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Article
Publication date: 27 March 2009

R. Ben Mansour, N. Galanis and C.T. Nguyen

The aim is to study the conjugate problem of developing laminar mixed convection flow and heat transfer of water‐Al2O3 nanofluid inside an inclined tube submitted to a uniform…

734

Abstract

Purpose

The aim is to study the conjugate problem of developing laminar mixed convection flow and heat transfer of water‐Al2O3 nanofluid inside an inclined tube submitted to a uniform wall heat flux.

Design/methodology/approach

The set of non‐linear, coupled and fully elliptic governing equations has been solved using a “finite‐control‐volume” numerical method, the classical power‐law scheme for computing heat and momentum fluxes staggered and non uniform grids for spatial discretization of various regions of the tube.

Findings

Numerical results have shown that the presence of nanoparticles slightly intensifies the secondary flow due to buoyancy, in particular in the developing region. It also increases the average Nusselt number and decreases slightly the product ReCf with respect to those of water. For the horizontal inclination, two new correlations have been proposed to calculate these two variables in the fully developed region, for Grashof number ranging from 103 to 105 and particle volume concentrations up to 7 per cent.

Practical implications

The results of this study can be employed for various practical heat transfer and thermal applications using nanofluids.

Originality/value

The present study constitutes an original contribution to the knowledge of nanofluid thermal behaviour.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 19 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 March 2005

M.A. Habib, R. Ben‐Mansour, H.M. Badr, S.A.M. Said and S.S. Al‐Anizi

In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various…

1084

Abstract

Purpose

In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various flow passages. Erosion in the tube entrance region of a typical shell and tube heat exchanger is numerically predicted.

Design/methodology/approach

The erosion rates are obtained for different flow rates and particle sizes assuming low particle concentration. The erosion prediction is based on using a mathematical model for simulating the fluid velocity field and another model for simulating the motion of solid particles. The fluid velocity (continuous phase) model is based on the solution of the time‐averaged governing equations of 3D turbulent flow while the particle‐tracking model is based on the solution of the governing equation of each particle motion taking into consideration the viscous and gravity forces as well as the effect of particle rebound behavior.

Findings

The results show that the location and number of eroded tubes depend mainly on the particle size and velocity magnitude at the header inlet. The rate of erosion depends exponentially on the velocity. The particle size shows negligible effect on the erosion rate at high velocity values and the large‐size particles show less erosion rates compared to the small‐size particles at low values of inlet flow velocities.

Originality/value

In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various flow passages. The results indicate that erosion in shell and tube heat exchanger can be minimized through the control of velocity inlet to the header.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 15 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 12 March 2019

ZhenYu Qiu, Qiang Ma, Ying Zhang and Yiwu Yi

This paper aims to discuss the dynamic adsorption processes of carbon dioxide in a porous fixed bed on the industrial scale, using a multiple-relaxation-time lattice Boltzmann…

243

Abstract

Purpose

This paper aims to discuss the dynamic adsorption processes of carbon dioxide in a porous fixed bed on the industrial scale, using a multiple-relaxation-time lattice Boltzmann (LB) model.

Design/methodology/approach

A multiple-relaxation-time LB model is developed to predict the dynamic adsorption processes of carbon dioxide in a porous fixed bed on the industrial scale. The breakthrough curves from the simulation results are compared with the experimental data to validate the reliability of this model, and the effects of flow velocity, porosity and linear driving force mass transfer coefficient on the adsorption behaviors of carbon dioxide are explored further.

Findings

The numerical results show that the improved fluid flux leads to the reduction in the time required for completion of adsorption processes nonlinearly, and the differential pressure significantly raises with the decreasing porosity of porous fixed bed for fixed values of Reynolds number and total adsorption capacity. The maximum adsorption ratio of carbon dioxide was found at Re = 12 in this work. In addition, the higher mass transfer resistance of adsorbent particles advances the appearance time of the breakthrough point and delays the completion time of the adsorption processes.

Originality/value

This work will provide a way to study the adsorption technology of carbon dioxide in the fixed-bed using the LB method.

Details

Engineering Computations, vol. 36 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 28 December 2020

Ahmad Riaz, Chao Zhou, Ruobing Liang and Jili Zhang

This paper aims to present a numerical study on the natural convection, which operates either as an evaporator or condenser unit of the heat pump system to pre-cool and pre-heat…

199

Abstract

Purpose

This paper aims to present a numerical study on the natural convection, which operates either as an evaporator or condenser unit of the heat pump system to pre-cool and pre-heat the ambient fresh air.

Design/methodology/approach

This study focuses on natural air cooling or heating within the air channel considering the double skin configuration. Particular focus is given to the analysis of airflow and the heat transfer processes in an air channel to cool or heat the ambient fresh air. In this study, the physical model consists of one wall, either heated uniformly or cooled uniformly, whereas the other wall is adiabatic.

Findings

The results show that the variation of both velocity and temperature is observed as the flow transition occurs at the evaporator or condenser wall. In either case, the temperature rises in the range of 6.3–8.4°C with an increase in mass flow rate from 0.07–0.08 kg/s in the photovoltaic thermal condenser part, while in the photovoltaic thermal evaporator part, the change in mass flow rate from 0.048–0.061 kg/s causes a decrease in temperature from 7.1–4.5°C.

Practical implications

The solar-assisted photovoltaic thermal heat pump system, in building façade having an air layer application, is feasible for pre-heating and pre-cooling the ambient fresh air and also reduces the energy needed to treat the fresh air.

Originality/value

The influence of condensing and evaporating temperature under natural convection mode in double skin conformation is considered for pre-heating and pre-cooling of ambient fresh air.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 6
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 20 August 2019

B. Saleh, Ayman A. Aly, M. Alsehli, M.M. Bassuoni and A. Elfasakhany

This paper aims to investigate the performance and working fluids screening for an ejector refrigeration cycle (ERC) activated by solar energy. Several common and new…

158

Abstract

Purpose

This paper aims to investigate the performance and working fluids screening for an ejector refrigeration cycle (ERC) activated by solar energy. Several common and new hydrofluorocarbons, hydrocarbons, hydrofluoroolefins and hydrofluoroethers are proposed as refrigerants for the ERC to determine the most appropriate one.

Design/methodology/approach

The ejector performance is characterized by the ejector area ratio (EAR) and entrainment ratio (ω), while the cycle performance is described by the coefficient of performance (COP). The influences of many working parameters like the evaporator, condenser and generator temperatures on the ejector and cycle performances are investigated for all candidates as well.

Findings

The results indicate that the best ejector and cycle performances are attained with the highest critical temperature dry refrigerant, i.e. R601 under all studied working conditions. From the perspective of energy efficiency and environmental issues, R601 can be considered the most appropriate working fluid amongst all candidates. However, extra attention should be considered against its flammability. The maximum COP, the corresponding ω and the necessary EAR using R601 are 0.743, 1.02 and 15.5, respectively, with 25 ºC condenser temperature and the typical values for the rest operating conditions.

Originality/value

Many common and new hydrofluorocarbons, hydrocarbons, hydrofluoroolefins and hydrofluoroethers are suggested as working fluids for the ERC to determine the most appropriate one. The mixing process inside the ejector constant-area section is assumed constant-pressure process.

Details

World Journal of Engineering, vol. 16 no. 5
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 25 February 2021

Leo Lukose and Tanmay Basak

The purpose of this paper is to address various works on mixed convection and proposes 10 unified models (Models 1–10) based on various thermal and kinematic conditions of the…

306

Abstract

Purpose

The purpose of this paper is to address various works on mixed convection and proposes 10 unified models (Models 1–10) based on various thermal and kinematic conditions of the boundary walls, thermal conditions and/ or kinematics of objects embedded in the cavities and kinematics of external flow field through the ventilation ports. Experimental works on mixed convection have also been addressed.

Design/methodology/approach

This review is based on 10 unified models on mixed convection within cavities. Models 1–5 involve mixed convection based on the movement of single or double walls subjected to various temperature boundary conditions. Model 6 elucidates mixed convection due to the movement of single or double walls of cavities containing discrete heaters at the stationary wall(s). Model 7A focuses mixed convection based on the movement of wall(s) for cavities containing stationary solid obstacles (hot or cold or adiabatic) whereas Model 7B elucidates mixed convection based on the rotation of solid cylinders (hot or conductive or adiabatic) within the cavities enclosed by stationary or moving wall(s). Model 8 is based on mixed convection due to the flow of air through ventilation ports of cavities (with or without adiabatic baffles) subjected to hot and adiabatic walls. Models 9 and 10 elucidate mixed convection due to flow of air through ventilation ports of cavities involving discrete heaters and/or solid obstacles (conductive or hot) at various locations within cavities.

Findings

Mixed convection plays an important role for various processes based on convection pattern and heat transfer rate. An important dimensionless number, Richardson number (Ri) identifies various convection regimes (forced, mixed and natural convection). Generalized models also depict the role of “aiding” and “opposing” flow and combination of both on mixed convection processes. Aiding flow (interaction of buoyancy and inertial forces in the same direction) may result in the augmentation of the heat transfer rate whereas opposing flow (interaction of buoyancy and inertial forces in the opposite directions) may result in decrease of the heat transfer rate. Works involving fluid media, porous media and nanofluids (with magnetohydrodynamics) have been highlighted. Various numerical and experimental works on mixed convection have been elucidated. Flow and thermal maps associated with the heat transfer rate for a few representative cases of unified models [Models 1–10] have been elucidated involving specific dimensionless numbers.

Originality/value

This review paper will provide guidelines for optimal design/operation involving mixed convection processing applications.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 31 no. 9
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 26 July 2021

Radha S., G. Josemin Bala and Nagabushanam P.

Energy is the major concern in wireless sensor networks (WSNs) for most of the applications. There exist many factors for higher energy consumption in WSNs. The purpose of this…

53

Abstract

Purpose

Energy is the major concern in wireless sensor networks (WSNs) for most of the applications. There exist many factors for higher energy consumption in WSNs. The purpose of this work is to increase the coverage area maintaining the minimum possible nodes or sensors.

Design/methodology/approach

This paper has proposed multilayer (ML) nodes deployment with distributed MAC (DS-MAC) in which nodes listen time is controlled based on communication of neighbors. Game theory optimization helps in addressing path loss constraints while selecting path toward base stations (BS).

Findings

The simulation is carried out using NS-2.35, and it shows better performance in ML DS-MAC compared to random topology in DS-MAC with same number of BS. The proposed method improves performance of network in terms of energy consumption, network lifetime and better throughput.

Research limitations/implications

Energy consumption is the major problem in WSNs and for which there exist many reasons, and many approaches are being proposed by researchers based on application in which WSN is used. Node mobility, topology, multitier and ML deployment and path loss constraints are some of the concerns in WSNs.

Practical implications

Game theory is used in different situations like countries whose army race, business firms that are competing, animals generally fighting for prey, political parties competing for vote, penalty kicks for the players in football and so on.

Social implications

WSNs find applications in surveillance, monitoring, inspections for wild life, sea life, underground pipes and so on.

Originality/value

Game theory optimization helps in addressing path loss constraints while selecting path toward BS.

Details

Circuit World, vol. 48 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 6 June 2016

Ammar Mushtaq, M. Mustafa, T. Hayat and A. Alsaedi

– The purpose of this paper is to consider a laminar two-dimensional incompressible flow of an electrically conducting fluid over a moving flat plate with a parallel free stream.

177

Abstract

Purpose

The purpose of this paper is to consider a laminar two-dimensional incompressible flow of an electrically conducting fluid over a moving flat plate with a parallel free stream.

Design/methodology/approach

The governing equations are first reduced into self-similar forms and then solved for the numerical solutions by shooting method.

Findings

The results are compared with the available studies is some special cases and found in excellent agreement. It is noticed that an increase in the magnetic field strength leads to a decrease in the momentum boundary layer thickness and enhancement in the rate of heat transfer from the plate. It is also observed that temperature and heat transfer from the plate increase when radiation effect is strengthened.

Originality/value

A recently proposed idea of nonlinear radiative heat transfer with Joule heating and viscous dissipation effects is analyzed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 27 March 2009

Zdzislaw Mazur, Rafael Campos‐Amezcua and Alfonso Campos‐Amezcua

This paper aims to validate an axial turbine modified nozzle design, looking for a reduction of the nozzle erosion process during operation in power plants.

565

Abstract

Purpose

This paper aims to validate an axial turbine modified nozzle design, looking for a reduction of the nozzle erosion process during operation in power plants.

Design/methodology/approach

The approach taken is numerical simulation using the computational fluid dynamics (CFD) tool, comparing original and proposed/modified nozzle designs.

Findings

The paper provides information about how to achieve a solution of the turbine operational problem (abrasive wear) by an analysis of flow patterns under a variety of conditions.

Research limitations/implications

It does not give a detailed interpretation of flow behaviour due to the lack of validation data.

Practical implications

A very useful flow simulation methodology that can be used in industry is provided.

Originality/value

The proposed design modification of an axial turbine nozzle with the aid of CFD simulation has not been performed yet. This paper investigates the possibility of nozzle erosion reduction by modifying local flow patterns.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 19 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 30 July 2024

Srikar Sarma Kona, Navdeep Sharma Dugala and Gurmeet Singh

This study aims to investigate the erosion wear rate of a stainless steel automobile exhaust manifold, both computationally and physically.

11

Abstract

Purpose

This study aims to investigate the erosion wear rate of a stainless steel automobile exhaust manifold, both computationally and physically.

Design/methodology/approach

The experiment was performed on a motorcycle exhaust manifold as well as on a 3D model, created using SolidWorks 2022 CAD software. The analysis was later achieved using ANSYS 19.2 simulation software using Fluent – code.

Findings

The analysis of solid particle erosion in the exhaust manifold revealed that erosion wear is concentrated predominantly at the extrados of the manifold, with the most significant wear occurring at the lowermost bend. The erosion wear rate increases with larger particulate sizes and varies among bends, with negligible wear observed in straight pipes. The SEM analysis further confirmed surface degradation, with rugged textures, pits and grooves indicating abrasive wear. Spine-like structures and fractured soot particles suggest erosive and abrasive forces caused by high-speed contact of exhaust gas compounds. Energy dispersive X-ray spectroscopy revealed significant carbon abundance, indicating carbonaceous compounds from fuel combustion, along with notable amounts of oxygen and iron, typical of oxidized metallic constituents. The discrete phase modeling (DPM) analysis highlighted peak particulate matter deposition at the first bend exit, with maximum concentrations observed at specific angles. This deposition is influenced by centrifugal force, leading to increased PM concentration at outer bend walls. Velocity magnitude contours showed asymmetrical flow profiles, with high turbulence levels and secondary flow induced by centrifugal effects in bend areas. Dynamic pressure contours revealed varying pressures at intrados and extrados, with maximum pressure observed at the intrados of the manifold’s bends. These findings provide valuable insights into erosion wear, particulate dispersion and flow dynamics within the exhaust manifold.

Originality/value

The study investigated an automobile exhaust manifold model using ANSYS Fluent code and DPM to analyze erosion wear rate phenomena and its various constituents. This analysis was conducted in comparison with a physically eroded sample. The study offers insights into the mechanism underlying the exhaust manifold of an automobile.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

Keywords

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