The purpose of this work is to consider heat transfer inside wall‐rooted‐fins systems.
Abstract
Purpose
The purpose of this work is to consider heat transfer inside wall‐rooted‐fins systems.
Design/methodology/approach
The coupled two‐dimensional heat diffusion equations are nondimensionlaized and solved numerically using an iterative finite volume method. Approximate fine analytical solutions for various augmentation indicators are derived. Excellent agreement is obtained between the numerical and the analytical results. A parametric study including all of the involved dimensionless parameters is conducted and presented graphically. Accurate correlations are generated.
Findings
It is found that fin‐roots with large root lengths experience bi‐directional heat transfer rates. Moreover, the wall‐rooted‐fins system is found to possess an effectiveness that can be more than 60 percent above that with rootless fins at wall Biot numbers of unity order. This value is found to increase as the Biot number increases or as the wall‐to‐fin thermal conductivities and volumes ratios decrease. In addition, heat transfer rates through wall‐rooted‐fins systems can be more than 100 percent above those having uniform thermal conductivities. Eventually, the heat transfer coefficient between the fin‐roots and wall are derived, which is found to be independent on the wall thickness.
Originality/value
Finally, this work paves a way for an effective passive method for augmenting heat transfer inside wall‐fins systems.
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Diego Celentano and Antonio Campo
The purpose of this paper is to investigate the heat transfer attributes of annular fins with quarter circle profile in terms of the Biot number Bi and the radius ratio rr. The…
Abstract
Purpose
The purpose of this paper is to investigate the heat transfer attributes of annular fins with quarter circle profile in terms of the Biot number Bi and the radius ratio rr. The latter corresponds to the internal radius of the tube divided by the length of the fin in question.
Design/methodology/approach
To this end, the governing two-dimensional (2-D) heat conduction equation in cylindrical coordinates is numerically solved via finite element analysis for different Bi (i.e., 0.1, 1 and 5) and rr (i.e., 0.5, 1 and 2).
Findings
The obtained results for the mid-plane and surface temperatures show that these profiles, which exhibit nearly rr-independent responses, only present one-dimensional (1-D) radially linear distributions for the case Bi = 1. For Bi = 0.1, the temperature profiles also possess a 1-D character but with a clearly defined concave pattern. Finally, for Bi = 5, a 2-D temperature field in a wide zone from the fin base is achieved with a convex pattern for the mid-plane and surface temperatures.
Originality/value
Exhaustive assessment of the heat transfer in annular fins with quarter circle profile in terms of different Biot numbers and radius ratios
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Keywords
– Heat transfer inside wavy fins is analyzed in this work. The paper aim to discuss this issue.
Abstract
Purpose
Heat transfer inside wavy fins is analyzed in this work. The paper aim to discuss this issue.
Design/methodology/approach
Six different types of wavy fins are considered. The fin equation for each fin type is solved using a high accurate finite difference method. Excellent agreement is obtained between the numerical solution under zero wave amplitude and the exact solution of the plain fin.
Findings
The following wavy fin types and conditions are found to produce larger heat transfer rate and its volumetric value than those for the plain fin and other wavy fins: short fins with parallel wavy profiles and large surface-wave frequency; long fins with symmetric wavy surface around the length axis, positive cross-sectional area gradient at the base, and large surface-wave frequency; and long fins with symmetric wavy profiles around the length axis, positive cross-sectional area gradient at the base, and small surface-wave frequency.
Research limitations/implications
In addition, both fins with symmetric wavy surface around the width axis and parallel wavy surfaces along the width axis have same performance indicators. Also, these wavy fins possess higher fin efficiency than either that of the plain fin or those of the other types of wavy fins.
Originality/value
Finally, heat transfer enhancements in the studied wavy fins are increased by increases in the excess of the surface area, cross-sectional area gradient at the base, arc length and arc width relative to those of the plain fin.
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Mahmood Khalid, Khalid A. Juhany and Salah Hafez
The purpose of this paper is to use a computational technique to simulate the flow in a two-dimensional (2D) wind tunnel where the effect of the solid walls facing the model has…
Abstract
Purpose
The purpose of this paper is to use a computational technique to simulate the flow in a two-dimensional (2D) wind tunnel where the effect of the solid walls facing the model has been addressed using a porous geometry so that interference arriving at the solid walls are duly damped and a flow suction procedure has been adopted at the side wall to minimize the span-wise effect of the growing side wall boundary layer.
Design/methodology/approach
A CFD procedure based on discretization of the Navier–Stokes equations has been used to model the flow in a rectangular volume with appropriate treatment for solid walls of the confined volume in which the model is placed. The rectangular volume was configured by stacking O-Grid sections in a span-wise direction using geometric growth from the wall. A porous wall condition has been adapted to counter the wall interference signatures and a separate suction procedure has been implemented for reducing the side wall boundary layer effects.
Findings
It has been shown that through such corrective measures, the flow in a wind tunnel can be adequately simulated using computational modeling. Computed results were compared against experimental measurements obtained from IAR (Institute for Aerospace, Canada) and NAL (National Aeronautical Laboratory, Japan) to show that indeed appropriate corrective means may be adapted to reduce the interference effects.
Research limitations/implications
The solutions seemed to converge a lot better using relatively coarser grids which placed the shock locations closer to the experimental values. The finer grids were more stiff to converge and resulted in reversed flow with the two equation k-w model in the region where the intention was to draw out the fluid to thin down the boundary layer. The one equation Spalart–Allmaras model gave better result when porosity and wall suction routines were implemented.
Practical implications
This method could be used by industry to point check the results against certain demanding flow conditions and then used for more routine parametric studies at other conditions. The method would prove to be efficient and economical during early design stages of a configuration.
Originality/value
The method makes use of an O-grid to represent the confined test section and its dual treatment of wall interference and blockage effects through simultaneous application of porosity and boundary layer suction is believed to be quite original.
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Government spending plays a crucial role in fiscal policy in any country, both as a tool for implementing individual government policies and as a possible instrument for…
Abstract
Government spending plays a crucial role in fiscal policy in any country, both as a tool for implementing individual government policies and as a possible instrument for mitigating uneven economic developments and economic shocks. This chapter provides direct empirical evidence on the development and structure of general government expenditure and its relationship with real economic growth in Czechia and the European Union countries. Compared to theoretical recommendations, general government expenditure has not been used as a stabiliser in Czechia and EU countries and has been observed to be pro-cyclical in the period under review. Granger causality analysis identified the direction of causality between the macroeconomic variables analysed and found that in most cases economic growth came first, followed by government spending.
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Elteyeb Eljack, Ibraheem AlQadi and Mahmood Khalid
The purpose of this paper is to identifying ways to reduce the effects of wing-vortex interaction by applying surface porosity on selected areas of the exposed surface. A number…
Abstract
Purpose
The purpose of this paper is to identifying ways to reduce the effects of wing-vortex interaction by applying surface porosity on selected areas of the exposed surface. A number of papers recently have investigated the aerodynamic implication of free-stream vortices impinging upon airfoils.
Design/methodology/approach
The free-stream disturbance in these studies were represented by planting a vortex ahead of the wing or using some other disturbance invoking mechanism like von-Karman vortices in the wake of a cylinder or using a flipping plate to invoke a discrete vortex. In the present work, a well-defined method was used to germinate a system of controlled vortices of known strength, size and frequency ahead of the wing, and the impact of the subsequent interaction was studied with and without the presence of the surface porosity. The simulations tackled a number of cases when porosities of up to 20 and 22 per cent were applied to selected regions near the leading edge, with vortices of controlled strengths directed at the wing surface.
Findings
The results showed that the effects of large vortices spanning the entire lengths of the wing can indeed be damped when porosity is selectively applied at strategic regions.
Practical implications
Surface porosity application at strategic regions of a wing may dampen the effects of the unsteadiness of the incoming flow. This has profound implications on flight safety and structural damage prevention. Further implications could possibly be extended to UAV and wind turbines that operate at heavy gusting environment.
Originality/value
Implementation of this particular method resolves some of the issues arisen when an airplane encounters atmospheric turbulence.
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This paper aims to identify the effectiveness, student perceptions and impacts of integrating comics into the English as a foreign language (EFL) writing curriculum for…
Abstract
Purpose
This paper aims to identify the effectiveness, student perceptions and impacts of integrating comics into the English as a foreign language (EFL) writing curriculum for undergraduate Ecuadorian polytechnic students.
Design/methodology/approach
This research followed a mixed method design to obtain quantitative information through a researcher-made survey and paired T-test, which would be corroborated by the qualitative data obtained from semistructured interviews.
Findings
From the descriptive and T-test results and the interview answers, it is concluded that students have a favorable view of the effectiveness of using comics to improve their writing skills. They also expressed their engagement and motivation to work with comics.
Research limitations/implications
First, the research sample, comprised of 109 students, may restrict the generalizability of the findings beyond the specific context of this study. This constraint suggests caution in extrapolating these findings to broader student cohorts, emphasizing the need for larger-scale studies to validate the robustness and applicability of the outcomes. Second, the study’s focus solely on students from a polytechnic state university introduces a potential limitation concerning the diversity and representativeness of the participant pool. Consequently, the findings might be limited in their applicability and may not fully encompass students’ varied responses and attitudes from other educational backgrounds.
Practical implications
The scaffolding afforded by comics aligns with genre-based literacy perspectives, valuing instruction in textual genres and social purposes. From a practical pedagogical point of view, this paper’s results suggest the potential of comic narratives and storyboarding. Comics writing could be added to classroom activities to vibrantly aboard brainstorming, drafting and peer reviewing before dealing with higher-stakes assignments. Legitimizing alternative mediums like comics for academic writing tasks has social implications for promoting literacies in a multimedia world.
Social implications
Writing comics nurtures multiliteracies aligned with participatory digital cultures by expanding traditional linguistic-centric norms. This multimodal composing can potentially increase access and representation and amplify voices across identities and cultures.
Originality/value
Although the paper addresses a topic that is not entirely novel in research, its originality lies in its focus on data originating from Ecuador, where specific cultural nuances and educational contexts may influence the effectiveness of using comics to enhance EFL writing skills. Thus, it fills a gap in the existing literature on this subject.
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Mohammed I. Al‐Madhoun and Farhad Analoui
The economy of the Palestinian Territories (PT) is small, poorly developed, and highly dependent on Israel; at the same time, the land is limited, Israel controls 80‐85 per cent…
Abstract
The economy of the Palestinian Territories (PT) is small, poorly developed, and highly dependent on Israel; at the same time, the land is limited, Israel controls 80‐85 per cent of the Palestinian water, and there is large‐scale unemployment. Faced with this situation, small and micro‐enterprises have come to play a critical role in the economy of the PT. Donors, the Palestinian Authority (PA), and UNRWA have recognised that many of the managers suffer from managerial weaknesses, and training is one of the long‐term keys to promote the development of small and micro‐enterprises and alleviate the problem of persistent unemployment in the PT. To support the peace agreement, the International Community promised to support the Palestinian economy. Part of this aid has been spent for small and micro‐enterprise development, and for establishing managerial training programmes. These programmes aim to encourage economic development of the PT, through supporting small business education and entrepreneurship training. These programmes suffered from various problems, such as lack of professional trainers, the majority of the managers did not attend the training programme courses, some of these programmesmissed funding. Therefore, some training programmes were closed during the last two years. On the other hand, the managers of small businesses still suffer from various managerial problems. However, this article presents a description of the current situation in PT. Especially, the economic and managerial situation, particularly for the SMEs and TPs in the PT.
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Ehab Alshamaileh, Mazen Al-Sulaibi, Ahmad Al-Khawaldeh, Mansour H. Almatarneh, Dina El-Sabawi and Aiman Al-Rawajfeh
The current status of nanotechnology research and development in Jordan is analyzed. In recent years, Jordanian institutions demonstrated considerable interest in the development…
Abstract
Purpose
The current status of nanotechnology research and development in Jordan is analyzed. In recent years, Jordanian institutions demonstrated considerable interest in the development and production of nanotechnology. Here the purpose of this paper is to provide detailed information about the status of nanotechnology in Jordan in terms of several factors that influence selectivity in nanotechnology and the number of published peer-reviewed research articles.
Design/methodology/approach
Several factors that influence selectivity in nanotechnology and the number of published peer-reviewed research articles were analyzed. A detailed analysis of the collected data reveals that the number of publications, citations, and patents is highly dependent on the amount of research fund.
Findings
The development in nanotechnology is associated with presence and accessibility of sensitive laboratory equipment. The nanotechnology research output in Jordan is still lower than it should be due to the lack of necessary laboratory infrastructure. This is due to the insufficient funds allocated to scientific research, the restrictive access to available instruments and the bureaucracy of some governmental departments. Compared to some developed countries, Jordan is noticeably behind in developing a nanotechnology system of research and industry. It will take time as well as technical and financial resources in order to achieve an advanced level in the field of nanotechnology in Jordan. Nevertheless, many Jordanian researchers are doing their best and are producing some good research articles.
Research limitations/implications
The many applications to the same approach.
Practical implications
Time and publications’ resources.
Social implications
Peer cooperation.
Originality/value
First comprehensive review ever. A base for researchers and decision makers.
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Pimsuporn Poyoi, Ariadna Gassiot-Melian and Lluís Coromina
Posting and sharing about food on social media has surged in popularity amongst younger generations such as Millennials and Generation Z. This study aims to analyse and compare…
Abstract
Purpose
Posting and sharing about food on social media has surged in popularity amongst younger generations such as Millennials and Generation Z. This study aims to analyse and compare food-tourism sharing behaviour on social media across generations. First, this study specifically investigates the factors influencing the intention to share food experiences on social media; second, it examines the impact of sharing intention on actual behaviour and loyalty; and third, it determines whether Millennials and Generation Z differ in these relationships.
Design/methodology/approach
A survey was carried out of Millennial and Generation Z travellers who shared food experiences on social media. Structural equation modelling (SEM) and multi-group analysis were performed to examine the cause-and-effect relationship in both generations.
Findings
The findings reveal differences in motivation, satisfaction, sharing intention, sharing behaviour and loyalty between generations (Millennials and Generation Z).
Research limitations/implications
This study contributes to the literature on the antecedents of food-sharing behaviour in online communities by indicating factors that influence the sharing of culinary experiences and brand or destination loyalty across generations. Suggestions for future research include exploring online food-sharing behaviour through cross-cultural comparisons in various regions.
Practical implications
As Millennials and Generation Z will expand their market share in the coming years, the findings of this study can help improve marketing strategies for culinary tourism and generate more intense food experiences for both generations.
Originality/value
The outcome of the research provides new insights to develop a conceptual model of food-sharing behaviour and tourism on social media by drawing comparisons across generations.