用于太阳能超临界CO_(2)布雷顿循环的流态化颗粒换热试验与模拟

EXPERIMENT AND SIMULATION OF FLUIDIZING-PARTICLE HEAT EXCHANGER FOR SUPERCRITICAL CO_(2) BRAYTON CYCLE OF CSP

搭建30 kW浅层多级流态化颗粒换热试验台,在约1.5倍临界流化速度、换热器采用直管管束逆流形式布置时颗粒侧换热系数可达590~860 W/(m^(2)·K)。采用双欧拉流体模型对流化床内水平埋管管束换热进行数值模拟,模拟结果与试验结果偏差在10%以内。利用析因设计与线性回归模型研究颗粒粒径、颗粒导热系数和流化气体速度对流态化换热效果的影响。发现颗粒粒径是换热系数的主要影响因素,流化气体速度是次要因素。对于100 MW级太阳能超临界CO_(2)布雷顿循环系统,流态化颗粒换热温度范围为650~900℃,换热器热效率约为98.7%,效率约为80.6%,效能约为61.9%,满足设计要求。

A lab-scale 30 kW particle heat exchanger of fluidized bed was designed and tested,with straight tube bundles for countercurrent-flow heat exchange.The heat transfer coefficient of particle side reached 590-860 W/(m^(2)·K)at a fluidization speed of1.5 times of the critical.Euler-Euler Two-Fluid Model was adopted to simulate heat transfer characteristics between fluidizing particles and immersed horizontal tubes.The deviation was within 10%between simulation and experimental results.Factorial design and linear regression model were used to study the effects of particle size,particle thermal conductivity and fluidizing gas velocity on heat transfer It was found that the particle size was a main factor while the fluidization speed was a minor.As to a 100 MW supercritical CO_(2)Brayton system of CSP,the temperature range of heat exchanger was 650-900℃,and the thermal efficiency was about 98.7%,exergy efficiency was about 80.6%,effectiveness was about 61.9%.