太阳能固体颗粒吸热器数值模拟研究

Numerical simulation on solid particle solar receiver

太阳能固体颗粒吸热器是一种利用自由下落的固体颗粒来吸收聚焦太阳辐射的吸热器。考虑了颗粒相与流场之间的相互作用以及颗粒相对辐射场的影响,基于离散相模型和DO辐射换热模型,对固体颗粒吸热器中幕状物的形态以及吸热性能进行了数值模拟,讨论了辐射强度、颗粒直径、颗粒质量流率、颗粒吸收率和颗粒初温对固体颗粒吸收器的流场和热性能的影响规律。模拟结果表明:颗粒质量流量和颗粒粒径对吸热器效率的影响明显;入射辐射强度从500 kW/m^2增加到1 500 kW/m^2时,颗粒出口温度提高,吸热器效率从46.51%逐步增加到49.74%;颗粒粒径从1 297μm减小到500μm时,吸热器效率由35.5%增加到52.1%;颗粒质量流量从1.2 kg/s增加到6.7 kg/s时,颗粒出口温度降低,吸热器效率从23.8%增加到57.6%;颗粒初温由300 K升高到900 K时,颗粒温升降低,吸热器的效率从42.2%下降到37.9%。

The solid particle solar receiver is a direct absorption receiver in which solar energy heats a curtain of falling particle to a high temperature.The hydrodynamics and the performance of the solid particle solar receiver are investigated numerically.The momentum and energy exchange between the solid particle phase and fluid phase and the influence of particle phase on the radiation transfer are taken into account.The effects of the incident radiation intensity,particle diameter,particle mass flow rate,particle absorptivity and particle inlet temperature on the performance of the solid particle solar receiver are discussed.The hydrodynamics of the particle curtain predicted is in good agreement with experimental data.The results show that the effect of the particle mass flow rate and particle diameter is more important than other parameters.The efficiency increases from46.51%to49.74%with the increment of the incident radiation intensity.As the particle diameter decreases from1297μm to500μm,the particle exiting temperature increases,and the thermal efficiency increases from35.5%to52.1%.As the particle mass flow rate increases from1.2kg/s to6.7kg/s,the particle exiting temperature decreases and the thermal efficiency increases from23.8%to57.6%.As the particle inlet temperature increases from300K to900K,the particle temperature increment reduces and the efficiency of the receiver decreases from42.2%to379%.