A numerical study of bed expansion in supercritical water fluidized bed with a non-spherical particle drag model

Technological innovations on direct carbon mitigation by ordered energy conversion and full resource utilization

Coal consumption leads to over 15 billion tons of global CO₂ emissions annually, which will continue at a considerable intensity in the foreseeable future. To remove the huge amount of CO₂, a practically feasible way of direct carbon mitigation, instead of capturing that from dilute tail gases, should be developed; as intended, we developed two innovative supporting technologies, of which the status, strengths, applications, and perspective are discussed in this paper. One is supercritical water gasification-based coal/biomass utilization technology, which orderly converts chemical energy of coal and low-grade heat into hydrogen energy, and can achieve poly-generation of steam, heat, hydrogen, power, pure CO₂, and minerals. The other one is the renewables-powered CO₂ reduction techniques, which uses CO₂ as the resource for carbon-based fuel production. When combining the above two technical loops, one can achieve a full resource utilization and zero CO₂ emission, making it a practically feasible way for China and global countries to achieve carbon neutrality while creating substantial domestic benefits of economic growth, competitiveness, well-beings, and new industries.

Revisiting the Homogenized Lattice Boltzmann Method with Applications on Particulate Flows

The simulation of surface resolved particles is a valuable tool to gain more insights in the behaviour of particulate flows in engineering processes. In this work the homogenized lattice Boltzmann method as one approach for such direct numerical simulations is revisited and validated for different scenarios. Those include a 3D case of a settling sphere for various Reynolds numbers. On the basis of this dynamic case, different algorithms for the calculation of the momentum exchange between fluid and particle are evaluated along with different forcing schemes. The result is an updated version of the method, which is in good agreement with the benchmark values based on simulations and experiments. The method is then applied for the investigation of the tubular pinch effect discovered by Segré and Silberberg and the simulation of hindered settling. For the latter, the computational domain is equipped with periodic boundaries for both fluid and particles. The results are compared to the model by Richardson and Zaki and are found to be in good agreement. As no explicit contact treatment is applied, this leads to the assumption of sufficient momentum transfer between particles via the surrounding fluid. The implementations are based on the open-source C++ lattice Boltzmann library OpenLB.

Experimental study and transient CFD/DEM simulation in a fluidized bed based on different drag models

Under the architecture of CFD/DEM, Gidaspow drag model gives the better prediction of the inner flow in the dense gas–solid fluidized bed.