液体冷媒融霜系统回液时间的实验研究

对液体冷媒融霜系统的回液时间进行实验研究。在保温体温度-15℃工况下分别对回液时间7s、27s、25s、30s、40s、50s进行实验,记录并分析被融霜蒸发器融霜前和回液时间内压缩机吸气口的温度和压力变化,相机拍摄制冷压缩机吸气口和机身的结霜状况。实验表明:回液时间7s时,压缩机吸气过潮,回液时间在27s左右可以避免压缩机吸气过潮,确保系统安全正常的运行,大于27s被融霜蒸发器恢复制冷时间过长将影响库房温度的稳定并降低制冷系统的效率。

The Effect of Coal Fly Ash Treatment with NaOH on the Characters and Adsorption Capacity toward Pb（Ⅱ） in the Solution

Coal fly ash （CFA） generated by coal-based thermal power plants is mainly composed of some oxides having high crystallinity, including quartz and mullite. In this study, the effect of CFA crystallinity toward its capacity on Pb（Ⅱ） adsorption was investigated. CFA with various crystaUinity was obtanied by refluxing it with sodium hydroxide （NaOH） solution having various concentrations （1-7 M） at various temperature and reflux time. To evaluate the effect of crystallinity of treated CFA on the adsorption capacity, adsorption of Pb（Ⅱ） solution with treated CFA was carried out. The research shows that the reflux of CFA with NaOH solution leads to the crystallinity of quartz and mullite in CFA decreased. The decrease is proportional with the concentration increasing, the temperature elevation, and the longer time. The reflux using NaOH solution with high concentration （〉 3 M） in addition causes a decrease in the crystallinity of quartz and mullite, also results in the formation of hydroxysodalite. The decrease of the CFA crystalllinity gives an increase in CFA adsorption capacity toward Pb（Ⅱ） solution.