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Mixed convection heat transfer in ventilated cavities submitted to a constant heat flux has been numerically studied using the Navier‐Stokes equations with the Boussinesq approximation. Results in terms of streamlines and isotherms are produced for different values of the governing parameters, namely, the Rayleigh number (10³ ≤q Ra ≤q 10⁶) and the Reynolds number (5 ≤q Re ≤q 5, 000). The geometrical parameters are the aspect ratio of the cavity A = L^’/H^’ = 2 and the relative height of the openings B = h^’/H^’ = 1/4. Results of the simulations show that the maximum interaction between natural and forced convection occurs for couples (Ra, Re) which can be correlated as Re = a Ra^b.

This paper aims to develop a selective energy optimisation of the photovoltaic–thermal (PV/T) system performance. The PV cell inside the PV/T system could be periodically manipulated to produce domestic hot water without applying an external power supply.

A numerical simulation model of the proposed PV/T model was developed in MATLAB/Simulink to analyse the selective energy optimisation of the model. The extrinsic cell resistance (R_se) is adjusted to control the ratio of thermal to the electrical energy, generated from the PV cell inside the PV/T system. Therefore, the internal heat of the PV cell inside the PV/T system is periodically used as a thermal element to produce electrical power and hot water.

The optimisation of PV/T energy shows that the electrical power efficiency can increase by 11.6% when R_se was 0 Ω, and the 200 L water tank temperature increased by 22ºC when R_se was 50 Ω.

This study showed that the use of the PV cell could be extended to domestic hot water and space heating, and not only for electricity.

The interaction between mixed convection and thermal radiation in ventilated cavities with gray surfaces has been studied numerically using the Navier‐Stokes equations with the Boussinesq approximation. The effect of thermal radiation on streamlines and isotherms is shown for different values of the governing parameters namely, the Rayleigh number (10³ ≤ Ra ≤ 10⁶), the Reynolds number (50 ≤ Re ≤ 5000) and the surfaces emissivity (0 ≤ ε≤ 1). The geometrical parameters are the aspect ratio of the cavity A = L’/H’ = 2 and the relative height of the openings B = h’/H’ = 1/4. Results of the study show that thermal radiation alters significantly the temperature distribution, the flow fields and the heat transfer across the active walls of the cavities.

The aim of this work consists of studying numerically the coupling between natural convection and radiation in a tall rectangular cavity by examining the effect of the emissivity of the walls, ε, the Rayleigh number, Ra, and the inclination of the cavity, θ, on the flow characteristics and the existence ranges of the multiple solutions obtained.

The Navier‐Stokes equations were discretized by using a finite difference technique. The vorticity and energy equations were solved by the alternating direction implicit method. Values of the stream function were obtained by using the point successive over‐relaxation method. The calculation of the radiative heat exchange between the walls of the cavity is based on the radiosity method.

For an inclined cavity (θ=45°), up to four different solutions are obtained and their range of existence is found to be strongly dependent on the Rayleigh number and the emissivity of the cavity walls. In the case of a vertical cavity (θ=90°), the weak reduction of the convection effect due to radiation is largely compensated for by the contribution of the radiation which enhances the overall heat transfer through the cold surface of the cavity and favours the appearance of secondary cells.

The existence of multiple steady‐state solutions in an inclined cavity (θ=45°) and the number of the obtained solutions are affected by the presence of radiation. In face, the increase of the emissivity reduces the number of solutions for weak values of the Rayleigh number. Also, the increase of this parameter favours the multiplicity of solutions for all the considered values of the emissivity. For a vertical cavity (θ=90°), the effect of radiation generates an oscillatory convection for large values of the Rayleigh number.

The purpose of this paper is to consider flow over heat generating bodies in an open‐ends cavity, which finds applications in electronics cooling and industrial processing. Heat transfer rates depend on the flow situation in the cavity, which is influenced by the cavity inlet and exit port locations, heat transferring body size and its orientation in the cavity, and the cavity size. Consequently, modeling of flow over heat transferring bodies in an open‐ends cavity and examination of the effect of the aspect ratio and orientation of the heat transferring bodies on the flow field and heat transfer rates becomes essential.

The flow over heat generating solid blocks situated in an open‐ends cavity is considered and the effects of blocks' orientations and aspect ratios on flow field as well as heat transfer rates are examined. A numerical scheme using a control volume approach is introduced to predict flow field in the cavity and heat transfer rates from the blocks.

It is found that complex flow structure is generated in the cavity due to the aspect ratios and orientations of the blocks. This, in turn, influences significantly heat transfer rates from the blocks in the cavity.

Surface areas of blocks are kept the same and aspect ratio is varied such that the surface area of each block remains the same in the simulations. In addition, Steady flow situation is considered for governing equations of flow and heat transfer in the cavity. However, for the future study transient heating and flow situations can be considered while varying the surface araes of the blocks. This will provide useful information on the circulations in the cavity and the enhancement of heat transfer due to the complex flow structure.

In practice, cooling effectiveness can be improved through changing the aspects ratio of the heat generating bodies in the cavity.

The findings are original and will be useful for the scientists and the design engineers working the specific area of heat transfer and fluid flow.

This study attempts to identify and analyze the pragmatic functions of religious expressions, that is, invocations that include the name of Allah (God), in naturally occurring social interactions in Najdi Arabic, which is spoken in Central Saudi Arabia.

Drawing on the speech act theory and politeness model, an analysis of the data illustrates that religious expressions, in addition to their prototypical religious meanings and uses in everyday interactions, are employed to communicate a wide range of pragmatic functions.

These include signaling the end of a conversation, persuading, mitigating and hedging, showing agreement and approval, reinforcing emphasis, expressing emotions, seeking protection from the evil eye, conveying skepticism and ambiguity, expressing humor and sarcasm, and showing respect and honor. The embedded multifunctional dimension of religious expressions in the present data is interpreted as serving as a politeness marker with which speakers promote both positive politeness (by showing solidarity, claiming common grounds, and building rapport) and negative politeness (by reducing imposition and emphasizing personal autonomy).

This study further highlights the interplay between religion, culture, and language use in Najdi Arabic.

This study aims to investigate the impact of the 2013 privatization of Nigeria’s energy sector on the technical performance of the Benin Electricity Distribution Company (BEDC) and its workforce.

This study used a questionnaire-based approach, and 196 participants were randomly selected. Analytical tools included standard deviation, Spearman rank correlation and regression analysis.

Before privatization, the energy sector, managed by the power holding company of Nigeria, suffered from inefficiencies in fault detection, response and billing. However, privatization improved resource utilization, replaced outdated transformers and increased operational efficiency. However, in spite of these improvements, BEDC faces challenges, including unstable voltage generation and inadequate staff welfare. This study also highlighted a lack of experience among the trained workforce in emerging electricity technologies such as the smart grid.

This study’s focus on BEDC may limit its generalizability to other energy companies. It does not delve into energy sector privatization’s broader economic and policy implications.

The positive outcomes of privatization, such as improved resource utilization and infrastructure investment, emphasize the potential benefits of private ownership and management. However, voltage generation stability and staff welfare challenges call for targeted interventions. Recommendations include investing in voltage generation enhancement, smart grid infrastructure and implementing measures to enhance employee well-being through benefit plans.

Energy sector enhancements hold positive social implications, uplifting living standards and bolstering electricity access for households and businesses.

This study contributes unique insights into privatization’s effects on BEDC, offering perspectives on preprivatization challenges and advancements. Practical recommendations aid BEDC and policymakers in boosting electricity distribution firms’ performance within the privatization context.

The rites and practices of folk religion in Nigeria cut across virtually all conventional and emerging social institutions in the country. The inability of the State to perform many of its functions has encouraged this trend, with many turning to folk religion and associated practices in attempts to control uncertain situations. Unemployed/underemployed young gamblers have begun to incorporate and normalise the combination of spiritual elements with sports betting activities in a bid to translate games of uncertainty into games of certainty. This study attempts to conceptualise how and why young people adopt, practice and make sense of folk religion in relation to sports betting.

Semi-structured, in-depth interviews were used to interrogate and analyse the lived experiences of key actors living in the capital city of Ilorin, Kwara State, a place renowned for the widespread practice of folk religious rites: 20 unemployed/underemployed young sports bettors and 10 folk doctors. Collected data were transcribed manually and subjected to inductive content analysis, using grounded theory. The combination of folk religion with sports betting is fast becoming normalised as young Nigerians seek to survive harsh economic conditions. Adoption is also linked with belief in traditions, in-group conflicts, gambling adverts, lack of luck and greed. Folk religious practices combine elements from the natural and spiritual worlds. This study formulates concepts for understanding the complexity of such practices concerning gambling among young sports bettors in Nigeria.

This paper aims to numerically analyze the effect of non-gray gas radiation on mixed convection in a horizontal circular duct with isothermal partial heating from the sidewall. The influence of heater location on heat transfer, fluid flow and entropy generation is given and discussed in this study.

The numerical computation of heat transfer and fluid flow has been developed by the commercial finite element software COMSOL Multiphysics. Radiation code is developed based on the T₁₀ Ray-Tracing method, and the radiative properties of the medium are computed based on the statistical narrow band correlated-k model.

The obtained results depicted that the radiation considerably contributes to the temperature homogenization of the gas. The findings highlight the impact of the heater location on swirling flow. It is also shown that the laterally heating process provides better energy efficiency than heating from the top of the enclosure.

This study is performed to improve heat transfer and to minimize entropy generation. Therefore, it is conceivable to improve the model design of industrial applications.

The purpose of this paper was to formulate porridge using orange-fleshed sweet potato (OFSP), soybean and moringa ingredients that optimizes its nutritional quality and acceptability.

A 16-run constrained D-optimal mixture design was used to evaluate proximate compositions and sensory acceptability of the products. Each composition and acceptability response variable was optimized separately, and then, the sweet spot that optimizes all was determined.

The protein, fiber, total ash, carbohydrate, iron and carotenoid contents as well as major sensory quality indicators were significantly affected by soybean, moringa and OFSP blends. However, the influence of the mixture on fat content was weak. Sensory acceptability was high for porridges processed from high OFSP and soybean, but higher nutritional quality was obtained from higher moringa levels. Graphical optimization showed that blends containing 68-75 per cent OFSP, 17-26 per cent soybean and 5-8 per cent moringa have produced nutrient enriched porridges with desirable sensory quality.

The study showed that OFSP, soybean and moringa have a potential for making protein, carbohydrate, dietary fiber, pro-vitamin A carotenoids and iron enriched product that will contribute to the fight against malnutrition in developing nations such as Ethiopia. In addition, having OFSP in the blend masks undesirable odor and taste imparted by moringa.