共查询到20条相似文献,搜索用时 281 毫秒
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介绍了作为预制直埋保温管保温层的聚氨酯泡沫塑料的特性。通过恒温失重率测试,结合预制直埋保温管实际运行情况,探讨了预制直埋保温管合理的运行温度。预制直埋保温管连续运行温度应控制在120℃以下,尖峰温度不宜超过140℃。 相似文献
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针对传统的供热管道在地沟敷设方法中存在的弊病,提出了聚氨酯直埋式保温管的敷设方式,并就施工过程中遇到的热伸长问题提出了有效的解决措施及减小管道热伸长的办法,介绍了管道敷设施工中的具体要求,通过工程实践,显示出了聚氨酯直埋式保温管敷设方式的优越性。 相似文献
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本文探讨了不同敷设方式下聚氨酯预制直埋保温管中保温层的受力问题,明确直埋保温管中保温层的力学性能参数与直埋设计相关参数的影响关系,提出计算保温层受力的方法,提出控制保温受力的设计要点。 相似文献
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介绍了直埋管的特点及施工工艺,对直埋聚氨酯保温管与砖砌暖沟敷设进行了经济比较,对其导热系数、热损失与其它保温材料及保温管道进行了比较,得出了在达到同样保温效果的前提下,使用聚氨酯保温直埋管有较多优越性的结论。 相似文献
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归纳了直埋式预制保温管较之传统的各类保温管材具有的优点,介绍了预制直埋保温管的生产工艺、技术指标、安全流程及验收标准,以完善预制直埋保温管生产工艺,确保该保温管的质量。 相似文献
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国产直埋敷设预制保温管保温层厚度的优化分析哈尔滨建筑工程学院贺平,何立群,孙刚沈阳市热力工程设计研究院刘同跃前言在城市集中供热系统的热水网路上,直埋敷设预制保温管的应用日益广泛。目前国内已有许多厂家生产以高密度聚乙烯为保护壳,以聚氨酯作为保温材料的预... 相似文献
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混凝土热传导与热应力的细观特性及热开裂过程研究 总被引:2,自引:0,他引:2
通过对混凝土热传导与热应力细观特性的分析,探讨细观非均匀性对混凝土热学和力学性能的影响作用。计算结果表明:细观非均匀特性对混凝土导热性能的影响并不明显,但对其力学性能的影响作用却不能忽视;骨料颗粒对混凝土的热学和力学性能都有显著的影响作用。温度梯度和热膨胀不匹配共同作用所产生的温度应力极容易导致混凝土开裂,其中温度梯度引起的混凝土开裂过程与热传导系数密切相关。通过对厚壁筒混凝土试样在孔内温度升高情况下裂纹萌生和扩展过程的数值模拟研究,从机理上揭示试验观测的四个裂纹发展阶段。研究结果表明裂缝扩展的局部化效应是主裂纹形成的根本原因。 相似文献
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绝热材料低温导热系数的测试 总被引:2,自引:1,他引:1
采用防护热平板法进行绝热材料低温导热系数测试,测试实践解决了4个关键试验条件:测试堆的制冷、冷却水套及其管路中残留水的清除、冷凝水的去除和隔热、外防护套的配置。通过对国家标准参比低温导热系数的测试,结果表明:采用防护热平板法测试结果得出的导热系数方程与《绝热材料导热系数参比板》国家标准样品证书提供的导热系数方程吻合得很好,并认为将此方程外推至-60-0℃的数据可以作为校准导热仪的参考值。 相似文献
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通过测试装置测定出测试孔输入功率、环路平均温度,采用线热源模型对现场测试数据进行推导分析,计算出测试孔岩土导热系数,该数值对在当地以及周边地区进行土壤源热泵系统设计具有重要的参考价值。 相似文献
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Effective thermal conductivity of soils can be enhanced to achieve higher efficiencies in the operation of shallow geothermal systems.Soil cementation is a ground improvement technique that can increase the interparticle contact area,leading to a high effective thermal conductivity.However,cementation may occur at different locations in the soil matrix,i.e.interparticle contacts,evenly or unevenly around particles,in the pore space or a combination of these.The topology of cementation at the particle scale and its influence on soil response have not been studied in detail to date.Additionally,soils are made of particles with different shapes,but the impact of particle shape on the cementation and the resulting change of effective thermal conductivity require further research.In this work,three kinds of sands with different particle shapes were selected and cementation was formed either evenly around the particles,or along the direction parallel or perpendicular to that of heat transfer.The effective thermal conductivity of each sample was computed using a thermal conductance network model.Results show that dry sand with more irregular particle shape and cemented along the heat transfer direction will lead to a more efficient thermal enhancement of the soil,i.e.a comparatively higher soil effective thermal conductivity. 相似文献
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Three human test series were conducted to evaluate the uniformity of the thermal environments in a stratum‐ventilated chamber with dimensions of 8.8 m (L) × 5.1 m (W) × 2.4 m (H). In all, nineteen conditions were generated by adjusting the room temperature, supply airflow rate, and supply terminal type. An air diffuser performance index (ADPI) of at least 80% was achieved for most cases. This result shows that the air velocity and temperature in the occupied zone are reasonably uniform. Subjective assessments using the ASHRAE 7‐point scale indicate that the thermal sensations of the subjects in stratum ventilation are also uniform. This study examines the applicability of the predicted mean vote (PMV) model for evaluating stratum ventilation. When compared to the actual mean thermal sensation votes (ATS), the PMV values are acceptable. The PMV results at a height of 1.1 m above the floor show better agreement with the ATS than at a height of 0.1 m. 相似文献
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《Energy and Buildings》2001,33(2):141-150
The real-time predictive dynamic operation of building thermal systems is explored in this paper. A systematic methodology is described for predictive supervisory operation. The focus of this study is on the development of an operation supervisor that can determine optimal operation strategies for building thermal processes, and its application to a floor heating system in a passive solar room with thermal mass. An optimal model associated with a number of practical operation constraints is formulated, and an approach that combines dynamic programming and on-line simulation is developed, to efficiently solve the problem in real-time. Simulations for the minimisation of energy consumption and operating cost, with different operation schedules under various weather conditions, are performed. Results show that the techniques are computationally efficient and that the predictive supervisory operation of floor heating systems may lead to significant savings in energy consumption and operating cost. 相似文献