多级相变太阳能通风吊顶蓄放热特性研究

STUDY ON HEAT TRANSFER CHARACTERISTICS OF MULTISTAGE PHASE CHANGE MATERIALS VENTILATION CEILING FOR SOLAR HEATING

提出一种基于太阳能热风供暖系统的多级相变通风吊顶新型供暖末端。建立多级相变太阳能通风吊顶传热数值模型,对比研究了单级、两级和三级相变太阳能通风吊顶的蓄放热特性,分析相变材料的长度配比、空气流速对供暖末端蓄放热性能的影响规律。研究结果表明,与采用单一相变材料的通风吊顶相比,多级相变太阳能通风吊顶在蓄放热过程中出口平均温度差异更小。相变蓄热级数为3时,通风吊顶的蓄、放热效率及相变材料利用率改善最大,分别为6.5%、7.9%和25.1%,各级相变材料长度的配比为1∶1∶1时,蓄、放热效率及相变材料利用率最佳,分别为51.0%、88.7%和93.9%。空气流速不宜大于1.6 m/s,在保证供暖效果的前提下可适当减小空气流速。

A new type of multistage phase-change solar ventilation ceiling(MPCSVC)based on solar hot air heating system is investigated in this paper. Numerical model of MPCSVC was established,and the heat charging and discharging characteristics of singlestage,two-stage and three-stage phase change solar ventilation ceiling were compared. The effects of the proportions of phase change material(PCM)and air velocity on the heat storage and release performance were analyzed. The results show that compared with the ventilation ceiling with single PCM,the average outlet temperature difference of that with MPCSVC is smaller in the heat storage and release process. In addition,the heat charging and discharging efficiency and the utilization rate of PCM for the three-stage MPCSVC are improved up to 6.5%,7.9% and 25.1%,respectively. The optimal length ratio of PCM in MPCSVC is 1∶1∶1,and the heat charging and discharing efficiency and the utilization rate of PCM are 51.0%,88.7% and 93.9%,respectively. The air velocity should not be larger than 1.6 m/s,and the air velocity can be appropriately reduced under the premise of ensuring the heating effect.