Study On Ice-making Performance Of Liquid-solid Fluidized Bed Based On LNG Cold Energy

With the aggravation of energy and climate crisis,as a solution to the crisis of energy capacity,supply security and climate change,energy efficiency can become the"first fuel"of all energy transformation.Under the guidance of the goal of"double carbon",China’s LNG consumption has increased rapidly,and its supply and demand have further expanded.The utilization of cold energy in LNG market is an urgent problem for LNG industry.At present,the utilization of LNG cold energy can be mainly used in air separation,power generation,cold chain transportation,seawater desalination,cold energy storage,carbon dioxide capture,etc.For ice making in liquid-solid fluidized bed with LNG cold energy as cold source,its ice production efficiency will be limited by the ability of particles to remove ice crystals.However,the mechanism of removing ice crystals by particles and the influence of particle properties on the ice making performance of fluidized bed are not completely clear.Based on CFD-DEM numerical simulation method,this paper studies the influence of the ratio of particle size to the inner diameter of heat transfer tube on the enhanced heat transfer and ice-making performance of fluidized bed.Considering the interaction between particles and between particles and wall surface,the internal flow field of liquid-solid two-phase flow is simulated and analyzed with rigid pellets with a density of7900kg/m~3 and an equivalent diameter of 3.2mm,and the characteristics of flow field,pressure and velocity distribution,particle movement trajectory and cause are obtained.The results show that with the decrease of the ratio of particle size to diameter,the pressure difference between inlet and outlet increases and the maximum flow rate increases,and the average erosion rate of tube wall first increases and then decreases in a certain range.When the particle size is 3.2mm and the fluid inlet flow rate is 8m/s,the diameter of 45mm can not only increase the removal efficiency of ice crystals by particles,but also enhance the heat exchange capacity of tube wall.Combining these two improvements,the ice-making performance of fixed fluidized bed can be improved.For the whole fluid field,the preparation of inlet tube section and central tube section,In order to further analyze the influencing factors of liquid-solid two-phase flow and collision frequency and collision intensity between particles and the wall,the flow fields with different inlet velocities and different particle diameters were simulated and calculated,and the influence trend of different ratio of particle diameter to pipe diameter on the ice making performance of fluidized bed ice maker was analyzed and fitted according to the results.The results show that the maximum erosion rate of particles on the wall will increase with the increase of fluid inlet velocity.Within a certain particle size range,with the increase of pipe diameter,the average erosion rate of pipeline will increase gradually.Within a certain pipe diameter range,the smaller the ratio of particle size to pipe diameter,the better the ice-making performance of fluidized bed.