İsmail Ekmekçi

Bin weather data for different climates of Turkey

In this study, bin weather data and bin method for Turkey which is a well-known and simple method to estimate heating and cooling loads were investigated. The bin weather data for dry-bulb temperature from -50°C to +50°C with 3°C increments were generated in six daily 4-h shifts. Typical meteorological year datasets were used to generate bin weather data for the selected eight cities (Istanbul, Ankara, Trabzon, Van, Diyarbakr, Adana, Sivas and Denizli) representing the distinct climatic zones of Turkey. Using typical meteorological year data in bin data generation is the original part of this study. Yearly total Nbin values for the selected cities were tabulated. Results of this study are important due to the data used, fill an important gap for Turkey about bin data and can simply be used in prediction of heating and cooling energy consumptions of buildings. Additionally, this study contributes well to the world literature on bin data.

Weibull distribution for determination of wind analysis and energy production

In recent years, decreasing reserves and environmental problems related with fossil fuels have increased the demand for clean and renewable energy sources, as with all over the world and also in Turkey. Wind energy is the one of the most rapidly growing among the renewable energy sources in terms of technological and utilization. Turkey is one of the rich countries in Europe in respect to wind energy potential. Productive and effective use of this potential is very important for Turkey that is depended on foreign countries especially in respect to fossil energy sources. Wind speed values are the most important data in calculation of electrical energy from wind turbines. In this study, latest developments and energy-power equations related to wind turbines are investigated. Using of the data obtained from the wind measurement station installed in Sakarya-Esentepe region, annual electrical energy production of an example wind plant is predicted.

Economical evaluation of a cogeneration system for a building complex

In this study, the suitability of using cogeneration system for the Aktürk Building Complex (located in İstanbul) was investigated using electricity and heat consumption data by considering five different cogeneration system capacities (800, 1200, 1400, 2000 and 2600 kW). The different capacities were compared using data of the payback period of investment, amount of net savings, ratio of meeting demand and part-load efficiency of the cogeneration system. Although payback periods of the investment for different capacities are close to each other, 1200 kW capacity cogeneration system is proved to be suitable for the Aktürk Building Complex because it has the shortest payback period (1 year 5 months).

Energy Efficiency Study on Air-Cooled Condensers

Cooling systems for HVAC applications in aviation area have a great importance and due to the limited space in complex aviation systems and equipment, energy efficiency is becoming increasingly importance. Energy efficiency affects the design of chillers that account for a significant ratio of the energy consumption in plants. Legal legislations in the short-term limit, and in the long term prohibit the use of refrigerants that have high global warming potential, which are very harmful to the ozone layer. Since air-cooled condensers are among the essential components of cooling groups, efforts to improve their energy efficiency are made incessantly, the related national and international standards are upgraded and limitations on their energy consumptions are always increasing. In light of the latest applicable standards, detailed and comparative information on applications aimed at improving the energy efficiency in air-cooled condensers, highlighting the importance of energy efficiency in cooling installations.

Different Efficiency Calculations of a Combined Cycle Power Plant

Brayton cycle has a great importance for aviation industry in gas turbines of aircrafts. The aim of this study is to obtain the different efficiency values of one of the combined thermal power plant in our country that its working principle mainly depends on gas turbine Brayton cycle. Ambarli Combined Cycle Power Plant has been examined to make some comparisons with different efficiency approaches. This power plant is examined by using different efficiency definitions: Thermal, Carnot, Curzon-Ahlborn, Caputo Efficiency and Exergetic Efficiency.

Novel Fin Design for the Panel Type Radiators Using CFD

There are many panel radiator manufacturers in Turkey. Their panel radiator designs are very similar, and radiators that have been manufactured by various producers have very similar thermal efficiency values and specific heating per unit weight of the radiator. In this study, CFD analysis of existing panel radiators was made with a commercial CFD software of STAR-CCM+ with top-bottom-opposite-end connection method in three-dimensional space. Panel-convector-convector-panel, Type-22-600×500 steel panel radiator, was used in this numerical study. In the content of this analysis, new configurations at fin design were performed to increase the rate of heat transfer of the panel radiator. Four fin designs were drawn and examined. Since triangular profile fin design contains less material and has higher heat flux, it is more efficient than the other profiles, and therefore it is more suitable for applications requiring minimum weight.

Prediction of circular jet streams with Artificial Neural Networks

In this study, an ANN model was established by using experimental measurement values at low speed sub-audio level in an air tunnel of which length is 75cm and experiment room cross sections are 32cm × 32cm and model results were compared to experimental values and then, the prediction was made for unmeasured jet stream values. The jet stream at value of 30m/s in the wind tunnel is ensured with a compressor connected to the inlet of wind tunnel experiment room. The tunnel speed values of 0, 10 and 20m/s is ensured with a frequency converter axial fan by making suction in same direction with jet stream. In experimental studies, the jet speed in wind tunnel and radial speed diffusion measures are obtained with a hot wire anemometer enable to make two-dimension measure in the wind tunnel experiment room. In the experiment room, measurements are made with measurement stations located in four different distances. To establish the ANN model, the tunnel speed, length rate and radial distances were taken as an input, with these data, by training the ANN model, networks were established and the radial speed diffusions corresponding to these inputs were obtained as an output. With the data obtained from that network, experimental measurement was made and speed profiles in data ranges were predicted and compared to experimental results. To verify the predicted results, these values and experimental results were compared relatively on non-dimensional speed diffusion graphics. Additionally, similar speed diffusion values and non-dimensional speed diffusion graphics were obtained for 5 and 15m/s tunnel speeds without experimental measurements and comparative comments were made.