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幾種塑料管的性能價格比較 目前各國對熱水系統(tǒng)用塑料管的選擇,均遵循 ISO/DIS 10508 “冷熱水用熱塑性塑料管材和管件”標(biāo)準(zhǔn)的 規(guī)定。這里把交聯(lián)聚乙烯管和鋁塑復(fù)合管也歸并為熱塑性塑料管之列,它們的比較如下表: 塑料管 比較內(nèi)容 交聯(lián)高密度聚 乙烯管 聚丁烯 -1 管 聚丙烯管 鋁塑復(fù)合管 備 注 代 號 PEXa PEXb PEXc PB PP-H PP-B PP-R PE-AL-PE PE-AL- PEXb PEXb-AL- PEXb PEXa:過氧化物交聯(lián),交聯(lián) 度≥70% PEXb:硅烷交聯(lián),交聯(lián)度 ≥65% PEXc:輻射交聯(lián),交聯(lián)度 ≥60% 110℃8760 小時試驗 可 通 過 可 通 過 可 通 過 不詳 ISO 9080 規(guī)定 Po 塑料管材 只有通過此試驗,才可推導(dǎo) 70℃下其使用壽命達(dá) 50年 熱強(qiáng)度 最高 較高 低 較高 * * 高溫分層
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The modelling and experimental investigation of a thermally coupled humidification-dehumidification desalination process using a carbon-filled-polypropylene shell-tube column are presented.A heat/mass transfer model is established to study the correlation among productivity,thermal efficiency,physicochemical parameters (gas/liquid phase temperature,heat/mass transfer coefficient,Reynolds number etc.),and operating conditions(the temperature of feed water,the flow rates of external steam,feed water,and carrier air);at the same time,the effects of operating conditions on the productivity and thermal eficiency of the column are investigated both theoretically and experimentally,which indicate that the optimum flow rates of external steam,feed water,and carrier gas are 0.18,60,and 10kg.h- 1,respectively,and the higher the feed water temperature(≤95℃)is,the greater the productivity and the thermal efficiency will be.Furthermore,performance comparison with the previous study shows that the condensate productivity of this carbon-filled-plastic column is not lower than that of the copper column,which demonstrates the practicability and feasibility of applying such a plastic column to the humidification-dehumidification desalination process.