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|The design of efficient cooling systems plays a decisive role in the development of modern gas turbine combustion chambers. Guaranteed adherence to the maximum permissible material temperatures is required while at the same time using as little cooling air as possible. The required mass flows of cooling air therefore need to be known as already at the development stage, since they directly influence the available combustion air and hence pollutant emissions from the combustion chambers.|
By developing a suitable model, the goal is to determine the wall temperature of a combustion chamber taking into account the radiant gases in the combustion region, the radiation interaction with particles (such as soot) suspended in the flame and the radiation of the combustion chamber walls. The temperature distribution determined in this way can then be used to optimise different cooling concepts.
The so-called Monte Carlo method is used for the numerical simulation of the radiation processes in the combustion chamber. The principle of this simulation method rests on tracking a large number of randomly distributed photons through the combustion space. The distribution of the absorbed photons ascertained in this way can ultimately be interpreted as the radiant heat transferred.
Within this research focus the following research projects are associated:
Coil coating is an important industrial process applied in a major part of industrial steel and metal alloy production and associated with big facilities and large primary energy consumption. A major part of the overall plant size and the energy demand of coil coating facilities is associated with the drying/curing process that occur inside a curing oven, which is the bottleneck concerning the increase of the production capacity. In this drying/curing process, organic solvents are vaporized from the applied liquid coating film and since they are flammable, the usually applied curing ovens with convective air drying technology have to be operated far below the Low Explosive Limit (LEL), due to safety constraints. ECCO proposes a novel solution for the curing oven operation, which can not only drastically increase the compactness and energetic efficiency of the system, but leads to an increased production flexibility due to a fuel-flexible, modular and potentially energetically self-sustainable process. The main idea is to heat the metal strip by IR-radiation and operate the curing oven well above the Upper Explosive Limit (UEL), thus, performing the drying and curing process in an atmosphere mainly consisting of the solvent vapours, which are used as fuel in IR radiant porous burners. This solution leads to a size/ production capacity ratio reduction of 70% and a reduction of investment and operating costs of at least 40% each. Starting from previous activities at TRL 4, an interdisciplinary approach is foreseen, based on advanced-materials, combustion technology and prediction tools for system design/ optimization, with active participation of key industrial stakeholders, to bring this technology to TRL 6 and realize a prototype furnace at industrially relevant size and environment.
The SOPRANO project’s main scientific objective is to make a breakthrough in the overall investigation efforts in the field of soot particles chemistry, particles size distribution (PSD), and their radiative effect on combustors typical of aero-engines. SOPRANO aims at a qualitative shift in the knowledge and experimental and numerical approaches related to the characterization and prediction of soot emission and interaction with radiative Low NOx combustor environment.
The main industrial objective of SOPRANO is to carry out an in-depth characterization of soot particles emitted by a modern combustor at engine relevant operating conditions and at increased pressures to pave the way for the future design of high-performance combustors: a more accurate evaluation of the radiation effect and, therefore, a more reliable liner temperature prediction, will drive a review of the design criteria in terms of combustor air distribution and will improve durability of some key modules, e.g. the combustor’s liners.
Within this research focus in the past the following research projects were associated:
It has been shown that the commonly used surface radiation models without consideration of chemical reaction (combustion models) and without turbulence and soot formation models have to be re-considered. Instead, fluid dynamically driven coherent structures and CFD simulations of interacting fires have to be considered using the above mentioned sub models which partly have to be developed.
In particular, the knowledge about the interaction phenomena between two or even more pool fires will be investigated both, experimentally and numerically using CFD simulations. Additionally the knowledge about the length of the so-called clear combustion zone, which is not covered by black sooting regions, has to be deepened. Also the knowledge on the specific radiation (SEP) of single and interacting black sooting fires needs to be extended.
Of high importance and a pre-requisite for success of the above mentioned goals the knowledge on the elementary chemical reactions in peroxide pool flames has to be deepened, especially with respect to soot formation in such hydro-carbon pool flames. For this, mechanisms of soot formation will be improved and reaction mechanisms for the combustion of organic peroxides will be developed and integrated into CFD tools. Such tools can be flamelet models, which will be used int the present research work.