新型石蜡乳液冰浆制备与性能实验研究

选用液体石蜡为油相,油酸钠和十六烷基三甲基溴化铵(CTAB)作为乳化剂,利用高速搅拌和超声乳化的方法制备了一种新型液体石蜡乳液作为冰浆蓄冷介质。电导率测试表明:该乳液为O/W型,乳液的D50粒径为1.56μm。在乳液中添加乙醇和丁醇可有效抑制冰浆粘附聚甲基戊烯(PMP)、玻璃和不锈钢烧杯壁面。乳液在解除过冷后的初期,冰浆在不锈钢烧杯中形成速度最快,在PMP烧杯中形成速度最慢。在解除过冷相同时间内,添加乙醇的乳液体系蓄冰率(IPF)比添加丁醇的高,但随着结晶时间的增加,差值逐渐减小。解除过冷3 h后冰粒呈颗粒状,IPF在55%~65%之间,具有良好的流动分散性。     

采用非共沸混合工质机械过冷的跨临界CO_2制冷循环性能分析

本文提出了非共沸混合工质机械过冷跨临界CO_2制冷循环。在最优排气压力和最优过冷度下循环取得最大COP。最大COP、最优排气压力和过冷度与混合制冷剂的温度滑移密切相关。当选取合理温度滑移的混合工质作为机械过冷循环的制冷剂时,可明显提升CO_2制冷循环能效,降低排气压力。与基本CO_2制冷循环相比,在蒸发温度为-40℃、环境温度为35℃时,采用R32/R152a(40/60)循环总COP可提升46.53%,CO_2排气压力可降低2.758 MPa。总COP的提升程度受混合制冷剂的温度滑移影响显著,推荐机械过冷循环使用温度滑移合理的混合制冷剂。在温暖和炎热的气候地区及冷冻冷藏等低温应用领域,采用非共沸混合制冷剂机械过冷跨临界CO_2制冷循环整体性能的提升更加显著。     

中压受热通道密度波不稳定性研究

采用RELAP5/Mod3.4软件对某一中压受热通道进行密度波不稳定性分析,探讨了节点个数对流动不稳定性的影响,分析了入口单相水的质量流量、入口长度和上升长度、入口和出口局部阻力系数、入口过冷度对受热通道密度波不稳定性的影响,并通过引入过冷数和相变数得到了受热通道的稳定边界.结果表明:在使用RELAP5程序进行不稳定性分析前,有必要进行节点划分敏感性分析;当增大受热通道入口单相水质量流量或增大入口局部阻力系数时,受热通道的流动稳定性增强;当增大受热通道入口长度或上升长度和出口局部阻力系数时,受热通道的流动稳定性降低;过冷数和相变数可用于描述受热通道稳定性边界.     

Correlation of Quench Phenomena for Bottom Flooding during Loss-of-Coolant Accidents

The three quench modes based on the observation with an outside-heated quartz tube experiment, i.e. (1) liquid column type, (2) dryout type and (3) droplet-rewetting type are discussed quantitatively to provide correlations for a reflood analysis code.

For the quench velocity of liquid column type and dryout type, using the data of PWR-FLECHT experiments, a correlation is obtained. This correlation is compared with experimental data and found that it can predict the inverse quench velocity within ±20% accuracy under the following conditions: pressure 1.0–4.1 kg/cm²-a, quench temperature 370~510°C, local subcooling 0~30°C, flow rate 5~25 cm/sec.

For the quench temperature of droplet-rewetting type, a correlation is derived and the prediction from it gives the qualitative agreement with few available data.     

Applications of Artificial Neural Network for the Prediction of Flow Boiling Curves

An artificial neural network (ANN) was applied successfully to predict flow boiling curves. The databases used in the analysis are from the 1960's, including 1,305 data points which cover these parameter ranges: pressure P=100–1,000 kPa, mass flow rate G=40–500 kg/m²-s, inlet subcooling ΔT_sub =0–35°C, wall superheat ΔT_w = 10–300°C and heat flux Q=20–8,000kW/m². The proposed methodology allows us to achieve accurate results, thus it is suitable for the processing of the boiling curve data. The effects of the main parameters on flow boiling curves were analyzed using the ANN. The heat flux increases with increasing inlet subcooling for all heat transfer modes. Mass flow rate has no significant effects on nucleate boiling curves. The transition boiling and film boiling heat fluxes will increase with an increase in the mass flow rate. Pressure plays a predominant role and improves heat transfer in all boiling regions except the film boiling region. There are slight differences between the steady and the transient boiling curves in all boiling regions except the nucleate region. The transient boiling curve lies below the corresponding steady boiling curve.     

过冷却技术提高制冷效率的节能效果浅析

介绍了制冷剂过冷技术应用于普通空气调节系统,可提高制冷效率,挖掘节能潜力。应用过冷却技术提高制冷效率,即通过增加外部过冷却装置,在直接膨胀式蒸汽压缩空气调节装置中,具有显著的节能效果。对该技术原理和应用状况进行分析,为我国同类型中央空调系统的节能运行及改造提供一种新的思路和方案,对建筑节能改造具有积极的推进作用。     

替代CFC工质R141b气体水合物蓄冷实验研究

详细地描述了在间接式蓄放冷方式下，在以Ｒ１４１ｂ作为相变物质进行蓄放冷的过程中，蓄冷罐内水合物生成的现象以及温度，压力随时间的变化情况。细致地分析了影响水合物形成和分解的因素，并且指明了间接蓄冷罐结构的优化措施。     

秸秆相变材料板材的制备研究

利用秸秆高孔隙率和高吸水性,浸渍无机盐固液相变材料,以改性水玻璃胶结,并模压成型制备秸秆板材。研究无机盐相变材料的过冷性质、稻秆相变材料板材的制备工艺及相变循环耐久性。研究表明:硼砂掺量3%时,Na2SO4.10H2O过冷度减少了12.6℃;纯丙乳液掺量为20%时,成型的稻秆板材浸泡24 h后达A级耐水性指标,3次涂膜封装30次相变循环后的质量损失仅为1.9%。