فهرست مطالب shiva gorjian

Concentrators have many functions, one of which is their use in the evaporation of liquids. Since a high level of heat is present in concentrator absorbers, it is possible to develop a heat exchanger system that enables the vaporization of salt water. One of the main components of these systems is the heat absorber, which is located at the focal point. In this study, an attempt was made to investigate two geometries of annular and hollow absorbers using the computational fluid dynamics (CFD) method. For this purpose, the working fluid was defined based on the properties of seawater in the Fluent Ansys software, and the creation of the geometry and thermal analysis was considered based on the initial and boundary conditions of the system. The results of the validation of the grid quality showed that the use of a tetrahedral grid with square grid order is suitable for the cylindrical geometry. Due to the dimensional symmetry of the geometry of the ring converter, the use of the simplest grid method leads to a high accuracy of the solver. The thermal analysis of the absorber has shown that with the cavity geometry, the heat distribution at the bottom of the geometry is greater than at the top. The results of the Nusselt number change analysis showed the concentration of thermal stress in the area of the liquid outlet. This stress concentration leads to a shift of the evaporation process from the inside of the chamber to the transfer tubes.

Iran is one of the countries with a radiation potential that is very suitable for the construction of solar carports. Considering the high initial cost of constructing these parking lots, the importance of their feasibility and optimal design is very high. In the present study, the design and simulation of a solar carport connected to the power grid that was implemented at the Faculty of Agriculture of Tarbiat Modares University (TMU) in Tehran was carried out. For this purpose, the photovoltaic system was calculated in PVsyst software considering the geographical location and weather conditions of Tehran. In this case, the optimal side angle for installing the photovoltaic modules on the parking lot was set at 35 degrees to maximize the annual electricity production. Then, in determining the type and model of the photovoltaic modules and the solar inverter, their optimal electrical arrangement was designed. In addition, the losses of the various parts of the system were calculated, including the losses caused by shading, temperature rise, connecting wires, and so on; besides, the optimal spacing and arrangement of the modules were presented. Based on the final results of the simulation, the amount of electricity generated by the parking lot was 48.2 MWh/year; the annual power factor was 0.791; the reduction rate of CO2 production was 499.89 tons in a total of 30 years, and the sensitivity analysis and lower return on investment were calculated from 5 years onwards. The results of this study showed that the implementation of the project at the investigated site was economically justified in addition to the benefit of providing renewable electricity.

Iran's energy sector, which includes power generation, transportation, industry, buildings, and homes, is a significant source of greenhouse gas emissions. Plans for efficient design and development of maximum power control systems aim to increase the share of renewable energy in electricity usage. Floating photovoltaic systems combine existing photovoltaic systems with a floating structure to generate clean energy and integrate existing dams to enhance power sources. The results indicate that installing a hybrid floating solar power plant at a level of more than 1 km2 over the dam reservoir's surface provides 194 GWh to 257 GWh of electricity per year. Installation floating photovoltaic plant would supply electricity for 2260 green cottages while also improving the environment and reducing water evaporation. Adding a floating solar power plant with 10% of the lake reservoir cover of six dams saves 70.7 million cubic meters of water per year which is enough to meet the annual needs of one million people. This study fills a research gap in the energy sector by studying the economics of hybrid renewable energy systems in Net-zero energy buildings.

In the current energy and environmental conditions, it is necessary to implement systems based on renewable energy sources in order to reduce energy consumption worldwide. Solar collectors have been studied for years, and many researchers have focused their attention on increasing their efficiency and cost-effectiveness. Solar collectors are implemented for heating domestic water, heating or industrial processes. A promising system that is not yet widely known is air heating by solar collectors, which can be an efficient way to use solar energy with lower investment costs, a system that can preheat the fresh air needed for heating, drying. In this research, the air was established between the absorbent space and its glass cover at speeds of 2, 4, and 6 m/s using a fan, and the effect of incoming air speed and weather conditions such as solar radiation intensity, wind speed, and ambient temperature on the outlet air temperature from the collector and the absorber rod temperature were checked. Based on the obtained results, the temperature of the air coming out of the collector and the temperature of the absorber decreases with the increase in the speed of the incoming air. The greatest impact of weather conditions on the temperature of the absorber rod is related to the intensity of the sun's radiation. The numerical analysis results were obtained with an error of 5% compared to the experimental results.

In this study, the effect of covering the aperture area of a conical cavity receiver with an ultra-white glass on operational parameters of a Parabolic Dish Collector (PDC) was numerically and experimentally investigated under climate conditions of Tehran (35.44° N latitude and 51.10° longitude). The main components of the experimental setup include a dish reflector, a conical cavity receiver, Heat Transfer Fluid (HTF), hydraulic and cooling cycle, and a sun tracker. For this purpose, a conical cavity receiver with an ultra-white glass cover on its aperture was numerically modeled in Fortran software. During the evaluation, environmental parameters including ambient temperature, solar radiation, and wind speed were considered as inputs of the model. The results revealed fair agreement between the numerical and experimental data with the maximum error of approximately 4.63 % and 7.89 % for receivers with and without the glass cover on the aperture, respectively. For a steady-state analysis, the mean values of useful energy ( ) absorbed by the receiver were calculated as 1,253.25 W and 987.68 W, while thermal efficiency ( ) of the receiver was calculated as 52.61 % and    40.69 % for receivers with and without glass cover, respectively. The results revealed that both  and  followed a similar trend of the variations in the HTF’s temperature between the inlet and outlet of the receiver. Also, the overall heat loss coefficient ( ) and the collector heat removal factor ( ) were calculated as 420.76 W/m2°C and 0.62 for the conical cavity receiver with the glass cover.

Hybrid renewable energy systems (HRES) with potential environmental, economic and social benefits are designed to improve energy efficiency and reliability. In this study, artificial intelligence and smart grids were studied to supply electricity for a green cottage. The obtained results are essential for designing, implementing, and building HRES. Three cost-benefit and environmental, economic scenarios were assessed. The first scenario aimed for a 23.8% renewable energy penetration. The second scenario aimed for "renewable and cost-effective" with a 54% renewable energy penetration rate. The third scenario aimed to supply the green cottage Electrical energy with renewable energy entirely. Using the first scenario, with average daily fuel consumption of 1.11 liters, the annual hybrid renewable energy conversion system produces 1697 kWh of energy, with a net present value (NPV) of $553.68 and an internal rate of return (IRR) of 21.49% and a payback period of 15.71 years. In the second scenario, with average daily fuel consumption of 0.694 liters, total annual energy production is 1652 kWh, NPV is $341.47, IRR is 19.5%, and the payback period is 17.61 years. In the third scenario, the system produced 1933 kWh per year, with an NPV of -372.9 dollars and an IRR of 15.08 percent. This scenario has financially not feasible, and the depreciation and return on investment periods are outside the project life. The least effective is on fixed assets and increasing the feed-in tariff of renewable energy is the most important factor in project economics, followed by reducing operating costs.