Modelling of Combustion, NOx Emissions and Radiation of a Natural Gas Fired Glass Furnace

Paper presented at AFRC 2014 Industrial Combustion SymposiumThis work performs numerical simulations of a natural gas fired glass furnace. The purpose of this work is to provide useful insights in the design of glass furnaces and the appropriate modelling strategy for such types of simulations. The results are compared to the available experimental data and the importance of the recirculating region for the effective heat transfer at the glass wall is highlighted. The formation of NOx is a crucial parameter in the design of glass furnaces. Therefore, additional calculations for NOx are performed. The simulations, which are in agreement with the available experimental data, indicate the approximate intensity and location of NOx formation. Finally, the importance of radiation effects is highlighted by performing a simulation without radiation. The results indicating that radiation is an important physical phenomenon in glass furnaces and certainly cannot be ignored

Dissipation and inter-scale transfer in fully coupled particle and fluid motions in homogeneous isotropic forced turbulence

This work examines in detail the coupling mechanism between a stationary, homogeneous and isotropic turbulent (HIT) flow and particles, including the effect of particle-particle collisions. In order to illustrate how the physics can be elucidated of four-way interactions, a series of coupled Direct Numerical Simulations (DNS) of forced HIT are performed on a 1283 periodic box at two Taylor Reynolds numbers, 35.4 and 58.0, with interacting particles of different global Stokes numbers and volume fractions. The results show that fluid dissipation decreases up to 32% with increasing global Stokes numbers and particle volume fractions. Moreover, the corresponding dissipation when ignoring particle-particle collisions is over-estimated by up to 7% compared to the fully coupled simulations. A spectral analysis of the coupling mechanism reveals that the particles transfer energy from the large to the small scales, thereby explaining the difference in dissipation. Finally, a model spectrum for the coupling between the turbulent fluid and the particles is proposed

Modelling of gas–solid turbulent channel flow with non-spherical particles with large Stokes numbers

AbstractThis paper describes a complete framework to predict the behaviour of interacting non-spherical particles with large Stokes numbers in a turbulent flow. A summary of the rigid body dynamics of particles and particle collisions is presented in the framework of Quaternions. A particle-rough wall interaction model to describe the collisions between non-spherical particles and a rough wall is put forward as well. The framework is coupled with a DNS-LES approach to simulate the behaviour of horizontal turbulent channel flow with 5 differently shaped particles: a sphere, two types of ellipsoids, a disc, and a fibre. The drag and lift forces and the torque on the particles are computed from correlations which are derived using true DNS.The simulation results show that non-spherical particles tend to locally maximise the drag force, by aligning their longest axis perpendicular to the local flow direction. This phenomenon is further explained by performing resolved direct numerical simulations of an ellipsoid in a flow. These simulations show that the high pressure region on the acute sides of a non-spherical particle result in a torque if an axis of the non-spherical particle is not aligned with the flow. This torque is only zero if the axis of the particle is perpendicular to the local direction of the flow. Moreover, the particle is most stable when the longest axis is aligned perpendicular to the flow.The alignment of the longest axis of a non-spherical particle perpendicular to the local flow leads to non-spherical particles having a larger average velocity compared to spherical particles with the same equivalent diameter. It is also shown that disc-shaped particles flow in a more steady trajectory compared to elongated particles, such as elongated ellipsoids and fibres. This is related to the magnitude of the pressure gradient on the acute side of the non-spherical particles. Finally, it is shown that the effect of wall roughness affects non-spherical particles differently than spherical particles. Particularly, a collision of a non-spherical particle with a rough wall induces a significant amount of rotational energy, whereas a corresponding collision with a spherical particle results in mostly a change in translational motion

Modelling of gas–solid turbulent channel flow with non-spherical particles with large Stokes numbers

AbstractThis paper describes a complete framework to predict the behaviour of interacting non-spherical particles with large Stokes numbers in a turbulent flow. A summary of the rigid body dynamics of particles and particle collisions is presented in the framework of Quaternions. A particle-rough wall interaction model to describe the collisions between non-spherical particles and a rough wall is put forward as well. The framework is coupled with a DNS-LES approach to simulate the behaviour of horizontal turbulent channel flow with 5 differently shaped particles: a sphere, two types of ellipsoids, a disc, and a fibre. The drag and lift forces and the torque on the particles are computed from correlations which are derived using true DNS.The simulation results show that non-spherical particles tend to locally maximise the drag force, by aligning their longest axis perpendicular to the local flow direction. This phenomenon is further explained by performing resolved direct numerical simulations of an ellipsoid in a flow. These simulations show that the high pressure region on the acute sides of a non-spherical particle result in a torque if an axis of the non-spherical particle is not aligned with the flow. This torque is only zero if the axis of the particle is perpendicular to the local direction of the flow. Moreover, the particle is most stable when the longest axis is aligned perpendicular to the flow.The alignment of the longest axis of a non-spherical particle perpendicular to the local flow leads to non-spherical particles having a larger average velocity compared to spherical particles with the same equivalent diameter. It is also shown that disc-shaped particles flow in a more steady trajectory compared to elongated particles, such as elongated ellipsoids and fibres. This is related to the magnitude of the pressure gradient on the acute side of the non-spherical particles. Finally, it is shown that the effect of wall roughness affects non-spherical particles differently than spherical particles. Particularly, a collision of a non-spherical particle with a rough wall induces a significant amount of rotational energy, whereas a corresponding collision with a spherical particle results in mostly a change in translational motion

The Effect of Hydrogen Addition on the Pollutant Emissions of a Marine Internal Combustion Engine Genset

Hydrogen, as a maritime fuel, is one of the solutions that will assist the shipping sector in addressing the challenges regarding decarbonization, taking into consideration the targets set for 2030 and 2050. The extensive utilization of hydrogen requires massive production of green hydrogen and the development of proper infrastructure to support a sustainable supply chain. An alternative solution is based on the on-board production of hydrogen, where production units are installed on-board the vessel. Along these lines, the HYMAR project aims to test the utilization of a hydrogen production unit for on-board use. The article deals with the use of hydrogen as a fuel for internal combustion engines, taking into consideration reports from literature and the preliminary results of the HYMAR project, focusing on the environmental impact and the reduction in emissions. Experimental investigation on a marine auxiliary engine for power generation, under the HYMAR project, leads to promising results regarding the environmental footprint of the internal combustion engine when hydrogen is added in the fuel mix with increasing percentages

Early Spatial Memory Impairment in a Double Transgenic Model of Alzheimer’s Disease TgF-344 AD

Before the course of Alzheimer’s disease fully manifests itself and largely impairs a patient’s cognitive abilities, its progression has already lasted for a considerable time without being noticed. In this project, we mapped the development of spatial orientation impairment in an active place avoidance task—a highly sensitive test for mild hippocampal damage. We tested vision, anxiety and spatial orientation performance at four age levels of 4, 6, 9, and 12 months across male and female TgF-344 AD rats carrying human genes for presenilin-1 and amyloid precursor protein. We found a progressive deterioration of spatial navigation in transgenic animals, beginning already at the age of 4 months, that fully developed at 6 months of age across both male and female groups, compared to their age-matched controls. In addition, we described the gradual vision impairment that was accentuated in females at the age of 12 months. These results indicate a rather early onset of cognitive impairment in the TgF-344 AD Alzheimer’s disease model, starting earlier than shown to date, and preceding the reported development of amyloid plaques