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磁场对铜板冷表面抑霜的可视化研究

低温工程 2024年第1期 88-96页

作者：秦仪勾昱君张文博刘佳成王者华北理工大学冶金与能源学院唐山063210

为了研究弱磁对凝结液滴冻结和结霜过程的影响。通过在冷表面两侧施加永磁铁的方式,探究磁场(0—70 mT)和液滴冻结时间、大小、霜厚及结霜质量的关系。实验结果表明:在相同的工况下,随着磁场强度的增加,冷表面上发生液滴冻结的时间逐渐... 详细信息

为了研究弱磁对凝结液滴冻结和结霜过程的影响。通过在冷表面两侧施加永磁铁的方式,探究磁场(0—70 mT)和液滴冻结时间、大小、霜厚及结霜质量的关系。实验结果表明:在相同的工况下,随着磁场强度的增加,冷表面上发生液滴冻结的时间逐渐延长,但随湿度增加到一定程度时,液滴冻结的时间与磁场强度的关系并不是呈线性关系;另外,在不同磁场强度下,冻结液滴的尺寸不同;在结霜过程中,霜层生长的速度随着磁场强度的增加而变缓,结霜质量随之减少。以上的结果表明,一定的磁场强度对冷表面上液滴的冻结和霜层的生长均能起到一定的抑制作用,但随着冷表面温度的降低和环境湿度的增加,磁场对液滴冻结和结霜过程的抑制作用会减弱。

关键词：磁场铜板表面液滴冻结结霜

Development and experimental study of a miniature vapor compression refrigeration equipment

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Science China(Technological Sciences) 2008年第5期51卷 632-640页

作者： ZHONG XiaoHui gou yujun WU YuTing MA ChongFang Key Laboratory of Beijing Municipality on Heat Transfer and Energy Conversion Key Laboratory of the Ministry of Education on Enhanced Heat Transfer and Energy ConversionCollege of Environmental and Energy EngineeringBeijing University of TechnologyBeijing 100022China

A miniature vapor compression refrigeration equipment prototype was developed for a range of microclimate control applications, including man portable cooling and distributed space conditioning. The miniature refrigeration equipment has dimensions of 260 mm × 250 mm × 120 mm, and weighs approximately 2.85 kg. The optimal motor and its transmission ratio, the optimal dimension of capillary tube and the optimal quantity of refrigerant charge were obtained by matching and operating performance experimental study. Experimental results show that the miniature refrigeration equipment can provide 300 W cooling, and its COPc is above 2.0.

关键词： miniature refrigeration equipment miniature Wankel compressor miniaturization

Deformation of freezing water droplets on a cold copper surface

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Science China(Technological Sciences) 2006年第5期49卷 590-600页

作者： WANG Jieteng LIU Zhongliang gou yujun ZHANG Xinhua CHENG Shuiyuan College of Environmental and Energy Engineering Beijing University of Technology Beijing 100022 China College of Environmental and Energy Engineering Beijing University of Technology Beijing 100022 China College of Environmental and Energy Engineering Beijing University of Technology Beijing 100022 China College of Environmental and Energy Engineering Beijing University of Technology Beijing 100022 China College of Environmental and Energy Engineering Beijing University of Technology Beijing 100022 China

Freezing processes of water and peanut oil droplets on a cold surface are investigated in this paper. We observed during our experiments that the base surface of a water droplet that is in direct contact with the cold surface keeps its original shape, but the other part of the droplet shows an obvious growth along the direction normal to the base surface. One small protrusion appears on the top of the water droplet at the end of the freezing process. The experimental observations also show that no obvious shape change happens during the freezing of peanut oil droplets. It is postulated that the effects of sur- face tension and volume dilatation resulted from liquid-to-solid phase change cause the shape change and protrusions formation. Based on this postulation, a physical and mathematical model is developed. The results of the model of a water droplet’s freezing process correspond with our experimental observations. The observed phenomenon that frost-growth speed on the protrusion is higher than that on the other part of the water droplet is also analyzed.

关键词： frost, droplet, freezing, protrusion formation, surface tension.

Availability Modeling and Simulation of Satellite Navigation System based on Integration of PDOP and Reliability Maintainability Supportability

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Availability Modeling and Simulation of Satellite Navigation...

Enhancing activity of Endoglucanase Cel12B from Thermotoga maritime by site-directed mutagenesis

第九届中国卫星导航学术年会

作者： Zhuopeng Yang yujun gou Yanhua Zhu Heng Zheng China Academy of Aerospace Standardization and Product Assurance

Due to the satellite-launcher-station interactive operation, coupling of PDOP, reliability and maintainability and supportability(RMS), an availability modeling and simulation method of a navigation system is proposed by GSPN, Bayesian network and outage analysis. The availability of a per-slot is conformed based on GSPN, considering short scheduled or unscheduled outage of bus and payload,long outages, on-orbit or ground backup, testing time in launching site as well as launching reliability. Taking PDOP under different outages as the relationship of slots and the service availability is conformed based on Bayesian network. The vulnerable slots are identified and different optimization designs are compared. The simulation results have demonstrated that this method can be applied for navigation system design optimization, and satellite-launcher-station quantitative decision.

关键词： navigation system PDOP Designed life RMS GSPN Bayesian network

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Enhancing activity of Endoglucanase Cel12B from Thermotoga m...

20钢/316L复合管固液复合制坯工艺研究

The Ninth National Symposium on Enzyme Engineering

作者： Xu linyu gou yujun Shi hao Li xiangqian Faculty of Life Science and Chemistry Huaiyin Institute of Technology Jiangsu Provincial Engineering Laboratory for Biomass Conversion and Process Integration Huaian High-Tech Research Institute of Nanjing University

The thermal stability and catalytic activity of endoglucanase（EngD）from thermophilic Thermotoga maritima were significantly improved by rational design on the basis of our previous Directed *** activity of two mutants,K207G and E225H,increased to varying degrees comparing with original *** relative activity was improved 30.38%and 29.62%*** enzymatic properties of the purified mutant proteins were *** results show that the optimum temperature of recombinated endoglucanase Cel12B-207 is 95℃,the optimum pH is *** left enzyme activity hold 70%compared to the unkept one after putting in 90℃for 2 *** optimum temperature of recombinated endoglucanase Cel12B-225 is 75℃,the optimum pH is *** left enzyme activity hold 95%compared to the unkept one after putting in 75℃for 8 hours.

关键词： Thermotoga maritime Endoglucanase site-directed mutagenesis enzymatic properties

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材料研究与应用 2024年第1期18卷 172-178页

作者：桂海莲胡晓彤刘浩张琛李强胡建华陈建勋苟毓俊双远华张鹏岳太原科技大学材料科学与工程学院山西太原030024 太原科技大学机械工程学院山西太原030024 太原科技大学车辆与交通学院山西太原030024 山西钢合力新材料科技有限公司山西太原030021

双金属复合管在石油运输行业中应用前景广阔,结合性能是考察复合管是否合格的重要指标之一。为了能在轧制成形过程中得到高品质的复合管材,在复合管制坯过程中要求实现界面处的冶金复合。以20钢和316L为原材料,基于结合温度及元素扩散情... 详细信息

双金属复合管在石油运输行业中应用前景广阔,结合性能是考察复合管是否合格的重要指标之一。为了能在轧制成形过程中得到高品质的复合管材,在复合管制坯过程中要求实现界面处的冶金复合。以20钢和316L为原材料,基于结合温度及元素扩散情况,采用固液复合方式,并且结合界面的温度模型及通过Pro CAST软件模拟,获得了外模最佳预热温度为1050—1100℃。通过现场试制界面处实现了冶金复合,在最佳温度范围既保证了固态20钢和液态316L之间能达到冶金复合,又能使元素有充分的扩散时间而增强了界面结合强度,同时又可以防止因元素过渡扩散而导致316L腐蚀性能下降。该方法为后续复合管连轧提供了优良的管坯,可实现高品质复合管的现场生产。

关键词：固液复合复合管坯热传导界面结合强度扩散 20钢/316L 模型

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Experimental investigation of the influence of electric field on frost layer growth under natural convection condition

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Progress in Natural Science:Materials International 2006年第4期16卷 410-415页

作者： ZHANG Xinhua, LIU Zhongliang, WANG Jieteng, gou yujun, MENG Sheng and MA Chongfang Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education Key Laboratory of Heat Transfer and Energy Conversion, Beijing Education Commission, Beijing University of Technology, Beijing 100022, China Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of Education China

The influence of direct current (DC) electric field on the thickness and mass of frost on a cold vertical plate was investigated. The photos of frost layer growth were taken with and without the presence of electric field, and results showed that the electric field has a strong influence on the frost thickness. The influences of cold plate temperature and ambient temperature on frost thickness and frost mass were also investigated under the natural convection condition with electric field. Experimental results demonstrated that the cold plate temperature has very strong effect on the frost layer thickness, but its influence on frost mass is minor; the influence of ambient temperature on the frost mass is more obvious than that on the frost thickness.

关键词： frost formation electric field natural convection.

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钛合金无缝管斜连轧新工艺研究

稀有金属材料与工程 2023年第3期52卷 959-967页

针对钛合金材料热轧温度范围窄、温降快、变形抗力大等特点,将钛合金与无缝管斜连轧(TSR)新工艺有机结合并开展系统研究。根据斜连轧工艺结构与特点,分别构建连轧过程速度模型与张力模型;通过有限元数值模拟研究钛合金斜连轧过程金属变... 详细信息

针对钛合金材料热轧温度范围窄、温降快、变形抗力大等特点,将钛合金与无缝管斜连轧(TSR)新工艺有机结合并开展系统研究。根据斜连轧工艺结构与特点,分别构建连轧过程速度模型与张力模型;通过有限元数值模拟研究钛合金斜连轧过程金属变形机制、分析金属流动规律,获得其应力应变场、温度场、速度场分布及张力变化规律,基于有限元模拟进行现场实验研究。结果表明:初轧温度1050℃、合理匹配穿孔段与轧管段参数的情况下,可成功制备钛合金无缝管,且尺寸精度高、无明显表面缺陷。理论及实验分析证明斜连轧新工艺完全适用于钛合金无缝管材制备,同时缩短生产流程,提高生产效率。

关键词：斜连轧有限元模拟钛合金无缝管

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超疏水表面制备及防冰抑霜性能研究

低温工程 2022年第6期 48-55页

作者：韩佳勾昱君秦仪华北理工大学唐山063210

采用喷涂工艺,用改性处理的纳米二氧化钛和聚二甲基硅氧烷在紫铜板表面制备出一种涂料与基底牢固黏结的超疏水表面,在不同冷面温度和环境湿度条件下,对表面进行了防冰抑霜性能测试。结果表明,与紫铜板表面相比,制备出的超疏水表面接触... 详细信息

采用喷涂工艺,用改性处理的纳米二氧化钛和聚二甲基硅氧烷在紫铜板表面制备出一种涂料与基底牢固黏结的超疏水表面,在不同冷面温度和环境湿度条件下,对表面进行了防冰抑霜性能测试。结果表明,与紫铜板表面相比,制备出的超疏水表面接触角高达165°,可以有效抑制表面凝结液滴的冻结,并且凝结液滴在超疏水表面上会发生自跳跃现象,有效减少表面霜晶的覆盖率。在冷面温度-7℃和湿度50%的条件下,表面凝结液滴几乎不会发生冻结,随着冷面温度的降低和环境湿度的增大,当冷面温度-15℃和湿度70%时,与紫铜板表面相比,超疏水表面仍然可将凝结液滴冻结的时间延迟10倍。通过对表面的霜层高度进行测量,超疏水表面霜高仅为紫铜板表面霜高的0.7—0.8倍。

关键词：超疏水表面防冰抑霜霜高自跳跃