The Experts below are selected from a list of 5400 Experts worldwide ranked by ideXlab platform
Harald Kruggelemden - One of the best experts on this subject based on the ideXlab platform.
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discrete element analysis of experiments on mixing and bulk transport of wood pellets on a forward acting grate in Discontinuous Operation
Chemical Engineering Science, 2013Co-Authors: Harald Kruggelemden, Rimantas KacianauskasAbstract:Abstract Grate systems are of significant importance in many energy technology applications, where heterogeneous fuel like biomass which is composed of non-spherical particles of varying sizes is processed. Particulate solid mixing and transport on a grate have direct influence on the thermal conversion process. Therefore, a detailed understanding of the mixing and transport of the particulate solid is essential for the further development of biomass and waste incineration plants. The discrete element method (DEM), in which all particles and their interactions are tracked over time, allows obtaining in-depth information on mixing and bulk transport on grate systems and provides an easy way to avoid extensive experimental investigations. Up to now, grate systems have mainly been addressed by the discrete element method for particles of spherical shape. In the current paper simulations with the discrete element method of a scale model of a forward acting grate are performed neglecting particle/gas interaction, heat and mass transfer as well as chemical reactions. The grate is operated Discontinuously with cylindrical shaped wood pellets applied as bed material. Different motion patterns and grate Operational conditions are investigated. The particle motion and the mixing are monitored through image analysis and the discharged particle mass is analyzed. The obtained results indicate a reasonable agreement of simulations and experiments, and show that the discrete element method is capable of predicting mixing and bulk transport on grate systems.
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an experimental investigation of mixing of wood pellets on a forward acting grate in Discontinuous Operation
Powder Technology, 2013Co-Authors: Harald Kruggelemden, S Wirtz, Viktor SchererAbstract:Abstract The knowledge about mixing and the transport efficiency of non-spherical particles on grates is needed for the improvement of design and adaption of Operational parameters in grate combustion systems. To gain insight into details of the transport of non-spherical particles experimental investigations with a scale model of a forward acting grate are performed in Discontinuous Operation using wood pellets as bed material. Wood pellets are an important source of biomass within an energy market increasingly relying on renewable sources. Different motion patterns, grate Operational conditions and pellet types are investigated. A comparison to spherical particles is performed. The wood pellets as well as the spherical particles are dyed in different colors to distinguish between different layers applied vertically and horizontally on the grate. The particle motion and the mixing are monitored by image analysis from the top and the side of the grate through transparent walls. In addition the discharged particle mass is recorded. The particle mass, the stroke length as well as the particle shape and the motion pattern have a strong influence on the mixing. The stroke velocity only has minor effect on mixing and the amount of particles discharged from the grate. The results obtained under well established boundary conditions are suitable for use as reference data in the verification of particle based simulation approaches as, e.g. the discrete element method.
Rimantas Kacianauskas - One of the best experts on this subject based on the ideXlab platform.
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discrete element analysis of experiments on mixing and bulk transport of wood pellets on a forward acting grate in Discontinuous Operation
Chemical Engineering Science, 2013Co-Authors: Harald Kruggelemden, Rimantas KacianauskasAbstract:Abstract Grate systems are of significant importance in many energy technology applications, where heterogeneous fuel like biomass which is composed of non-spherical particles of varying sizes is processed. Particulate solid mixing and transport on a grate have direct influence on the thermal conversion process. Therefore, a detailed understanding of the mixing and transport of the particulate solid is essential for the further development of biomass and waste incineration plants. The discrete element method (DEM), in which all particles and their interactions are tracked over time, allows obtaining in-depth information on mixing and bulk transport on grate systems and provides an easy way to avoid extensive experimental investigations. Up to now, grate systems have mainly been addressed by the discrete element method for particles of spherical shape. In the current paper simulations with the discrete element method of a scale model of a forward acting grate are performed neglecting particle/gas interaction, heat and mass transfer as well as chemical reactions. The grate is operated Discontinuously with cylindrical shaped wood pellets applied as bed material. Different motion patterns and grate Operational conditions are investigated. The particle motion and the mixing are monitored through image analysis and the discharged particle mass is analyzed. The obtained results indicate a reasonable agreement of simulations and experiments, and show that the discrete element method is capable of predicting mixing and bulk transport on grate systems.
Viktor Scherer - One of the best experts on this subject based on the ideXlab platform.
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an experimental investigation of mixing of wood pellets on a forward acting grate in Discontinuous Operation
Powder Technology, 2013Co-Authors: Harald Kruggelemden, S Wirtz, Viktor SchererAbstract:Abstract The knowledge about mixing and the transport efficiency of non-spherical particles on grates is needed for the improvement of design and adaption of Operational parameters in grate combustion systems. To gain insight into details of the transport of non-spherical particles experimental investigations with a scale model of a forward acting grate are performed in Discontinuous Operation using wood pellets as bed material. Wood pellets are an important source of biomass within an energy market increasingly relying on renewable sources. Different motion patterns, grate Operational conditions and pellet types are investigated. A comparison to spherical particles is performed. The wood pellets as well as the spherical particles are dyed in different colors to distinguish between different layers applied vertically and horizontally on the grate. The particle motion and the mixing are monitored by image analysis from the top and the side of the grate through transparent walls. In addition the discharged particle mass is recorded. The particle mass, the stroke length as well as the particle shape and the motion pattern have a strong influence on the mixing. The stroke velocity only has minor effect on mixing and the amount of particles discharged from the grate. The results obtained under well established boundary conditions are suitable for use as reference data in the verification of particle based simulation approaches as, e.g. the discrete element method.
Zhaohong Fang - One of the best experts on this subject based on the ideXlab platform.
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numerical analysis and experimental validation of heat transfer in ground heat exchangers in alternative Operation modes
Energy and Buildings, 2008Co-Authors: Ping Cui, Hongxing Yang, Zhaohong FangAbstract:A finite element numerical model has been developed for the simulation of the ground heat exchangers (GHEs) in alternative Operation modes over a short time period for ground-coupled heat pump applications. Comparisons between the numerical and analytical results show that the finite line-source model is not capable of modeling the GHEs within a few hours because of the line-source assumption. On the other hand, the experiments with respect to the alternative cooling and heating modes have been undertaken during a short-time period. The comparisons show a reasonable agreement between the numerical and the measured data. The results illustrate that the finite element numerical model can be used to simulate the heat transfer behavior of the GHEs in short time scales instead of the typical finite line-source model. Finally, the variation of the U-tube pipe wall temperatures demonstrates that the Discontinuous Operation mode and the alternative cooling/heating modes can effectively alleviate the heat buildup in the surrounding soil.
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Discontinuous Operation of geothermal heat exchangers
Tsinghua Science & Technology, 2002Co-Authors: Zhaohong Fang, Nairen Diao, Ping CuiAbstract:Ground source heat pump (GSHP) systems for HVAC have aroused more and more interest in China in recent years because of their higher energy efficiency compared with conventional systems. The design and performance simulation of the geothermal heat exchangers is vital to the success of this technology. In GSHP systems, the load of the geothermal heat exchanger varies greatly and is usually Discontinuous even during a heating or cooling season. This paper outlines a heat transfer model for geothermal heat exchangers. The model was used to study the influence of the Discontinuous Operation of the heat pumps on the performance of the geothermal heat exchangers. A simple and practical approach is presented for sizing the geothermal heat exchangers.
Ping Cui - One of the best experts on this subject based on the ideXlab platform.
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numerical analysis and experimental validation of heat transfer in ground heat exchangers in alternative Operation modes
Energy and Buildings, 2008Co-Authors: Ping Cui, Hongxing Yang, Zhaohong FangAbstract:A finite element numerical model has been developed for the simulation of the ground heat exchangers (GHEs) in alternative Operation modes over a short time period for ground-coupled heat pump applications. Comparisons between the numerical and analytical results show that the finite line-source model is not capable of modeling the GHEs within a few hours because of the line-source assumption. On the other hand, the experiments with respect to the alternative cooling and heating modes have been undertaken during a short-time period. The comparisons show a reasonable agreement between the numerical and the measured data. The results illustrate that the finite element numerical model can be used to simulate the heat transfer behavior of the GHEs in short time scales instead of the typical finite line-source model. Finally, the variation of the U-tube pipe wall temperatures demonstrates that the Discontinuous Operation mode and the alternative cooling/heating modes can effectively alleviate the heat buildup in the surrounding soil.
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Discontinuous Operation of geothermal heat exchangers
Tsinghua Science & Technology, 2002Co-Authors: Zhaohong Fang, Nairen Diao, Ping CuiAbstract:Ground source heat pump (GSHP) systems for HVAC have aroused more and more interest in China in recent years because of their higher energy efficiency compared with conventional systems. The design and performance simulation of the geothermal heat exchangers is vital to the success of this technology. In GSHP systems, the load of the geothermal heat exchanger varies greatly and is usually Discontinuous even during a heating or cooling season. This paper outlines a heat transfer model for geothermal heat exchangers. The model was used to study the influence of the Discontinuous Operation of the heat pumps on the performance of the geothermal heat exchangers. A simple and practical approach is presented for sizing the geothermal heat exchangers.