蓄能型太阳能热泵系统中复合材料蓄热过程研究

设计了一种分季节蓄能型太阳能热泵热水系统,集太阳能集热容器、相变储能容器、热管于一体,利用Fluent软件对蓄能型太阳能集热器开展了数值模拟,使用Solidification/Melting和VOF模型模拟癸酸/62#石蜡复合相变材料蓄热过程,并采用Boussinesq近似法考虑了自然对流的影响. 结果表明,在集热器内只充灌单一相变材料不能满足不同季节蓄能型热泵系统的供热水需求. 由癸酸和62#石蜡组成的复合相变材料在蓄能过程中出现了两个相变温度,分别在32.66 ℃和59.45 ℃,可以满足本系统不同季节的蓄热需求. 蓄热过程中,由于癸酸和62#石蜡本身密度差以及浮升力的影响,真空管纵向截面出现了温度分层现象. 结果可为复合相变储能材料的推广应用提供可靠的理论依据.

Study on Thermal Storage Process of CompositeMaterial in Solar Energy Storage Heat Pump System

In this study,a seasonal energy storage solar heat pump hot water system is designed,which integrates solar energy heat collector,phase-change energy storage container and heat pipe. It uses composite phase change material to store energy,heat pipe to conduct efficient heat transfer,and energy-saving heat supply of heat pump system. The maximum utilization of solar energy is realized by switching working mode in different seasons. The numerical simulation of the solar collector with inserted heat pipe is carried out by Fluent software. Based on Solidfication/Melting and VOF model,the thermal storage process of CA/62# paraffin composite phase change material is simulated. The influence of natural convection is considered by Boussinesq approximation. The results show that the heat supply water demand of energy storage heat pump system in different seasons can not be satisfied by filling a single phase change material in the collector. The composite phase changed material composed of CA and 62# paraffin has two phase change temperatures during the energy storage process,respectively at 32.66 ℃ and 59.45 ℃,which can meet the heat storage requirements of the system in different seasons. In the process of heat storage,due to the density difference between CA and 62#paraffin and the effect of buoyancy,the phenomenon of temperature stratification appears in the longitudinal section of vacuum tube. The results can provide a reliable theoretical basis for the popularization and application of composite phase change energy storage materials.