铺设保温材料是降低渠道冻胀的重要措施之一。然而,保温材料在服役过程中会产生吸湿作用,将导致其保温性能降低。为探究吸湿对保温材料导热系数的影响,基于均匀化方法和最小热阻力原理,建立了考虑含水率影响的导热系数预测模型,并讨论孔隙率和含水率对导热系数的影响,最后对模型进行验证。结果表明:增大孔隙率将引起热阻增大、导热系数降低,但水分能够发挥热桥作用从而增大导热系数。该模型预测值与实测值的误差<5％,验证了用此方法计算保温材料的导热系数是可行的。研究成果证实水分是降低保温性能的重要因素,并提出了改善聚氨酯保温材料憎水性的建议措施。
Abstract
Laying insulation materials is an effective measure to mitigate the freezing damage to channels. However, the absorption of moisture by insulation materials can lead to a deterioration in their thermal insulation performance. To investigate the impact of moisture content on thermal conductivity of insulation materials, a model predicting thermal conductivity taking moisture content into account was established using the homogenization method based on the minimum thermal resistance law. Furthermore, the influence of porosity and moisture content on thermal conductivity was examined. The proposed model was then validated against experimental results and an existing model. The findings reveal that thermal conductivity decreases with the increase of porosity, but increases with the increase of moisture content. The error between the predicted and measured results is less than 5%, thereby confirming the feasibility of the proposed model in calculating the thermal conductivity of insulation materials. Additionally, moisture is identified as a significant factor in diminishing the thermal insulation performance of polyurethane rigid foam. Consequently, enhancing the hydrophobic properties of insulation materials holds great practical significance in improving its thermal insulation performance. Several suggestions are put forward to enhance the hydrophobicity of polyurethane insulation materials.
关键词
渠道 /
保温材料 /
导热系数 /
聚氨酯 /
预测模型
Key words
canal /
insulation material /
thermal conductivity /
polyurethane /
prediction model
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基金
国家自然科学基金项目(41701060);青海省科技计划项目(2023-SF-125)
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