature jump has been explored in non-Newtonian nanofluid in this essay. The assumption of homogeneity of nanofluid and fixed temperature of wall in microtube has been used in modeling processes.

Findings

The results have been presented as diagrams of velocity, temperature and Nusselt Number and the investigations have indicated that addition of nanoparticles to the base fluid and increase in microtube slip coefficient might improve rate of heat transfer in microtube.

Originality/value

The flow of non-Newtonian nanofluid of aqueous solution of carboxy methyl cellulose-aluminum oxide has been determined in a microtube for the first time.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 13 June 2019

Zhe Tian, Seyed Amin Bagherzadeh, Kamal Ghani, Arash Karimipour, Ali Abdollahi, Mehrdad Bahrami and Mohammad Reza Safaei

This paper aims to propose a new nonlinear function estimation fuzzy system as a novel statistical approach to estimate nanofluids’ thermal conductivity.

Abstract

Purpose

This paper aims to propose a new nonlinear function estimation fuzzy system as a novel statistical approach to estimate nanofluids’ thermal conductivity.

Design/methodology/approach

A fuzzy system having a product inference engine, a singleton fuzzifier, a center average defuzzifier and Gaussian membership functions is proposed for this purpose.

Findings

Results indicate that the proposed fuzzy system can predict the thermal conductivity of Al2O3/paraffin nanofluid with appropriate precision and generalization and it also outperforms the classic interpolation methods.

Originality/value

A new nonlinear function estimation fuzzy system was introduced as a novel statistical approach to estimate nanofluids’ thermal conductivity for the first time.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 10 December 2020

Zhixiong Li, Morteza Jamshidian, Sayedali Mousavi, Arash Karimipour and Iskander Tlili

In this paper, the uncertainties important components and the structure status are obtained by using the condition monitoring, expert groups and multiple membership…

Abstract

Purpose

In this paper, the uncertainties important components and the structure status are obtained by using the condition monitoring, expert groups and multiple membership functions by creating a fuzzy system in MATLAB software.

Design/methodology/approach

In the form of fuzzy type, the average structural safety must be followed to replace the damages or to absolutely control the decision-making. Uncertainty in the functionality of hydraulic automated guided vehicles (AGVs), without knowing the reliability of pieces, can cause failure in the manufacturing process. It can be controlled by the condition monitoring pieces done by measurement errors and ambiguous boundaries.

Findings

As a result, this monitoring could increase productivity with higher quality in delivery in flexible manufacturing systems with an increase of 70% reliability mutilation for the hydraulic AGV parts.

Originality/value

Hydraulic AGVs play a vital role in flexible manufacturing in recent years. Lately, several strategies for maintenance and repairing of hydraulic AGVs exist in the industry but are still confronted with many uncertainties. The hydraulic AGV is faced with uncertainty after 10 years of working in terms of reliability. Reconstruction of the old parts with the new parts may not have the quality and durability.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 3 October 2019

Wei He, Seyed Amin Bagherzadeh, Mohsen Tahmasebi, Ali Abdollahi, Mehrdad Bahrami, Rasoul Moradi, Arash Karimipour, Marjan Goodarzi and Quang-Vu Bach

This paper aims to present a black-box fuzzy system identification method coupled with genetic algorithm optimization approach to predict the mixture thermal conductivity…

Abstract

Purpose

This paper aims to present a black-box fuzzy system identification method coupled with genetic algorithm optimization approach to predict the mixture thermal conductivity at dissimilar temperatures and nanoparticle concentrations, in the examined domains.

Design/methodology/approach

WO3 nanoparticles are dispersed in the deionized water to produce a homogeneous mixture at various nanoparticles mass fractions of 0.1, 0.5, 1.0 and 5.0 Wt.%.

Findings

The results depicted that the models not only have satisfactory precision, but also have acceptable accuracy in dealing with non-trained input values.

Originality/value

The transmission electron microscopy is applied to measure the mean diameters, shape and morphology of the dry nanoparticles. Moreover, the stability of nanoparticles inside the water is evaluated by using zeta potential and dynamic light scattering (DLS) tests. Then, the prepared nanofluid thermal conductivity is presented at different values of temperatures and concentrations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 13 June 2019

Mohammad Reza Salimpour, Mohammad Hossein Karimi Darvanjooghi, Ali Abdollahi, Arash Karimipour and Marjan Goodarzi

A boiling surface with different initial roughness and under various nanoparticles volume fractions was studied in present work.

Abstract

Purpose

A boiling surface with different initial roughness and under various nanoparticles volume fractions was studied in present work.

Design/methodology/approach

Develop a correlation and sensitivity analysis.

Findings

The results showed that for small (7.3 nm) and much larger (about 2,000 nm) surface roughness, compared to nanoparticle size of around 25 nm, the heat transfer rate of nanofluid diminishes relative to that of base fluid. The results also demonstrated that the boiling heat transfer rate is reduced by increasing the concentration of nanoparticles. For larger boiling surface roughness (480 nm) and nanoparticles volume fractions of less than 0.1 Vol.%, the value of heat transfer increases with the increase of nanoparticles concentration; and for those of more than 0.1 Vol.%, heat transfer rate decreases by adding more nanoparticles, significantly.

Originality/value

Finally, an equation was presented for estimating the wall superheat and the Csf coefficient in terms of mentioned parameters.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 20 September 2019

Seyed Amin Bagherzadeh, Esmaeil Jalali, Mohammad Mohsen Sarafraz, Omid Ali Akbari, Arash Karimipour, Marjan Goodarzi and Quang-Vu Bach

Water/Al2O3 nanofluid with volume fractions of 0, 0.3 and 0.06 was investigated inside a rectangular microchannel. Jet injection of nanofluid was used to enhance the heat…

Abstract

Purpose

Water/Al2O3 nanofluid with volume fractions of 0, 0.3 and 0.06 was investigated inside a rectangular microchannel. Jet injection of nanofluid was used to enhance the heat transfer under a homogeneous magnetic field with the strengths of Ha = 0, 20 and 40. Both slip velocity and no-slip boundary conditions were used.

Design/methodology/approach

The laminar flow was studied using Reynolds numbers of 1, 10 and 50. The results showed that in creep motion state, the constricted cross section caused by fluid jet is not observable and the rise of axial velocity level is only because of the presence of additional size of the microchannel. By increasing the strength of the magnetic field and because of the rise of the Lorentz force, the motion of fluid layers on each other becomes limited.

Findings

Because of the limitation of sudden changes of fluid in jet injection areas, the magnetic force compresses the fluid to the bottom wall, and this behavior limits the vertical velocity gradients. In the absence of a magnetic field and under the influence of the velocity boundary layer, the fluid motion has more variations. In creeping velocities of fluid, the presence or absence of the magnetic field does not have an essential effect on Nusselt number enhancement.

Originality/value

In lower velocities of fluid, the effect of the jet is not significant, and the thermal boundary layer affects the entire temperature field. In this case, for Hartmann numbers of 40 and 0, changing the Nusselt number on the heated wall is similar.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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