Energy Systems Engineering / Enerji Sistemleri Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4752
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Article Citation - WoS: 33Citation - Scopus: 42Thermodynamic Assessment of Downhole Heat Exchangers for Geothermal Power Generation(Elsevier, 2019) Yıldırım, Nurdan; Parmanto, Slamet; Akkurt, Gülden GökçenDownhole heat exchanger is a device to extract heat from geothermal fluid. While it is widely used for heating purposes, its use for power generation has not been reported. The aim of this study is to examine the feasibility of power generation from a 2500 m deep existing geothermal well with high temperature gradient and insufficient flowrate by using a downhole heat exchanger. For this purpose, a thermodynamic and an economic evaluation model are developed by the use of Engineering Equation Solver software. Additionally, the parametric studies have been carried out to identify the effects of insulation, geothermal well conditions, geometry of downhole heat exchanger, mass flowrate and type of working fluids on the performance of downhole heat exchanger system. Consequently, work output of the best alternative is computed as 2511 kW(e) with 64 kg/s mass flowrate of R-134a for 2500 m-deep downhole heat exchanger having inner pipe diameter of 0.127 m. Electricity generation cost and simple payback time are calculated as 46 $/MWh and 2.25 years, respectively. The obtained results showed that the downhole heat exchanger system can be a feasible alternative for wells with very low geothermal flowrate to generate power. (C) 2019 Elsevier Ltd. All rights reserved.Article Citation - WoS: 15Citation - Scopus: 11The Relation Between Thermal Comfort and Human-Body Exergy Consumption in a Temperate Climate Zone(Elsevier, 2019) Turhan, Cihan; Gökçen Akkurt, GüldenHuman body exergy balance calculation method gives minimum human body exergy consumption rates at thermal neutrality (TSV = 0) providing more information on human thermal responses than other methods. The literature is lacking the verification of this method in various climatic zones. The aim of this study is to investigate the relationship between thermal comfort and human body exergy consumption in a temperate climate zone. A small office building in Izmir Institute of Technology campus, Izmir/Turkey, was chosen as a case building and equipped with measurement devices. The occupant was subjected to a survey via a mobile application to obtain his Thermal Sensation Votes. Objective data were collected via sensors and used for predicting occupant thermal comfort and for exergy balance calculations. Under given conditions, the results show that Thermal Sensation Votes are generally zero at a T-i range of 21-23 degrees C and, are mostly lower than Predicted Mean Votes in summer while the opposite is observed in winter. Predicted Mean Votes at minimum Human Body Exergy Consumption rates were on slightly warm side while Thermal Sensation Votes are zero. It means that for given case, the HBexC rate calculation gave a better prediction of the environmental parameters for the best thermal comfort. (C) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 32Citation - Scopus: 37Mcdm Analysis of Wind Energy in Turkey: Decision Making Based on Environmental Impact(Springer Verlag, 2018) Değirmenci, Sinem; Bingöl, Ferhat; Sofuoğlu, Sait CemilDevelopment of new wind energy projects require complex planning process involving many social, technical, economic, environmental, political concerns, and different agents such as investors, utilities, governmental agencies, or social groups. The aim of this study is to develop a tool combining Geographic Information System (GIS) and Multi-Criteria Decision-Making (MCDM) methodologies, and its application for Turkey as a case study. A variety of constraints and criteria were identified based on a literature review and regulations gathered from variety of agencies, use of which resulted in determination of infeasible sites. Then, pairwise comparisons were carried out using analytic hierarchy process as the MCDM method to estimate relative importance of the criteria, and to visualize a suitability map with three classes. As the final stage, decision making was carried out based on environmental impact where 45.5% of the Turkish territory was found as infeasible area. Sixty percent of the remaining area are covered by the moderate suitability class, followed by the highly suitable area (20.3%) and low suitable area (19.8%). The output of this study can be used by energy planners to estimate the extent that wind energy can be developed based on public perception, administrative, and environmental aspectsArticle Citation - WoS: 29Citation - Scopus: 39Investigation of Indoor Microclimate of Historic Libraries for Preventive Conservation of Manuscripts. Case Study: Tire Necip Paşa Library, Izmir-Turkey(Elsevier Ltd., 2017) Şahin, Cem Doğan; Çoşkun, Turgay; Durmuş Arsan, Zeynep; Gökçen Akkurt, GüldenConservation of library collections requires an interdisciplinary approach. Dealing with the agents of deterioration via curative and preventive conservation methods has become a significant goal with new standards and norms in recent years. Preventive conservation aims indirect physical interventions such as climate control, good housekeeping and pest management. The aim of this study is to assess the degradation potential of indoor climate on valuable manuscripts that date back to 12th century, in a historic library in Tire-İzmir, Turkey. Through the study, first the library, namely Necip Paşa Library was continuously monitored by measurements of thermo-hygrometric parameters for one year. Then, the measured data were evaluated for the risk assessment based on the control classes of ASHRAE Chapter 21 to evaluate the mechanical, chemical and biological degradation risks. Finally, the conservation-oriented measures were proposed in order to keep the manuscripts under the better conditions. Results suggest that introducing a heating, ventilation and air-conditioning system to the building should be considered as the last option since natural hygrothermal behavior of the library gives reasonably sufficient evidences to prevent the manuscripts from degradations to some extent. Therefore, passive solutions should be given higher priorities not to disturb environmental past of the historic library.Article Citation - WoS: 270Citation - Scopus: 299Interface-Engineered All-Solid Li-Ion Batteries Based on Garnet-Type Fast Li+ Conductors(John Wiley and Sons Inc., 2016) Van Den Broek, Jan; Afyon, Semih; Rupp, Jennifer L.M.All-solid-state Li-ion batteries based on Li7La3Zr2O12 (LLZO) garnet structures require novel electrode assembly strategies to guarantee a proper Li+ transfer at the electrode–electrolyte interfaces. Here, first stable cell performances are reported for Li-garnet, c-Li6.25Al0.25La3Zr2O12, all-solid-state batteries running safely with a full ceramics setup, exemplified with the anode material Li4Ti5O12. Novel strategies to design an enhanced Li+ transfer at the electrode–electrolyte interface using an interface-engineered all-solid-state battery cell based on a porous garnet electrolyte interface structure, in which the electrode material is intimately embedded, are presented. The results presented here show for the first time that all-solid-state Li-ion batteries with LLZO electrolytes can be reversibly charge–discharge cycled also in the low potential ranges (≈1.5 V) for combinations with a ceramic anode material. Through a model experiment, the interface between the electrode and electrolyte constituents is systematically modified revealing that the interface engineering helps to improve delivered capacities and cycling properties of the all-solid-state Li-ion batteries based on garnet-type cubic LLZO structures.Article Citation - WoS: 74Citation - Scopus: 85A Transdisciplinary Approach on the Energy Efficient Retrofitting of a Historic Building in the Aegean Region of Turkey(Elsevier Ltd., 2015) Şahin, Cem Doğan; Durmuş Arsan, Zeynep; Tunçoku, Selim Sarp; Broström, Tor; Gökçen Akkurt, GüldenAbstract Buildings account for 40% of total energy consumption in the European Union, yet at the same time they have considerable energy saving potentials. Historic buildings should be treated different from contemporary ones when it comes to energy improvements. The specifications which underline historical, sociocultural and architectural values require certain care during realization of energy saving implementations to sustain these values. The purpose of this study is to demonstrate how the energy efficient retrofitting in historic buildings should be managed in a transdisciplinary approach with a case study conducted on the historic building in ̄zmir - Turkey. A detailed building energy simulation tool was used to determine the impacts of energy efficient retrofits. The actual energy consumption of case building was based on the utility bills regarding electricity and heating fuel consumption. Building energy simulation tool was calibrated by comparing the measured and simulated indoor air temperatures and total energy consumptions. The inappropriate retrofits, which contradict to the cultural heritage values, were eliminated with a transdisciplinary approach. Later appropriate retrofits were gathered into three packages to evaluate their effects on the energy consumption. The results show that energy saving of more than 34% can be obtained without damaging the heritage values.