Yazarlar
- Akkurt, Nevzat(10)
- Gul, Muhammet(7)
- Işık, Erdem(7)
- Yucesan, Melih(6)
- Acar, Ramazan(5)
- Konurhan, Zekeriya(5)
- Bayrakdar, Cihan(4)
- Kahraman, Gökhan(4)
- Keserci, Ferhat(4)
- Tuğan, Volkan(4)
- Utku, Anıl(4)
- Çılğın, Zeynel(4)
- İnallı, Mustafa(4)
- Göçmen, Elifcan(3)
- Korkmaz, Meral(3)
- Utku, Anil(3)
- Akbas, Ergun(2)
- Aksağan, Zülfükar(2)
- Akyol, Sinem(2)
- Bjarnadottir, Brynhildur(2)
- Black, Andrew(2)
- Celik, Erkan(2)
- Demir, Yakup(2)
- Derse, Onur(2)
- Erdem, Necla Seval(2)
- Evans, Ian S.(2)
- Geçkil, Tacettin(2)
- Gunnarsdottir, Gunnhildur E.(2)
- Güçlü, Yavuz Selim(2)
- Hudaverdi, Burcu(2)
- Imak, Andaç(2)
- Kjartansson, Bjarki T.(2)
- Koycegiz, Cihangir(2)
- Oddsdottir, Edda S.(2)
- Oskarsson, Hlynur(2)
- Saplıoğlu, Kemal(2)
- Sarı, Sacit(2)
- Shao, Shuangquan(2)
- Sigurdsson, Bjarni D.(2)
- Susam, Selim Orhun(2)
Yayınlar
- MakaleYalnız künye2020Scopus SJRQ1Study on model uncertainty of water source heat pump and impact on decision making
Zhang, Ying; Akkurt, Nevzat; Yuan, Jiaqi; Xiao, Ziwei; Wang, Qianjiang; Gang, Wenjie
Water source heat pump systems are widely used for cooling and heating due to high efficiency. The energy source can be surface water or underground water. Accurate modeling of water source heat pump systems is the basis for performance prediction, design and control optimization. However, various heat pump models are available to predict the system performance and results obtained can be very different under different models due to the model uncertainty. Without considering these uncertainties, the performance of water source heat pump systems would be overestimated or underestimated and the decision making would be affected. This paper attempts to quantify the model uncertainty of water source heat pump and its impact on the system performance. Thirteen commonly-used models are selected and validated using the manufacture data. By importing these models into the water source heat pump system, the impact of heat pump model uncertainty on the system performance is quantified. It shows that the model uncertainty can result in a deviation of up to 30% in the annual energy consumption. The energy saving potential of water source heat pump systems can vary from -18.43% to 14.78% compared with the chillers & boiler in the hot summer and cold winter area. The priority of water source heat pump systems is also controversial. The difference in the annual average coefficient of performance of the system can be up to 1.22. It demonstrates that the model uncertainty of water source heat pumps affects the system performance significantly and should be taken into account in building energy prediction and design optimization. The models considering the correction of part load ratio are recommended.
AtıfScopus40WoS34OpenAlex45
İncele - MakaleYalnız künye2020Scopus SJRQ1Techno-economic analyses of multi-functional liquid air energy storage for power generation, oxygen production and heating
Wang, Chen; Akkurt, Nevzat; Zhang, Xiaosong; Luo, Yimo; She, Xiaohui
Liquid air energy storage (LAES) is increasingly popular for decarbonizing the power network. At off-peak time, ambient air after purification is liquefied and stored; at peak time, the liquid air is discharged to generate power. One of the key challenges for the LAES system is the lower economic benefit as peak electricity is usually the only source of income, leading to a longer payback period of ~15 years. To address this issue, this paper, for the first time, proposes a multifunctional LAES system, which not only generates peak electricity but also provides pure oxygen and heating. The proposed system is composed of an air separation unit (ASU), a nitrogen liquefaction unit (NLU) and a power generation unit (PGU). Thermodynamic and economic analyses are carried out on the proposed system. Compared with the baseline LAES system (NLU + PGU), the multifunctional LAES system has a lower round trip efficiency of ~0.39 due to the extra electricity consumption by the ASU. However, it shows a much better economic performance with additional benefits from pure oxygen and heating. In a project life-span of 30 years, the multifunctional LAES system (10 MW/80 MWh) has a short payback period of ~5.7 years. Furthermore, it has a savings-to-investment ratio of 3.12, which is ~153% higher than that of the baseline LAES system. Investigation on the system operation strategy suggests that the ASU should operate at full time. The proposed system provides a feasible way to improve the economic benefits of the LAES system, thus promoting its wide applications.
AtıfScopus82OpenAlex86İncele - MakaleYalnız künye2020Traces of late quaternary glaciations and paleoclimatic interpretation of Mount Akdağ (Alanya, 2451 m), Southwest Turkey
Bayrakdar, Cihan; Çılğın, Zeynel; Keserci, Ferhat
Mount Akdağ, located 25 km northeast of Alanya (2451 m above sea level a.s.l.), and largely made up of carbonates, is one of the mountains exposed to Late Quaternary glaciation in the Western Taurus Mountains. Although today, there are no modern glaciers, the traces of the Late Quaternary glaciers and rock glaciers are still fresh. In this study, geomorphological features related to the glaciations in Mount Akdağ, which were not previously reported in the literature, were first identified from satellite images, and then verified by field studies. The geomorphological development of Mount Akdağ during the Quaternary was explained by considering its climatic and karstic characteristics. For this purpose, spatial data obtained from field studies, unmanned aerial vehicles and meteorological stations were analysed using geographic information systems. Akdağ is directly open to humid air masses coming from the SW sector over the Mediterranean Sea, resulting in heavy orographic precipitation that encouraged the growth of glaciers. In addition, glacier reconstruction and pELA estimates have been made to contribute to the interpretation of glacial geomorphology. The pELA in Mount Akdağ was calculated with the AABR ratio of 1.69, and was found to be around 2030 m a.s.l. More than 15 cirques and a 6.5 km long glacial valley in Mount Akdağ indicate the presence of glaciers. Reconstruction of the paleoglaciers shows that the lowest altitude reached was 1410 m a.s.l. At their maximum extent glaciers covered an area of ~ 14 km2, with a volume of ~ 1 km3 and had an average thickness of 60 m with a maximum glacier thickness of ~ 200 m.
AtıfScopus19OpenAlex23İncele - MakaleYalnız künye2020Scopus SJRQ3Increasing the Power Generation by Raising the Capacity of the Thrust Bearing Oil Cooling System in Hydroelectric Power Plants
Kahraman, Gökhan
Cooling capacity decreases due to faults appearing over time in the thrust bearing oil cooling systems of hydroelectric power plants and cooling process cannot proceed sufficiently. For this reason, while the turbine-generator unit generates energy, the thrust bearing heats up. This temperature problem prevents the unit from operating at full capacity and therefore decreases in energy production. Producing deficient energy in hydroelectric power plants, which is a renewable energy source, causes long-term economic losses for countries. In this study, the thrust bearing cooling system of a vertical Francis turbine, which produces 150 MW of energy per hour, is investigated. The reduction in the cooling capacity over time in turbine thrust bearing cooling system is solved by using exchanger system with additional plate and the power produced by the turbine-generator unit is increased 15 MW/h. This improvement has greatly contributed to the national economy. The method of increasing the cooling capacity applied to the hydroelectric power plant thrust bearings can be applied to all hydraulic turbines. This method will increase the energy production amount of the unit by approximately 10% and it costs approximately 80% cheaper than completely replacing the existing cooling system.
AtıfScopus5WoS2OpenAlex5İncele - MakaleAçık Erişim2020Scopus SJRQ33d surface modeling of late pleistocene glaciers in the Munzur mountains (Eastern Turkey) and its paleoclimatic implications
Çilğin, Zeynel
Located in the Eastern Anatolian Region in Turkey, the Munzur Mountains (Munzurs; 3463 m above sea level) are one of the most important glacial landscapes in Turkey, with evidence for extensive glaciations in the past and small-scale glaciation at present. As Turkey’s second-largest glaciated region, these mountains include various glacial landforms, primarily glacial valleys, hanging valleys, cirques, and moraines. However, only limited data are available on the extent and chronology of former glaciations in the Munzur Mountains. This study produced data on the extent of paleoglaciers, calculated their equilibrium line altitudes (ELAs), revealed paleoclimate conditions, and modeled paleo temperatures during maximum ice extent using numerically derived reconstruction methods (GlaRe and ELA calculation tools) based on geomorphic evidence. The major glacial landforms were first mapped in detail before the reconstruction. Six hundred and eighty cirques and 30 glaciated valleys were identified. Paleoglaciers did not override the entire mountains, however, valley glaciers converged where topographic conditions were suitable.The maximum extent of glaciation covered an area of ca. 600 km2. The largest glacier was ca. 19 km in length. Moreover, 15 of the valley glaciers were over 10 km in length. Their average thickness was 75 m, and the maximum glacial thickness, in the Eastern Munzurs, was found to be ca. 300 m. The total volume of ice reached ca. 45 km3. The paleoglaciers reached as low as 1350 m above sea level. The average ELA was calculated approximately 2600 m above sea level, indicating an equilibrium line altitude depression of 1000–1100 m. The paleotemperatures, estimated based on different scenarios at the time of the maximum extent of Munzur glaciers, were 8–10 °C lower than today. The mountains experienced an increase in precipitation through this period with respect to the current precipitation scheme.
AtıfScopus9WoS10OpenAlex16TR Dizin8
İncele - MakaleAçık Erişim2019The Impact of Urbanization On Energy Consumption and Carbon Emissions in Turkey
Kahraman, Gökhan
Turkey's economic development in terms of urbanization, consumption of electricity is a significant pressure on the natural environment. In order to reduce the effects of this pressure in parallel with economic growth, it is necessary to reduce the dependence on foreign sources in energy while reducing the amount of carbon emissions that cause environmental pollution. Therefore, Turkey's economic growth of urbanization in order to continue in a healthy way, the relationship between the amount of energy consumption and carbon emissions need to be better understood. The target to reduce the economic and environmental impacts of economic growth and urbanization with increasing energy needs to the minimum should be to use renewable energy sources efficiently. The aim of this study urbanization in Turkey, the relationship between electricity consumption and carbon emissions is to examine the amount of time series analysis. The increase in the amount of carbon emission, the increase in population and the increase in electricity demand in comparison with years and sectoral basis were compared. discussing the results obtained from the graph are interpreted in how it has changed that and more weight which results results obtained from the graphic industry where the bet is causing the increase of electricity demand with urbanization between 1990-2017 years in Turkey. Graphic shows the results obtained from the last 27 years the amount of carbon emissions in Turkey, the population and electricity demand is increasing in parallel with each other. Especially the rise in demand for electricity and carbon emissions, but not appear as a result of this parallel Turkey's recent emphasis on renewable energy sources.
AtıfOpenAlex15TR Dizin11İncele - Derleme MakaleAçık Erişim2019Scopus SJRQ2ANN and ANFIS Approaches to Calculate the Heating and Cooling Degree Day Values: The Case of Provinces in Turkey
Işık, Erdem; İnallı, Mustafa; Celik, Erkan
Energy analysis plays a vital role in developing an optimum and cost-effective design for the heating, ventilating and air conditioning system of a building. The values of heating degree days (HDD) and cooling degree days (CDD) are used to analyze the demand for energy for buildings. In this study, the HDD and CDD values for Turkey were calculated using estimated temperature values. An artificial neural network (ANN) and an adaptive network-based fuzzy inference system (ANFIS) were applied for the estimation of temperature values. The Levenberg–Marquardt training algorithm was used for the feedforward backpropagation of the ANN, whereas the Sugeno-type fuzzy inference system was used for the ANFIS. Meteorological data from the last 11 years were used for the proposed approaches, and these were applied to different stations (n = 50) of the Turkish State Meteorological Service. In relation to the insulated building design, base temperatures have been considered as 16 °C and 18 °C for the HDD and 22 °C and 24 °C for the CDD based on a literature review. Two novel maps were prepared for the CDD and HDD. The calculated degree days and the maps are consistent with those from the Turkish State Meteorological Service.
AtıfScopus13WoS13OpenAlex18İncele - MakaleAçık Erişim2018Scopus SJRQ1Artificial neural networks and adaptive neuro-fuzzy inference systems approaches to forecast the meteorological data for HVAC: The case of cities for Turkey
Işık, Erdem; Inallı, Mustafa
Limited energy resources and increasing need for energy due to population growth seem to lead researchers to focus on these issues. Forecast of meteorological data has significant importance in design of thermal systems. In this study, forecasting of meteorological data used in thermal system design was performed for fifty cities to represent the entire Turkey. Data obtained from General Directorate of Meteorology (MGM) were modelled by artificial neural networks and adaptive-network based fuzzy inference systems. Matlab software was used for modeling and forecasting of prospective data with high sensitivity in thermal systems. Surfer and ArcGIS software were used to create humidity, temperature, solar radiation maps for Turkey. Root mean square error (RMSE), mean absolute error and (MAE), coefficient of variation (COV) and the coefficient of determination (R2) were used to validate the result of the proposed approaches. The results were satisfactory with respect to RMSE, MAE, COV and R2 to forecast the meteorological data. Annual solar power potential maps for Turkey were also proposed and compared with MGM results. The results of the proposed approaches are compatible with the result of the MGM. The Turkey policy maker(s) from MGM can easily use these approaches if a software is constructed.
AtıfScopus66WoS52OpenAlex68İncele - BildiriAçık Erişim2017Economic Analysis of Hybrid Renewable Energy Systems with V2G Integration Considering Battery Life
Baloglu, Ulas Baran; Demir, Yakup; Caetano, N.S.; Faculty of Engineering University of Porto (FEUP), LEPABE, Rua Dr. Roberto Frias, Porto; Polytechnic Institute of Porto (IPP), CIETI, School of Engineering (ISEP), Rua Dr. Antonio Bernardino de Almeida 431, Porto; Felgueiras, M.C.; Forment, M.A.
Hybrid renewable energy systems considered as candidate solutions for environmental problems. Solar energy and wind energy are important components of these systems, but both of them cause fluctuations in the grid. Batteries of Electric Vehicles (EVs) can be connected to the grid to create an ancillary resource. These systems known as Vehicle to Grid (V2G) and they could be the most suitable solution to the fluctuation problems of renewable resources. In this paper, economic analysis of V2G is investigated from various perspectives. The findings of this study indicate that battery aging costs of a V2G system can be minimized with an intelligent energy management system, and these systems are both economically and environmentally better alternatives to fossil-fuelled generators.
AtıfScopus15WoS13OpenAlex16İncele - MakaleYalnız künye2016Scopus SJRQ1Large interannual variability in net ecosystem carbon dioxide exchange of a disturbed temperate peatland
Aslan-Sungur, Guler; Lee, Xuhui; Evrendilek, Fatih; Karakaya, Nusret
AtıfOpenAlex42İncele - MakaleYalnız künye2016Scopus SJRQ2Storm water retention and actual evapotranspiration performances of experimental green roofs in French oceanic climate
Yilmaz, D.; Sabre, M.; Lassabatère, L.; Dal, M.; Rodriguez, F.
Green roofs are promising urban management tools from the standpoint of both rainwater management and microclimatology. They are considered as a storm water mitigation technique and may also favour evapotranspiration fluxes, which can be beneficial for urban comfort during summer periods. In France, however, water retention performance of green roofs remains unknown, and published values are often unsuitable. Six experimental roofs, including two thicknesses of growing media, three types of vegetation cover and bare surfaces, were monitored for two years in Nantes and compared to an experimental gravel flat roof. The thickest media combined with the most densely vegetated cover yields the best results in terms of storm water mitigation and actual evapotranspiration. In winter, the rainwater retention performance is clearly dependent on the type of experimental roof vegetation. This kind of experimental set-up is well suited to assisting urban planners design tools for storm water mitigation in buildings.
AtıfWoS22OpenAlex28İncele
