Members of the Combustion Research Group at the Department of Energy Engineering focus on low emission combustion research. Interview with Viktor Józsa, senior lecturer, and Gyöngyvér Hidegh, PhD student.
What does the phrase ’combustion’ exactly mean? It is related to fire, flames, certain technologies...
Viktor Józsa: The phrase ‘combustion’ covers multiple fields, including combustion theory, combustion technology, combustion-related numerical simulations, and in a general context, the use of fire by mankind. Even cooking can be classified here, however, instead of stoves, we focus on industrial and power plant applications.
What made you pursue research in this field? Why combustion?
Gyöngyvér Hidegh: This topic grabbed my attention in the spring of 2015. I was impressed by that Viktor, and another colleague, Attila Kun-Balog, are how enthusiastic about their research to find explanations for various interesting phenomena and challenges in this field.
Viktor Józsa: When I was a child, I wanted to be a pilot. I never liked cars but jet aircraft. Following that, my goal was to work with jet engines and gas turbines; thus I applied to the Faculty of Mechanical Engineering of BME. Firstly, I turned to mechanics then fluid dynamics, because I was the only applicant for heat engineering specialization in 2011. The current research thread dates back to the scientific student conference (TDK) in 2010; my topic of bioethanol utilization in gas turbines, supervised by Dr. Krisztián Sztankó. Then we turned to heavier alternative fuels like crude rapeseed oil, which is highly viscous.
This is the point when the current research topic came to life.
VJ: However, instead of directly spilling it into the tank, the combustion of low-quality fuels were evaluated in a single burner – since poor combustion conditions of, e.g., crude sunflower oil, also used for cooking, would have otherwise severely damaged our turbine. If we succeed with flame stabilization, and even if we are happy with the concentration of pollutants in the flue gas, then it is highly probable that the operation inside the gas turbine would be flawless.
Since it is still impossible to power an intercontinental flight on batteries only, the domination of hydrocarbons will endure for long decades. The word ’hydrocarbons’ instead of fossil fuel was mentioned with purpose since the origin of the fuel is almost irrelevant due to the high combustion chamber temperature. Hence, such fuels can be derived from oils or waste, but fossil fuels are significantly cheaper these days. (The video shows diesel oil combustion. The flame color tends to purple instead of blue, if biodiesel is the fuel in the volumetric operation mode. This marginal difference leads to the conclusion that the two fuels may substitute each other.)
What discoveries did you make? How can we apply them?
VJ: The flame emission spectrometry analysis – in which Gyöngyvér was also involved – is popular, and we got numerous citations for these papers. These analyses are highly useful today since everyone in the industry strives to reduce the pollutant emissions of their combustion chamber. However, the dynamic loading, not only in power plants, requires tools that enable online diagnostics and control. Since this technique is an optical tool, the signal travels with the speed of light, while flue gas sensors react in tens of seconds that is too late.
In parallel with spectrometry, combustion acoustic analyses provide similar information. The difference is that the signal is traveling with the speed of sound by pressure waves. This technique requires only acoustical contact; the microphone membrane can be put behind a heat shield. We also have an invention notification regarding flame acoustics analysis, which is now on its way to become a patent in Hungary.
This dynamic operation mode is entirely new and challenging for the industry. In aviation, low fuel consumption requires active control, which is rapidly becoming also crucial in power generation of thermal power plants, due to the growing number of wind turbines and solar cells. Adaptive means market advantage, so our results are particularly valuable for industrial purposes.
Currently, we are focusing on mixture temperature-controlled combustion, which is capable of cutting the pollutant emissions dramatically, far below the corresponding regulation limits.
Ammonia combustion became highly popular among the combustion community. Although it is a toxic substance, it is free from carbon and sulfur, and the flue gas ideally contains only nitrogen gas and steam. We are unable to combust ammonia currently, but we plan to extend our research in this direction.
Recently, a department head from the National University of Public Service proposed a research topic focusing on various renewable fuels to power the Hungarian military aircraft. Of course, to avoid failures of the engines, we start with simple investigations in our combustion chamber before they are introduced into service, which is expected to take a few years.
Our research earned international popularity. One of our projects is running in collaboration with the Shanghai Jiao Tong University, which is the 83rd university in the world rankings. This is about the analysis of biodiesels, which are recently introduced into the aviation sector as biojet fuel – which slightly differs from the conventional biodiesel both chemically and physically.
In cooperation with our friends at Brno Technical University, we are focusing on liquid fuel atomization, which is a more fundamental topic. This phenomenon, apart from combustion, can be found in metallurgy, in which the fine metal droplets for powder metallurgy are produced by this technique. Its pharmaceutical application is also significant in drug production, and a final application example is paint spraying.
What are your plans for the future?
GyH: We continue our investigations with other fuels, using novel diagnostic and evaluation methods and bring them into applications.
VJ: We are applying for a Lendület (Momentum) grant by the Hungarian Academy of Sciences with the research group. We are eight, and although I am the group leader, all of us are equal while I deal with the majority of administration work, allowing the others to focus on the research.
Is this combustion test rig serves only lab purposes, or can it be used for, e.g., heating?
Beyond the difficulties in legal issues of connecting such a device to the utility network, we are using it only a few hours a week. Hence, it serves only research purposes.
Photos: energia.bme.hu, Linkedin
Video: ViktorJózsa, Gyöngyvér Hidegh, Attila Kun-Balog, Jo-Han Ng, Cheng TungChong (2020) Ultra-low emission combustion of diesel-coconut biodiesel fuels by a mixture temperature-controlled combustion mode. Energy Conversion and Management. Volume 214. 15 June 2020. 9p. DOI: 10.1016/j.enconman.2020.112908
László Benesóczky
Since it is still impossible to power an intercontinental flight on batteries only, the domination of hydrocarbons will endure for long decades. The word ’hydrocarbons’ instead of fossil fuel was mentioned with purpose since the origin of the fuel is almost irrelevant due to the high combustion chamber temperature. Hence, such fuels can be derived from oils or waste, but fossil fuels are significantly cheaper these days. (The video shows diesel oil combustion. The flame color tends to purple instead of blue, if biodiesel is the fuel in the volumetric operation mode. This marginal difference leads to the conclusion that the two fuels may substitute each other.)
What discoveries did you make? How can we apply them?
VJ: The flame emission spectrometry analysis – in which Gyöngyvér was also involved – is popular, and we got numerous citations for these papers. These analyses are highly useful today since everyone in the industry strives to reduce the pollutant emissions of their combustion chamber. However, the dynamic loading, not only in power plants, requires tools that enable online diagnostics and control. Since this technique is an optical tool, the signal travels with the speed of light, while flue gas sensors react in tens of seconds that is too late.
In parallel with spectrometry, combustion acoustic analyses provide similar information. The difference is that the signal is traveling with the speed of sound by pressure waves. This technique requires only acoustical contact; the microphone membrane can be put behind a heat shield. We also have an invention notification regarding flame acoustics analysis, which is now on its way to become a patent in Hungary.
This dynamic operation mode is entirely new and challenging for the industry. In aviation, low fuel consumption requires active control, which is rapidly becoming also crucial in power generation of thermal power plants, due to the growing number of wind turbines and solar cells. Adaptive means market advantage, so our results are particularly valuable for industrial purposes.
Ammonia combustion became highly popular among the combustion community. Although it is a toxic substance, it is free from carbon and sulfur, and the flue gas ideally contains only nitrogen gas and steam. We are unable to combust ammonia currently, but we plan to extend our research in this direction.
Recently, a department head from the National University of Public Service proposed a research topic focusing on various renewable fuels to power the Hungarian military aircraft. Of course, to avoid failures of the engines, we start with simple investigations in our combustion chamber before they are introduced into service, which is expected to take a few years.
Our research earned international popularity. One of our projects is running in collaboration with the Shanghai Jiao Tong University, which is the 83rd university in the world rankings. This is about the analysis of biodiesels, which are recently introduced into the aviation sector as biojet fuel – which slightly differs from the conventional biodiesel both chemically and physically.
In cooperation with our friends at Brno Technical University, we are focusing on liquid fuel atomization, which is a more fundamental topic. This phenomenon, apart from combustion, can be found in metallurgy, in which the fine metal droplets for powder metallurgy are produced by this technique. Its pharmaceutical application is also significant in drug production, and a final application example is paint spraying.
What are your plans for the future?
GyH: We continue our investigations with other fuels, using novel diagnostic and evaluation methods and bring them into applications.
VJ: We are applying for a Lendület (Momentum) grant by the Hungarian Academy of Sciences with the research group. We are eight, and although I am the group leader, all of us are equal while I deal with the majority of administration work, allowing the others to focus on the research.
Is this combustion test rig serves only lab purposes, or can it be used for, e.g., heating?
Beyond the difficulties in legal issues of connecting such a device to the utility network, we are using it only a few hours a week. Hence, it serves only research purposes.
Photos: energia.bme.hu, Linkedin
Video: ViktorJózsa, Gyöngyvér Hidegh, Attila Kun-Balog, Jo-Han Ng, Cheng TungChong (2020) Ultra-low emission combustion of diesel-coconut biodiesel fuels by a mixture temperature-controlled combustion mode. Energy Conversion and Management. Volume 214. 15 June 2020. 9p. DOI: 10.1016/j.enconman.2020.112908
Video: ViktorJózsa, Gyöngyvér Hidegh, Attila Kun-Balog, Jo-Han Ng, Cheng TungChong (2020) Ultra-low emission combustion of diesel-coconut biodiesel fuels by a mixture temperature-controlled combustion mode. Energy Conversion and Management. Volume 214. 15 June 2020. 9p. DOI: 10.1016/j.enconman.2020.112908
László Benesóczky
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