壳管式相变储能换热器性能研究与场协同效应分析

PERFORMANCE STUDY AND FIELD SYNERGY ANALYSIS OF SHELL AND TUBE PHASE CHANGE ENERGY STORAGE HEAT EXCHANGER

建立壳管式相变储能换热器仿真模型,利用Fluent软件对蓄能、释能工况分别进行模拟。从温度场、速度场、固液交界面3个方面分析逐时换热强度的变化原因;探讨在蓄热过程中热源管壁温、热管口径规格对传热效率的影响。研究结果表明:蓄热工况下管间热扰及自然对流作用明显,10000 s时液相分数达到95%。放热工况以导热为主,60000 s时相变材料仅凝固了75%。从场协同效应分析,采用小尺寸热源管能缩短时间,但单位面积换热强度有明显下降。换热温差≤20℃时,其强化效果开始衰弱。

A simulation model of shell and tube phase change energy storage heat exchanger was established in this paper,and the heat transfer characters of the studied heat exchanger was analyzed under the energy storage and energy release conditions by Fluent software. The change reasons of hourly heat exchange intensity were analyzed based on the three aspects of temperature field,velocity field and solid-liquid interface. The influence of heat source tube wall temperature and caliber of heat pipe on heat transfer efficiency was discussed. The results show that the effects of thermal agitation and natural convection on the studied heat exchanger performance are obvious under the heat storage condition,and the liquid fraction reaches 95% at 10000 s. The heat conduction is dominated under the heat release condition,and there is only 75%of the phase change material solidified at 60000 s. Based on the analysis of the field synergy theory,the heat transfer time is shorter when the pipe diameter reduces,however,the heat transfer rate in per unit area is decreased significantly. It is indicated that the heat transfer efficiency begins to decline when the heat transfer temperature difference is less than 20 ℃.