A two-dimensional double Multiple Relaxation Time-Thermal Lattice Boltzmann Equation (2-MRT-TLBE) method is developed for predicting convective flows in a square differentially heated cavity filled ...with air (
Pr
=
0.71
). In this Letter, we propose a numerical scheme to solve the flow and the temperature fields using the MRT-D2Q9 model and the MRT-D2Q5 model, respectively. Thus, the main objective of this study is to show the effectiveness of such model to predict thermodynamics for heat transfer. This model is validated by the numerical simulations of the 2-D convective square cavity flow. Excellent agreements are obtained between numerical predictions. These results demonstrate the accuracy and the effectiveness of the proposed methodology.
The ongoing evolution of electronic systems that operate under extreme conditions has led to persistent concern about potential failures caused by escalating temperature levels which provokes the ...decline the operating quality. In response to this challenge, cooling solutions based on microchannels have emerged as promising prospects for improving thermal management in such scenarios. This paper explores the importance of these innovative cooling techniques and their potential for mitigating the risks of overheating in electronic systems. Furthermore, the introduction of microfluidic techniques and microchannels, specifically constricted microchannels, offers promising approaches to improve cooling efficiency. These cooling systems enable efficient heat dissipation and thermal regulation, mitigating the risk of overheating and enhancing system performance. Constricted microchannels facilitate compact and efficient heat transfer by leveraging increased surface area-to-volume ratios and improved convective cooling. Nowadays, microchannel-based heat sinks, heat exchangers, and cooling systems have been developed, showcasing improved heat dissipation, reduced temperature gradients, and enhanced energy efficiency. This research focuses on a parametrical study that examines the fluid nature, Reynolds number analysis, and system design. Numerical results demonstrate successful thermal management of high-temperature electronic systems using constricted microchannel cooling. These results mitigate temperature-related failures and support the development of robust systems for harsh operating conditions.
The developed Annual Columnar Radiative Absorptivity (ACRA19) model that describes, in annual mean, the terrestrial radiation balance of an atmospheric column, allows the determination of the various ...regional, absorption and reflection of solar and infrared radiation using 2018’s annual data of eight sites in MENA region ( between 22N-38N) of latitude obtained from AERONET and NASA POWER. The atmospheric thermal absorptivity (ATA) is very significant at high temperatures with an average of 0.85±0.1 for 1020 nm and the atmospheric visible absorptivity (AVA) registers 0.36 ± 0.06 when the total optical depth observes its maximum linked to dust aerosol advection.
This work aims at answering the question–to what extent thermally compliant buildings are involved in ensuring the winter indoor thermal comfort of occupants in cold semi-arid climates in Morocco. ...Real-time monitoring of a new-built university building located in eastern Morocco was conducted. The good agreement between the measured and simulated temperatures of the case study building confirmed the accuracy of the developed model. Thereafter, the thermal performance of different external wall configurations was investigated. The results show that compliant buildings guarantee better comfort conditions in winter by passively increasing the indoor air temperature by up to 2 °C, resulting in a maximum percentage of dissatisfaction of less than 13%. The winter discomfort hours based on a temperature set point of 16 °C are reduced by 95% compared to typical buildings. Moreover, the thermal compliance of buildings significantly reduces the daily air temperature amplitude, leading to a periodic dynamic behaviour without peak loads, which could be effective for the building energy management. The efficacy of earthen walls in regulating indoor temperatures was also confirmed due to the excellent thermal inertia of earth. For optimum winter comfort (20 °C), the implementation of the Moroccan building energy code shows up to 72% of reduction in heating demand when applied to conventional buildings.
•Combination of bio-sourced building materials and renewable energies for low energy building design.•Biosourced earth blocks exhibit excellent thermal propetries compared to earth blocks without ...plant-fiber addition.•Techno-economic feasibility assessment of standalone PV systems for a biosourced earth building.•Future constructions should take into account not just renewable energy technologies but also renewable raw materials.•Building's electricity consumption with 100% renewable energy and zero emissions was achieved.
Off-grid rural electrification programs involving renewable energy provide effective ways to boost the availability of power in remote areas. Herein, the combination of local bio-based building materials with appropriate sizing of a photovoltaic (PV) system to achieve energy-efficient rural housing in developing countries is investigated. The study focused on the fabrication and laboratory testing of a building material incorporating plant fibers, followed by a feasibility analysis of an integrated stand-alone PV system. EnergyPlus software was used to assess the energy-saving potential of bio-based building envelopes, and Homer Pro software was used for techno-economic optimization. Using a case-study building, various configurations were evaluated in terms of levelized energy cost and net present cost. According to the experimental results, the inclusion of 8 wt% Alfa fibers in earth blocks led to a noteworthy enhancement in the thermal resistance and time lag of the building envelope. Specifically, the improvement ranged from 0.549 to 1.125 m2K/W and from 18.5–h to 23.2–h, respectively, compared to using earth alone. This improvement resulted in a substantial decrease in the building's annual energy consumption, with a reduction of 24.3% for heating and 26.7% for cooling. Furthermore, the techno-economic analysis revealed that the electricity provided by a PV-battery hybrid system was 100% renewable and emission-free, with an energy cost of approximately $0.218/kWh and a present net cost of $11,560.21 These findings indicated that combining available solar energy with locally produced bio-based construction materials could be a viable approach for achieving carbon neutrality and building energy-efficient ulta-low-cost rural housing.
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•10.8 mm of rain per day is considered as threshold for self-cleaning of the mirror.•Self-cleaning of the mirror reduced the soiling index from 63% to 18.6%•Artificial neural network ...is an efficient approach to simulate and predict the performance of the mirror for short-term period.•Wind speed, relative humidity, ambient temperature, and dust AOD are the most influencing parameters on the soiling of the mirror.•Modeling of soiling index using ANN model reached perfect results with the structure (4-20:20-1).
The main purpose of the current work is to examine and evaluate the impact of outdoor soiling on the performance of a sample concentrating solar power reflector. The exposure period is from April 2019 to October 2019, and during this period the mirror was left without cleaning. Achieved results from the experiment showed that the soiling index increased by almost 63 % with a maximum accumulation of dust on the mirror after approximately 20 weeks of exposure, then, it decreased due to rain event. Modeling the performance of the exposed mirror is also investigated in this paper. Thus, correlations between essential weather parameters (ambient temperature, wind speed, wind direction, relative humidity, rainfall, and dust optical depth) and soiling index are determined to select the most appropriate attributes for predicting daily soiling. The prediction is performed using Multilayer Perceptron Neural Networks approach with the adjustment of hidden layers, hidden neurons, and epoch iterations. Hence, three artificial neural networks configurations are trained, validated, and compared to other methods. The modeling study presented satisfying results, and the adapted structure includes two hidden layers and 20 hidden nodes for each layer. The best achieved performance showed a correlation coefficient of 1 and 0 % for the different calculated statistical metric errors.
The coupled double diffusive natural convection and radiation in a tilted and differentially heated square cavity containing a non-gray air-CO
2
(or air-H
2
O) mixtures was numerically investigated. ...The horizontal walls are insulated and impermeable and the vertical walls are maintained at different temperatures and concentrations. The hybrid lattice Boltzmann method with the multiple-relaxation time model is used to compute the hydrodynamics and the finite difference method to determine temperatures and concentrations. The discrete ordinates method combined to the spectral line-based weighted sum of gray gases model is used to compute the radiative term and its spectral aspect. The effects of the inclination angle on the flow, thermal and concentration fields are analyzed for both aiding and opposing cases. It was found that radiation gas modifies the structure of the velocity and thermal fields by generating inclined stratifications and promoting the instabilities in opposing flows.
Hybrid Renewable Energy Systems have been considered as a suitable way to supply electricity. The hybrid energy (Solar-Wind-Storage-hydrogen-diesel) is increasingly used in various applications, ...especially at isolated sites. This study proposes the optimization and analysis of a stand-alone photovoltaic/battery/fuel cell/electrolyzer/hydrogen hybrid system (HS) to find out the optimal sizes and costs. In the first step, SAM software was used to estimate the global solar irradiance (GHI) for the studied area and to select the best PV, battery and fuel cell components. MATLAB software was handled to predict the power output of the renewable source (PV system) using an Artificial Neural Network (ANN) model. Then, simulation, optimization and techno-economic analysis were carried out in the second step with HomerPro software. Four proposed configurations are optimized in this work and different comparisons have been made regarding the found results. The results of the cost optimization were found to be 50861.21 $ and 0.95657 $ for NCP and COE, respectively. Moreover, the same HS configurations are simulated and optimized under Moroccan climate.
•Hybrid Renewable Energy Systems is a suitable way to supply electricity.•A stand-alone photovoltaic/battery/fuel cell/electrolyzer/hydrogen hybrid system.•SAM software was used to estimate the global solar irradiance.•MATLAB was handled using an Artificial Neural Network model.•Optimization and techno-economic analysis with HomerPro software.
This study presents the effect of the position of the control partitions on fluid flow around a square cylinder in a rectangular open channel. The numerical simulations are carried out with the ...lattice Boltzmann method at a fixed Reynolds number (Re=150). In the first case, two downstream partitions are inserted, whose spacing gap (g) varies as a function of the cylinder dimension (d), ranging from 0 to 13d. In the second case, four partitions are implemented such that g is fixed at 3.9d and the upstream spacing varies from 0 to 4d. The numerical results of the first study reveal the existence of a critical spacing at g=3.9d, where the average drag coefficient reaches a minimum (16.28%). Likewise, the vortex shedding between the square cylinder and the two detached partitions or behind these two partitions are also affected. Furthermore, a significant decrease in the drag coefficient, reaching 36.33%, is attained when situating the two upstream partitions at a distance of g1=0.25d.
•The presence of control partitions reduces the number of vortexes shedding.•Increasing the number of control partitions increases the percentage reduction in the drag coefficient from 36.33% to the case without control.•The most violent behaviour of the flow is observed at g = 5 d, this case is undesirable.
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