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31.
通过对耐沟状腐蚀现象的研究,结合生产设备能力,设计了6种成分钢带和6种退火工艺。借助光学显微镜、扫描电镜、拉伸试验、中性盐雾试验等手段,研究了采暖系统用耐沟状腐蚀钢带生产过程中冷轧退火工艺对其性能的影响。结果发现:低于Ac1温度(650、700 ℃)的退火不可能改变原来冷轧铁素体晶界的遗传结构,冷轧α相的再结晶长大不充分,碳化物的聚合和长大过程也不充分;当退火温度达到Ac1左右(750 ℃),由于碳元素的固溶加剧,导致α相再结晶和析出物的聚合长大,得到极优的延展性,对深冲非常有利;退火温度位于Ac1~Ac3之间(850 ℃),发生α→γ相再结晶,可以取得最好的软化效果。对于含Ti的试验钢,随着退火温度的降低,其塑性应变比r值呈下降趋势。Cr的加入不利于耐沟状腐蚀性能,但是Al的加入有利于耐沟状腐蚀性能。采用两段式退火工艺进行工业化生产,可以得到外观和性能优良的采暖系统用耐沟状腐蚀产品。 相似文献
32.
Damage of chicory tissue by combined electroporation and ohmic heating is studied for better solute extraction. Moderate (400–1000 V/cm) and high (10,000 V/cm) PEF treatments were applied varying pause duration between the trains of individual pulses. Ohmic heating was induced with increase of the number of trains N. Temperature dependence of tissue damage degree Z is evaluated for the different PEF intensities. With higher ohmic heating, chicory tissue is faster and better damaged. Electric field strengths of 600–800 V/cm combined with ohmic heating permit to enhance noticeably the solute extraction from chicory tissue. The solute diffusivity D for the different PEF treatments, is nearly the same for same values of Z. Chicory tissue treated to the same damage degree (Z = 0.8–1.0) using different PEF conditions (800, 1000 and 10,000 V/cm) has nearly the same diffusivity.Combined electroporation/ohmic heating pretreatment by moderate PEF (400–1000 V/cm) presents an interesting alterative for the treatment of high product throughputs (e.g. in the case of inulin production from chicory). 相似文献
33.
Poultry feather was hydrolyzed at relatively mild high temperature ranging from 433 to 473 K and autogenous pressure by intensification of microwave heating. The hydrolysate mainly contains arginine, alanine, threonine, glycine, praline, serine, glutamic acid, aspartic acid, cystine and tyrosine, which corresponds with hydrochloric acid catalytic hydrolysis. Based on the orthogonal experimental result, the total yield of amino acid attains about 54.72% with feather containing about 71.83% keratin at optimum reaction condition of temperature 473 K, time 20 min and weight ratio of water/feather 37.5. The high yield of amino acid and high efficiency of hydrolysis indicate that the microwave has better intensification on hydrolysis comparing with traditional strong acid catalytic or sub-critical hydrolysis. The apparent activation energies (Ea) are 85.12 and 63.00 kJ/mol as to the hydrolysis of feather and the degradation of produced amino acid with consecutive pseudo-first-order reaction kinetic model, and the great decrease of the values comparing with non-microwave heating should be the reason of the enhanced effect of microwave. 相似文献
34.
35.
Numerous industrial and engineering systems, like, heat exchangers, chemical action reactors, geothermic systems, geological setups, and many others, involve convective heat transfer through a porous medium. The diffusion rate, drag force, and mechanical phenomenon are dealt with in the Darcy–Forchheimer model, and hence this model is vital to study the fluid flow and heat transport analysis. Therefore, numerical simulation of the Darcy–Forchheimer dynamics of a Casson material in a circular tube subjected to the energy losses due to the viscous heating and Joule dissipation mechanisms is performed. The novelty of the present investigation is to scrutinize the convective heat transport characteristics in a circular tube saturated with Darcy–Forchheimer porous matrix by utilizing the non-Newtonian Casson fluid. The flow occurs due to the elongation of the surface of a tube with a uniform heat-based source/sink. The similarity solution of the nonlinear problem was obtained using dimensionless similarity variables. The effects of operating parameters related to the flow phenomena are analyzed. Further, the friction factor and Nusselt number are also analyzed in detail. The present flow model ensures no flow reversal and acts as a coolant of the heated cylindrical surface; the existence of the magnetic field, as well as an inertial coefficient, acts as the momentum-breaking forces, whereas Casson fluidity builds it. The Joule heating phenomenon enhances the magnitude of temperature. The thermal field of the Casson fluid is higher at the surface of the circular pipe due to convective thermal conditions. 相似文献
36.
K. V. B. Rajakumar M. Umasankara Reddy K. S. Balamurugan K. V. B. S. Raja Ram 《亚洲传热研究》2020,49(3):1583-1612
In the present study, the influence of Hall and ion‐slip current on steady magnetohydrodynamics mixed convective, Ohmic heating, and viscous dissipative Casson fluid flow over an infinite vertical porous plate in the presence of Soret effect and chemical reaction are investigated. The modeling equations are transformed into dimensionless equations and then solved analytically through the multiple regular perturbation law. Computations are performed graphically to analyze the behavior of fluid velocity, temperature, concentration, skin friction, Nusselt number, and Sherwood number on the vertical plate with the difference of emerging physical parameters. This study reflects that the incremental values of Casson fluid parameter and Schmidt number lead to reduction in velocity. However, fluid velocity rises due to enhancement of ion‐slip parameter but an opposite effect is observed in case of Hall parameter. In addition, the Sherwood number declines with enhancing dissimilar estimators of the chemical reaction, Schmidt number, as well as Soret number. 相似文献
37.
Sumeng Wei Yuling Yang Xiao Feng Shanshan Li Lei Zhou Jingyu Wang Xiaozhi Tang 《International Journal of Food Science & Technology》2020,55(7):2691-2699
Structures and properties of myofibrillar protein gel prepared at different power (300–800 W) were evaluated. Amino acid analysis demonstrated that changes in microwave power did not alter primary structure of gel. However, an increase in microwave power could change higher structures of gel. As microwave power increased, α-helix content decreased and β-sheet content increased. Increased microwave power probably facilitated protein to unfold and expose the internal groups, causing surface hydrophobicity and the formation of disulphide bonds were enhanced, which indicated changes in tertiary and quaternary structures of protein. At 500 W, gel had the best ultrastructure where surface morphology, springiness and water holding capacity reached the optimum. Our findings suggested that microwave at an appropriate power (500 W) could change higher structures of myofibrillar protein gel to achieve desired processing and quality protein gel characteristics. 相似文献
38.
为了解决硒化镓(GaSe)晶体制备困难、化学性能差的问题,对GaSe晶体传统的化学汽相沉积制备方法进行了改进,采用移动加热源法制备GaSe晶体。搭建了GaSe晶体的制备装置,通过单片机精确调控制备晶体的高温炉的加热温度、移动位置等参数,并采用光学显微镜和原子力显微镜对所制备的GaSe晶体进行辅助表征。研究表明,利用移动加热源法可以制备出表面光滑且尺寸较大的单层二维GaSe晶体。由于对机电设备实现了自动精密移动,可对单层二维GaSe晶体实现高质量大批量的制备,有利于GaSe晶体在光电子学和纳电子学中的广泛应用。 相似文献
39.
研究风光水中长期互补协调调度对探索风光的接入对水电运行的影响有重要意义。以流域Y下游两库五级梯级水电站及其周边的风光资源为例,建立了计及发电量最大化和时段最小出力最大化的双目标模型,在求解时将时段最小出力最大化目标转化为约束条件,在约束破坏时对目标函数加以惩罚,以达到简化求解的目的。最后通过分析互补协调调度的效果及风光对水库蓄泄水的影响提取了互补运行中梯级水电的调度策略,即互补运行中,水库群蓄水时期的调度策略以水资源最优化为原则,供水时期需重点关注,应根据风光总发电特性进行策略调整。 相似文献
40.
针对漆包机烘炉加热失效形式及产生原因,进行了深入的研究和分析。结果表明,影响烘炉加热失效的主要原因是加热管损坏及装配异常、催化剂表面粘有金属化合物等颗粒杂质、排废风机转速设定不合理,并对加热管、催化剂、排废风机提出了合理实用的技术措施,为降低烘炉加热失效提高加热效果提供帮助。 相似文献