具有Na2CO3·10H2O相变材料的太阳能混合墙体的烟囱效应

CHIMNEY EFFECT OF SOLAR HYBRID-DOUBLE WALL WITH PCM OF NA_2CO_3·10H_2O

通过利用配有调压器的电热设备模拟太阳光源,对附有1 cm厚的Na2CO3·10H2O相变材料的太阳能混合墙体烟囱效应进行实验研究,讨论并分析在Na2CO3·10H2O蓄热效应作用下,光照强度对蓄热层两侧温度场、烟囱通道内温度场、速度场分布情况的影响及其对烟囱所诱导的自然通风量和空气得热量的影响。实验结果表明,蓄热层的平均温度随时间一直升高,但两侧的温差随时间的增加不断减小,随电压的升高而不断增大;通道内空气温度、平均风速以及自然通风量均在加热开始后大约1 h内升高到某一值继而趋于稳定,且电压越大,其值越大;通道内空气得热量增量在加热开始的1 h内先急剧上升后急剧下降,最终稳定在零附近,且电压越大,得热量增量的峰值越大。蓄热层的作用使整个系统处于相对较低的温度,并且烟囱排风温度下降,空气得热量减少,有利于节能,蓄积的热量可作为没有光照时烟囱效应的动力。

The experiment of chimney effect of solar hybrid-double wall with a thickness of 1 cm of Na2CO3·10H2O was carried out by the simulated solar energy resulted from the adaptable voltage heater. The effect of the light density on the temperature distribution of the both side of PCM, air gap and on the velocity distribution of the air gap were discussed and analyzed. The nature ventilation air volume induced by the chimney effect and the heat gained by the air were also discussed. The results showed that the average temperature of PCM increases continually, while the difference between the sides of PCM decreases. Both of the average and difference temperature increase with the increasing of the voltage. The value of the air temperature, the air velocity and the mass volume in the air gap will be kept constantly after one hour, which increases with increasing of the voltage. As for the addition of the heat gained by air in the gap, it will increase quickly to reach the maximum value before the first hour and then decreases to zero. The maximum addition of the heat gained by the air will also increase with increasing of the light voltage. The application of PCM （Na2CO3·10H2O） will reduce the temperature of outlet air resulting in a lower heat gained by the air, which is important for energy saving in nature ventilation. And the heat stored by PCM can be used to produce the chimney effect at night when there is no solar energy.