Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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Author: search.filters.author.Yıldırım, Eda Didem

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  • Article
    Citation - Scopus: 10
    Exergy Analysis and Performance Evaluation of Kizildere Geothermal Power Plant, Turkey
    (Inderscience Enterprises Ltd., 2004) Yıldırım, Eda Didem; Gökçen Akkurt, Gülden; Gökçen Akkurt, Gülden; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Conventional 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.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 19
    A Numerical Simulation Study for the Human Passive Thermal System
    (Elsevier Ltd., 2008) Yıldırım, Eda Didem; Özerdem, Barış; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The objective of this study is to create a dynamic model representing a transient three-dimensional passive thermal model of the human body. The model is a multi-segmental, multi-layered representation of the human body with spatial subdivisions which simulates the heat transfer phenomena within the body and at its surface. In order to represent the mechanisms of heat transfer within the body, energy balance equations including conduction with adjacent tissue, heat storage, metabolic heat generation, and convective heat transfer due to the blood flow in the capillaries are taken into consideration for each tissue. The present model of the passive system accounts for the geometric and anatomic characteristics of the human body and considers the thermo-physical and the basal physiological properties of tissue materials. It is assumed that the body is exposed to combination of the convection, evaporation and radiation which are taken into account as boundary conditions when solving the passive thermal system equation. The model is capable of predicting human body temperature in any given environmental conditions. Finite difference solution scheme is used to find out the temperature distribution of human body. The results are compared with the experimental data of previous studies present in the literature. Consequently, the numerical results of present model show good agreement with the experimental data.