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Solar energy is an excellent source of renewable energy and has many advantages, such as being pollution-free, non-exhaustible, and freely available. The use of solar panels is an important way to convert solar energy into electricity, but high temperatures affect their performance, so they always need cooling to increase the conversion efficiency. A spectral selective filter can be used to manage sunlight by blocking some infrared wavelengths and allowing visible radiation to pass while increasing thermal emissions from the PV modules through the use of gas-filled double glazing technology, which effectively contributes to their cooling, which is a more feasible method. And attractive for cooling solar panels. The current work presents a passive radiative cooling technique to increase the efficiency of electrical conversion by reducing the operating temperature through a glass filter consisting of two layers of glass with a thickness of 4 mm and with different gaps ranging from 10 to 25 mm. The gaps are filled with carbon dioxide. The filter is placed above the plate. 50-watt solar panel, leaving a 30 mm gap between the gas filter and the solar panel. This filter absorbs or reflects infrared rays that cause excess heat and prevents them from reaching the surface of the solar panel for the purpose of cooling it and allowing the wavelengths useful for operating the photovoltaic panel to pass through it. The practical experiments were carried out under the local weather conditions of the city of Baghdad, Iraq (latitude 33.22 degrees north and longitude 23.44 degrees east). The photovoltaic panel was oriented towards the south at an angle of 33 degrees. Trial readings were taken for the months of July and August, and August 15 was approved for discussion. The results showed that the weather conditions were suitable in terms of dust and clear skies. The technologies used in cooling were tested on two photovoltaic panels, the first with carbon dioxide glass filtration technology, and the second panel was left as a reference to compare the improvement in thermal and electrical performance. The results showed that the ideal gap was 20mm, the greatest amount of PV panel surface temperature reduction was 5 to7.3 °C, the efficiency improved to 8.7%, and the output power improved by 11.2%. [ABSTRACT FROM AUTHOR]

Due to the excess use of air conditioning systems led to significantly increase the demand for electric power in the household sector. Therefore, to decrease energy consumption, it can use an Earth-Air Heat Exchanger (EAHE); it has been demonstrated to be promising method for heating and cooling applications. In this paper, simulation study was performed using ANSYS FLUENT 19.0 (CFD) program as a numerical analysis on the impact of different pipe shape and air velocity on the performance according to the climatic conditions of Baghdad-Iraq in the summer and winter seasons. The pipes shapes in EAHE system that were used are spiral, wave and straight at the same length and diameter, and it has been studied their impact on performance at different speeds (5, 10 and 15 m / s). The results of numerical analysis showed that the shape of pipes and velocity of inlet air have an effect for the temperature of outlet air and performance of EAHE. Through the results obtained, it was found that the shape of straight tube presents the best performance compared to the other two shapes of spiral and wave. Therefore, the better performance for EAHE can be achieved on operating the system at low air velocity together with straight shape for the exchanger pipe. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the thermal properties of energy storage units that use phase change material (PCM) by using the ANSYS FLUENT software program. The study focused on four different cases based on the shape of the fins. Numerical and predicted values of temperature distribution inside PCM were compared using the Surface Response Methodology (SRM). The fins were tested with three different sizes of radii 1, 1.5, and 2 mm. The results indicated that using this type of fin resulted in a significant improvement in the efficiency of the thermal energy storage system. Smooth fins had higher thermal performance compared to perforated fins in improving heat transfer, primarily by enhancing conduction inside the PCM, and reducing melting time by 16%, while solidification time was reduced by 5%. It was observed that an increase in the diameter of the perforations led to a reduction in thermal conductivity in PCM. This study contributes to the development of efficient thermal energy storage systems for different applications. [ABSTRACT FROM AUTHOR]

Solar radiation with all the other energies such as wind, hydropower, and biomass, is the most common source of renewable energy on the planet. Only a small percentage of available solar energy has been used to date, Solar energy is an important source for making life on Earth possible because it can be used for a variety of purposes, including heating water for domestic purposes, heating air for comfort in homes during the winter, and generating electricity, by using photovoltaic modules that convert the sun's rays falling on them to electricity. Solar radiation can also be utilized to generate steam, which is then used in power generators to generate electricity. One of the most important factors to consider when choosing a renewable energy source is that solar energy is available around the world, is free, environmentally friendly, and does not cause pollution. One of the applications of solar energy that has started to have increased interest in is a parabolic trough collector, this collector receives the direct sunlight and converts them to thermal energy by absorbing heat and transmitting it to a heating fluid, such as air, water, or nanofluid, parabolic are characterized by their simple designs, high flexibility (they may be installed anywhere that is free of shadow and has sunlight), low construction costs, and low maintenance requirements. Under the climate conditions of Baghdad, Iraq, the performance of a (PTSC) without a solar tracking system was tested practically. The highest efficiency of the collector was 70 % while using water as a working fluid with a mass flow rate of 200 kg/h at direct solar irradiation with an incidence angle of 45℃. This article describes the testing method and system design for the collector. [ABSTRACT FROM AUTHOR]

Solar energy is one of the most important renewable energy sources that is used in thermal applications and photovoltaic applications. Iraq is one of the countries that suffers from problems in generating electricity and seeks to exploit solar energy. Solar radiation reaches to this region at 2000 kWh/m2/year. In this work, the power of photovoltaic cells was improved by using two types of V-trough solar concentrators. The first type is a concentrator with stainless steel reflectors, and the second type is with an aluminum foil reflector. The experiment was conducted in the city of Baghdad on February 21. The results showed that the solar concentrating system increases the intensity of solar radiation and thus increases the output power of the solar cells and that the solar concentrating system with aluminum foil reflectors is better than the solar concentrating system with stainless steel reflectors, where the average improvement in the output power value of the photovoltaic panel with an aluminum foil reflector is 29%, while the photovoltaic with a stainless steel reflector is only 13%. The average improvement in solar radiation is 27% when using CPV2, while it is only 16% when using CPV1. [ABSTRACT FROM AUTHOR]

Natural materials (be it fibers or particles) are porous materials due to their nature, which make them valuable in sound absorbing. Natural materials (NM) in general are environmentally friendly. Composite sandwich plates made from different types of natural materials in contribution with glass fibers and polyester had been used in this study, precisely, Dried Cooked Tea Leaves DCTL, Husks of Fresh Beans FBH, Egg Peels EP, Garden's Sand GS, Wood Fiber WF, Chicken Feathers CF and Palm Fronds PF with different thicknesses (6, 8, and 10) mm. These composites were tested as sound insulating materials. A test rig is prepared. Different frequencies from a function generator were used and sound waves were measured utilizing sound pressure level (SPL) practically to estimate the sound transmission losses (TL) and the coefficient of sound transmission losses (TC). The preferable results in transmission losses recorded for the samples fabricated from (Palm Fronds, Wood Fiber, Garden's Sand and FBH) and the 10 mm thickness samples were the best. The TL for these samples were greater than the neat random fiberglass samples (195%, 155%, 133%, 116% and 92%) respectively at high frequencies. The other two natural materials also have permissible results but with less percentages than the others, the results were (50% and 45%) greater than the neat random fiberglass samples for the (DCTL and CF) respectively. [ABSTRACT FROM AUTHOR]

This study investigates heat transmission and thermal performance factor characteristics in a tube with coil wire and twisted tape inserts using air as the working fluid. This study investigates heat transmission and thermal performance factor characteristics in a tube with coil wire and twisted tape inserts using air as the working fluid. The goal of this research is to improve forced convection heat transfer in tubes with and without swirl inserts and coil wire inserts for air Reynolds numbers ranging from 10.328×103 to 11.769×103. The impacts of different parameters of heat transfer are considered in this work with heat flux are constant conditions of 600 W/m2 and 800 W/m2 with using the coil wire and twisted tapes with three ratios (y/w = 3, 4 and 5). The test section is a horizontal annular passage with outer diameter 10 cm. The results showed that using coil wire inserts to improve heat transfer coefficient factors in tubes resulted in local heat transfer coefficient percentages of (5.1%) to (7.8%) with heat flux are constant conditions of 600 W/m2 and 800 W/m2, respectively. While tube with swirl inserts provide local heat transfer coefficient percentages of (3.6% to 6.1%) for heat fluxes (600) W/m2 and (800) W/m2, respectively. The obtained results demonstrate that as the twisted ratio (y/w) decreases, the mean Nusselt number and heat transfer coefficient in the tube with twisted tape and coil wire rise. Experimental results is shown, heat transfer coefficient for the coil wire when compared with that of swirl inserts tube were ranged between (10.6%) to (16.5%) and (11.5%) to (17.3%) for the heat flux (600) W/m2. [ABSTRACT FROM AUTHOR]

In this study focuses primarily on the effect of adding needle ends on NACA 4412 airfoil and compare the result with NACA 4412 airfoil without needle ends. Theoretical analysis by using Ansys Fluent on NACA 4412 airfoil with needle ends to calculate the effects of these ends on lift and drag coefficients. Five angles of attack were taken (0°, 4.5°, 9°,13.5°, and 18°) for Reynolds number (Re = 106) based on airfoil chord length. The result shows that there is a 10% increase in the lift coefficient for modified airfoil more than standard airfoil. the drag coefficient of NACA 4412 with needle ends has value less than a standard airfoil. [ABSTRACT FROM AUTHOR]

This study will focus on the Kurdistan region of Iraq. Irrigation is an essential of agriculture, and the process of irrigation takes place by transfer of water from water source to farm. However, energy is the main aspect to consider when carrying out the irrigation process. Due to shortages of electricity and the high cost of diesel, there are difficulties in meeting the demands of irrigation. In this study, solar energy is considered as one way to design a solar water pump that can be used on farms in the Kurdistan region of Iraq. Photovoltaic solar panels have been assessed as a way to provide a successful solar water pump system with a minimum cost. The weather conditions for Duhok city in Kurdistan have been analysed to assess the solar water pump system for local use. The outcome of this study revealed that the solar water pump is applicable and can provide many benefits for the use of clean and renewable energy to transfer water from a water source to farms in the Kurdistan region of Iraq. A proposed design system with cost analysis is provided as an outcome of this study. [ABSTRACT FROM AUTHOR]