Nuri Özek

Estimation of Horizontal Solar Radiation in Isparta (Turkey)

Abstract The solar radiation, as it comes through the atmosphere to the Earths surface, can be used in a variety of fields, such as solar engineering, architecture, agriculture, and hydrology. It is important to investigate solar radiation, especially in a place such as Turkey, where solar-energy potential is high. Thus, in this study, the daily (during sunshine duration) and monthly average global, diffuse, and direct solar radiation in the Isparta (37° 18′ and 38° 30′ N latitude) region of Turkey has been obtained. In the comparison of calculated and meteorological data, a good agreement has been observed.

The Development of a Computer Program for Estimating Solar Radiation

Abstract It is important to know solar energy potential before setting up any solar energy system. It is usually simulated, as the measurement is not easily attainable in every place. For this purpose, a computer program has been developed to determine solar radiation. The program, which is developed using Delphi language and can run under Windows operating systems, uses altitude, latitude, date, and temperature of the place as an input and both daily and monthly solar radiation containing direct, diffuse, and global can be obtained from output. Moreover, it provides solar radiation data to compute for horizontal and tilted surfaces.

Turkey's Energy Production, Consumption, and Policies, until 2020

Abstract Energy has always been critical for economic growth and social development. As economies develop, energy consumption grows more or less in parallel. An adequate and affordable energy supply is needed to meet the demands of industry, commerce, and domestic users and to enable the movement of people and goods. In this study, Turkish energy production, energy consumption, installed electric power capacity, energy reserves, energy policies, primary energy demand projection, and market evaluation are investigated and evaluated. Turkey has been experiencing substantial demand growth in all segments of the energy sector. The primary energy need of Turkey has been growing. Recent forecasts indicate that this trend will continue as a result of rapid urbanization and industrialization. Primary energy demand is projected to reach 150 million toe in 2020.

Optical, Energetic and Exergetic Analyses of Parabolic Trough Collectors

Parabolic trough collectors generate thermal energy from solar energy. Especially, they are very convenient for applications in high temperature solar power systems. To determine the design parameters, parabolic trough collectors must be analysed with optical analysis. In addition, thermodynamics (energy and exergy) analysis in the development of an energy efficient system must be achieved. Solar radiation passes through Earths atmosphere until it reaches on Earths surface and is focused from the parabolic trough collector to the tube receiver with a transparent insulated envelope. All of them constitute a complex mechanism. We investigate the geometry of parabolic trough reflector and characteristics of solar radiation to the reflecting surface through Earths atmosphere, and calculate the collecting total energy in the receiver. The parabolic trough collector, of which design parameters are given, is analysed in regard to the energy and exergy analysis considering the meteorological specification in May, June, July and August in Isparta/Turkey, and the results are presented.

Energetic and exergetic performance assessment of some coals in Turkey for gasification process

This paper undertakes a study on energetic and exergetic performance evaluation of various types of coals in Turkey, such as Armutcuk, Amasra, Zonguldak and Catalagzy hard coals and Tuncbilek, Beypazari, Cayirhan, Afsin, Soma, Yatagan, Can and Sorgun lignites for gasification purposes, where syn-gas may subsequently be used for the production of electricity, heat, hydrogen, etc. in industry. The chemical exergy contents of these coals are determined and compared for a potential use in gasification, and their energetic and exergetic efficiencies are also assessed for performance comparison. In the analysis, exergetic efficiencies are evaluated for an idealised gasifier in which chemical equilibrium is reached, ashes of coals are not considered and heat losses are neglected. It is observed that coals having lower heating value have higher gasification efficiency, and the ratios of hydrogen to chemical exergy of coal are related to the gasification process efficiencies of this coal.

Energy Market Structure of Turkey

Abstract The State has been the dominant player in the energy market. But, as a result of the liberalization and privatization studies in the Turkish energy market since 2001, it is now facilitated for private national and international companies to take part in the energy market. The chances are quite good for private companies. First of all, the country requires a considerably high amount of investments with an average 6.4% annual energy demand increase. Second, there are privatization studies for both electricity distribution and generation facilities of the State. These two fields offer good chances for both national-international power generation investors and engineering/consulting companies. Besides, the natural gas market may be an interesting field of cooperation for foreign companies for various market activities, in parallel to the countrys increasing natural gas demand. This study aims to examine the Turkish energy market with possible development fields and legal and organizational conditions, problems, and development fields of the Turkish energy sector.

Thermodynamic and life cycle assessment of flat–plate collector, photovoltaic system and photovoltaic thermal collector

In this study, an energy, exergy and Life Cycle Assessment (LCA) analysis of a Flat–Plate (FP) collector, a Photovoltaic (PV) system and a Photovoltaic–Thermal (PV–T) collector is carried out for better evaluation. It is observed that instantaneous energy, daily energy and exergy efficiency of the FP collector, the PV system and the PV/T collector vary between 53–61%, 19–30%, 23–37% and 56–74%, 11–15%, 21–34% and 2–7%, 6–22% and 8–16%, respectively. The energy and CO2 payback time of these solar collectors varies between 2, 12, 3.8 and 1.6, 3.6 and 1.8 years, respectively. Thermodynamic and LCA analysis show that a considerable amount of electrical and thermal energy is generated by the PV–T collector and the sustainability of the system is improved. Hence, the PV system has features better for the PV–T collector, especially when both electricity and heat are required for domestic applications.

Theoretical and Experimental Analysis of a Salt Gradient Solar Pond with Insulated and Reflective Covers

Abstract In this study, a salt gradient solar pond having a surface area of 3.5 × 3.5 m2 and depth of 2 m has been built for supplying hot water to a leather workshop on the campus area of Vocational College of Isparta/Yalvaç. A cover system was used on the surface of the pond to reduce the thermal losses from the top to air and to increase the thermal efficiency of the pond. Such an arrangement is used for the very first time. The system is composed of two covers that can be rotated between 0 and 180 degrees by a controlled electric motor and has insulation and reflection properties, i.e., the covers function as insulators when closed and as reflectors when opened. The ponds thermal analysis has been carried out theoretically and experimentally for different operating conditions. Results obtained from this study show that salt gradient solar ponds can be used as a source of warm water required at the leather workshop and for suitable domestic applications. The covers were effective both for reducing the night thermal losses and for increasing the daytime performance, although the former effect is negligible.

Thermodynamic analysis and assessment of space heating with ground–source heat pump for sustainable future

In this paper, the thermodynamic modelling of exergy loss, exergy efficiency, exergy destruction rate, environmental destruction coefficient, improvement potential, exergy destruction factor, relative irreversibility, productivity lack and exergetic factor of ground source heat pump (GSHP) system are investigated. The results show that these exergy indexes should be used integratively. Compressor has the maximum exergy destruction rate, followed by the condenser and ground heat exchanger. Exergy efficiencies are obtained as 54.54% and 38.52% for the GSHP unit and whole system, respectively. Related parametric studies concerning about exergy destruction rate and exergy efficiency of the system components are carried out at different ambient temperatures.