J. Batina, M. Batchi, S. Blancher, R. Creff and C. Amrouche
The purpose of this paper is to analyse the convective heat transfer of an unsteady pulsed, laminar, incompressible flow in axisymmetric tubes with periodic sections. The flow is…
Abstract
Purpose
The purpose of this paper is to analyse the convective heat transfer of an unsteady pulsed, laminar, incompressible flow in axisymmetric tubes with periodic sections. The flow is supposed to be developing dynamically and thermally from the duct inlet. The wall is heated at constant and uniform temperature.
Design/methodology/approach
The problem is written with classical homogeneous boundary conditions. We use a shift operator to impose non‐homogeneous boundary conditions. Consequently, this method introduces source terms in the Galerkin formulation. The momentum equations and the energy equation which govern this problem are numerically solved in space by a spectral Galerkin method especially oriented to this situation. A Crank‐Nicolson scheme permits the resolution in time.
Findings
From the temperature field, the heat transfer phenomenon is presented, discussed and compared to those obtained in straight cylindrical pipes. This study showed the existence of zones of dead fluid that locally have a negative influence on heat transfer. Substantial modifications of the thermal convective heat transfer are highlighted at the entry and the minimum duct sections.
Practical implications
Pulsated flows in axisymmetric geometries can be applied to medical industries, mechanical engineering and technological processes.
Originality/value
One of the original features of this study is the choice of Chebyshev polynomials basis in both axial and radial directions for spectral methods, combined with the use of a shift operator to satisfy non‐homogeneous boundary conditions.
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Jean Batina, Serge Blancher and Tarik Kouskou
Mathematical and numerical models are developed to study the melting of a Phase Change Material (PCM) inside a 2D cavity. The bottom of the cell is heated at constant and uniform…
Abstract
Purpose
Mathematical and numerical models are developed to study the melting of a Phase Change Material (PCM) inside a 2D cavity. The bottom of the cell is heated at constant and uniform temperature or heat flux, assuming that the rest of the cavity is completely adiabatic. The paper used suitable numerical methods to follow the interface temporal evolution with a good accuracy. The purpose of this paper is to show how the evolution of the latent energy absorbed to melt the PCM depends on the temperature imposed on the lower wall of the cavity.
Design/methodology/approach
The problem is written with non-homogeneous boundary conditions. Momentum and energy equations are numerically solved in space by a spectral collocation method especially oriented to this situation. A Crank-Nicolson scheme permits the resolution in time.
Findings
The results clearly show the evolution of multicellular regime during the process of fusion and the kinetics of phase change depends on the boundary condition imposed on the bottom cell wall. Thus the charge and discharge processes in energy storage cells can be controlled by varying the temperature in the cell PCM. Substantial modifications of the thermal convective heat and mass transfer are highlighted during the transient regime. This model is particularly suitable to follow with a good accuracy the evolution of the solid/liquid interface in the process of storage/release energy.
Research limitations/implications
The time-dependent physical properties that induce non-linear coupled unsteady terms in Navier-Stokes and energy equations are not taken into account in the present model. The present model is actually extended to these coupled situations. This problem requires smoother geometries. One can try to palliate this disadvantage by constructing smoother approximations of non-smooth geometries. The augmentation of polynomials developments orders increases strongly the computing time. When the external heat flux or temperature imposed at the PCM is much greater than the temperature of the PCM fusion, one must choose carefully some data to assume the algorithms convergence.
Practical implications
Among the areas where this work can be used, are: buildings where the PCM are used in insulation and passive cooling; thermal energy storage, the PCM stores energy by changing phase, solid to liquid (fusion); cooling and transport of foodstuffs or pharmaceutical or medical sensitive products, the PCM is used in the food industry, pharmaceutical and medical, to minimize temperature variations of food, drug or sensitive materials; and the textile industry, PCM materials in the textile industry are used in microcapsules placed inside textile fibres. The PCM intervene to regulate heat transfer between the body and the outside.
Originality/value
The paper's originality is reflected in the precision of its results, due to the use of a high-accuracy numerical approximation based on collocation spectral methods, and the choice of Chebyshev polynomials basis in both axial and radial directions.
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Timothy Keiningham, Joan Ball, Sabine Benoit (née Moeller), Helen L. Bruce, Alexander Buoye, Julija Dzenkovska, Linda Nasr, Yi-Chun Ou and Mohamed Zaki
This research aims to better understand customer experience, as it relates to customer commitment and provides a framework for future research into the intersection of these…
Abstract
Purpose
This research aims to better understand customer experience, as it relates to customer commitment and provides a framework for future research into the intersection of these emerging streams of research.
Design/methodology/approach
This research contributes to theoretical and practical perspectives on customer experience and its measurement by integrating extant literature with customer commitment and customer satisfaction literature.
Findings
The breadth of the domains that encompass customer experience – cognitive, emotional, physical, sensorial and social – makes simplistic metrics impossible for gauging the entirety of customers’ experiences. These findings provide strong support of the need for new research into customer experience and customer commitment.
Practical implications
Given the complexity of customer experience, managers are unlikely to track and manage all relevant elements of the concept. This research provides a framework identifying empirically the most salient attributes of customer experience with particular emphasis on those elements that enhance commitment. This offers insight into service design to correspond with specific commitment and experience dimensions.
Originality/value
This research is the first to examine the customer experience as it relates to customer commitment – a key factor in customer loyalty, positive word of mouth and other desired outcomes for managers and marketers. This paper provides a framework for future research into these emerging topics.
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Jing-Kui Zhang, Miao Cui, Ben-Wen Li and Ya-Song Sun
The purpose of this paper is to develop a combined method for three-dimensional incompressible flow and heat transfer by the spectral collocation method (SCM) and the artificial…
Abstract
Purpose
The purpose of this paper is to develop a combined method for three-dimensional incompressible flow and heat transfer by the spectral collocation method (SCM) and the artificial compressibility method (ACM), and further to study the performance of the combined method SCM-ACM for three-dimensional incompressible flow and heat transfer.
Design/methodology/approach
The partial differentials in space are discretized by the SCM with Chebyshev polynomial and Chebyshev–Gauss–Lobbatto collocation points. The unsteady artificial compressibility equations are solved to obtain the steady results by the ACM. Three-dimensional exact solutions with trigonometric function form and exponential function form are constructed to test the accuracy of the combined method.
Findings
The SCM-ACM is developed successfully for three-dimensional incompressible flow and heat transfer with high accuracy that the minimum value of variance can reach. The accuracy increases exponentially along with time marching steps. The accuracy is also improved exponentially with the increasing of nodes before stable accuracy is achieved, while it keeps stably with the increasing of the time step. The central processing unit time increases exponentially with the increasing of nodes and decreasing of the time step.
Research limitations/implications
It is difficult for the implementation of the implicit scheme by the developed SCM-ACM. The SCM-ACM can be used for solving unsteady impressible fluid flow and heat transfer.
Practical implications
The SCM-ACM is applied for two classic cases of lid-driven cavity flow and natural convection in cubic cavities. The present results show good agreement with the published results with much fewer nodes.
Originality/value
The combined method SCM-ACM is developed, firstly, for solving three-dimensional incompressible fluid flow and heat transfer by the SCM and ACM. The performance of SCM-ACM is investigated. This combined method provides a new choice for solving three-dimensional fluid flow and heat transfer with high accuracy.
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Lioua Kolsi, Fatih Selimefendigil and Mohamed Omri
The purpose of this study is to explore the phase change (PC) dynamics in a T-shaped ventilated cavity having multiple inlet and outlet ports during nanofluid convection with…
Abstract
Purpose
The purpose of this study is to explore the phase change (PC) dynamics in a T-shaped ventilated cavity having multiple inlet and outlet ports during nanofluid convection with phase change material (PCM) packed bed-installed system.
Design/Methodology/Approach
Finite element method was used to analyze the PC dynamics and phase completion time for encapsulated PCM within a vented cavity during the convection of nanoparticle loaded fluid. The study is performed for different Reynolds number of flow streams (Re1 and Re2 between 300 and 900), temperature difference (ΔT1 and ΔT2 between −5 and 10), aspect ratio of the cavity (between 0.5 and 1.5) and nanoparticle loading (between 0.02% and 0.1%).
Findings
It is observed that phase transition can be controlled by assigning different velocities and temperatures at the inlet ports of the T-shaped cavity. The PC becomes fast especially when the Re number and temperature of fluid in the port vary closer to the wall (second port). When the configurations with the lowest and highest Re number of the second port are considered up to 54.7% in reduction of complete phase transition time is obtained, while this amount is 78% when considering the lowest and highest inlet temperatures. The geometric factor which is the aspect ratio has also affected the flow field and PC dynamics. Up to 78% reduction in the phase transition time is obtained at the highest aspect ratio. Further improvements in the performance are achieved by using nanoparticles in the base fluid. The amounts in the phase transition time reduction are 8% and 10.5% at aspect ratio of 0.5 and 1.5 at the highest nanoparticle concentration.
Originality/Value
The thermofluid system and offered control mechanism for PC dynamics control can be considered for the design, optimization, further modeling and performance improvements of applications with PCM installed systems.
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Nidal H. Abu-Hamdeh, Ömer Akbal, Hakan F. Öztop, Abdullah M. Abusorrah and Mohannad M. Bayoumi
The purpose of this paper is to solve the problem of a three-dimensional computational analysis for an elliptic-shaped cavity in a pipe under constant temperature.
Abstract
Purpose
The purpose of this paper is to solve the problem of a three-dimensional computational analysis for an elliptic-shaped cavity in a pipe under constant temperature.
Design/methodology/approach
The three-dimensional computational solution of governing equations was performed by using finite volume method with different temperature difference.
Findings
The parafin wax was chosen as a phase change material (PCM), and melting fraction, streamlines and isotherms are formed for different time step. It is found that position B give better results than that of position A, and temperature difference effects the duration of melting of PCM.
Originality/value
The three-dimensional analysis of melting in an ellipsoidal pipe with inner pipe with higher temperature is the main originality of this work.
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Laura Zapata, Gerardo Ibarra and Pierre-Henri Blancher
New ways of working have rapidly increased in organizations, promising employees a better control over their work time, space, and more autonomy. The present study analyzes the…
Abstract
Purpose
New ways of working have rapidly increased in organizations, promising employees a better control over their work time, space, and more autonomy. The present study analyzes the relationship between new ways of working and employee engagement and productivity.
Design/methodology/approach
A survey was conducted to evaluate organizational practices developed based on flexible schemes and the relevance of employee engagement for better productivity based on digital tools. Data were analyzed using structural equation modeling.
Findings
New ways of work requires an integration of workspaces' design, social interaction, and individual wellness. Organizations need to recognize how employees' trust, commitment, and passion are fundamental to face current and future changes. Flexibility in time and space and digital tools for work are critical.
Practical implications
A personalization of organizational practices to support individual well-being and flexible and hybrid schemes of work are needed. Developing policies collaboratively to work together respectfully in a hybrid environment is necessary.
Social implications
Hybrid work format is allowing women to balance career and childcare, reducing the wage gap with men. The green imperative has also played a role reducing the amount of carbon monoxide produced via commuter.
Originality/value
The present study exposes how organizational practices must ensure employee well-being and autonomy to perform their tasks. In this regard, employees need to be recognized as individuals, physically and mentally. Attempting to force a one-size-fit-all solution can have detrimental effects on the workforce, particularly on women, people of lower socioeconomic status, and people in less advanced economies. Personalization requests empowerment and democratization at work.
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The New Year will see Britain a member of the largest multi‐national free trade area in the world and there must be few who see it as anything less than the beginning of a new…
Abstract
The New Year will see Britain a member of the largest multi‐national free trade area in the world and there must be few who see it as anything less than the beginning of a new era, in trade, its trends, customs and usages and especially in the field of labour, relations, mobility, practices. Much can be foreseen but to some extent it is all very unpredictable. Optimists see it as a vast market of 250 millions, with a lot of money in their pockets, waiting for British exports; others, not quite so sure, fear the movement of trade may well be in reverse and if the increasing number of great articulated motor trucks, heavily laden with food and other goods, now spilling from the Channel ports into the roads of Kent are an indication, the last could well be true. They come from faraway places, not all in the European Economic Community; from Yugoslavia and Budapest, cities of the Rhineland, from Amsterdam, Stuttgart, Mulhouse and Milano. Kent has had its invasions before, with the Legions of Claudius and in 1940 when the battle roared through the Kentish skies. Hitherto quiet villagers are now in revolt against the pre‐juggernaut invasion; they, too, fear more will come with the enlarged EEC, thundering through their one‐street communities.
Sharon Loane and Jim Bell
As part of their growth strategy, many firms choose to expand internationally. Such expansion is an especially important decision for small- and medium-sized enterprises (SMEs)…
Abstract
As part of their growth strategy, many firms choose to expand internationally. Such expansion is an especially important decision for small- and medium-sized enterprises (SMEs). These SMEs are vital to China's economy and have grown in importance since the reform and opening-up, measured in terms of size, number, financial status, or profitability. In addition, the Chinese electronics sector plays an important role in the economy. This inquiry explores the internationalisation behaviour of 50 Chinese electronics SMEs. The findings are presented and implications drawn for future research, along with those for policy makers and practitioners.