This research proposes an optimum grid-connected photovoltaic (PV) installation to meet the energy requirements of residential buildings in Saudi Arabia (KSA). Load profile data is used to establish a realistic electricity demand pattern. Sensitivity analyses are performed for 19 cities, varying the renewable fraction from 0% to 100%, to determine the minimum renewable energy fraction required to achieve competitive Cost of Energy (COE) values. The results show that increasing the renewable fraction reduces the COE of PV systems but leads to higher capital costs and Net Present Cost (NPC). The study also emphasizes the importance of considering CO2 emissions reduction achievable through PV system integration. Based on tradeoffs between renewable fraction and NPC, Hail, Sakaka, and Jeddah rank as the top three sites, balancing economic viability and renewable energy utilization. The outcomes provide valuable insights for decision-making and promote sustainable energy transition in KSA. Grid-connected PV systems bring social benefits, including job creation, improved living conditions, reduced emissions, enhanced energy security, and increased public awareness. This research contributes to understanding the renewable energy landscape in KSA and provides a methodology based on a multi-criteria assessment, using a search space algorithm to minimize the NPC or identify optimal PV installation sites that support the decisions of energy policymakers.

The integration of hybrid renewable energy systems (HRES) with reverse osmosis (RO) desalination plants presents a promising solution for sustainable water production, particularly in regions facing water scarcity and possessing a high renewable energy potential. This study conducts a comprehensive analysis of HRES optimized for 14 RO desalination plants across Saudi Arabia, addressing the critical need for techno-economic optimization in this context. The optimized systems demonstrate consistent renewable energy fractions ranging from 31 % to 36 % across various locations, with Duba achieving the highest value at 35.99 %. Total installed capacities vary widely from 3.022 MW in Farassan to 287.94 MW in Khobar, reflecting diverse local conditions and energy demands resulting from a wide interval of water capacity productions. Despite this variation, the Cost of Energy (COE) remains competitive across all projects, ranging from $0.0700/kWh to $0.0783/kWh. A detailed case study of Ras Al Khair, the only site incorporating wind turbines, reveals a 31.82 % renewable fraction with 47.7 MW PV and 45.5 MW wind capacity. Sensitivity analyses at this site indicate that increasing the renewable fraction from 0 % to 60 % raises the Net Present Cost (NPC) from $509 M to $685 M at 2 kWh/m(3) process energy intensity, with a dramatic spike to $2320 M at 80 % renewable fraction. While significant grid interaction persists, with annual purchases ranging from 311 GWh to 829 GWh, the study demonstrates that increasing renewable fractions can lead to long-term cost savings. These findings provide valuable insights for decision-makers and establish guidelines for implementing next-generation RO power plants in KSA, offering a framework applicable to countries facing similar challenges in water scarcity and energy transition.

This study investigated experimentally and numerically heat transfer of air jet impingement by comparing the surfaced averaged Nusselt number for several turbulence models and gap spacings. A plate with a constant temperature of 60 degrees C was fixed at 30.30 mm and 50.64 mm spacing from vertical jets. Air was pressurized out of orifices to create jets of air with flow open area percentages of 1%, 2% and 3% relative to area of the test plate. The numerical analysis was performed on three grids using the fitting method to produce grid independent solutions. Three turbulence models were employed in the numerical analysis, namely Transition SST, Transition SAS, and DES Transition SST models. The predicted and the measured average Nusselt numbers on the test plate were compared and high accuracy agreement between experimental and numerical results was observed with a maximum deviation of 7.85%. DES Transition SST model was found to be relatively reliable in predicting jet impingement heat transfer with a maximum deviation of 4.55% as compared to the data produced experimentally. The findings of this paper are critical for accurate prediction and optimization of heat transfer for jet impingement problems with the proper turbulence model and numerical methods.

The present study aims to reach the best design of the fins installed on the basin absorber surface that achieves the highest performance of the hemispherical solar distillers. The fins represent one of the most important improvement techniques utilized to increase the evaporation rates inside the solar distillers, by increasing the heat transfer area between the absorption surface and the basin water. However, some designs of the fins have negative effects due to the shading problem, which causes a reduction of the absorption rates of solar rays. Therefore, the current study aims to find the best design of the fins that achieve the least shading effects and the highest performance of hemispherical solar distillers. To achieve this idea, two types of fins (cylindrical and conical) with a diameter of 1.5 cm and a height of 3 cm, with different gap distances of 3, 3.75, and 4.5 cm were studied. To achieve these, three hemispherical solar stills were tested under the same weather conditions, first is a conventional hemispherical still without fins (CHSWF) which is the reference distiller. The second is the hemispherical distiller with cylindrical fins (CyFHS), and the third is the hemispherical distiller with conical fins (CoFHS). The results show that the hemispherical distiller with cylindrical fins (CyFHS) productivity values are 5.55, 6.00, and 6.70 kg/m2, respectively, while the hemispherical distiller with conical fins (CoFHS) productivity values are 6.20, 6.65, and 7.15 kg/m2 at the gap distances of 3, 3.75, and 4.5 cm, respectively, compared to 4.20 kg/m2 produced by CHSWF. The results showed that the use of conical fins with a gap distance of 4.5 cm represents the optimal fin design that achieves the least shading and the highest performance of hemispherical solar distillers, with improvement rates of 70.24% compared to reference distiller (CHSWF).

In this work, an Hybrid Renewable Energy System (HRES) based on microgrid power is proposed and optimized to meet the electric demand of a sustainable multi-family buildings with possible generation of clean hydrogen. Hourly building simulation is carried out based on meteorological data to predict the year-round electrical consumption of the designed buildings. The proposed hybrid system includes a Solar Dish Stirling (SDS) tech-nology combined with a Wind Turbine (WT) for power generation, an electrolyzer, a hydrogen storage tank, as well as a battery bank. The novelty of the study resides in the replacement of conventional hybrid systems, such as a photovoltaic PV/WT assembly, with an SDS/WT system that has the potential to reach higher efficiencies and economic competitiveness. An optimization process is investigated to evidence the optimum HRES design based on the lowest Net Present Cost (NPC). Sensitivity studies are performed to illustrate the effect of main functioning parameters and how they impact the overall project viability. Moreover, the performance of the model is evaluated in two selected sites in Morocco, namely Ouarzazate and Dakhla, and a comprehensive techno-economic study of the integrated system is investigated. The findings indicate that the HRES design and configuration are site-dependent due to discrepancies in wind and solar energy potential of the examined sites. The optimum architecture of the assessed HRES in Dakhla greatly promote the implementation of WT technology with a NPC/ LCOE of about 3.053 Meuro/0.0697 euro/kWh, respectively. In Ouarzazate, it was found that the optimum design configuration relies exclusively on the SDS technology and correspond to NPC/ LCOE of 3.391 Meuro/ 0.126 euro/kWh, respectively. LCOH values obtained by the optimum HRES configuration were determined 21.4 euro/kg and 23.6 euro/kg for Dakhla and Ouarzazate, respectively. This study demonstrates the viability of SDS implementation in future HRESs and open the perspectives for its role in carbon-neutral buildings.

Sorption cooling technology is considered to be a good alternative to traditional vapor compression cycles regarding energy savings and environmental issues. This technology has to be enhanced to overcome the problem of low efficacy. In this work, a novel solar-powered combined absorption–adsorption cooling system (ABADS) is proposed and investigated under different climatic conditions. The system combines a single-effect LiBr-H2O absorption chiller (ABS) and a single-stage silica gel/water adsorption chiller (ADS) in series configuration. TRNSYS simulation software integrated MATLAB code is used to simulate the solar-driven ABS, ADS, and ABADS mathematical models. Both of ABS and ADS models are validated experimentally with experimental data. Performance comparison between the proposed combined ABADS and the standalone ABS and ADS is also performed. Results shows that the proposed combined ABADS produced average monthly cooling capacity (19.86 kW) higher than that of ABS and ADS by 154.42% and 59.74%, respectively, around typical year. Furthermore, the overall COP (1.17) of ABADS is higher than that of the standalone ABS and ADS by 154.42% and 59.74%, respectively. Under the same hourly weather conditions of June 15 at 16:00 pm, cooling capacity of the ABADS is higher than that of the standalone ABS and ADS by 150% and 66%, respectively. The overall system COP of ABADS (1.16) improved by 60% and by 167% over the standalone ABS and ADS, respectively. In addition, the chilled water production is increased.

Traditional cooling and desalination cycles consume great amount of energy and pollute the environment. Reverse osmosis (RO) process is the most used desalination system due to high operation efficiency, but it produces large concentrated brine leading to damage the ecosystem. In this study, a new proposed hybrid absorption desalination cooling (ABDC) system integrated with RO is theoretically investigated. The rejected brine from RO is fed to the evaporator of the ABDC system for further distillation process. This would be a possible solution to treat the rejected RO brine, increasing the recovery rate, minimizing the overall operating cost, and preserving the ecosystem. A simultaneously cooling effect is also obtained. Results showed that, the cooling capacity of the stand-alone ABDC is about 0.346 kW with 0.774 coefficient of performance (COP), and 13.887 m(3)day(-1) fresh water productions at driving heat source of 85 degrees C, which can be easily obtained from low grade heat source. The proposed combined RO-ABDC system increases the overall recovery rate by 72.86% and the water quality by 59.3% and reduces the specific electrical energy consumption by 49.1% compared to the stand-alone RO. (C) 2020 Elsevier Ltd. All rights reserved.

This paper investigates modelling strategies on the prediction of lift and drag coefficients of a NACA0012 airfoil at Reynolds number of 360,000. Two computational methods are employed; namely Navier-Stokes equation and panel method, by using different tools for computing lift and drag coefficients. The obtained results are compared against experiment in order to assess the accuracy of each technique. Two turbulence models are employed; Reynolds stress model, which is not based on Boussinesq assumption and accounts for flow anisotropy and realizable model which is based on the Boussinesq assumption for computing Reynold stresses. Grid independent solution is produced using the 2-D URANs by employing the fitting method and the obtained lift and drag coefficients are compared against experiment. The fitting method is found to be efficient in saving computational time and power. It is also found that Boussinesq approximation is efficient in predicting lift coefficient. However, the 3rd order panel method produced a remarkably accurate drag coefficient compared to other investigated computational models. Combining the findings of this paper with the existing computational methods in the literature would significantly in improve the accuracy of predicting lift and drag coefficients and may significantly enhance the accuracy of simulation of several aerodynamics applications.

Significant research is being conducted in the simulation of fluid flows due to the increase in employing the physics of the fluid flow to either commercial, in-house or open source codes. The analysis of the fluid flow is mainly based on the Lagrangian or the Eulerian approach. Many of the simulation codes employ the Eulerian approach due to its simplicity. These codes are based on several numerical techniques and yet few benchmarks have been conducted. However, the codes which employ the Lagrangian approach seem to be promising and may accurately simulate fluid flow phenomena. In this paper, a comparative analysis of the Lagrangian and Eulerian approach is investigated for a water droplet in a tank. The velocity field and the total pressure of the fluid are generated for the simulation by employing Ansys Fluent for the Eulerian approach and DualPhysics for the Lagrangian approach. The fluid structure and the fluid flow development are compared in order to assess the capability of each approaches in analysing the investigated fluid flow. This study may play a significant role on the importance of employing the Lagrangian approach for fluid flows where complex fluid structure occurs.

A backward facing step (BFS) flow has been investigated extensively by the research community experimentally and computationally due to its significant flow features because of the presence of the separation-reattachment mechanism. The strength of this mechanism varies based on the Reynolds number (RN). For turbulent flow at low RN, the separation-reattachment mechanism computations may be expensive due to high requirements of fine grid which varies based on the employed turbulence model. Several classes of turbulence models have been attempted for capturing complex fluid flow phenomena, namely zero, one, two, three, four and seven equation models. Selected turbulence models from each class have been employed in this paper in order to predict the reattachment length behind BFS at RN of 37,000. The grid independent solution is obtained using modified general Richardson method based on three relatively coarse grids which significantly reduces the computational cost. It is found that the predicted reattachment length for employed turbulence models agrees well with experiment and is considered as a grid independent solution. The visualization of computational domain on the wind tunnel shows similar trends for flow developed in the region of reattachment length. This work can substantially reduce cost of computations for the prediction of reattachment length in BFS flow problem and shows how closely turbulence models perform when grid independent solution is obtained.

Adsorption cooling systems have low energy efficiency and large sizes compared to traditional cooling systems and still have to be improved and optimized in order to become more competitive. The objective of this study is to enhance and optimize the performance of a solar powered adsorption cooling system (SDACS) by defining its optimal operating conditions. A multi-objective genetic algorithm (MOGA) combing a Kriging based response surface is employed to optimize the operating parameters. Eight operating parameters include hot, cooling, and chilled water temperatures and mass flow rates, and cycle and switching times are considered. An innovative SDACS with three axial finned tubes heat exchangers connected in parallel has been designed and tested. A non-equilibrium lumped parameter model has been developed to predict the system performance. Results from optimization algorithm and simulation are compared with those obtained experimentally and good agreements are obtained with +/- 10% maximum error. The proposed SDACS is able to produce about 0.56 kW (145 W kg(-1)) cooling power with a COP of about 0.52 at the rated operating conditions. The optimized operating conditions using MOGA improves the SCP by 51.7% and the system COP by 21% compared to the rated operating conditions at the same design parameters. (C) 2020 Elsevier Ltd. All rights reserved.

This paper investigates the development of the dynamic stall of a full straight blade vertical axis wind turbine (SB-VAWT) using computational fluid dynamic modeling for solving the 2D Navier–Stokes equations. The 2D unsteady Navier–Stokes equations are solved with the concept of Reynolds averaging. A mesh independency test is analyzed using the General Richardson Extrapolation technique. Two turbulence models are applied, namely the SST k−ω and the Transition SST models. It has been found that the stall development is extremely sensitive to the transitional modeling and small laminar separation bubbles will only be accurately predicted by accounting for the transition. However, the transition affects the overall turbine performance by up to 20% and delays the peak of the predicted torque by about 11°, and therefore it is crucial to include laminar-turbulence transition in the design and optimization process of SB-VAWTs.

The flow around straight blade vertical axis wind turbines is typically complex at low tip speed ratios (TSR < 2). In this paper, the turbulence models which are based on the assumption of fully developed turbulent flow, such as S-A, RNG κ-ε and SST κ-ω have been investigated in comparison to the SST transitional model (both with and without curvature correction) to account for the laminar-turbulence transition. The investigation is based on the 2D unsteady Reynolds averaged Navier–Stokes (URANS) equations using a sliding mesh technique. It has been found that applying turbulence models based on the assumption of fully developed flow shows significant differences in velocity magnitude if the flow is under stall condition or wake effect compared to the transitional model. Also, the predicted flow structure in the vicinity of the stalled airfoils using different types of turbulence models is found to be different compared to the un-stalled airfoils where no significant differences in the flow field have been observed. In the wake region, the flow varies less significantly compared to the stalled airfoils.

This paper numerically investigates four methods, namely mesh refinement, General Richardson Extrapolation (GRE), Grid Convergence Index (GCI), and the fitting method, in order to obtain a mesh independent solution for a straight blade vertical axis wind turbine (SB-VAWT) power curve using computational fluid dynamics (CFD). The solution is produced by employing the 2D Unsteady Navier–Stokes equations (URANS) with two turbulence models (Shear Stress Transport (SST) Transitional and ReNormalized Groups (RNG) κ−ɛ models). The commonly applied mesh refinement is found to be computationally expensive and not often practical even for a full 2D model of the turbine. The mesh independent power coefficient produced using the General Richardson Extrapolation method is found to be encouraging. However, the Grid Convergence Index may not be applicable in mesh independency tests due to the oscillatory behaviour of the convergence for the turbine power coefficient. As an alternative, the fitting method shows a good potential for the predicting of the mesh independent power coefficient without the necessity to consider a massive number of meshes.

This paper investigates the flow field features and the predicted power coefficient of a straight blade vertical axis wind turbine (SB-VAWT) using computational fluid dynamics modeling using 2D simulations. The Unsteady Navier-Stokes equations are solved with the concept of Reynolds averaging using the commercial software FLUENT and the sliding mesh technique is applied. In the mesh phase, three parameters have been investigated, namely the cell type, the cell aspect ratio on the airfoil surface, and the total number of cells in the computational domain. In the simulation phase, two parameters have been investigated, namely the time step/Courant number, and the turbulence intensity. Significant differences have been observed in the flow field features and on the predicted power coefficient for some of these parameters which if not considered in details could lead to unreliable predictions. The sensitivity of the parameters is not equally significant and this paper suggests which parameters should be focused on in the modeling process. The convergence behavior of the quadrilateral based mesh is found to be more consistent compared to the triangular based mesh. In the mesh phase, the cell aspect ratio on the airfoil surface was found to be a significant factor, whereas the turbulence intensity was found to be a significant fac-tor in the simulation phase.