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制冷空调系统替代工质的发展现状及方向 总被引:3,自引:0,他引:3
本文主要针对CFC11、CFC12以及HCFC22介绍了目前替代工质的发展现状,阐述了混合工质以及氨、二氧化碳、碳氢化合物等自然工质作为替代工质的特点以及其发展现状,总结了制冷空调系统替代工质的发展方向。 相似文献
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Alex Alberto Silva Huerta Flvio Augusto Sanzovo Fiorelli Otvio de Mattos Silvares 《Experimental Thermal and Fluid Science》2007,31(8):957-966
This work presents the results of an experimental study with pure refrigerants R-134a and R-600a and refrigerant–oil mixtures flowing through capillary tubes in order to analyse the metastable flow. A large number of experiments were carried out to verify the influence of several variables on the underpressure of vaporization, mainly the inlet subcooling, internal diameter and inlet pressure. Capillary tubes with internal diameter of 0.69 mm and 0.82 mm were tested for condensation temperatures between 40 °C and 50 °C and subcooling degrees between 3 °C and 12 °C. Measurements for oil concentrations of 1% and 3% were conducted and compared with those for pure refrigerant R-134a. The oil influence on the metastable flow was tested and the effect on the underpressure of vaporization is addressed for lower oil concentrations. 相似文献
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通过数学方法较为精确地建立了吸收式制冷机需满足负荷要求的数学模型,确立了蒸发器冷冻水出口温度与室外温度之间的关系式。进而建立了吸收式出水温度控制系统的动态特性模型,并采用并联程序法对水温控制系统进行仿真。 相似文献
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大气臭氧层的破坏和温室效应的加剧,是当前世界面临的主要环境问题。文中通过对R600a制冷剂物理化学特性的介绍以及与R12制冷剂的对比,得出在冰箱领域,R600a是一种可以永久替代CFCs的环保型制冷剂,分析了R600a替代R12的制冷系统设计的一些要点,最后基于提高工作效率以及保障操作安全的考虑,阐述了R600a冰箱的维修工艺。 相似文献
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制冷系统故障信息样本中的部分特征缺失时,已有的故障诊断模型无法使用这些样本。为解决该问题,提出了一种新颖的故障诊断策略。该诊断策略可通过以下步骤实现:(1)在部分问题描述与历史数据库的相互作用及领域知识的基础上,产生了用于特征转换的相似转换矩阵;(2)将不完整描述样本中的未知特征转变为与其相关的已知特征,形成检索目标;(3)通过计算和比较检索目标与数据库中样本间的相似度,得到最佳案例,将该案例中的相应值赋予未知特征;(4)运用已有的故障诊断模型及再生的完整描述样本,对制冷系统进行故障诊断。利用实验数据对该诊断策略进行验证,取得了满意的结果。 相似文献
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Arjun K. Pathak Igor DubenkoShane Stadler Naushad Ali 《Journal of magnetism and magnetic materials》2011,323(20):2436-2440
The magnetic, magnetocaloric, and magnetotransport properties of RCo1.8Mn0.2 (R=Er, Ho, Dy, and Tb) were studied by room temperature X-ray diffraction, magnetization, and resistivity measurements at a temperature interval of 5-400 K and magnetic fields up to 5 T. The Curie temperature of RCo2 was found to increase significantly when 10% Mn was substituted for Co. The effective paramagnetic moments were found to be in reasonable agreement with their theoretical values. A large magnetoresistance (MR) of Δρ/ρo≈−13.5% for R=Ho at T≈153 K for ΔH=5 T has been observed. The maximum relative cooling capacities vary from 467 J/kg at low temperature for R=Er to 202 J/kg at the near room temperature for R=Tb. 相似文献