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Due to global warming in the world, energy production systems connected to fossil energy sources are gradually decreasing. Due to this, the use of renewable energy sources is increasing. Solar energy is one of the most important renewable energy sources. In order to meet the increasing energy needs, the use of solar energy in photovoltaic systems is increasing rapidly. Studies for the use of solar energy in thermal systems are also continuing to increase. The parabolic solar collector stands out among the thermal energy applications. With these collectors, it is possible to produce heat energy up to 300 oC temperatures. At this temperature, electricity can be generated by heat energy. On the other hand, in summer, when cooling energy is very much needed, cooling can also be done with absorption cooling systems using abundant solar energy.. High coefficient of performance(COP) can be obtained in double-stage absorption cooling systems with high temperature heat energy. In this study, the instantaneous thermal performance of parabolic trough type solar collectors was investigated by modeling. For this, a simulation program has been written in the MATLAB programming language. In this program, the DPP model was used to calculate the instantaneous direct solar radiation value(DNI). With the calculations made using this model, it has been shown that it would be appropriate to place such collectors, which follow the sun in one dimension, in a North-South direction so that they can produce more energy.Using the characteristics and dimensions of a sample collector, instantaneous efficiency and useful heat calculations were performed. Daily, monthly and annual thermal power values and efficiency calculations were made with the sum of these instantaneous values. For the regions selected as an example, comparisons were made by finding annual thermal power values depending on environmental parameters. The ideal environmental parameters for the installation of such systems have been determined and discussed. [ABSTRACT FROM AUTHOR]

The 1973 oil crisis caused the price of a barrel to rise from $2.59 to $11.65. There have been many oil crises since 1973. These crises have led countries around the world to seek alternative solutions. As a result of the researches, orientation towards renewable energy sources has emerged as a solution. Renewable resources are inexhaustible and cleaner energy sources than fossil fuels. Among the renewable energy sources, solar energy is the most promising source. Solar energy is distinguished from other renewable energy sources by its ease of use, ubiquity and being the cheapest energy at the same time. There are many different technologies and methods to generate electricity from solar energy. The most efficient and common technology for generating electrical energy is to run a turbine by concentrating the sun's rays in one place and obtaining high temperatures. Parabolic trough type solar collectors are at the forefront of this method. In this method, direct sunlight is concentrated by reflecting it to the receiver pipe, which is placed across the focal point of the parabolic collector, thanks to a reflective surface. In this study, a theoretical study was carried out in order to find a solution to the energy problem of the Comoros Islands, which are dependent on foreign and fossil fuels for energy supply. In this study, information about the Comoros solar energy potential, solar radiation and the equations required for the calculation of solar radiation and concentrator systems are given. In addition, the equations required for sizing the parabolic trough type solar concentrator and calculating the thermal and optical losses in the system are explained in detail. Then, calculations of electrical energy production in Comoros were made with a parabolic trough type solar collector. Parabolic trough solar concentrator system with 400kWe installed power and ORC turbine power generation system have been used for electric power generation in Comoros. Finally, the calculations and analyzes were evaluated and the suitability of this system in the Comoros Islands was demonstrated. [ABSTRACT FROM AUTHOR]

Most country supply their energy need from fossil energy resources such as oil, coal, natural gas called as primary energy resources. Emission that occurs due to use of fossil fuels causes to the global in addition environmental pollution. Since the reserve of fossil fuels is limited, these energy resources will be exhausted. After first energy crisis in 1971, all the countries is directed to renewable energy sources in order to be independent in energy. Since solar energy is the free of emission, easy to find and cheap if it is compared with other renewable energy resources, most of countries are concentrated on solar energy. Because of technological development, electricity production from solar energy studies increased and particularly production of high temperature vapor become widespread. In order to produce electricity using vapor and vapor turbine, high temperature is needed. Concentrated solar systems can be used for medium and high temperature. One of the most important solar receivers is Parabolic Trough Solar Receivers in that category. Solar radiation is reflected through the parabolic surface to focal point surface. Most important parts of the system are reflective surfaces and receivers. Receiver part is combine of absorbent pipe that coated with selective surface. In this study, the performances of Parabolic Trough Solar Receivers will be investigate for different selective surface and absorbent pipes material. [ABSTRACT FROM AUTHOR]