Since buildings make a major contribution to the distribution of total energy, it is essential to take into account their functionality and the repercussions this has. Passive solar technology is a vital part of contemporary architecture, and the Trombe wall, as one of its principles, certainly stands out from the others. The new transparent Trombe wall (T-T-W) can receive solar intensity from all four sides. We developed the addition of parallel slats of transparent insulating material (TIM-PS) in the newly designed T-T-W with the help of a numerical study using CFD simulation. Taking the actual climatic conditions of a winter solstice day with a Mediterranean climate, the optimal design of a T-T-W was investigated. The use of perpendicular TIM-PS can eliminate convective heat loss through the south glass wall, increasing thermal efficiency from less than 5

In solar energy concentration systems, the receiver configuration affects how effectively the concentrated sunlight can be converted into usable thermal energy. Therefore, careful consideration and optimization of the receiver geometry shape are essential to improve the efficiency of the solar-thermal energy conversion process. In this article, the impact of inserting disc in the cylindrical absorber is studied numerically using Ansys Fluent. Performance assessment is carried out for various numbers of discs. As the number of discs increases from 0 to 8, both the working fluid outlet temperature and the solar receiver thermal efficiency rise. The results demonstrate a significant enhancement in these two parameters, with increases of 12.08 % and 29.14 %, respectively, as the discs number rises from 0 to 8.Haut du formulaire This study represents the first detailed investigation of a disc receiver, making it a novel contribution to the field of parabolic solar collectors.

An innovative fa & ccedil;ade system in which the roof and side walls are transparent to solar radiation, with transparent insulating material parallel slats (TIM-PS) embedded between the glass fa & ccedil;ade and the solid wall, is proposed as a strategy to effectively reduce convective losses and intensify solar radiation penetration. This study proposes the validation of a model equipped with glass side walls and roof, using data provided by an experimental device. A numerical study was then carried out to investigate the effect of the TIM-PS included in the air duct and how the position of slats affects the performance of the proposed solution. The Optimal design is a T-T-W featuring with -45 degrees TIM-PS. For the innovative T-T-W equipped with -45 degrees TIM-PS heating duration has been extended by two hours. This original model allowed raising the thermal efficiency at 17H from 5% provided by the normal T-T-W up to 40%.

The purpose of this research is the evaluation of heat transfer by natural convection in an innovative flat plate solar collector operating in natural convection mode. The design consists of inclined, perforated slats of transparent insulation material installed between the absorber and the glass cover. Hourly climatic data on the four specific days of solstices and equinoxes was used to investigate the behavior of the novel collector design in the city of Monastir; Tunisia. A comprehensive process, ANSYS FLUENT, was implemented to properly evaluate the thermal performance of the collector. In order to obtain accurate thermal properties of the smart collector façade unit containing the TIM-PS to exploit in the simulation, a validated three-dimensional finite volume model developed using the CFD software was used to solve the conductive, convective and radiative heat transfer properties of the system. We have explored in depth the effect of optical characteristics of the TIM-PS on the collector performance. Present research focuses on the analysis of thermal efficiency profile of flat plate collector with innovative façade in comparison with conventional collector for different climatic conditions. The analysis indicated that innovative façade collector’s efficiency is highly influenced by solar intensity. It was found that TIM-PS façade can effectively reduce the convective heat losses through the front of collector. The simulation results show that perforated tilted TIM-PS offer better performance than conventional façade of collector during all the seasons of the year. Simulations performed for one year predict that with careful selection of the parallel slats properties, the new façade system can generate an efficiency up to 83% in June, 76% in September, 53% in March and 42% in December. The results of the thermal evaluation of this research will help guide the future development of this system, as we have demonstrated that the innovative façade collector can be used all year round. In conclusion, the TIM-PS have great potential and a very wide range of applications in the field of flat plate solar collector.

The flat plate solar air collector operating in the mode of free convection is an essential element, which contributes to make easier the valorization of solar energy in the residential and industrial sectors. The existing FPCs suffer from comparatively low efficiency and high losses. Being efficient, inexpensive and simple to manufacture, their importance has been increased by the recent intensification of attempts to maximize the profitability of solar energy. To address this challenge, this paper is a numerical investigation of an innovative design and manufacturing approach of a FPC operating with natural convection. A new configuration of FPC, including transparent insulation material parallel slats (TIM-PS), is proposed and investigated. A thorough numerical investigation has been carried out to evaluate the contribution of the TIM-PS in the improvement of the air heating collector performance. The influence of slats'; number, angle of inclination and geometry on the FPC's performance are studied. This CFD survey yielded the highest optimized and most cost-effective configuration for a vertically mounted collector with seven perforated TIM-PS inclined at +45 degrees. The innovative facade collector can achieve a thermal efficiency around 60% with keeping the lightweight of the collector and the low cost. The peculiarity of this result lies in the combination of perforated and tilted TIM-PS that are investigated in our new study. These results introduce a new design of solar air heater operating in a natural convection mode, designed to be adapted to a range of geographical locations and sunlight conditions.

Building integrated photovoltaic (BIPV) systems constitute a key concept for the realization of sustainable buildings. However, these systems have limited efficiency and durability due to their insufficient cooling capabilities. To overcome this drawback, it is necessary to maintain the operating temperature as low as possible. This study investigates the effectiveness of a passive low-cost strategy to improve the photovoltaic module (PV) performance of naturally ventilated BIPV systems by decreasing the module operating temperature. This strategy consists of inserting twisted baffles on the rear side of a PV module to enhance its cooling performance. A numerical investigation was performed using Computational Fluid Dynamics (CFD) simulations in order to explore the module surface temperature and its electrical efficiency. The effects of solar irradiance, the number and position of twisted baffles, and twist ratio have been investigated. The results revealed that the average temperature of the PV surface decreases with the increase of the number of twisted baffles (N), which leads to an improvement in the electrical efficiency. Indeed, the optimum performance enhancement is attributed to N = 15, and the corresponding PV temperature was decreased from 312.66 K to 310.15 K and from 348.42 K to 342.64 K for a solar irradiance variation from 200 to 1000 W.m(-2), resulting in an improvement of 1.21-3.36% in electrical efficiency compared to the case without inserts. Concerning the effect of the twist ratio, it is shown that the optimum electrical efficiency improvement is reached for the lowest twist ratio, which is in the range of 1.7-6.1% for solar irradiance range from 200 to 1000 W.m(-2).

We present, in this work, the main results obtained from a two-dimensional numerical modeling of a tunnel kiln used for production hollow bricks. The results obtained made it possible to present contours of the temperature inside a tunnel kiln using a home-made two-dimensional code written with the open-source software SCILAB. The results showed the existence of a vertical temperature gradient in the brick stacks which can affect the final quality of the baked products.

This study aims to characterize some safety aspects by examining the geometries of the infrastructure, currently used by societies, against the accumulation of hazardous hydrogen clouds during an accidental leak in areas with limited ventilation. Using ANSYS FLUENT as a modeling tool, the influence of garage roof shape; pyramidal and domed roof compared with the basic model (flat roof), for different leak times, on dispersion and stratification of hydrogen layers, is analyzed. As a result, the domed roof promotes to have a lower hydrogen concentration and presents two remarkable peaks of the Richardson number (Ri) with the highest value more than 2 x 10(5), which is three times higher than the flat roof. Besides, the influence of the leak time on the dynamic of the flow, concentration, and stratification process are observed: the mole fraction of hydrogen is more than 0.25 after 1 h of leak, whereas it is lower than 0.05 after 100 s. The volume flow and therefore the flammable volume increase. This study highlights the importance of geometrical and sizing parameters on the characteristics of hydrogen leaks and subsequently gives insights to establish performance standards for the availability and reliability of safety critical systems. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Nowadays, building integrated photovoltaic (BIPV) systems are considered as a key concept for sustainable buildings. But these systems present some drawbacks which are mainly related to the negative effects of the solar cells temperature on these systems electrical efficiency and life time. An attempt to reduce this effect and improve the performance of BIPV is presented in this paper. The proposed solution consists of solar cells cooling systems application. Different structures of the cooling duct such as square, triangular and cylindrical are so studied and their effect on the performance of corresponding solar system is discussed. Results show that for all tested configurations, the water cooled duct can effectively reduce the surface temperature of the PV panel, allow a uniform distribution of this temperature and consequently improve the corresponding system performance. Regarding the electrical performance, the cylindrical duct showed the best cooling effect which consequently presented the best electrical efficiency for the considered solar system. However, the triangular duct was found to better improve the thermal and thus the overall efficiency of the BIPV.

For nearly a century, fluidized beds have been the backbone of the processing industries. However, the complex hydrodynamic behavior aggravated, by the diversified solids handling has largely hindered its scaling up. The flow pattern may be influenced by the solid particles' feeders, and thus can have an impact on the system performance. In the first part of the present work, the hydrodynamic behavior of a 2D circulating fluidized bed is simulated under different superficial gas velocities to investigate their effect on the overall flow patterns. The numerical results are validated against available experimental data and a good agreement is achieved. In the second part, a special concern was dedicated to the effect of the gas/solid feeding configuration over the established flow structure. For the matter, five different configurations were tested and the corresponding results showed the high relevance of the feeding configuration, particularly in the bottom zone and on both phases. This impact decreases as we progress higher in the riser.

The exploitation of solar energy using hybrid photovoltaic/thermal (PVT) system can represent a viable choice for the rising energy demand. Due to the wide range of PVT applications, many designs have been developed to improve the solar system global performance by cooling PV cells. The proposed system offers a practical heat gain in addition to the electrical efficiency enhancement. The integration of optical water filters (OWF) in photovoltaic systems could be an advantageous solution for their performance improvement. In this work, three different optical water filter models are evaluated using Cinematic fluid dynamics CFD modeling and their effect on the global system operating is discussed. Three shapes of OWF models are considered. Model (I) is an OWF under the PV cell. Model II is an OWF which passes over and under PV cells with separated inputs. Model III consists of a double pass mode OWF. Results showed that the maximum photovoltaic efficiency is corresponding to model (III) and reaches 12.08% at 14 h. The paper highlighted the different impacts associated with different OWF models. The results showed a significant increase in water outlet temperature. Consequently, an enhancement of the PVT system thermal efficiency is achieved. Finally, various water-based nanofluid (Al2O3, Cu, Ag, Au) optical filters are elucidated. The optimal photovoltaic performance is obtained by the water-Au nanofluid which allowed an electrical efficiency varying between 2% and 10%. Nanofluid filters have thus been shown to improve the performance of the CPVS concentrated photovoltaic system, not only because of the thermodynamic properties but also as a spectrally separated cooling system.

In this paper, various designs of concentrating solar water heater systems are studied. Our reference system is an integrated collector storage (ICSSWH). The proposed changes concern the concentrating technology by considering a dish instead of a CPC reflector, and the design of the concentrating solar water heater (CSWH) by considering a vertical instead of the horizontal mounting of the cylindrical storage tank in addition to the removal of the glass covering the system. Numerical results of the water temperature evolution and distribution show that the solar system which consists of a dish with a vertical storage tank performs better than the other systems. Indeed, in this solar system, the water temperature achieves 365 K while that in the ICSSWH does not exceed 328 K. The optimum storage tank diameter for the hottest day of the year is also evaluated for the chosen concentrated solar water heater and its operating is simulated for a typical day of each season. Results show that a tank diameter of 0.14 m allows the best hot water production throughout all the year. So CFD results show a satisfactory performance of the dish-based system with a vertical storage tank of 0.14 m diameter and prove the suitability of this point-focus solar collector for a solar water heater application through all the year.

In this paper, a parabolic trough collector (PTC) is studied, and its thermal performance is compared to that of an integrated collector storage solar water heater (ICSSWH). The effect of the concentration technology is so investigated using computational fluid dynamics (CFD) simulations. Results show that the PTC presents higher useful heat and, consequently, higher water temperature relative to the ICSSWH. It is also shown that its main disadvantage is its fast temperature drop and, thus, its high night losses. This drawback can be limited by covering the storage tank with a particular material layer. Phase change materials (PCM) are so introduced, and a PTC in which the storage tank is covered with a PCM layer is studied. Three different materials, respectively, durene, methyl bromobenzoate, and octatricontane, and three PCM radiuses, respectively, 0.03, 0.04, and 0.04 m, are considered. Simulation results show that the latent heat storage unit presents better thermal performance than the sensible one. Concerning the phase change, it is noted that for methyl bromobenzoate, the melting temperature that is relatively the highest in comparison with other PCM is not reached, and the phase change does not occur. The thermal behavior is similar to that in the sensible unit in which the water temperature increases, reaches its maximum value, and decreases next. However, for the other PCM, the melting temperature is reached, and the solid/liquid transition occurs. We notice that in an isothermal behavior during all this period and even after its end, the water temperature decreases very slightly during the rest of the night. Durene can be so selected as the most appropriate PCM for this PTC's design relative to octatricontane as it allows higher useful heat and lower night losses. The effect of the PCM's radius shows that the best performance corresponds to the lowest value, which is 0.03 m.

a hybrid Other investigations Tiwari, were interested to hybrid phοtοvοltaic-thermal systems cοοled by forced air circulation [6-9] . In this solar system; the heat produced the PV is the by ABSTRACT This paper presents a numerical investigation of a novel Optical Water Filter (ΟWF) integration in a Concentrator Photovoltaic System (CPVS). The ΟWF consists of a water layer placed on top of the PV module that serves as a solar spectrum splitter and a heat absorber. The water layer transmits the visible and a part of the infrared radiation, while filtering the ultraviolet and some of the infrared radiation which are not used by the PV cells. In this paper, numerical simulations were carried out for different filter’s nature and dimension. Five water layers are considered, respectively 1 cm, 2 cm, 3 cm, 4 cm and 5 cm. Results showed the significant effect of the water layer thickness on the PV cell temperature and proved that the best total efficiency is obtained for the water thickness range of 3 cm to 5 cm for which it exceeds 50%. The article pointed out the effects of the inclination of CPVS and the solar irradiation for the different water thicknesses. It is shown that the filter does not change the known results of the CPVS but it influences the gain in electrical efficiency which can reach an average value of about 3%. Moreover; a comparison οf the performance of different working fluids (propylene glycol, ethylene glycol, water and coconut oil) for the optical filter was performed and the results showed that water and coconut oil are found the best filters. The study presents also the concept of energy-saving efficiency to evaluate and to provide criterion fοr checking the overall performance of PVT systems. It is found that the energy-saving efficiency of optical filters with coconut oil exceeds 0.7 fοr higher thickness layers than 2 cm. selective οptical filters [30] . Otanicar studied οptical prοperties of fοur liquids (water, ethylene glycol, prοpyleneglycοl and therminοl VP-1) cοmmοnly used in sοlar energy applicatiοns [31] . Joshi alsο suggested different ideas of systems with a selectiοn of easily available transparent liquids (water, cοcοnut oil, Al 2 Ο 3 Nanοfluid, silicοnοil) [32] . Tο determine which filter shοuld be cοnstructed, we shοuld take care οffοur aspects: οptical prοperties (absοrptiοn transmissiοn spectrum), aging effect which is related to the effect of cοntinuοus expοsure to sunlight, thermal prοperties (heat capacity, viscοsity, flammability) and ecοnοmical aspects (easily available, inexpensive for large-scale cοmmercial applicatiοn).

Concerns about sustainability of solar energy have resulted in continuous efforts to improve the performance of flat plate solar air collector. The most advanced collector must provide the highest thermal efficiency and satisfy strict requirements for low weight, ease of manufacture and low cost. The purpose of this new study is to examine potential improvements in the performance of flat plate solar air collector. An innovative facade collector, with transparent insulation material (TIM) parallel slats is presented. A numerical modelling of new designed solar air collector was conducted. The performance of this collector was investigated using a three-dimension simulation model, following steady state. Thermal, thermo-hydraulic and exergy efficiencies of the collector containing (TIM-PS) system with different slats; number, height, materials, as well as the slats tilt angle and collector tilt angle (0°,30°,45°,90°) are studied. The CFD predictions show that, the incorporation of TIM-PS decreases the thermal losses, leading to higher efficiencies. This study has realized the most promising and most efficiently optimized design of the 45° tilted collector equipped with 6 TIM-PS tilted by −45°, this new FPC is capable of achieving 81% thermal efficiency. The new design presented in this study, deserves further exploitation as it seems to be a promising alternative for increasing thermal efficiency with a low cost and weight. It could be used in industrial and domestic applications.

Green hydrogen can play a considerable role in helping the world achieve net zero emissions by forming a bridge between the energy sector and transportation. Currently, it is, at the initial phase of development, due to the low demand for hydrogen (H2) fuel for transportation in general. However, an increase in the H2 fuel demand in the future will require high investments in the infrastructure sector. In this regard, parking hydrogen vehicles in residential garages pose a potential safety hazard because of the accidents that could arise from hydrogen leaks. The diffusion of hydrogen in a ventilated garage has been investigated using FLUENT software. This study provides some insight into the hydrogen extraction efficiency of a natural ventilation system. We studied the influence of important ventilation parameters (shape and aspect ratio R of opening ventilation) on hydrogen stratification. First, results show a remarkable efficiency in the case of the square shape. Second, when the aspect ratio R decreases, there is an augmentation in fresh air drawn and hydrogen evacuation which generates the decrease of hydrogen concentration inside the garage and increases the extraction efficiency.

The present study considers multiple tandem jets in cross flow under an injection ratio less than 1. The jets are emitted through 60°-inclined, 8 mm-diameter cylindrical nozzles that are razed at different levels from the ground of the working wind tunnel. The understanding of this configuration is likely to provide a good support for the comprehension of more complicated and then real situations. The main objective of this paper consists of the exploration of the different flow structures induced by the emitted jets with the oncoming mainstream in one hand, and with each other and the different domain boundaries on the other hand. A particular attention is dedicated to the established flow field and the induced vortical structures. It is mainly observed that an injection rate inferior to 1 promotes the jets’ flattening and even more the rear jet. A higher injection height, on the other hand, operates differently by providing the jets with a further impulse to cross deeper and higher the mainstream and stay away from the ground attachment effect.

The most promising collector must achieve the best thermal efficiency and fill out high requirements of low weight, low power consumption, ease of manufacturing, and low cost. In this study; a novel efficiently optimized flat plate solar air collector is modeled with a selective absorber and three rows of rectangular fins installed beneath the structure that provides 81% of thermal efficiency and 0.5 W of pumping power. A three dimensional CFD model of a flat plate solar air collector is developed and solved in steady-state conditions. We propose a suitable approach for assessing and optimizing a 1.28 m2 surface collector’s performance with forced convection flow. Results indicate that additional fin rows (from 35 rows to 142 rows) and fins relative height (0.5 to 0.8) with a nonselective absorber increase the thermal performance from 63% to 80%, and additional turbulent flow causes an increase of pump power from 1.8 W to 16 W. The adoption of a selective absorber contributes to efficiency 5% higher than that of a collector with 35 rows of fin for a volume flow of 85.33 m3/hm2. In contrast, the gain achieved by adding 142 rows of fin (l’/L=0.006) remains the most important, where it leads to an effective efficiency of 79.2% for a volume flow rate of 85.33 m3/hm2. Thus, it has been proposed to combine the selective absorber with the addition of rectangular fins in the new design.