Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 1Citation - Scopus: 1Energy and Exergy Analysis of a Geothermal Energy Sourced Hot-Air Drying System(Inderscience Enterprises, 2023) Helvacı, Hüseyin Utku; Keleş, Nazlı; Gökçen Akkurt, GüldenA geothermal energy-sourced drying system was tested for the thin-layer drying process of tomato slices at air temperatures of 40 degrees C, 50 degrees C and 60? and velocities of 0.5 m/s and 1.5 m/s to investigate system performance in terms of the first and second laws of thermodynamics. The energy and the exergy efficiency of the system were found to be 6.6% and 22.31%. The energy utilisation and energy utilisation ratio were calculated in the range of 1.271 kW-5.102 kW and 9.644%-39.56%, respectively. The exergy destruction, exergy efficiency and improvement potential of the drying chamber varied between 0.0198 kW-0.2621 kW, 59.74%-81.95% and 0.00486 kW-0.07396 kW, respectively.Article Citation - WoS: 1Citation - Scopus: 1Thermodynamic Re-Assessment of a Geothermal Binary Power Plant Operated in a Moderate-Temperature Geothermal Field(Inderscience, 2023) Özcan, Zeynep; Gökçen Akkurt, GüldenAn existing organic rankine cycle power plant which uses isobutane as working fluid is re-evaluated for different working fluids. The plant is first modelled by EES software; then the model is simulated for different working fluids obtaining heat transferred through the heat exchanger, net work output, energy and exergy efficiencies, and mass flowrate of the working fluid. Two parametric studies are conducted to evaluate the thermodynamic performance of the plant under a range of turbine inlet temperature (130°C–155°C) and geothermal resource temperature (152°C–161°C) for each working fluid. The study reveals that the highest cycle energy and exergy efficiencies are observed for R-152a at any geothermal resource temperature. R-152a resulted with 13.1% and 58.2% cycle energy and exergy efficiency, respectively at operation condition, whilst the lowest efficiency and net work output is calculated under n-butane presence.Conference Object Citation - Scopus: 1Comfort Based Investigation on Historic Libraries for User Satisfaction and Preservation of Paper-Based Collections(IOP Publishing, 2021) Turhan, Cihan; Topan, Çağrı; Durmuş Arsan, Zeynep; Göksal Özbalta, Türkan; Gökçen Akkurt, GüldenHistoric libraries preserve cultural heritage values while housing rare manuscripts and paper-based collections. The collections in the libraries are deteriorated chemically, biologically and mechanically due to inappropriate indoor environment conditions such as temperature and relative humidity fluctuations and microbiological conditions. Apart from preserving vulnerable paper-based collections, accommodating of a considerable thermal comfort level for visitors is essential in historic libraries. The aim of this study is to analyse indoor environment of a historic library in terms of thermal comfort and preventive conservation of paper-based collections. Izmir National Library, built in 1933, is selected as a case study. Indoor air temperature, relative humidity and air velocity in the library were monitored with a one-year measurement campaign. Meanwhile, thermal comfort of the visitors was assessed with PMV/PPD indices and thermal sensation surveys. The results show that high chemical degradation risk is detected in the library while biological and mechanical degradations are in the low risk zone. On the other hand, 87% and 93% of the visitors feel thermally satisfied in heating and cooling seasons, respectively.Article Citation - WoS: 12Citation - Scopus: 13Assessment of Thermal Comfort Preferences in Mediterranean Climate a University Office Building Case(Vinca Inst Nuclear Sci, 2018) Turhan, Cihan; Gökçen Akkurt, GüldenThis study aims at evaluating the perceived thermal sensation of occupants with respect to thermal comfort standards, ASHRAE 55 and ISO 7730, for office buildings located in Mediterranean climate. A small office building in Izmir Institute of Technology Campus Area, Izmir, Turkey, was chosen as a case building and equipped with measurement devices to assess thermal comfort of occupants with respect to predicted mean vote and actual mean vote. Both objective and subjective measurements were conducted. The former included indoor and outdoor air temperature, mean radiant temperature, relative humidity and air velocity that were used for evaluating the thermal comfort of occupants. Oxygen concentration which can play an additional role in thermal comfort/discomfort, health and productivity of the office occupants, was also measured. Furthermore, occupants were subjected to a survey via a mobile application to obtain subjective measurements to calculate actual mean vote values. Based on objective and subjective measurements, the relationships among the parameters were derived by using simple regression analysis technique while a new combined mean vote correlation was also derived but this time by using multiple linear regression model. Neutral and comfort temperatures were obtained using indoor air temperature and actual mean vote values which were calculated from subjective measurements. The results showed that neutral temperature in the university office building was 20.9 degrees C whilst the comfort temperature range was between 19.4 and 22.4 degrees C for the heating season. By applying new comfort temperatures, energy consumption of the case building located in Mediterranean climate, can be reduced.Article Citation - WoS: 7Citation - Scopus: 8Performance Indices of Soft Computing Models To Predict the Heat Load of Buildings in Terms of Architectural Indicators(Yıldız Teknik Üniversitesi, 2017) Turhan, Cihan; Kazanasmaz, Zehra Tuğçe; Gökçen Akkurt, GüldenThis study estimates the heat load of buildings in Izmir/Turkey by three soft computing (SC) methods; Artificial Neural Networks (ANNs), Fuzzy Logic (FL) and Adaptive Neuro-based Fuzzy Inference System (ANFIS) and compares their prediction indices. Obtaining knowledge about what the heat load of buildings would be in architectural design stage is necessary to forecast the building performance and take precautions against any possible failure. The best accuracy and prediction power of novel soft computing techniques would assist the practical way of this process. For this purpose, four inputs, namely, wall overall heat transfer coefficient, building area/ volume ratio, total external surface area and total window area/total external surface area ratio were employed in each model of this study. The predicted heat load is evaluated comparatively using simulation outputs. The ANN model estimated the heat load of the case apartments with a rate of 97.7% and the MAPE of 5.06%; while these ratios are 98.6% and 3.56% in Mamdani fuzzy inference systems (FL); 99.0% and 2.43% in ANFIS. When these values were compared, it was found that the ANFIS model has become the best learning technique among the others and can be applicable in building energy performance studies.Article Citation - WoS: 7Citation - Scopus: 7The Importance of Internal Heat Gains for Building Cooling Design(Yıldız Teknik Üniversitesi, 2017) Coşkun, Turgay; Turhan, Cihan; Durmuş Arsan, Zeynep; Gökçen Akkurt, GüldenThis paper aims to investigate the effect of internal heat gains on the cooling load of a building. The house occupied by three adult men is selected as the case study for paper. The house is in the third floor of the apartment. The apartment has four flats and it has no insulation around the external walls. The heat dissipation from lighting devices, electrical equipment and the occupants are calculated by using the DesignBuilder v4 Beta release simulation program. The temperature of the house is observed during three weeks by using hobo data loggers and calibration of the measurements is made with respect to weather data file of the flat. Detailed schedule based on time of operation and occupancy is prepared to get more accurate results. Annual energy consumption and cooling load of the house is determined by using the dynamic simulation program.Article Citation - WoS: 12Citation - Scopus: 19Effect of Non-Condensable Gases on Geothermal Power Plant Performance. Case Study: Kızıldere Geothermal Power Plant-Turkey(Inderscience Enterprises Ltd., 2008) Gökçen Akkurt, Gülden; Yıldırım, NurdanNon-Condensable Gases (NCGs) are natural components of geothermal fluids, and they are a source of considerable capital and operating costs for power plants. The NCG content of geothermal steam varies over the world from almost zero to as much as 25% (wt). In this work, the influence of NCGs on the thermodynamic performance of geothermal power plants is analysed for various NCG content and turbine inlet temperatures. The results obtained can be useful on the feasibility study of single flash geothermal power plants. Depending on the NCG content of the field, the performance of the power plant can be determined roughly. © 2008, Inderscience Publishers.Article Citation - Scopus: 10Exergy Analysis and Performance Evaluation of Kizildere Geothermal Power Plant, Turkey(Inderscience Enterprises Ltd., 2004) Yıldırım, Eda Didem; Gökçen Akkurt, Gülden; Gökçen, GüldenConventional geothermal power plants (GPP) differ from fossil-fuel power plants (FFPP) in many ways. The most specific ones are GPPs, are not cyclic plants and the working fluid is not pure steam. Geothermal steam contains non-condensable gases (NCG) which degrade power plant efficiency. This discrepancy leads to two considerations in energy and exergy analysis of GPPs. One is that the amount of NCGs in the steam cannot be omitted during the calculations; the other is that the dead state composition varies throughout the process. In this work, energy and exergy analysis is conducted to assess the performance of Kizildere GPP under both considerations. The net second law efficiencies of the plant based on reservoir and wellhead exergy are 24.3 and 27.2% respectively. Both indicate that the plant performance is low comparing with the other single-flash GPPs and FFPPs. The losses are mainly associated with high NCG content and low steam fraction of the fluid.Conference Object Citation - WoS: 1Citation - Scopus: 2Analysis and Application of Advanced Control Strategies To a Heating Element Nonlinear Model(IOP Publishing Ltd., 2017) Turhan, Cihan; Simani, Silvio; Zajic, Ivan; Gökçen Akkurt, GüldenThis paper presents the design of different control strategies applied to a heating element nonlinear model. The description of this heating element was obtained exploiting a data-driven and physically meaningful nonlinear continuous-time model, which represents a test-bed used in passive air conditioning for sustainable housing applications. This model has low complexity while achieving high simulation performance. The physical meaningfulness of the model provides an enhanced insight into the performance and functionality of the system. In return, this information can be used during the system simulation and improved model- based and data-driven control designs for tight temperature regulation. The main purpose of this study is thus to give several examples of viable and practical designs of control schemes with application to this heating element model. Moreover, extensive simulations and Monte- Carlo analysis are the tools for assessing experimentally the main features of the proposed control schemes, in the presence of modelling and measurement errors. These developed control methods are also compared in order to evaluate advantages and drawbacks of the considered solutions. Finally, the exploited simulation tools can serve to highlight the potential application of the proposed control strategies to real air conditioning systems.