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This paper proposed that the flow characteristic of electronic expansion valve should be adapted to the evaporator superheat gain to refrigerant flow rate under different working conditions. Two native methods of geometry modeling of electronic expansion valve head were introduced. By analysis of them, some shortcoming was detected and a universal modeling method of electronic expansion valve head was put forward. Through this model, the flow characteristic of EEV and the influence factors can be investigated more deeply. 相似文献
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有机朗肯循环作为回收发动机废热的有效手段,在商用车领域受到关注。R245fa是常见的有机朗肯循环工质,随着碳排放标准日趋严格,GWP高于150的制冷剂未来将面临淘汰。本文中提出一种新型低GWP制冷剂R1233zde替代R245应用于有机朗肯循环,物性与R245fa相近,GWP为7。并针对有机朗肯循环,建立了系统仿真模型,比较相同工况下两种工质的性能参数:蒸发温度,泵耗功和循环热效率。分析表明R1233zde泵耗功相比减少约15.05%~17.02%,R1233zde最大热效率比R245fa高7.03%。 相似文献
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为满足该市政快速路钢箱梁架设施工需求,在钢箱梁架设前需要做临时支墩作为钢箱梁架设的辅助措施。根据现场现有材料状况,经过经济方案比选后选择型钢临时支架。通过Midas civil有限元软件对该支架整体建模分析计算,各杆件计算结果均满足计算要求,证明了该方案选择的可行性,方案的设计充分利用了现有材料,从而实现了项目利润的最大化。最后在支架关键部位(钢管柱和工字钢分配梁)布置应变片来监测钢管柱和分配梁的应力状况,并用全站仪监测分配梁最大位移。通过监测发现钢管柱最大应力为152MPa,分配梁最大位移为6. 4mm,应力及位移值与模型模拟数值接近。目前该快速路已完成施工并投入运营,在此过程中作为施工辅助措施的临时支架为钢箱梁的拼装施工起到了极为重要的作用。该临时支架所采用的模拟计算方法可行,对今后类似工程具有很好的参考价值。 相似文献
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In order to cut down excessive experiments, acoustic response of the different fan ducted discharge equipment was studied based on numerical method. The sound pressure level(SPL) in each component of a ductplenum-reverberant room model was drawn and SPL deviation was analyzed. The trends of the curves were explained by the diffracti on and end reflection at the duct discharge. Models with different room dimensions, duct lengths, duct cross sections, duct locations and duct elbow were constructed, and their response was analyzed and compared. The results show that the SPL curves are smooth in the duct discharge cross section, but seriously fluctuant in the reverberant rooms SPL in the duct discharge is only sensitive to duct dimensions, while that of the reverberant room is regularly influenced by all the dimension and arrangement factors. Small room and short duct help to increase room SPL. Elbow has an indistinct influence on all the components‘ sound field. Finally, suggestion to reduce the deviation of experiment results was proposed. 相似文献
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本文针对我国公路建设项目目标持续性评价存在的问题,分析了公路建设项目目标持续性的含义及公路建设项目目标持续性应遵循可持续发展的目标,即与社会经济、环境资源、公路建设项目运营及管理体制与政策保持协调发展,从而使项日本身可持续发展,并提出了可持续发展的目标持续性评价原则,最后采用物元分析法建立了可持续发展的目标持续性评价指标体系及模型. 相似文献