Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis Development of Energy-Efficient Personalized Thermal Comfort Driven Control in Hvac Systems(Izmir Institute of Technology, 2018) Turhan, Cihan; Gökçen Akkurt, Gülden; Simani, SilvioIncreasing thermal comfort and reducing energy consumption are two main objectives of advanced HVAC control systems. Studies conducted in the last decade show that intelligent HVAC systems can geatly affect thermal comfort, health, satisfaction, and productivity of building occupants while decreasing the energey consumption. Also, personelized thermal comfort driven control of the HVAC systems is the most effective way of saving energy and maintaining thermal comfort. In this thesis, an energy-efficient personalized thermal comfort control algorithm is developed to improve HVAC control systems. The thesis presents a complete system to control algorithm which includes the deployment of wireless sensor network. First a novel control algorithm is developed to perceived comfort conditions of occupants and to save energy. Then, a prototype of the personalized thermal comfort driven controller (PTC-DC) is manufactured an tested in a case building at İzmir Institute of Technology Campus, İzmir/Turkey. The proposed control strategy is tested betwen July 3rd, 2017 and November 1st, 2018, and compared with conventional controller in terms of energey saving and boath energetic and exergetic approaches of thermal comfort. The results showed that PTC-DC satisfies neutral thermal comfort for 92% of total measurements days while AM=0 for only 6% of total measurement days for conventional controller. From energy consumption point of wiev, PTC-DC decreased energy consumption by 13.2% compared to conventional controller.Doctoral Thesis Modeling, Simulation and Optimization of Flashed-Steam Geothermal Power Plants From the Point of View of Noncondensable Gas Removal Systems(Izmir Institute of Technology, 2010) Yıldırım Özcan, Nurdan; Gökçen Akkurt, GüldenGeothermal fluids contain noncondensable gases (NCGs) at various amounts. The presence of NCGs in geothermal steam results with a dramatic decrease in net power output increasing condenser pressure and total auxiliary power consumption. Hence, NCGs should be withdrawn by a gas removal equipment to improve the performance of geothermal power plants (GPPs). The flashed-steam GPPs (single-flash, double-flash) are a relatively simple way to convert geothermal energy into electricity when the geothermal wells produce a mixture of steam and liquid. The primary aim of the Thesis is to model and develop a code to simulate flashed-steam GPPs to examine the thermodynamic and economical performance of NCG removal systems, which are major concerns at planning and basic design stages of GPPs. The model is validated comparing model output with Kizildere GPP output, classified as deterministic and static. The model is simulated to identify the effects of input variables which are NCG fraction, separator pressure, condenser pressure, wet bulb temperature, interest rate, tax rate, O&M cost ratio and electricity sales price. Among the variables, NCG fraction is the most significant parameter affecting thermodynamic performance and profitability of flashed-steam GPPs. The net power output and overall exergetic efficiency of singleflash GPP is decreased 0.4% for compressor system (CS), 2.2% for hybrid system (HS), 2.5% for reboiler system (RS) and 2.7% for steam jet ejector system (SJES) by 1% increase in NCG fraction. Based on thermodynamic and economical simulations, SJES, HS and CS can be recommended to be used for a NCG fraction range of 0-2%, 2-10% and >10%, respectively. Furthermore, thermodynamic performance of single-flash plants can be improved by adding second flash by 45.5-127.9%.