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Air Pollution Control Studies
Studies on the removal of polluting gases (such as CO2, SO2) formed as a result of burning fossil fuels for power generation and heat play an important role in air pollution control. Carbon dioxide (CO2) is considered one of the most critical greenhouse gases that cause global warming. For this reason, CO2 must be captured directly from the atmosphere or from point emission sources. One of the most effective methods to remove CO2 in flue gas from point emission sources is the absorption of CO2 into a solution. Current studies are carried out to find efficient and alternative solutions, since the absorption solutions used in existing systems have many disadvantages. In this context, studies have been carried out in bubble column, packed column and structured packed column systems with various chemical and physical solutions to remove CO2 from flue gas streams. As an alternative to amine (MEA, DEA, etc.) solutions used in existing systems, mass transfer studies were carried out with sodium metaborate, calcium acetate, n-butanol, ethyl acetate, carbitol acetate, glycerol, glycerol+sodium hydroxide (NaOH) solutions. In addition, the removal of sulfur dioxide (SO2), which plays an important role in air pollution and is used as a "pollution indicator" in air pollution measurements, is also very important. Related to this, studies on the removal of SO2 with iron(II)hydroxide (Fe(OH)2) suspensions from the flue gas of biomass-based combustion systems were also carried out in the bubble column system. Currently, studies on the removal of CO2 and SO2 with alternative absorption solutions are continuing within TEMENAR-CERAC.
Electrolysis Studies
100% pure hydrogen can be produced by the electrolysis method of water, which is widely used for the production of hydrogen, which is accepted as the energy carrier of the future. However, this method is the most costly system among hydrogen production systems. For this reason, it is an important issue to develop and research innovative and unique technologies for reducing the cost by using different sources in the electrolysis method and thus for more economical production of high purity hydrogen. In this context, studies are carried out on the realization of hydrogen production by coal electrolysis, an innovative method, by integrating coal, our national resource, into electrolysis, which is the most reliable and well-known method in terms of obtaining 100% pure hydrogen. In the study carried out within the scope of the doctoral thesis, the electrochemical oxidation of different coal types and hydrogen production with the innovative coal electrolysis method are examined. Since the cell potential is lower in coal electrolysis than in water electrolysis, a more economical hydrogen production is possible. In the study, a unique system with two compartments, the compartments separated from each other by a membrane, is used for the electrolysis process. In the developed system, the oxidation behavior of coal varieties in different geological ages is examined. Hydrogen productions are investigated by electrochemical measurements and optimum hydrogen production conditions are tried to be determined with various parameter changes.
It is known that hydrogen is the most promising energy carrier and will play an important role in energy systems in the future. Ensuring the commercial conversion of glycerine, which is formed as a by-product in biodiesel production, into hydrogen and valuable compounds is an important step. In this way, high purity hydrogen from renewable sources was produced with an innovative method without the need for any other purification process. Within the scope of the study, the performance of the system under different operating conditions was evaluated by parameter studies conducted in different experimental systems and the most suitable conditions for the system were determined. Parameters such as glycerine solution concentration, electrode material, distance between electrodes, electrolyte, temperature, the effect of solution mixing, the effect of additives added to the electrolyte were examined and its contribution to hydrogen production was determined. The amount of hydrogen formation was increased by optimizing the parameters in different experimental systems.
Fuel Cell Studies
Most of the world's current energy needs are met by fossil fuels. The gases released during the production of energy from fossil fuels seriously threaten both the environment and human health. For these reasons, renewable and alternative energy sources are needed. Hydrogen energy technologies have an important place among renewable and clean energy sources. Fuel cells are the most striking of the hydrogen energy systems. Fuel cells are generally static energy conversion devices that convert the chemical reaction of fuels directly into electrical energy. Among the different fuel cell types, the proton exchange membrane (PEM) fuel cell is seen as the most promising fuel cell due to its advantages such as high power density, low operating temperature, and high starting speed. Membranes used in PEM fuel cells are called the heart of the fuel cell and are one of the most important components. Although Nafion membrane is used commercially, the search for alternative membranes continues due to high cost, high fuel permeability and loss of performance at high temperatures. Our research group carries out alternative membrane synthesis and characterization studies for use in PEM fuel cells. In this direction, single or mixed membranes of many polymers such as sulfonated polyether ether ketone (SPEEK), polyvinyl alcohol (PVA), polybenzimidazole (PBI), polyvinylidene fluoride (PVDF) are synthesized. In line with the need, many additive materials such as clay derivatives and metals are used, as well as boron compounds, where the majority of the world's reserves are in our country and may have high added value. Characterization studies and fuel cell performance test studies are carried out for fuel cell application with these membranes.
Fuel cells in which borohydride is used directly as fuel are known as direct borohydride fuel cells (DBFC). Although air is commonly used at the cathode in these cells, direct borohydride/peroxide fuel cells (DBPFC) have been formed in recent years, with the preference of peroxide. In the study, the effect of electrode modifications on cell performance was observed by deposition of Ni on the Pd/C anode surface and Prussian Blue coating on the Pt/C cathode surface in DBPFC. The cell performance, which was 40 mW/cm2, increased to 293 mW/cm2 as a result of the modifications. In this study, a direct borohydride/peroxane fuel cell was developed for the first time in the literature. Cell performance has been increased by using ozone (peroxane) together with peroxide as an oxidant. However, sintered graphite plates were used because ozone damages the graphite cell containing resinous binders. The use of these plates also showed a serious effect on the cell performance and the power of the cell nearly doubled. In the study, parallel and serpentine channel types were examined, and higher power values were obtained by using serpentine channels. Cell performance decreases over time as the concentrations of liquid oxidant and liquid fuel used in DBPFCs decrease during cell operation. In order to prevent this situation, a controlled oxidant feeding model has been developed. For this purpose, stable power output was provided by feeding certain amounts of oxidant to the main oxidant tank at certain time intervals from a second tank added to the system. In order to ensure system safety, appropriate concentrations for fuel and oxidant solutions have been determined in order to reduce the excess of hydrogen gas formed at the anode and oxygen gas formed at the cathode.
Gasification Studies
The energy need in the world is increasing rapidly with industrial applications and developing technology. With the increasing energy demand, the dependence of conventional systems on fossil fuels is faced with the rapid depletion of the remaining life of these reserves. In addition, basic problems such as conventional systems causing greenhouse gas emissions, inability to use low-carbon fuels, and increasing waste problems have led to the search for alternative energy sources. The best examples of alternative energy sources are local lignite, bituminous shale and biomass resources. Because, due to its location, Turkey has both young lignite and shale deposits and a wide variety of biomass resources due to its effectiveness in agricultural activities. In terms of clean energy production, today's research gives importance to the production and use of H2. In terms of being a good energy carrier, H2 has the feature of being used as a fuel. One of the main processes by which H2 can be produced is gasification processes. The gas product obtained from the gasification process is called “synthesis gas” and basically contains H2, CO, CH4 and CO2 gases in its composition. Hydrogen-rich synthesis gas production studies carried out within TEMENAR-CERAC were carried out in fixed and fluidized bed gasifier systems. In order to promote H2 production with the use of local lignite and biomass resources, a master's thesis named “Gasification of Tunçbilek Lignite and Pomace in Fluidized Bed with Water Vapor” was carried out. Researches continued for the production of hydrogen-rich syngas with the studies of “Production of Hydrogen-Rich Syngas in a Fluidized Bed” and “Gasification of Plastic City Waste in a Fluidized Bed Reactor with Himmetoğlu and Seyitömer Bituminous Shales”. Within the scope of Waste to Energy, “A Parametric Study to Optimize the Temperature of Hazelnut and Walnut Shell Gasification for Hydrogen and Methane Production” was presented to encourage the use of domestic biomass. Studies for the production of hydrogen-rich synthesis gas from different fuel sources continue.
Researchers (In order of title and surnames)
Lect. Dr. Hatice Begüm MURATHAN
Res. & Teach. Asst. Okay Serkan ANGI
Res. & Teach. Asst. İrem KOÇYİĞİT ÇAPOĞLU
Res. & Teach. Asst. Hazal ÖZTAN
Lect. Yavuz YAĞIZATLI
Lect. Merve GÖRDESEL YILDIZ
Lect. Özgü YÖRÜK
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