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Despite advances in enhancing the output of conventional solar stills, the pursuit of the most efficient solar distillation technique remains ongoing. Evacuated tubes, known for their superior thermal capacity compared to traditional single-basin solar stills, offer a promising solution for high-yield distillation. This study evaluates the performance of a semi-cylindrical tent-shaped solar still coupled with evacuated tubes (SCTSCET) against a conventional single-basin, single-slope solar still, used as a benchmark. Experiments conducted in Amman, Jordan, in May 2023, demonstrate that the SCTSCET significantly outperforms the conventional solar still in distilled water production. The SCTSCET achieved a daily yield of up to 9.7 liters, which is approximately 288 % higher than the 2.5 liters produced by the conventional still. This increased productivity is due to a 45.7 % enhancement in heat capacity provided by the evacuated tubes, which raised the water basin temperature to 61.4 °C, compared to 41.2 °C in the conventional still. This higher temperature facilitated a faster evaporation rate and improved water output. Additionally, the SCTSCET exhibited a 10 % higher hourly thermal efficiency and a peak exergy efficiency of 5.7 %, compared to 3.4 % for the conventional still, highlighting its superior ability to harness and utilize solar energy for distillation.

Biodiesel has emerged as a compelling substitute for conventional diesel fuel, providing a sustainable and eco-friendly choice for fueling compression ignition engines. This comprehensive study investigates the influence of biodiesel, specifically derived from sunflower oil, through the esterification method, on crucial engine performance parameters and environmental effects. The study examines the impact of varying engine torque on the performance of a single-cylinder, four-stroke compression ignition engine, encompassing parameters such as brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC), as well as exhaust emissions, including unburned hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). Four distinct biodiesel blends (B10, B20, B30, B40) with varying sunflower oil content are systematically compared to pure diesel (B0). The engine operates at a consistent speed of 1700 rpm, while the torque undergoes controlled adjustments from 0 to 10 Nm. Subsequently, this study explores the application of an alternating model tree (AMT) machine learning algorithm to establish relationships between independent factors, specifically torque and biodiesel volume (%vol), and dependent variables, including BTE, BSFC, CO, and NOx in a combustion engine. Additionally, the study employs a multi-objective ameliorative whale optimization algorithm (AWOA) to optimize the model's output. The objective is to identify optimal values for torque and%vol that maximize engine performance (BTE) while minimizing engine emissions (CO and NOx) and reducing fuel consumption (BSFC). The optimization process yields noteworthy results, with AWOA achieving peak BTE at 29.714 %, BSFC at 0.262 kg.kWh-1, and NOx emissions at 992 ppm at torque 7.3 N.m and 13% vol. In contrast, particle swarm optimization (PSO) secured the minimum CO level at 0.123 %, with torque set at 7.6 N.m and 26% vol. The AMT models demonstrate high prediction accuracy, with coefficient of determination (R2) values exceeding 0.98.

Enhancing biohydrogen production from microalgae is crucial in addressing environmental and energy challenges. It provides a sustainable, clean energy source while reducing greenhouse gas emissions. Moreover, it advances microalgae-based biotechnology, enabling innovative biofuel production and ecological revitalization. The main target of this study is to develop a robust ANFIS model to simulate the biohydrogen production process from microalgae within photobioreactors. The study focuses on enhancing hydrogen yield by optimizing three critical process parameters: sulfur concentration (%), run time (hours), and wet biomass concentration (g/L). Initially, an adaptive neuro-fuzzy inference system (ANFIS) model for biohydrogen production process is constructed based on empirical data. Subsequently, the red-tailed hawk algorithm (RTH) is used to determine the optimal values for the process parameters, corresponding to maximum hydrogen yield. The performance of ANFIS model in predicting hydrogen yield is assessed using root mean square error (RMSE) and coefficient-of-determination (R2) values. The obtained RMSE values for training and testing data are 2.8477 × 10−05 and 1.2807, respectively, while the corresponding R2 values are 1.0 and 0.9911 for training and testing. The introduction of fuzzy logic into the model significantly improves its predictive accuracy, as evidenced by the drop in RMSE from 10.79 with ANOVA to 0.7159 with ANFIS, representing a substantial 93.4 % decrease. The remarkable precision of the ANFIS model, indicated by its low RMSE and high R2 values, underscores the success of the modeling stage. The combination between ANFIS with the RTH technique yields impressive results, leading to a hydrogen yield enhancement of 6.87 % and 26.65 % when compared to both measured data and ANOVA.

The phenomenon of flow around a static or rotating circular cylinder has significant applications in various engineering fields, such as building, bridge, and structure engineering. It can be used to control flow-induced vibration, blowing or suction, moving surfaces, acoustic thriller, and synthetic jet. Additionally, there is a need to enhance heat transfer rates in many life and industrial applications, including cavity shape enhancement, heating or cooling spread inside a cavity, heat dissipation in electronic devices, thermal mixing in storage units, solar collectors, desalination, and journal bearing lubrication. This study explores the effect of a horizontal magnetic field and a rotating inner circular cylinder on mixed convection within a two-dimensional oval-shaped enclosure filled with a non-Newtonian nanofluid. The Galerkin Finite Element Method (GFEM) is utilized for analysis, with the enclosure undergoing differential heating and cooling on the inner cylinder wall and the enclosure wall, respectively. The nanofluid consists of water infused with copper nanoparticles. The study explores various simulation parameters, including the Richardson number (Ri), Hartmann number (Ha), the inclination angle of the enclosure (β), power-law index (n), circle center eccentricity (e), and nanoparticles volume fraction (φ). It has been observed that as the Ha and n index increase for different Ri values, a wavy trend in local Nusselt number (Nu) profiles along the heat source surface is observed. Additionally, the heat transfer rate decreases with increasing Ri for various combinations of Ha and n index. Under specific conditions, such as Ri = 0.001, Ha = 60, e = 0, φ = 0.09, and β = 90, the results show that, compared to a Newtonian fluid (n = 1), the heat transfer rate exhibits percentage gains of approximately 6.31% for a pseudo-plastic fluid (n = 0.6) and 8.47% for a Dilatant fluid (n = 1.4). The convective heat transfer was significantly enhanced when the eccentricity of the cylinder was positioned in the lower or upper regions of the oval-shaped enclosure, particularly at e = - 0.3. The highest heat transfer rates were observed at β = 60 and 240.

Understanding the impact of hybrid nanofluids (NF) on natural convection (NC) within complex enclosures can significantly advance the efficiency of heat transfer (HT) mechanisms. These advancements play a crucial role in various engineering applications, such as thermal systems in electronics, energy conversion, and heat exchangers. This study numerically examined the NC taking place within a sinusoidal corrugated enclosure filled with an Ag-MgO hybrid NF. This system was heated differentially by a vertical solid wall. The vertical right wall of the solid is maintained at an isothermal at a high-temperature Th, while the left vertical wall of the cavity is kept at an isothermal at a low-temperature Tc. The vertical left wall of the solid is in contact with the porous medium (PM) saturated with the cavity's hybrid NF. In contrast, the top and bottom horizontal walls are maintained adiabatic. The governing equations were solved by employing the Galerkin weighted residual finite elements approach. The porous domain is modeled by employing the Darcy-Brinkman formulation. The parameters being studied encompass the Darcy number (10−5 ≤ Da ≤ 10−2), Rayleigh number (103 ≤ Ra ≤ 106), nanoparticle volume fraction (0 ≤ ϕ ≤ 0.04), amplitude of waviness (0.05 ≤ A ≤ 0.2), and number of undulations (1 ≤ N ≤ 4). The results highlighted that the introduction of hybrid nanoparticles into the pure fluid enhances the HT rate across the parameter spectrum. The highest average Nusselt number (Nuav) is attained at Ra = 106, Da = 10−2, A = 0.2 and N = 4. The findings of the current study have practical implications for current industrial applications, particularly in the cooling of electronic devices.

Oil shale (OS) can significantly enhance energy security and diversify the energy mix in countries like Jordan. However, OS extraction and utilization are always associated with negative environmental impacts. This paper investigates a novel approach of using renewable energy to further retort the OS to produce oil. In this study, Al-Lajjun and Sultani OS resources in Jordan were analyzed using a mathematical model and simulation analysis using the system advisor model (SAM) software. The study aimed for in-situ shale oil extraction from a vast shale oil reserve in Jordan, with a focus on mitigating energy usage and environmental issues. The study suggested utilizing recovered heat from the production stream along with an external source, which may include natural gas, solar thermal energy, or a combination of both, to produce the substantial amount of heat energy necessary for in situ pyrolysis of OS. The study designed five different plants using the SAM program: gas steam boiler (GB), photovoltaic (PV) with batteries, parabolic trough with thermal energy storage (TES), PV integrated with GB, and parabolic trough coupled with GB. The economic analysis, project recovery, and environmental evaluation were conducted, and the results showed that drilling wells in the Sultani area was more expensive than in the Al-Lajjun area due to the thickness of overburden. The PV with GB was the most economically advantageous option, with a total cost of $79.4 M for Al-Lajjun and $89.89 M for Sultani. However, the levelized cost of energy (LCOE) for Al-Lajjun and Sultani are 10.41 and 9.18 ¢ per kWh, respectively. Conversely, PV systems with batteries and the parabolic trough with TES demonstrated a higher level of environmental friendliness compared to other shale oil recovery systems. Among these, the systems incorporating PV with GB and parabolic trough with GB, both featuring an SF of 30%, consistently demonstrate CO2 emissions of 0.016 kg CO2 per kg of shale oil produced. In contrast, the system solely reliant on GB without any solar contribution, holding a 0% SF, exhibited elevated CO2 emissions of 0.023 kg CO2 per kg of shale oil produced. The study recommends the use of PV with GB as the most economically viable option, while PV with batteries is the more eco-friendly choice for extracting shale oil from the Al-Lajjun and Sultani OS reserves located in Jordan. The study outcomes can be useful for policymakers and investors interested in developing the shale oil industry in Jordan. However, further research is needed to evaluate the long-term environmental impact and sustainability of the proposed method.

This study aims to derive valuable insights for utilizing computational fluid dynamics (CFD) based on reynolds-averaged navier–stokes (RANS) and detached eddy simulation (DES) turbulence models (TMs) to analyze a specific radial ejector configuration known as the variable geometry radial ejector (VGRE). The VGRE features the primary nozzle and ejector duct plates with adjustable disk-like surfaces, allowing for changes in the nozzle and ejector throat areas within a single ejector. Extensive numerical investigations of the VGRE are conducted by systematically validating CFD models with experimental datasets and subsequently using the most appropriate TM to design a new radial ejector. The study reveals that the DES SST k-ω turbulence model achieves the closest agreement with experimental data, with an average entrainment ratio (ω) discrepancy of only 5 %. However, there are challenges in accurately predicting the critical compression ratio (rc*), especially under varying conditions. Based on the CFD results, the original VGRE exhibited ω values ranging from 0.16 to 0.61, rc* values between 1.5 and 3.1, and ejector efficiency (η) values between 7 % and 17 % at expansion ratio (re) values ranging from 89 to 150 for different nozzle throat separations (d) and different duct throat separations (D). Furthermore, this study presents a comprehensive investigation into predicting and optimizing ω, rc*, and η parameters using a multi-output gaussian process regression (GPR) model and a marine predators algorithm (MPA) approach. The multi-output GPR model was constructed to predict the relationships between boundary conditions (primary pressure (Pprimary) and secondary pressure (Psecondary)), geometric parameters (d and D), and the response variables (ω, rc*, and η). The model evaluation employed a 5-fold cross-validation technique to assess predictive performance, demonstrating strong predictive accuracy with low root mean square error (RMSE) and high coefficient of determination (R2) values. The optimization results revealed that the highest achieved values were ω = 0.303, rc* = 2.678, and η = 0.156, corresponding to specific parameter settings (Pprimary = 160 kPa, Psecondary = 1.8 kPa, d = 0.6 mm, and D = 2.3 mm). This study demonstrates the effectiveness of the multi-output GPR model for accurate prediction and the multi-objective MPA optimization approach for identifying optimal input parameters to maximize entrainment ratio, critical compression ratio, and ejector efficiency in fluid dynamics systems.

The natural convection within enclosures along with entropy generation minimization plays a crucial role in various applications, particularly when they involve the utilization of nanofluids and porous media. This phenomenon plays a crucial role in enhancing heat transfer, fluid flow, and overall system performance. By understanding and optimizing the natural convection and entropy generation processes, it becomes possible to improve the efficiency and effectiveness of various thermal management systems, such as heat exchangers, electronic cooling systems, and renewable energy devices. Moreover, the integration of nanofluids and porous media introduces additional complexities and opportunities for enhancing heat transfer and fluid flow characteristics within enclosures. The current study investigates entropy generation (Sgen) and natural convection in a Z-staggered cavity filled with a porous media filled with a TiO2-water nanofluid. The symmetrical enclosures with dimensions of 0.6 L × 0.5 L are considered, and the media contain a porous material saturated with TiO2-water nanofluid. The wavy left and right vertical walls of the staggered enclosure were maintained hot and cold at temperatures (Th) and (Tc), respectively. All the straight horizontal walls were considered insulated and impermeable. The fundamental equations are solved using the Galerkin Finite Element Method (GFEM), and the results are described in detail. The key result was that raising the Rayleigh number (Ra) and nanoparticle volume fraction increased heat transmission. Specifically, increasing the Rayleigh number from (Ra = 105) to (Ra = 106) leads in an 80% increase in heat transfer. However, as the density of the nanofluid increases, the highest values of streamlines decrease. Decreasing the Darcy number (Da) educed the maximum values of the streamlines and average Nusselt number (Nu). Additionally, increasing the heat generation factor (λ) from (λ=0) to (λ=5) decreases the Nusselt number by 30%. Furthermore, the most effective streamline value was achieved at an inclination angle (γ) of 60.

This study aims to improve the productivity of traditional multi-slope solar stills, which are still employed in isolated villages with no power and no clean drinking water. The conventional multi-slope solar still was equipped with a photovoltaic array system that heated the water through an electric heater submerged in the basin to increase the productivity of the conventional solar stills. This study analyzed and compared the productivity of a PV-coupled solar still (PVSS) with a solar still basin area of 0.64 m2 to that of a conventional solar still (CSS). The results showed that the productivity of the PVSS improved more than triple times (9.39–10.9 L/m2.day) during active mode compared to the CSS, which had a daytime solar still production without a PV system (passive mode) that varied between 2.2–2.34 L/m2.day. The daily efficiency of the passive mode without any additional external energy input was around 27%, which resulted in a distilled water yield of 1.4 L. However, when operated in active mode with supplementary energy inputs, such as electrical heating elements that were powered by solar panels, the daily efficiency of the solar still was approximately 44.8%, resulting in a distilled water yield of 6 liters. The payback period for PVSS was found to be two years. The main observation is that the PVSS has demonstrated its applicability for distillation improvement and a significant increase in production for the entire day when employing a clean energy source.

The use of direct thermal energy storage can improve the reliability of solar dish technology by providing a steady source of heat, even when solar radiation levels are low or intermittent. In this experimental study, a solar-thermal hybrid system that transmits light to interior photovoltaic panels through an optical fiber while producing hot household water was developed. The system employs a parabolic solar dish (PSD) with a cylindrical solar receiver designed to capture both heat and solar radiation. Fiber optics are used to transport light from the solar collector to the building as a source of illumination. To improve the system efficiency, a design of a direct storage system with phase change material (PCM) of petroleum Jelly was employed in this experimental work to heat water for a longer discharge duration. Furthermore, Al2O3 nanoparticles account for 1% of the total volume of the PCM material are added to the PCM material to improve heat transfer during heat charge and discharge. In addition, a low-cost two-axis tracking system for a PSD was developed. The study examined the efficiency of the system and analyzed the temperature profiles inside the solar receiver using a direct energy storage system. The discharge time is approximately six hours with a water temperature of more than 30 °C. The results revealed that the use of Al2O3 nanoparticles boosted thermal efficiency by around 5.68%. The proposed system could assist in solving the limited space challenges by utilizing the roof of the building.

This study examines the impact of incorporating phase change material (PCM) in photovoltaic thermal (PVT) systems on their electrical and thermal performance. Although PVT systems have shown effectiveness in converting solar energy into both electricity and heat, there is a necessity for studies to investigate how integrating PCMs can further enhance performance. The study also aims to explore the effect of solar irradiation and coolant mass flow rate on the electrical and thermal output of both PVT and PVT-PCM systems. A graphical user interface was developed within the MATLAB Simulink under the weather conditions of Amman, Jordan. The results show that the incorporation of PCM in PVT systems significantly reduces solar cell temperature and increases electrical efficiency. The highest electrical efficiency of a PVT system with PCM was found to be 14%, compared to 13.75% in a PVT system without PCM. Furthermore, the maximum achievable electrical power in a PVT system with PCM was 21 kW, while in the PVT system without PCM it was 18 kW. The study also found that increasing the coolant mass flow rate in a PVT system with PCM further reduced PV cell temperature and increased electrical efficiency, while the electrical efficiency of both the PVT and PVT-PCM systems decreases as solar incident radiation flux increases, resulting in a significant rise in cell temperature. At an increased solar radiation level from 500 W/m2 to 1000 W/m2, the electrical efficiency of the PVT configuration decreases from 13.75% to 11.1%, while the electrical efficiency of the PVT-PCM configuration falls from 14% to 12%. The findings of this study indicate that the use of PCM in PVT systems can lead to significant improvements in energy production and cooling processes. The results provide valuable information for designing and optimizing PVT-PCM systems.

Low-temperature heat sources are widely available in nature, they are considered to be unusable, even though the conversion of such low-grade energy into electricity (high-grade energy) is highly desirable. Thermoelectric generators (TEGs) are achieving increasing interest in converting low temperature heat into electricity. TEG suffers from low performance, improving the performance of TEG will allow there use in huge engineering applications. In this paper the effect of heat transfer rate on the performance of TEGs will be analysed under both steady and transient conditions. Enhancing heat transfer from the TEG surface will be studied using a liquid saturated porous medium. Aluminium and copper particles are used and their influences are compared to forced convection heat transfer from TEG surfaces with and without liquids. The experimental results showed that power generated with Cu particles exceeds that of Al particles with 14%. The free to forced convection power generation ratio was 26.5% for Al,36% for Cu and the enhancement of TEG performance reached 149% for liquid saturated Cu particles.

Disasters, extreme weather conditions and rural recreation makes the availability of a portable heating and cooling device as a must. There are many devices that work on the heating and power generation in the market. The air-conditioner which works on the heat pump principle is well known. Harsh weather conditions, natural disasters and recreation in rural areas (deserts and mountains) requires the availability of a heating and cooling device that works on well available fuel and has a low fuel consumption rate. Such a device will help in saving lives and encourage rural tourism. In this paper, a heating and cooling device is proposed for rural places, harsh weather conditions and natural disasters where no electricity is available. The device is working on the principle of heat pump (HP) to optimize its performance. The source of energy selected for this device is fossil fuels; fossil fuel is used for its convenience where no electricity is available. Low vibration low noise Stirling Engine (SE) is used to drive the heat pump that produces heating/cooling effects. Analysis of the proposed device is performed for each of its components. The results attained from analysis coincide with the results in literature. An electricity free, low vibration, silent and improved performance CHC device was attained. With suitable selected sub-devices an OHR of 2.429 was achieved by the proposed device compared to currently available devices.

Flat solar collectors are extensively utilized in various domestic and industrial applications to reduce energy consumption. In this study, an-active flat plate solar collector (FPSC) with an internal absorber tube receiver was fabricated and tested in Al-Samawa city, Iraq (latitude 31.19°N and longitude 45.17°E). The ambient temperature and incident solar radiation at the experimental location were reached 39 °C and 840 W/m2, respectively. In this study, the number of riser tubes connected to headers that are covered with a glass sheet in a conventional FPSC were replaced with a single serpentine-shaped collector tube covered with a plastic sheet. The proposed solar collector used a smooth copper tube with internal and exterior diameters of 9.5 and 12 mm, respectively, and a total length of 1000 mm. A TRNSYS model of a flat plate collector integrated with an absorber tube was developed, simulated, and validated using the experimental data. Temperature and flow rate data were obtained concurrently throughout the experiments to evaluate the performance of the fabricated solar collector. The temperature at the solar collector input stayed relatively constant at 37.7 °C, and the water flow rate remained constant at 0.75 L/min. The results indicated that the temperature at the solar collector output ranged from 52 to 61 °C, with an average of 58 °C. The efficiency of the proposed solar collector ranges from approximately 45% to 67%, with an average of 58%. Overall, the simulation results of the TRNSYS model are in excellent agreement with experimental data. The average discrepancy between the tests and simulations for temperature differential and collector efficiency is approximately 1%.