腔式太阳能吸热器热性能的模拟计算

PERFORMANCE SIMULATION OF SOLAR CAVITY RECEIVER

腔式吸热器是塔式太阳能热发电系统中非常关键的一个部件,它的性能直接关系到整个发电系统的效率,因此对吸热器内的太阳能热流密度及吸热器的效率进行计算在吸热器设计中便显得尤为重要。本文提出了一种综合计算的方法来解决这个问题:首先利用蒙特卡罗(Monte Carlo)方法来模拟吸热器内太阳光束的行为,得到吸热器内的太阳能热流密度分布;然后利用流动换热的相应公式计算出吸热器内吸热管道的壁温;接着再对吸热器内空气的流场进行计算得到吸热器管道的热损失.利用这种综合计算的方法可以估算出太阳能在吸热器表面的热流密度分布以及吸热器的效率,为吸热器设计提供一定的理论指导。

One of the most important components of solar thermal power system is the receiver, which performance is in direct relation to the efficiency of the whole power generation system. The calculation of internal surface heat flux and thermal efficiency of the receiver therefore plays a very important role in receiver design. A calculation method of the cavity receiver is put forward. The first step of this method is using the Monte Carlo method to simulate the track of solar beam and compute surface heat flux inside the receiver. The second one is employing the correlations of flow boiling heat transfer to figure out the wall temperature of boiling tubes laid inside the receiver and the convective heat transfer coefficient in the tubes. The last one is simulating the air flow field inside the receiver to calculate convective thermal loss of the receiver. As every step can not be independently calculated, all steps are coupled and an iterative scheme is needed as well. Internal surface heat flux and thermal efficiency of the receiver can be finally gained with this method, and the result of calculation can provide theoretical guide for receiver design.