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61.
李彩虹 《南京工业职业技术学院学报》2008,8(2):1-3
根据PET薄膜的特点和高分子熔融态流动理论,分析了挤出回收用螺杆的各段结构,及螺杆参数选择,设计出大长径比、深槽、双排气、高效专用螺杆。 相似文献
62.
This study develops a mathematical model for coupled heat and mass transfer in an unsaturated porous slab exposed to a flowing hot gas. Effects of the initial saturation conditions on associated variables, i.e., total pressure, temperature, moisture content, and multiphase flow, are studied. The Newton-Raphson method based on a finite volume technique is applied. This study emphasizes the influence of initial saturation level and gravitational effect in heat and multiphase flow phenomena associated with this system. Gravity enhances the downward flow of liquid within the porous slab. Pressure buildup occurs near the interface between the wet and the dry zone. However, it appears that the order of magnitude to the total pressure is small. This study explains the fundamental mechanism of multiphase flow that involves heat and mass transfer in a heated unsaturated porous slab. 相似文献
63.
We present a numerical study of the packing of uniform spheres under three-dimensional vibration using the discrete element method (DEM), focusing on the effects of vibration condition (amplitude and frequency) and inter-particle frictions (sliding and rolling frictions). The results are analysed in terms of packing density, coordination number (CN), radial distribution function (RDF) and pore structure. It is shown that increasing either the vibration amplitude or frequency causes packing density to increase initially to a maximum and then decrease. Both vibration frequency and amplitude should be considered to characterize the effect of vibration process on packing structure. The sliding and rolling frictions between particles can decrease packing density since they dissipate energy, although the effect of rolling friction is less significant. In line with the change of packing density, microstructural properties such as CN, RDF and pore distribution also change: a looser packing often corresponds to smaller CN, less peaked RDF and larger but more widely distributed pores. 相似文献
64.
The main components of thermophotovoltaic (TPV) devices are the primary lens (or mirror), the absorber, the PV cell, and a photon recuperator system. A theory integrating all these components is used in this paper to analyse a particular type of TPV device (plane disk absorber and PV cell). The TPV efficiency is maximized by using three optimization parameters, namely absorber, PV cell temperatures, and cell voltage. Almost ideal operation conditions are envisaged and upper bounds are obtained for the TPV efficiency. They are strongly dependent on PV cell bandgap and radiation concentration. Preliminary results suggest the existence of an optimum solar radiation concentration ratio. The improvement in thermal design quality allows the usage of PV cells based on wide bandgap semiconductors. 相似文献
65.
In this work, the kinetics and mechanism of free-radical polymerisation of glycidyl methacrylate (GMA) using potassium peroxydisulphate
(PDS) as water soluble initiator in the presence of synthesized 1, 4-Bis (tributyl methyl ammonium) benzene dichloride (TBMABDC)
as multi-site phase transfer catalyst (MPTC) was studied. The polymerisation reactions were carried out under inert and unstirred
conditions at constant temperature of 60 ± 1°C in cyclohexane/water biphase media. The role of concentrations of monomer,
initiator, catalyst and volume fraction of aqueous phase, solvent polarity and temperature on the rate of polymerisation (Rp)
was ascertained. The order with respect to monomer and initiator was found to be unity. The order with respect to catalyst
was found to be 0.51. The rate of polymerisation is independent of ionic strength and pH of the medium. However, an increase
in the polarity of solvent has slightly increased the Rp value. Based on the results obtained, a suitable kinetic scheme has
been proposed to account for the experimental observations and its significance discussed. 相似文献
66.
裂齿矩形翅片板翅式换热器优化设计的分析 总被引:2,自引:0,他引:2
对裂齿矩形翅片板翅式换热器中的裂齿矩形翅片的传热效率作了分析,并以单位质量材耗的换热能力最大为目标函数,分析研究了在不同雷诺数(Re)的操作条件下裂齿矩形翅片间角度、翅片厚、长度、宽度及极厚之间的关系。结果表明:在气体换热的场合下,当Re在某一范围时翅片可有效地起到强化传热的作用。当板厚为5mm,翅片厚为3mm,翅片间夹角为45°~70°,Re为2×10~3~8×10~3,最佳翅片纵向间距与翅片长度和翅片厚度乘积的平方根的比为1.5~2.5,最佳翅片尺寸系数为3~5时,传热强化效果较好。 相似文献
67.
The effect of pressure on combustion and heat transfer is analyzed. The research is based on the basic combustion and heat
transfer theorem. A correction for the heat calculation method for pressurized furnace is made on the basis of the normal
pressure case. The correction takes the effect of pressurizing into account. The results show that the correction is reasonable
and the method is applicable to combustion and heat transfer of the marine supercharged boiler. 相似文献
68.
MIP-CGP工艺专用催化剂CGP-1的开发与应用 总被引:11,自引:3,他引:8
阐述了生产汽油组分满足欧Ⅲ排放标准并多产丙烯的催化裂化工艺(简称MIP-CGP)专用催化剂(简称CGP-1)的研究开发与工业应用结果。CGP-1催化剂的基质具有良好的容炭性能,使活性组元受到良好保护,其优势作用在第二反应区得以充分发挥,具有更高的氢转移活性和强的汽油小分子烯烃裂化活性。中国石化九江分公司和镇海炼化公司的MIP-CGP工业试验标定结果表明,与常规FCC相比,采用CGP-1催化剂的MIP-CGP技术在生产烯烃体积分数小于18%的汽油组分的同时,丙烯产率达到8%以上。此外,汽油诱导期大幅提高,抗爆指数增加;总液体收率有所提高,干气产率下降,焦炭选择性良好。 相似文献
69.
Non-pinched, minimum energy solutions are important class of distillation designs that offer the potential advantage of a better trade-off between capital investment and operating costs. In this paper, two important tasks associated with non-pinched distillation designs are studied. Thus the novel contributions of this work to the literature are
- (1) A comprehensive methodology for finding non-pinched minimum energy designs.
- (2) Understanding of the reasons for the existence of non-pinched distillation designs.
70.
Jennifer Spenader 《Journal of Logic, Language and Information》2003,12(3):351-368
There are three ways to refer to a fact from the complement of afactive verb: (1) Via abstract object anaphoric reference, or, witha full sentential complement that will be interpreted either (2) asa bound presupposition or (3) as triggering a presupposition of afact that will have to be accommodated. Spoken corpus examplesreveal that these three possibilities differ in relation to thetype of information they tend to contribute, and this has twoeffects. First, the information status of the fact and its role inthe discourse seem to affect the preference for one constructionover another in a particular context. Second, presupposed factivecomplements that need to be accommodated tend to be hearer-new andthe focus of the utterance, meaning that information structureseems to contribute to the felicity of accommodation ofpresupposed facts. 相似文献