جستجوی مقالات مرتبط با کلیدواژه « Solar energy » در نشریات گروه « مکانیک »

In this research, for the first time, a mathematical model based on the principles of thermodynamics and heat transfer has been developed for the improved inclined water softener, which previous experimental tests have shown to perform much better than the standard inclined water softener. In this research, a thermal model has been developed to investigate the performance of an improved stepped solar still system (ISS), which previous experimental tests showed that its performance can be much better than standard stepped solar still. For this purpose, the energy conservation equation in the transient state is implemented for six solar still components including the glass cover, brine water inside the basins, absorber plate, elastomeric insulation layer, back plate and condenser plate; and the mass and energy conservation equations are implemented to model the circulating air between the evaporation chamber and the condenser chamber. These equations lead to a set of interdependent nonlinear first-order ordinary differential equations that must be solved simultaneously for all basins. To evaluate the accuracy and reliability of the developed model in predicting the performance of the ISS solar still in different weather conditions, this model is used to estimate the performance and the temperature of different components of the ISS in spring and autumn. The results show that the developed model has good accuracy in such a way that the maximum root mean square error in estimating the temperature of glass, salt water and absorbent plate is equal to 6.9, 6.2 and 6 degrees Celsius.

In this contribution, a laboratory comparison of the cooling capability of two-hybrid and three-hybrid nanofluids in a photovoltaic/thermal system equipped with a spiral plate-tube collector is devoted. Stable suspensions of water-graphene oxide/titanium oxide, water-graphene oxide/iron oxide and water-titanium oxide/iron oxide as binary hybrid nanofluid and watergraphene oxide/titanium oxide/iron oxide nanofluid as ternary hybrid nanofluid have been used. Several experiments have been conducted to investigate the effect of nanofluid mass flow rate (20-80 kg/h) on system performance using a solar simulator. It was revealed that among the examined systems, the best thermal, electrical and overall performance always belongs to the photovoltaic/thermal system containing ternary hybrid nanofluid, while the worst performance always belongs to the system containing water-titanium oxide/iron oxide nanofluid. belongs to. The results showed that the thermal efficiency, electrical efficiency and overall efficiency of the system containing ternary hybrid nanofluid were in the ranges of 53.14-80.14, 13.01-13.02 and 89.78- 95.29, respectively. is a percentage Also, it was found that the thermal, electrical and overall performance of the investigated systems improves with the growth of mass flow rate of nanofluids.

Today, the water crisis has been issued in most parts of the world and for this reason, the production of fresh and potable water is one of the most important and considerable factors to deal with endangering human health in the last few decades. Solar water stills are one of the simplest and most available tools for purifying and producing drinking water, but unfortunately, due to their low efficiency they cannot be used to produce the daily needs of water. The purpose of the research is to increase productivity and improve the performance of the traditional solar water stills by injecting nano aerosol particles and creating a magnetic field by a solenoid. To simulate the present work, the equations of continuity, momentum, energy and concentration have been solved by finite volume method and for this purpose, a numerical code in C++ language has been developed to solve the humid air flow containing magnetic nano-aerosols. The effect of the presence of magnetic nano-aerosol in the magnetic field on the humid air flow pattern inside the desalinated water and the amount of desalinated water production are investigated. The results show an increase in the amount of drinkable water production up to 238%.

Increasing concern about the reduction of fossil fuel resources in today's societies has led to a greater tendency towards renewable energies. Therefore, solar energy is the most available renewable source. Most of the solar cells do not have the optimal efficiency. The most effective solution to solve this problem is to increase the efficiency of solar modules by combining them with other systems. One of these systems is the two-shell facade. By combining this system with solar panels, a new technology called photovoltaic systems integrated with the facade of the two building shells is introduced. The purpose of this research is to analyze several types of photovoltaic systems integrated with the facade of two building shells to observe its effect on the air conditioning load of the building and to optimize the parameters involved in this system for a hot and semi-arid climate. The results show that the temperature inside the building using the two-shell facade is two degrees Celsius lower than the simple case on average every month due to the greater heat transfer of the two-shell facade. The amount of cooling consumed inside the building is lower in the case of using the two-shell facade than in the simple case. In the summer, due to the intensity of solar radiation suitable for the city of Tehran and the lighting of the facade of two skins, the temperature inside the building rises and the need for more cooling is needed for proper air conditioning inside the building.

Solar energy is the most abundant source of energy among renewable energies, which can be directly converted into electricity by solar modules. To tackle the low energy output of solar modules in places where there are not enough spaces to install many solar modules, the use of reflectors is recommended. The use of reflectors increases the solar radiation on the surface of the module, hence will boost its power output. In this study, two-dimensional simulations were performed using ANSYS Fluent 2021 R2 package software in which the effects of a flat plate, parabolic, and hybrid reflectors on the temperature and efficiency of the module were investigated. The numerical simulation of the current study was validated against an experimental case study. Although there were so many simplifications and assumptions for the validation, the maximum deviation between the present numerical result and the experimental was less than 3.86%, which certifies the results of this paper. Based on the output, the surface temperature of the solar module with ˚85 flat plate reflector and ˚85 parabolic reflector reached 360.82 (K) and 371.11 (K), respectively, while the temperature with ˚50 reflector for both parabolic and flat plate modes reached 345.94 (K) and 346 (K), which are approximately equal. It was also observed that with increasing the angle of flat and parabolic reflectors, the module temperature increased, and parabolic reflectors had higher temperatures at higher angles. The module temperature using a type 6 reflector increased by 7.14% and 0.92% compared to the ˚80 flat plate reflector and ˚80 parabolic reflector, respectively. In terms of efficiency, since reflectors will intensify the solar radiation on a solar module surface, it will enhance the operating temperature of the module so that in all cases with reflectors, the efficiency will drop from an initial maximum value to a certain minimum value. This drop is more significant in the parabolic reflectors compared to the flat plate reflectors.

Among solar collectors, solar parabolic dishes have attracted the attention of researchers due to their high working temperature and high thermal performance. The purpose of this study is to compare two absorber receivers (normal-black color) for the solar parabolic dish. The analysis of energy and exergy was investigated for different conditions at different hours. Two-axis tracking system was applied to the outlet temperature in the solar parabolic dish system. The results show that the maximum temperature of the normal and black absorber is 101.52 and 115.53 ℃ , respectively, and the maximum energy and exergy efficiency of the black spiral absorber plate is 0.7 and 0.21. In addition, the designed parabolic solar container raised the temperature of 80 liters of water to 60 ℃ in 5 hours after sunlight, which is suitable for bathing and washing clothes in winter in backward and rural areas without electricity and fuel. Therefore, it is enough for four to five people.

Clean electrical energy and freshwater are two basic human needs that can be met by using solar energy properly. In this article, the goal is to produce electricity and freshwater simultaneously by installing a solar still coupled with a semi-transparent solar module. The coupled solar system was simulated in ANSYS Workbench 2022 software environment.To check the water yield, the system was simulated at different brackish water temperatures of 60 , 70 , and 80 and different wind speeds of 1, 2, 3, 4, and 5 m/s. Also, ten scenarios were defined and simulated according to radiation intensity and brackish water temperature. The results showed that the increase in brackish water temperature and the wind speed increased the amount of freshwater production, and the effect of brackish water temperature was greater compared to wind speed. By increasing the brackish water temperature from 60 to 70 and from 70 to 80 , the average water yield increment for the wind speed of 3 m/s is 64% and 120%, respectively. Also, by increasing the wind speed from 1 m/s to 5 m/s at 70 , the output power of the system increases by 10.53%. The simulation results in ten different scenarios showed that the coupled solar system was more efficient than the independent solar system in eight cases. According to the results of this research, it is suggested that the southern regions of the country with high radiation intensity and high wind speed should be considered for installing the coupled solar system.

In this paper, we investigate a two-effect adsorption refrigeration system that works with ammonium lithium nitrate and sodium ammonia thiocyanate solutions. The energy required by these systems is supplied by a solar collector. The efficiencies of the first and second laws of the absorption refrigeration system are obtained in three parallel and inverse series series arrangements and are compared with each other. In this study, we showed that the amount of energy efficiency and exergy of the two-effect system in the series arrangement is the lowest among the three arrangements. The system works with ammonia solution of lithium nitrate at a lower temperature than the ammonia solution of sodium thiocyanate . Energy consumption is supplied through preheating and collector solar energy. The system with sodium thiocyanate ammonia solution uses more solar energy, which in the lowest case is 29.64% more than the system with sodium thiocyanate ammonia solution. Burning natural gas is the heat that comes from solar energy to get the energy consumed by the generator. bring. The amount of carbon dioxide produced by preheating combustion is obtained, which in its lowest case for a series arrangement with ammonia lithium nitrate solution is 72.16% less than the same arrangement with ammonium sodium thiocyanate.