solar still

Nowadays, with the increasing consumption of energy, the use of renewable energy has become particularly important. Among the renewable energy resources, solar energy has significant potential due to its advantages like a lower price, stability, etc. One of the simplest and most effective means of collecting solar energy is the flat panel solar collector. In this project, a new model of the solar collector was simulated using Fluent software. The effect of important parameters in the design of the collector such as absorption plate thickness, tube diameter, and the number of tubes are evaluated. The simulation results show that increasing the diameter of the tubes, increasing the number of tubes which means reducing their distance, and increasing the thickness of the absorber plate all improve the efficiency of the flat plate solar collector system. To compare the performance of this type of geometry with the conventional collectors, another type of geometry for the solar collector in which half of the tubes are at the top of the absorber plate is simulated in Fluent software. The results of comparing these two types of geometry show that the geometry of the first type has an energy efficiency of 59.63% in the best simulation model and the geometry of the second type in which half of the tubes are above the absorber plate has an efficiency of 67.79%.

For installation and the sustainable development of floating solar photovoltaic systems, it is essential to understand their components and possible designs for implementation. Moreover, their proper performance in terms of energy, economic, and environmental factors should be ensured as well as optimized. These types of systems operate in different environments. As a result, selecting components for these systems, and designing as well as implementing their various structures all have their own challenges that either directly or indirectly influence power output, durability, cost, and environmental impact. Even though floating systems are located on the surface of water sources and reservoirs, different cleaning techniques may not be applicable due to the need for high-quality water or certain environmental conditions. This study, therefore, provides a comprehensive guide to selecting components, designing and installing floating photovoltaic solar systems, as well as the necessary conditions for maintenance and different cleaning methods for these systems, by reviewing related research and various implementation plans. By using content analysis, previous studies in this field were reviewed, classified, and evaluated, and the results were prepared for researchers and decision-makers.

This article focuses on the simulation and comparison of on-grid and off-grid solar power systems for a two-story office building in Tehran using PVsyst software. In this study, both types of solar power systems are analyzed in terms of energy production and economic viability. Simulations are performed using PVsyst software. The evaluation considers the number of infrastructure components, system performance, implementation costs, and the total area of the power plant.The results show that the off-grid solar power plant requires a larger area and is more expensive than the on-grid system. However, in terms of performance, particularly considering the ability to store energy even on cloudy and rainy days, the on-grid solar power system proves more efficient for generating electricity in this office building.

Scientists have always emphasized on reducing the temperature of solar cells and have used various methods with the aim of reducing the temperature of solar panels, because high temperature causes damage and various defects in the structure of photovoltaic panels. Among the effective and important researches that have been carried out on solar cells with the aim of reducing their temperature and increasing their efficiency, we can mention the radiation cooling method, which shows that the photovoltaic cell coated with a transparent layer is better than the bare solar cell. It is more efficient than any additional layer. In this study, the conventional (commercial) structure of the solar cell was compared with the coated structures in terms of optics and temperature. This comparison showed that the coated structures have higher efficiency than the commercial structure. In this research, three solar photovoltaic structures have been put together, which include 1- commercial (simple) structure, 2- solar panel with a PDMS layer, 3- solar panel with a PVB layer. Then to software research and simulation. The radiation and temperature properties of these three structures were discussed and by comparing them, it was shown that in the structures with PDMS and PVB, the layering temperature in terms of radiation intensity is reduced by about 5 and 9 K, respectively, compared to the commercial structure, which is an indication of the effect of cooling. The radiation of transparent polymer materials has on these two structures.

This study investigates the comparative effects of carboxyl-functionalized multi-walled carbon nanotube (MWCNT)/water nanofluids and titanium dioxide (TiO₂) /water nanofluids in direct absorption parabolic solar collectors. To achieve this, a standard testing apparatus was constructed, and the thermal and exergy efficiencies of the collector were calculated using nanofluids at various concentrations. UV/Vis analysis was used to analyze the radiative properties of the nanofluids, and their thermal conductivity was also measured. Experiments were conducted under laminar flow conditions with flow rates of 20, 60, and 100 liters per hour and inlet temperatures of 20, 30, and 40 °C under real conditions with direct solar irradiation. The highest thermal efficiency recorded for the carbon-based nanofluid was 44.96%, while the titanium-based nanofluid achieved a thermal efficiency of 34.98%. Given the substantial improvement in efficiency compared to the base fluid (distilled water), the combined effect of using both nanofluids was also examined, resulting in a maximum thermal efficiency of 48.77%. The exergy efficiency at the highest flow rate and inlet temperature for the base fluid, TiO₂ nanofluid, MWCNT nanofluid, and the hybrid nanofluid were 2.61%, 4.98%, 6.68%, and 7.26%, respectively. The pressure drop of all nanofluids in the absorber tube ranged from 5 to 39.6 Pascals. The studied nanofluids enhance the thermal performance of the system and create low pressure drop, indicating their high efficiency in direct absorption solar collectors.

In the present study, for the first time, the impact of presence of magnetic iron oxide nanoparticles into the humid air within the desalination chamber, as well as the application of Kelvin force induced by the magnetic field of a permanent magnet, on the performance of a solar desalination system has been numerically investigated. To model this phenomenon, an object-oriented C++ numerical code was developed in the OpenFOAM software. The governing equations, including continuity, momentum, energy, and the mass fraction transport equation for humid air containing magnetic nanoparticles (referred to as magnetic nanoaerosol), were discretized and solved using the finite volume method. The effects of various parameters, including magnetization, the angle, and the placement of the magnet, on the flow pattern and freshwater production rate were examined. The results of this study show that the use of nanoaerosols in the absence of a magnetic field weakens the desalination system's performance, such that with φ=8%, the amount of freshwater produced is approximately 23% lower than that of a desalination system with a base working fluid. On the other hand, the use of a permanent magnet, as a low-cost magnetic source, can increase the freshwater production rate by up to 260%, which justifies the economic feasibility of this method in the development of solar desalination systems.

The absorber tube is the main part of the solar collectors which its appearance and operational characteristic can play key role in absorbing of solar irradiation amounts. Researchers have proposed various offers to improve the solar collector performance such as inserting a turbulator in the absorber tube and using of nanofluid (especially hybrid nanofluids) instead of simple working fluid. In present study, the various shapes of turbulators proposed by the researchers have been reviewed. Turbulators can be classified according to their shapes. In the first category, turbulency in fluid flow is made by providing ribs or corrugations on the inner wall of absorber tube. But in the second category, external obstacles can be inserted in the absorber tube to improve its performance. Most literatures disscused about the second category of turbulators. By comparing the hydrothermal performance between the smooth absorber tubes with the improved one, it can be concluded that addition of turbulator enhances the thermal properties of all collector types up to 82%. The turbulators can increase the pressure drop and friction factor due to its operation as an obstacle in the fluid flow. Also, the use of nanofluids (especially hybrid nanofluids) beside the turbulators can improve the collector’s performance. However, several characteristics such as the concentration of nano particles, different kinds of hybrid nano fluid and collectors, the various shapes of the turbulator, etc., are all effective parameters on the collector performance.