Investigation on Mechanical Properties and Temperature Control Efficiency of Novel Load-Bearing and Heat-Storing Metastructure Walls in Hot Summer-Cold Winter Regions
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摘要: 相变蓄热墙体能够有效降低室外温度波动对内墙面温度的干扰,提升室内热环境的稳定性并降低建筑能耗. 由于冬夏季气象条件的差异,相变材料(phase change material,PCM)熔点的选择成为影响墙体热工性能的重要因素. 为了实现蓄热墙体冬夏两季的高效利用,该研究构建了新型承载蓄热超结构墙体数值模型,对墙体力学性能进行检验,并模拟了冬季典型日和夏季典型日空气对流换热下墙体传热特性. 结果表明,新型承载蓄热超结构墙体的力学性能满足工程应用需求,同时相较普通墙体具有良好的传热特性. 其中,熔点为20 ℃的墙体在冬季热工性能最好,峰值相变率达到0.30,且内壁面最大温度波动为5.8 ℃,在夏季工况中,熔点为30 ℃的墙体具有较高的相变利用率为0.48,熔点为24 ℃的墙体内壁面温度波动最小. 最后,综合考虑相变利用率和衰减倍数,获得了夏热冬冷地区最佳相变墙体熔点为24 ℃.Abstract: A phase change material (PCM) heat-storing wall can effectively mitigate the impact of outdoor temperature fluctuations on internal wall surface temperatures, enhance the stability of the indoor thermal environment, and reduce building energy consumption. The selection of the PCM melting point is crucial due to the differing weather conditions in the winter and the summer. To optimize the performances of heat-storing walls for both seasons in hot summer-cold winter regions, a numerical model for a novel load-bearing and heat-storing metastructure wall incorporating multi-melting point PCMs was developed. This model was used to evaluate the mechanical properties and simulate the heat transfer characteristics of the wall under air convection heat transfer conditions on representative winter and summer days. The results demonstrate that, the mechanical properties of the phase change thermal storing wall meet the engineering application requirements, and its heat transfer characteristics surpass those of ordinary walls. Specifically, the wall with a PCM melting point of 20 ℃ exhibits superior thermal performance in the winter, with a peak phase transformation rate of 0.30 ℃ and a maximum inner wall temperature fluctuation of 5.8 ℃. In the summer, the wall with a PCM melting point of 30 ℃ shows a higher phase transformation utilization rate of 0.48, while the wall with a melting point of 24 ℃ experiences the lowest temperature fluctuation. Therefore, with both the utilization ratio and the attenuation ratio considered, the optimal melting point for a phase change wall would be 24 ℃.
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Key words:
- load-bearing and heat-storing wall /
- phase change material /
- mechanical property /
- temperature control efficiency /
- numerical simulation
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表 1 墙体材料和新型相变材料的物理性质
Table 1. Physical properties of wall materials and novel phase change materials
parameter ρ/(kg·m-3) cp/(J·kg-1·K-1) λ/(W·m-1·K-1) L/(kJ·kg-1) ordinary wall 2 400 800 2.10 - PCM wall 1 680(S)/1 600(L) 2 000 0.54(S)/0.48(L) 180 表 2 不同熔点的蓄热墙体模型
Table 2. The heat storing wall models with different melting points
case case 1 case 2 case 3 case 4 case 5 case 6 Tm/℃ 20 22 24 26 28 30 表 3 网格无关性与步长独立性验证
Table 3. Grid and time step independence verifications
grid number time step Δt/s TA, 21 600/℃ TA, 43 200/℃ TA, 21 600/℃ 40 608 1 22.98 14.96 9.76 26 488 1 22.93 14.99 9.77 18 574 1 22.23 15.13 9.89 26 488 0.5 22.90 14.98 9.75 26 488 1.5 22.81 14.85 9.70 -
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