Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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  • Master Thesis
    Modelling and Simulation of Zinc-Air Batteries
    (01. Izmir Institute of Technology, 2024) Durak, Ege; Ebil, Özgenç
    Renewable energy sources are key components of a sustainable future. However, most of the renewable energy sources have intermittent natures, that can significantly affect the stability of grids. Thus, Energy Storage Systems (ESS) are introduced to store the energy produced for later use. Even though there are various ESS candidates, batteries are superior candidates due to technological readiness. Batteries still suffer from disadvantages that prevent their mass adoption as ESS for grid-scale applications. As an ESS, a battery that can last long cycles, have high power densities, and material availability should be designed and commercialized. Commercial batteries such as lead-acid and Li-ion batteries still suffer from material availability, environmental friendliness, or feasibility. Therefore metal-air batteries, especially zinc-air batteries (ZAB), have significant potential due to their high-power densities, material abundance, and technological readiness. However, ZABs are not ready enough to be commercialized as grid-scale ESS due to their low cycle lives due to aging mechanisms. Therefore, more research should be conducted to improve the rechargeability of a ZAB. However, experimental procedures are time and resource-consuming. To tackle this, accurate mathematical models and simulations should be implemented. In this study, the electrochemical behavior of zinc-air batteries was simulated with Finite Element Analysis (FEM) method. The motivation of the work was to demonstrate the feasibility of a simple 1-D zinc-air battery model to investigate the effect of various phenomena on the battery capacity and charge-discharge cycles. The results were compared to literature and experimental values to evaluate the model's accuracy.
  • Master Thesis
    Design of Advanced Process Control System for Delayed Coker Unit
    (2023) Zihinli, İrem; Kızılkaya, Ali Can
    It is essential for refineries to optimize the upgrading vacuum residue (VR) processes due to reducing of conventional light crude oil resources and increasing of fuel global demands. Delayed coking is a thermal cracking process used in refineries to upgrade and convert vacuum residuum into liquid and gas product streams including Light Coker Gas Oil (LCGO), Heavy Coker Gas Oil (HCGO), Sour Liquefied Petroleum Gas (LPG), Sour Coker Product Gas, Stabilized Naphtha and Petroleum Coke as a solid concentrated carbon material. Delayed coking is a semi-batch process where one or more pairs of coke drums are used for the thermal cracking and coking process. Simultaneously in each pair of coke drums, the feed stream is switched between two drums and one drum is online for the coking process while the other drum is offline undergoing decoking. The switching of the coke drums severely destabilizes the operation of the main fractionator and downstream process units. Applying advanced control concepts minimizes the disturbances and improves product quality and unit stability. Delayed coking is one of the most difficult refinery units to operate and control due to disturbances. Industrial chemical processes must operate at maximum efficiency and one of the ways to save energy and still obtain high quality product by using Advanced Process Control (APC) systems. The objective of thesis is to design an advanced process control system for main fractionator column of the delayed coker unit using Honeywell RMPCT. The aim of the APC is to decrease standard deviation of LCGO Final Boiling Point (FBP) quality in main fractionator column during steady state operation. The methods used in this thesis are the determination of the controller matrix and the application of pre-step and main tests to obtain process models for the advanced process control. According to obtained results, standard deviation for the LCGO FBP quality results are compared before and after APC implementation. It is shown that when the APC is turned on, the standard deviation of the LCGO product FBP quality is decreased by 3 ℃.