Applied Solar Energy最新文献

Optimizing the air gap between the absorber and the glass cover is a critical factor in designing solar air heaters. This study aims to analyze the effect of gap variation on a double pass solar air heater’s (DPSAH) performance through four distances 3, 6, 9 and 12 cm, using experimental data and numerical analysis via CFD (ANSYS Fluent). The numerical model was validated with experimental results in good agreement. The findings indicate that increasing the height of the upper channel correlates with the enlargement of a vortex, intensifying conduction over convection mode at the onset of this channel, and reducing heat loss by eliminating the stagnation vortex in the lower corner, the maximum local heat transfer coefficient was observed at the lower channel by 14.61 W/m² K. The thermal efficiency reached 66.4% in 12 cm, dropping by 2.4, 7.8 and 14.4% for 9, 6 and 3 cm configurations, respectively. Similar to the exergy efficiency, which ranges between 2.1 and 2.6%. Furthermore, the optimum configuration (12 cm) was tested to a variable mass flow rate of 0.006, 0.012, and 0.015 kg/s, with the highest rate yielding a thermal efficiency of 72.5%.

The primary challenge in renewable energy production is the unpredictable nature of renewable sources, leading to inconsistent electricity generation. This variability causes deviations in power supply frequency and voltage due to imbalances between load demand and power generation. This study focuses on regulating power flow in a solar-wind-based Hybrid Power Generating System (HPGS) to achieve a stable balance between energy generation and demand. A Fractional Order PID (FOPID) controller is employed to minimize power fluctuations by ensuring Maximum Power Point Tracking (MPPT) and efficient management of Superconducting Magnetic Energy Storage (SMES). The SMES utilizes a second-generation superconducting material with a high irreversibility field and critical current density, enhancing energy storage efficiency. Compared to a conventional PID controller, the FOPID controller offers greater stability, reduced oscillations and overshoot, and a shorter rise time. To validate its effectiveness, a comparative analysis between conventional PID and FOPID controllers is conducted. The results demonstrate that the proposed FOPID controller ensures precise MPPT, rapid SMES response, and stable power exchange between supply and demand, even during sudden load shifts and variations in power generation.

This study presents the geometric optimization of a CeO₂-based solar thermochemical reactor intended for hydrogen production, using temperature distribution analysis under concentrated solar power conditions. The investigation was carried out entirely through numerical modeling using the COMSOL Multiphysics software, assuming a concentrator input power of 2 kW. The reactor body was designed with a stainless-steel exterior, while aluminum oxide (Al₂O₃) was selected as the internal insulating layer. Cerium oxide (CeO₂) was employed as a porous reactive medium to facilitate a two-step redox thermochemical cycle. A three-dimensional cylindrical model of 1 mol CeO₂ was developed to evaluate the thermal performance under varying porosity levels (ε = 0.1–0.9) and different cylindrical geometries with equal volumes. The simulation results revealed that at a porosity of ε = 0.7, the desired endothermic operating temperature was distributed most uniformly within a CeO₂ volume of 50 mm diameter and 20 mm thickness. Based on the temperature field distributions and effective heat transfer conditions, the reactor’s geometrical parameters were optimized. The final design includes a cylindrical body with a 220 mm diameter and 140 mm length, a quartz window of 200 mm diameter and 6 mm thickness, a 20 mm cooling channel for water circulation, and an internal insulating layer of aluminum oxide (Al₂O₃) with a thickness of 100–120 mm. Furthermore, the dimensions of the light-receiving conical section were determined as 50 mm for the small diameter and 152 mm for the large diameter.

With the large-scale deployment of renewable energy, photovoltaic systems are installed worldwide, including in regions with humid continental climate. We present here the energy production of 2-axis tracking systems equipped with either monofacial or bifacial modules. We show that severe weather conditions, especially in winter, force the systems to operate in a degraded mode (i.e. 10° fixed tilt) that leads to yearly losses of ~4%. Other losses that include snow-induced losses lead to 12 and 9% additional losses for monofacial and bifacial systems, respectively. Bifacial modules are better suited than monofacial modules in the studied climate and system configuration, thanks to a higher sensitivity to albedo and higher ability to shed snow during winter, that both amplify the bifaciality gain during snowy months.

The article presents the results of studying the structural and optical characteristics of films based on a mixture and alloy of ZnO, Al₂O_3, and Dy₂O₃ with a weight concentration of the components ZnO—96%, Al₂O₃—2%, and Dy₂O₃—1%. The alloy has been obtained by melting a mechanical mixture at the focus of a solar furnace with a concentrator diameter of 2 m. The films have been deposited onto glass plates by the resistive method in a vacuum. X-ray phase analysis showed that the films obtained from the alloy have a higher degree of crystallization than coatings obtained from a mechanical mixture of oxides. Regardless of the method of preparing the film-forming material, the ZnO crystal lattice undergoes strong stretching due to the introduction of Al₂O₃ and Dy₂O_3. The lower value of the transmittance coefficient compared to the simulation results is explained by the presence of metallic Zn, i.e., the formation of a Zn + ZnO cermet film. As a result of annealing the film at 400°C, its transmittance increased due to a decrease in the concentration of Zn.

The limited number of identified gaseous, liquid, and solid hydrocarbons, which are the main types of primary energy resources used in Uzbekistan; technological and technical difficulties in extracting them from the subsoil and subsequent processing for transportation; insufficient capacity to ensure their storage and delivery for use in the daily and seasonal variability of the need for electric and thermal energy in various areas of the country, etc., indicate the significance of the risks to energy security and ensuring the sustainable development of the country. Renewable energy resources, such as hydraulic, solar, and wind energy are significant and their gradual large-scale use that has begun indicates their significant potential in ensuring energy security and sustainable development. This part of the paper shows the feasibility of using modern energy-efficient technologies for the use of various types of accumulation/generation of the above-mentioned variable types of renewable energy sources in Uzbekistan with the implementation of opportunities both in increasing the total generation volume and in creating highly maneuverable “peak” generating energy sources for various functional purposes in various energy hubs of the country.

Central Asia’s fossil fuel-based energy systems need to transition towards clean energy to ensure energy security and sustainability. According to Central Asian energy reports, the sector related greenhouse gas emissions contribute to more than 80% of the total emissions of the region. At the same time more than 80% of power generation is still fossil fuel based while other sectors (e.g. transport) are still almost exclusively consuming fossil fuels. As the country with the fastest growing energy demand of the region, Uzbekistan aims to reach a 25% of renewable energy in power generation and to develop substantial capacities to produce green hydrogen by 2030. Further, the nationwide electricity consumption is expected to increase by more than 60% by 2030, which poses a significant challenge to the energy sector development. This work critically assesses the Uzbek Renewable Energy Development Strategy for 2030. It reviews the government’s current energy strategy to transform its power system, considering renewable energy and green hydrogen deployment. The work provides a modeling approach to identify the cost-efficient pathways of the Uzbek power sector using the Open Energy Modeling Framework (OEMOF). Preliminary results suggest that the Uzbek Governments renewable electricity strategy can be achieved at reasonable prices and already lower overall power costs. However, further optimizations find that much higher renewable energy shares are also possible at competitive costs under the same framework conditions.

One of the major challenges associated with solar photovoltaic (PV) power harnessing is the intermittent nature of its output. The situation worsens in partial shading as it leads to greater mismatch losses and reduced efficiency of PV modules. Consequently, this work proposes two novel algorithms designed to overcome the impacts of various patterns and shading levels over PV panels. One algorithm is designed on a puzzle-based reconfiguration (PBR) scheme that suggests the physical reconfiguration of PV modules in an array. Governed by mathematical relations, PBR effectively distributes the impact of shading as a function of reconfiguration of modules within the array. Comparative analysis of the results of PBR has been carried out with existing alternative configurations. Numerous performance parameters such as global maximum power, fill factor, and mismatch losses have been evaluated for different shading patterns. It is found that proposed PBR algorithm results in greater values of maximum power and fill factor with lowest mismatch losses among all configurations for any level and pattern of shading. Similarly, inspired by the flower pollination (FP) technique, a second algorithm is proposed for enhanced tracking speed with reduced oscillations under various levels of shading. The tracking speed of proposed FP algorithm is found to be higher than most preferred PSO approach and better results are obtained with the increase in shading level.

A composite material of cordierite composition based on the oxides MgO, Al₂O₃, and SiO₂ with a concentration of components, was obtained in a solar furnace, wt %: MgO—15.3–19.2, Al₂O₃—34.34–24.34, SiO₂ —50.59–56.45. It has been established that cordierite films deposited on the surface of glass and silicon wafers are characterized by high mechanical strength and adhesion, are transparent in the sensitivity range of solar cells, and can be used as an anti-reflection coating.