The two-year R&D project of the Combustion Simulation Platform for advanced industrial design process is being undertaken from this fiscal year as one of the Academia-Industry Cooperation Programs of Combustion Society of Japan. This project is aiming not only to develop the platform for a numerical simulation of combustion that can be commonly utilized among the companies participating in the project but also to provide the opportunity for young researchers in the combustion community to enhance their possibilities under the Academia-Industry cooperation. The project is being conducted by R&D of Combustion Simulation Platform Project Team that consists of nine universities and thirteen companies. The subjects being developed in the project have been assessed and selected in the Project Team in terms of the applicability to the industrial applications. The platform will be validated with the target flames that are selected by the Project Team and be provided for these companies two years later to apply it to the industrial design processes.
An automotive engine cylinder simulation software is now being developed under the support of Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “Innovative Combustion Technology.” The software is named “HINOCA.” HINOCA is based on fully compressible Navier-Stokes equations which are filtered for LES(Large Eddy Simulation), and employs the Cartesian grid and immersed boundary (IB) methods to reduce the mesh generation cost and labor. The flow solver platform is developed by Japan Aerospace Exploration Agency by utilizing its aerospace CFD (Computational Fluid Dynamics) technology. The sub-models, spray, ignition, flame propagation and wall heat loss, are built into HINOCA by collaborating universities and research institutes. In the newly developed work flow based on the Cartesian grid and IB methods, mesh generation process is reduced to almost zero and flow simulation can be run directly from the cylinder configuration data defined in STL format. The simulation of Steady State Flow Bench shows a fairly good agreement with the measurement. The motoring simulation dealing with moving valves and a piston is successfully conducted by the employed CFD techniques. Built-in of the sub-models is now on going.
Large eddy simulation for gas-turbine combustor is improved due to recent advances in cluster computers and turbulent combustion models. Reduction of computation time makes it possible to apply LES to large domain problems with various turbulent combustion models. Numerical results for a Rich-Quench-Lean combustor with different chemical reaction models and annular combustor are presented in this paper. Results of the RQL combustor show that choice of turbulent combustion model affects behavior of intermediate species and combustion behavior. They indicate that choice of turbulent combustion model is still a key issue in the application of LES for gas-turbine combustor. Results of the annular combustor reveal non-uniform oxygen concentration in the combustion chamber due to ignitor position and so on. They indicate applicability of LES for parameter survey in designing gas-turbine combustors. These results indicate that verification and validation of LES with various turbulent combustion models in various combustion systems are still required to utilize LES in the development of combustors.
For pulverized coal combustion boilers, efficiency improvement, biomass co-firing, and CCS (carbon capture and storage) are required to reduce carbon dioxide emissions. Complex phenomena regarding flow, heat transfer, and chemical reaction are occurred in the furnace of the boilers. Computational fluid and combustion dynamics simulation is necessary to develop an advanced furnace because it is useful for understanding and controlling the complex phenomena. This paper introduces the combustion related phenomena and models used for the simulation (turbulence, gas-solid two-phase flow, moisture drying, devolatilization, char combustion, gas phase combustion, NOx reaction, radiation, ash deposition, and corrosion).
As natural gas is environmentally friendly fuel and can be supplied stably, its utilize as the primary energy has been promoted. In Japan, besides the fuel for the gas fired power plants, natural gas is supplied by pipe lines to factories, buildings and households and used for various purposes. In this report, examples of numerical simulation for gas fired industrial burners and furnaces will be presented.
Ammonia is a carbon-free fuel and one of the candidates of hydrogen carrier. R&D of a gas turbine firing ammonia is not new issue but there are not successful results for a long time. AIST carried out demonstration tests with the aim to show the potential of ammonia-fired power plant. 50kW class turbine system firing kerosene is selected as a base model. A standard combustor is replaced by a prototype combustor which enables a bi-fuel supply of kerosene and fuel gas. The gas turbine started firing kerosene and increased its electric power output. After achievement of stable power output, ammonia gas was started to be supplied and its flow rate increased gradually. Over 40kW power output was achieved by firing ammonia gas only and over 40kW power output was also achieved by co-firing methane and ammonia. Ammonia gas supply increases NOx in the exhaust gas dramatically. However NOx removal equipment can reduce NOx successfully. The emission of NO and unburnt ammonia depends on the combustor inlet temperature.
In this study a series of steam gasification experiments were performed on three thermoplastics - Acrylonitrile butadiene styrene (ABS), Polycarbonate (PC) and Polyethylene (PE), in a batch reactor. The effects of steam flow rate and reactor temperature (600～1000℃.) on the amount of tar, soot and char have been studied. The results were then compared with those of Pyrolysis, from our previous study. In addition time of flight mass spectrometry (TOF-MS) analysis was performed to identify the fingerprints of several different tars. It was found out that steam addition has varying effects on each of the studied polymers. It had a positive effect on soot reduction in the case of ABS and PE; tar reduction in PE; and some char reduction in PC. Temperature increase was found to decrease the relative amount of tar while increasing char production. According to the TOF-MS data, the average molecular weight of tar increases with temperature increase.