Effects of Combined Instantaneous High-Pressure and Medium Temperature on Peroxidase Activity in Wax Gourd Juices

Based on the instantaneous pressurization and depressurization produced by high pressure single pole cylinder pump and valve, the effects of the continuous processing on the peroxidase (POD) activity in wax gourd juices were investigated. Results showed that the processing factors such as pressure, temperature, pH and processing time are important to the POD activity. POD in crude juices could be inactivated apparently above 50 MPa(pH 4.6, 35℃, 4 min), and activated at 20 MPa ( P < 0.01). Its remarkable inactivation could also be observed at 45 and 55℃ (20 MPa, pH 4.6, 4 min), and the evident activation appears at the material temperature 35℃ ( P < 0.01). The pH 3.0 could destroy POD almost completely (20 MPa, 35℃, 4 min), while pH 6.0 could not influence apparently the POD activity in crude juices( P > 0.05). In addition, the rules of POD activity along with the treatment time are variational under different processing pressures. The higher the treating pressure is, the shorter the processing time is needed to inactivate POD.

Methane Production via High Temperature Steam Electrolyser from Renewable Wind Energy: A German Study

The transformation of the energy supply needs further development of energy storage technologies in order to integrate the fluctuating renewable energy. The conversion of renewable wind power into green methane offers a technical approach with the necessary storage and transport capacities. Thus, the concept of Power-to-Gas which is illustrated here by the coupling of wind energy with a High Temperature Steam Electrolyser (HTSE) and a methanation unit enabling the production of green fuel like hydrogen and methane is presented is this paper. In fact, hydrogen can be used as energy carrier as well for the production of green fuels, like methane which is simpler to store and to transport and which can be thus used as storage medium for the stabilization of the electrical power supply as well as fuel for transport and heat sector. Its production using high temperature electrolysis is able to reduce the carbon dioxide emissions if performed with renewable resources. This is the case if the electricity needed for the HTSE comes from a wind turbine and the CO2 needed for the methanation step comes from biogas. For such a plant, the location and the boundary conditions have a great importance. Thus, this study considers the coupling of a HTSE with a wind turbine and a methanation reactor, and focuses about the site selection, depending of the geographical and economic considerations. The study is limited first to the European area. Schleswig-Holstein is found as a very good location for this plant. It is one of the regions with the largest wind reserves in Germany. This region has also available a lot of biogas and meets all the other necessary requirements.

Effects of Combined Instantaneous High-Pressure and MediumTemperature on the Retention of Total Vitamin Cin Wax Gourd Juices

Based on the instantaneous high-pressure(IHP)produced by high-pressure single pole-cylinder pump, the effects of combining this pressure with medium temperature on the retention of total vitamin C(Vc)in wax gourd juices were investigated under 20 - 80 MPa, 35 - 58℃, pH 3. 0 - 6. 0 and processing time 0-8 min. Results showed that the loss of Vc increased with elevated processing temperatures(50 MPa, 4 min). When the temperature of raw juices was 35℃, the retention of total Vc was higher under 40 - 60 MPa than that under the pressure < 40 MPa or > 60 MPa, and it was up to 94%(4 min). The retention of total Vc decreases slowly within 6 min, but rapidly after 6 min. The pH can also influence the retention of total Vc, and this retention can come to a highest point at pH 6.0.

Coupling of Wind Energy and Biogas with a High Temperature Steam Electrolyser for Hydrogen and Methane Production

The production of environment friendly green fuels is based on energy from renewable sources. Among the renewable sources, wind power is a very growing power technology. An example which has been discussed very widely is hydrogen which is an ideal fuel for a fuel cell. Hydrogen is the energy of the future. It will be used as energy carrier as well as reactant to produce green fuels, like methane which is easier to handle. Direct coupling of a High Temperature Steam Electrolyser (HTSE) with a wind turbine can be used to generate hydrogen. Indeed performing the electrolysis process at high temperatures offers the advantage of achieving higher efficiencies compared to the conventional water electrolysis. The hydrogen produced can be then reacted with the CO2 content of biogas to form methane as green fuel. Thus, the concept presented in this paper illustrates the potential of the HTSE technology coupled with a wind turbine, this system being combined with biogas in a methanation unit. Developing scenarios and flow sheets and using mass and energy balance, the technical performance of the concept is investigated. A plant capacity of 10 MWel is considered. An annual production of 1104 metric tons per year (Mt/a) hydrogen and thus of 5888 Mt/a methane is reached. The overall plant efficiency is calculated to be 38%. The combination of wind power and biogas offers thus many advantages which can facilitate the penetration of the wind resource and the progression to the hydrogen economy.

Oxidation behaviors of wrought nickel-based superalloys in various high temperature environments

Oxidation characteristics of Alloy 617 and Haynes 230 at 900 oC in simulated helium environment,hot steam environment containing H2 as well as in air and pure helium conditions were investigated.Compared to air condition,the oxidation rate of Alloy 617 was not significantly affected in helium and hot steam environments,while Haynes 230 showed lower oxidation rate in helium environment.On the other hand,the oxide morphology and structure of Alloy 617 were strongly affected by the environments,but those of Haynes 230 were less dependent on the environments.For Haynes 230,a Cr2O3 inner layer and a protective MnCr2O4 outer layer were formed in all environments,which contributed to the better oxidation resistance.As the mechanical properties,such as creep and tensile properties,were significantly affected by the oxidation behaviors,surface treatment methods to enhance oxidation resistance of these alloys should be developed.

基于三代测序技术高温和中高温大曲真菌多样性解析及酵母菌的分离鉴定

为明确不同类型大曲真菌多样性及可培养酵母菌的差异,本研究采用三代测序技术对高温和中高温大曲的真菌类群进行了解析,并结合传统微生物纯培养方法和分子生物学技术对其蕴含的酵母菌资源进行挖掘。α多样性分析结果表明,2种类型大曲真菌群落丰富度和多样性上存在显著差异(P<0.05);种属分析结果表明,高温大曲主要以疏棉状嗜热霉(Thermomyces lanuginosus)为主,平均相对含量为73.81%,中高温大曲主要以多育曲霉(Aspergillus proliferans)为主,平均相对含量为52.58%;β多样性分析结果表明,高温和中高温大曲真菌群落结构存在非常显著的差异(P<0.01);LEfSe分析表明,嗜热真菌属(Thermomyces)和曲霉科(Aspergillaceae)可以分别作为高温和中高温大曲的生物标志物;纯培养技术结果表明,从10份大曲样品中共分离得到18株酵母菌,高温和中高温大曲的优势分离株均为扣囊复膜孢酵母(Saccharomycopsis fibuligera)。由此可见,高温和中高温大曲真菌多样性上存在明显差异。

中大容量工业余热高温热泵的压缩机技术现状

热泵技术是一种节能技术,能够有效应对全球变暖,降低碳排放。工业热泵回收供热过程的废热加热水或空气,可减少电力消耗及碳排放。工业热泵节能环保,供热稳定,已广泛应用于生产及生活的各个阶段。分析了国内外工业余热高温热泵的压缩机类型及特点,针对中大容量的双螺杆压缩机及离心压缩机,分析其应用及技术现状。螺杆式热泵压缩机在高蒸发温度时应采用开启式结构,高冷凝温度时可采用高速无油方案;离心式热泵压缩机除高效的叶轮外,应关注耐高温电机与无油润滑轴承。螺杆式水蒸气压缩机关注转子热变形及轴封问题,向大温升方向发展。

采用顶空固相微萃取结合全二维气相色谱飞行时间质谱解析不同等级中高温大曲的挥发性组分差异特征

采用定量描述分析和顶空固相微萃取结合全二维气相色谱-飞行时间质谱技术对不同等级的中高温大曲香气感官差异特征和挥发性组分差异特征进行解析。感官描述分析表明一级大曲的烘焙、粮香、木香和烟熏香气比较突出;二级大曲甜香比较突出;三级大曲的泥土、蘑菇和酸腐味比较突出。在大曲中共鉴定出270种潜在香气化合物,一级大曲中的萜烯类、酯类、醇类和吡嗪类等物质种类较二级和三级大曲丰富。通过显著性分析发现,一级大曲中2,3-二甲基吡嗪、2,6-二甲基吡嗪、苯乙醛、(E,E)-2,4-壬二烯醛、愈创木酚、香兰素和4-乙烯基愈创木酚等物质含量较为突出;二级大曲中丙酸乙酯和2-辛酮等物质含量较为突出;三级大曲中土味素、2-异丙基-3-甲氧基吡嗪、1-辛烯-3-醇、1-辛烯-3-酮、丁酸和异戊酸等物质含量较为突出。偏最小二乘回归分析结果显示不同等级中高温大曲的感官特征与香气化合物之间有较为明显的关联性。通过对不同等级中高温大曲挥发性组分差异的研究,可为量化评价大曲香气质量以及完善质量评价体系提供参考。

600 MW超超临界机组S30432钢内壁氧化膜变化规律及水蒸气氧化动力学

通过SEM对某600 MW超超临界机组运行80000 h后的S30432钢高温再热器管内壁氧化膜进行氧化膜形貌和膜层结构分析,再用EDS、XRD对氧化物中成分测定,并分析氧化膜形成.依据氧化膜厚度评估其脱落风险.测定在640、670、700℃下S30432钢水蒸气的氧化膜厚度和时间的动力学曲线,确定炉管的运行温度和对氧化的影响.结果表明:氧化膜在形成和变化中,存在晶粒变化和成分变化.晶粒变化主要是由融合状的纳米级晶粒长大为颗粒状或碗状微米级晶粒,由表及里,晶粒越来越细小.依氧化膜厚度推算的运行温度为670℃,处于超温运行状态;S30432钢产生氧化膜脱落的厚度为39.81μm,初生氧化膜厚度远大于39.81μm,处于随时脱落状态,再运行8552 h后次生氧化膜会达到脱落阈值厚度,管内存在氧化膜大量脱落并堵塞弯管引起爆管的巨大风险.

浅谈GC1级蒸汽管道监督检验

GC1级蒸汽管道(高温、高压)的监督检验,文中从材料、设计、制造与安装、检验与试验具体分析监督检验过程中需要重点关注的地方。

Advance in highly efficient hydrogen production by high temperature steam electrolysis

High Temperature Steam Electrolysis (HTSE) through a solid oxide electrolytic cell (SOEC) has been receiving increasing research and development attention worldwide because of its high conversion efficiency (about 45%-59%) and its potential usage for large-scale production of hydrogen. The mechanism, composition, structure, and developing challenges of SOEC are summarized. Current situation, key materials, and core technologies of SOEC (solid oxide electrolytic cell) in HTSE are re- viewed, and the prospect of HTSE future application in advanced energy fields is proposed. In addition, the recent research achievements and study progress of HTSE in Tsinghua University are also intro- duced and presented.

Composite Cathode based on Mn-doped Perovskite Niobate-Titanate for Efficient Steam Electrolysis

Redox-active Mn is introduced into the B site of redox-stable perovskite niobate-titanate to improve the electrocatalytic activity of composite cathode in an oxide-ion-conducting solid oxide electrolyzer. The XRD and XPS results reveal the successful partial replacement of Ti/Nb by Mn in the B site of niobate-titanate. The ionic conductivities of the Mndoped niobate-titanate are significantly improved by approximately 1 order of magnitude in reducing atmosphere and 0.5 order of magnitude in oxidizing atmosphere compared with bare niobate-titanate at 800 ℃. The current efficiency for Mn-doped niobate-titanate cathode is accordingly enhanced by ,-25% and 30% in contrast to the bare cathode with and without reducing gas flowing over the cathode under the applied voltage of 2.0 V at 800 ℃ in an oxide-ion-conducting solid oxide electrolyzer, respectively.

Study on high frequency brazing of brass-red copper

Two kinds of silver based medium temperature brazing filler metals(45AgCuZnSn and 60AgCuSn) were selected to braze and seal brass flange pipe and copper pipe by high frequency heating brazing. In this paper, the quality of the braze was evaluated by immersion ultrasound, and the microstructure of the brazed joint was observed by SEM and EDS. The experimental results show that the high frequency heating brazing can quickly achieve the device sealing;through the ultrasonic flaw detection image calculation, the brazed bonding rate obtained by 60AgCuSn brazing is 87%, and by 45AgCuZnSn brazing is 71%;the cross-sectional area of the brazed joint obtained by two kinds of silver based medium temperature brazing filler metals is observed, the brazed joint obtained by 45AgCuZnSn brazing has defects visual, and a large amount of Zn element gathered in the defects, there is no obvious porosity in the brazed joint by 60AgCuSn brazing,and the bonding layer is dense and coherent. Through the contrast test, the choice of 60AgCuSn alloy brazing can meet the needs of high frequency brazing of brass flange pipe and copper pipe.

Oxidation Behaviors of Different Grades of Ferritic Heat Resistant Steels in High-Temperature Steam and Flue Gas Environments

For steam tubes used in thermal power plant,the inner and outer walls were operated in high-temperature steam and flue gas environments respectively.In this study,structure,microstructure and chemical composition of oxide films on inner and outer walls of exservice low Cr ferritic steel G102 tube and exservice high Cr ferritic steel T91 tube were analyzed.The oxide film was composed of outer oxide layer,inner oxide layer and internal oxidation zone.The outer oxide layer on the original surface of tube had a porous structure containing Fe oxides formed by diffusion and oxidation of Fe.More specially,the outer oxide layer formed in flue gas environment would mix with coal combustion products during the growth process.The inner oxide layer below the original surface of tube was made of Fe–Cr spinel.The internal oxidation zone was believed to be the precursor stage of inner oxide layer.The formation of internal oxidation zone was due to O diffusing along grain boundaries to form oxide.There were Fe–Cr–Si oxides discontinuously distributed along grain boundaries in the internal oxidation zone of G102,while there were Fe–Cr oxides continuously distributed along grain boundaries in that of T91.

Synthesis and Characterization of Ordered Mesoporous Aluminosilicate Molecular Sieves with High Stability in High-Temperature Steam

The ordered mesoporous aluminosilicate molecular sieve （MASMS-1） stable in the high-temperature steam has been successfully synthesized from the assembly of diluted ZSM-5-type precursor with mesoporous MCM-41. The material was characterized by XRD, N2 adsorption-desorption, FE-SEM, TEM, FT-IR spectroscopy and 27A1 MAS NMR techniques. This mesoporous material shows high stability in the high-temperature steam [H2O （φ=20%） in N2 at 800 ℃ for 4 h], which might be ascribed to the synergistic effect of both thick walls containing zeolite-like five-membered ring subunits and highly condensed surface silanol groups.

Modeling of Packed Bed Methanol Steam Reformer Integrated with Tubular High Temperature Proton Exchange Membrane Fuel Cell

This work proposes a novel tubular structure of high-temperature proton exchange membrane fuel cell(PEMFC)integrated with a built-in packed-bed methanol steam reformer to provide hydrogen for power output.A two-dimensional axisymmetric non-isothermal model was developed in COMSOL Multiphysics 5.4 to simulate the performance of a tubular high temperature proton membrane fuel cell and a packed bed methanol reformer.The model considers the coupling multi-physical processes,including methanol reforming reaction,water gas shift reaction,methanol cracking reaction as well as the heat,mass and momentum transport processes.The sub-model of the tubular packed-bed methanol reformer is validated between 433 K and 493 K with the experimental data reported in the literature.The sub-model of the high temperature proton exchange fuel cell is validated between 393 K and 433 K with the published literature.Our results show that power output and temperature distribution of the integrated unit depend on methanol flow rates and working voltages.It was suggested that stable power generation performance of 0.14 W/cm_(2)and temperature drop in methanol steam reformer of≤10 K could be achieved by controlling the methanol space-time ratio of≥250 kg·s/mol with working voltage at 0.6 V,even in the absence of an external heat source.

高温气冷堆热态功能试验中一回路加热动态特性研究

高温气冷堆反应堆压力容器堆内构件由石墨和碳化硼烧结陶瓷材料组成,热态功能试验过程中需对一回路堆内构件进行加热除湿。针对高温气冷堆一回路热试系统特点,采用COMSOL Multiphysics 5.4计算软件构建了压力容器、蒸汽发生器和主氦风机三维数值模型,并通过示范工程加热试验值验证了模型的可靠性,并获得了一回路加热过程中温度场动态特性。为了解决高温气冷堆示范工程一回路首次加热效率低的问题,提出了将辅助蒸汽通入到蒸汽发生器,并动态调整辅助蒸汽运行参数来加热一回路氦气的方法,结果表明:相较于主氦风机单独加热方式,外加辅助蒸汽热源可节省加热时间约31.3 h,同时可将堆芯最终平衡温度由250℃提高至265℃;在满足运行准则的前提下,更有利于碳砖和石墨堆内构件的除湿。该研究结果为高温气冷堆一回路热试提供了有力支持。

高地温铁路隧道温度场影响因素分析

目的常规的隧道冷负荷预测方法不适用处于高地温极端环境的川藏铁路隧道,亟须开展相关研究。方法以川藏铁路色季拉山隧道为背景,建立热湿耦合的多孔介质模型,分析围岩渗流水、保温层、送风速度和温度等对隧道温度场的影响。结果保温层可以显著降低隧道空气温度,含水围岩的隧道有效通风距离提高了5.87%,固体围岩的有效通风距离增加了25.51%,增加保温层厚度并没有显著降低隧道温度;围岩温度和送风速度对隧道温度有显著影响,围岩温度决定了隧道温度的上限;送风速度从1 m/s分别增加到2、3 m/s,隧道温度分别降低20.53%、24.83%;各因素对隧道温度场强度影响由大到小依次为围岩温度、送风速度、送风温度、保温层厚度。结论围岩温度决定了隧道的温度上限和降温难度,增加保温层厚度降温效果不明显,提高送风速度可以显著降低隧道温度。

高温中压长输蒸汽管道的热补偿方式及支架约束

高温中压长输蒸汽管道热补偿方式有别于电厂内部短距离输送管道,既要考虑安全性,又要考虑项目的经济性。论文对比常用热补偿方式的优缺点,提出高温中压长输蒸汽管道采用旋转补偿器补偿为主、自然补偿为辅的热补偿方式较为合理。对直线线路段、平行线路段、转角及转角叠加标高微调段、直线高差段、直线跨越段这几种常见的管道布置形式,通过START应力计算软件建模分析,确定较优的热补偿方式及支架约束条件。

刀具冷却方式对FGH96高温合金切削温度的影响分析

利用有限元模型确定FGH96高温合金的模型参数和力学性能,引入金属切削传热学理论,建立刀具表面温度解析模型,利用切削热来源计算出刀具接触区的切削温度,并提出汽雾冷却的FGH96高温合金冷却方式。以干式冷却、环形浇注和汽雾冷却为实验研究对象,分析各切削参数对高温合金切削性能的影响,包括温度场的径向分布、残余应力、切削力以及切削温度。仿真模拟结果表明:环形浇注、汽雾冷却的孔壁温度对比干式冷却方法分别下降48.8%和109.3%;汽雾冷却残余应力与切削力均最小;切削速度、进给量和切削深度的增加会使切削温度增加,汽雾冷却的最优切削温度为678.59℃,影响切削温度因素依次为进给量>切削速度>切削深度。研究结果揭示了不同冷却方式对这些因素的综合作用,为优化切削工艺和提高加工质量提供了重要依据。