考虑蒸汽温位因素的全局能量集成方法

建立了考虑蒸汽温位因素的全局能量集成超结构,描述了在全局热源、公用工程、汽轮机、全局热阱之间进行热量传递和交换的所有可能的拓扑结构。基于此超结构,建立了全局能量集成的混合整数非线性规划模型,并用列队竞争算法进行求解。通过优化求解,得到高压、中压和低压蒸汽的优化温位和流量,使全局能量集成更有效。实例表明:本文所提出的方法优于没考虑蒸汽温位因素的全局能量集成。

银山热管蒸汽发生器特点与SO_3中温位热回收

截面呈椭圆形的挠性管板蒸汽发生器是银山热管蒸汽发生器的主要特点,热管为碳钢-水重力式。介绍其结构、主要设计参数、运行情况,并进行经济兮析。指出在4～20万t/a硫酸装置中回收SO_3中温位热时。均可只用一台该设备,价格低、经济效益好。

一种分步匹配的换热网络优化方法

针对复杂换热网络全局优化中可操作性、优化效率与优化质量三者间的矛盾问题,基于换热网络优化中的最佳温位匹配的原则,提出了一种复杂换热网络分步优化方法。该方法将复杂的网络集成问题分解为以冷(热)流体数目为基础的多个单一流体匹配优化的子问题,以最优匹配优选的原则进行网络结构的分步生成,最终获得网络的总体结构。结果表明,以优选匹配的换热网络结构优化结果优于焓差匹配、温位匹配的结果,匹配的原则中,优选匹配要作为首选的匹配原则,可以避免前两种匹配原则上的匹配失当,该方法极大地提高了复杂换热网络优化的可操作性,优选匹配顺序使得分步优化能够取得更高的质量。

High density dislocations enhance creep ageing response and mechanical properties in 2195 alloy sheet

The creep strain of conventionally treated 2195 alloy is very low,increasing the difficulty of manufacturing Al-Cu-Li alloy sheet parts by creep age forming.Therefore,finding a solution to improve the creep formability of Al-Cu-Li alloy is vital.A thorough comparison of the effects of cryo-deformation and ambient temperature large pre-deformation(LPD)on the creep ageing response in the 2195 alloy sheet at 160℃with different stresses has been made.The evolution of dislocations and precipitates during creep ageing of LPD alloys are revealed by X-ray diffraction and transmission electron microscopy.High-quality 2195 alloy sheet largely pre-deformed by 80%without edge-cracking is obtained by cryo-rolling at liquid nitrogen temperature,while severe edge-cracking occurs during room temperature rolling.The creep formability and strength of the 2195 alloy are both enhanced by introducing pre-existing dislocations with a density over 1.4×10^(15)m^(−2).At 160℃and 150 MPa,creep strain and creep-aged strength generally increases by 4−6 times and 30−50 MPa in the LPD sample,respectively,compared to conventional T3 alloy counterpart.The elongation of creep-aged LPD sample is low but remains relevant for application.The high-density dislocations,though existing in the form of dislocation tangles,promote the formation of refined T1 precipitates with a uniform dispersion.

8.5万吨/年润滑油加氢处理装置节能改造分析与探讨

分析某炼化企业8.5万吨/年润滑油加氢处理装置生产中存在的问题:汽提蒸汽浪费、泵设计安全裕量过大、换热流程设计不合理。针对这些问题提出改造方案:使用0.3MPa蒸汽替代原1MPa蒸汽作为汽提蒸汽;对原料泵叶轮进行拆级改造;根据温住匹配原则优化减三线、中润、重润及低分油换热流程。改造后,预计燃料气用量减少36%,循环水用量减少60%,原料泵用电量减少15%,空冷器用电量减少53%,得到了较好的改造效果。

用自然温标来研究太阳能锅炉的最佳热力学设计

本文以自然环境为参照系,提出自然温标:温位=T—T_和比温位φ=/T_a这两个概念。本概念适于(火用)分析法,并可简化对问题的分析和表述。本文还以此概念研究了太阳能锅炉以及具有线性热损的单容集热装置的最佳热力学设计,导出准则关系式击φ_m/φ=φ+2,和最佳集热效率η_(Qop)=(φ+1)/(φ+2)。

Opto-mechanical-thermal integration analysis of Doppler asymmetric spatial heterodyne interferometer

In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation between the interference phase and temperature is established according to the working principle and the phase algorithm of the interferometer.Secondly,the optical mechanical thermal analysis model and thermal deformation data acquisition model are designed.The deformation data of the interference module and the imaging optical system at different temperatures are given by temperature load simulation analysis,and the phase error caused by thermal deformation is obtained by fitting.Finally,based on the wind speed error caused by thermal deformation of each component,a reasonable temperature control scheme is proposed.The results show that the interference module occupies the main cause,the temperature must be controlled within(20±0.05)℃,and the temperature control should be carried out for the temperature sensitive parts,and the wind speed error caused by the part is 3.8 m/s.The thermal drift between the magnification of the imaging optical system and the thermal drift of the relative position between the imaging optical system and the detector should occupy the secondary cause,which should be controlled within(20±2)℃,and the wind speed error caused by the part is 3.05 m/s.In summary,the wind measurement error caused by interference module,imaging optical system,and the relative position between the imaging optical system and the detector can be controlled within 6.85 m/s.The analysis and temperature control schemes presented in this paper can provide theoretical basis for DASH interferometer engineering applications.

对LNG冷能利用中几个问题的讨论

我国已规划建设10个以上从国外进口LNG的大型接收站,还在不断建设一些中小型LNG气化站。进口LNG不仅进口了燃料,同时也进口了宝贵的冷能。不同气化管输压力下LNG的可利用冷能和冷能的品位或利用价值有很大的不同。阐述了常压LNG和加压LNG气化时可利用冷能的数量和冷能的品位或低温价值所发生的变化。讨论了LNG冷能的梯级利用和LNG加压气化后天然气的外输压力问题。认为目前我国最应关注的是以成熟的LNG冷能利用技术为基础,在现有和即将建设的LNG接收站尽可能充分地利用冷能。接收站在规划之初就应同时把冷能的利用给予通盘考虑。对接收站的建设提出了建议。

LNG冷能回收及梯级利用研究进展

本文在分析LNG冷能利用特点的基础上,根据“高能高用、低能低用、温度对口、梯级利用”原理,总结了LNG冷能用于发电、空气分离、海水淡化、CO_(2)捕获和低温冷库等单元利用的工艺方法、温位区间、工质选择以及优缺点,对比了现有的LNG冷能梯级利用工艺温度范围,以实现温位的良好匹配。并分别针对大型LNG气化站、小型LNG气化站和大型远洋LNG船舶,给出LNG冷能梯级利用的具体方案。

Heat transfer behavior of AZ80-1%Y alloy during low-frequency electromagnetic casting

Heat transfer behaviors of AZ80?1%Y alloy during low frequency electromagnetic casting (LFEC) and direct chilling casting were studied by in-situ temperature measurement. The results demonstrated that the low frequency electromagnetic field (EM) caused forced convection in the melt during LFEC. The forced convection led to uniform solidification velocity and temperature field. EM frequency, excitation current intensity and casting temperature could control the heat transfer behavior. The forced convection could improve the microstructure and degrade the difference in microstructure between the edge and center of billet. Appropriate parameters of low frequency EM for casting Mg alloy are 20 Hz of frequency and 60 A of electric current intensity.

Strained Si Channel Heterojunction pMOSFET Using 400℃ LT-Si Technology

A novel MBE-grown method using low-temperature (L T) Si technology is introduced into the fabrication of strained Si channel heter ojunction pMOSFETs.By sandwiching a low-temperature Si layer between Si buffer and SiGe layer,the strain relaxation degree of the SiGe layer is increased.At th e same time,the threading dislocations (TDs) are hold back from propagating to t he surface.As a result,the thickness of relaxed Si 1-xGe x epitax y layer on bulk silicon is reduced from several micrometers using UHVCVD to less than 400nm(x=0.2),which will improve the heat dissipation of devices.AFM t ests of strained Si surface show RMS is less than 1.02nm.The DC characters meas ured by HP 4155B indicate that hole mobility μ p has 25% of maximum enhanc ement compared to that of bulk Si pMOSFET processed similarly.

Preparation and evaluation of ophthalmic thermosensitive in situ gels of penciclovir

Aim To develop pluronic F127 （PF127） based formulations of penciclovir （PCV） aimed at enhancing its ocular bioavailability. Methods Thermosensitive in situ gels of penciclovir were prepared through combination of HPMC K4M or carbopol 934P and pluronic F127. Optimized formulations were examined through measuring gelation temperature, rheology speciality, drug release behavior, pharmacokinetics and ocular irritation. Results The gelation temperature was reduced by adding HPMC K4M or carbopol 934P, and the viscosity was enhanced slightly. Either HPMC K4M or carbopol 934P delayed the release of PCV from in situ gel. PCV was released by non-Fickian diffusion. The study of ocular irritation for different PCV formulations did not show any irritation or damage for the cornea. PCV bioavailability from combination of carbopol 934P and pluronic F127 gels was higher than that obtained from any other gels. Conclusion Pluronic F127 formulations of PCV can be used as liquid for administration by instilling into the eye. Facilitated by the appropriate eye temperature, the formulations were transformed to gel phase. On the basis of in vitro and in vivo results, PCV formulations containing HPMC K4M or carbopol 934P and low concentration of pluronic F127 （12%） showed potential for use as a drug delivery system with improved ocular bioavailability.

Effects of supersonic fine particles bombarding on thermal barrier coatings after isothermal oxidation

This work was attempted to modify the current technology for thermal barrier coatings（TBCs） by adding an additional step of surface modification,namely,supersonic fine particles bombarding（SFPB） process,on bond coat before applying the topcoat.After isothermal oxidation at 1000 °C for different time,the surface state of the bond coat and its phase transformation were investigated using X-ray diffraction（XRD）,scanning electron microscopy（SEM） equipped with energy-dispersive X-ray spectrometry（EDS）,transmission electron microscopy（TEM） and Cr3＋ luminescence spectroscopy.The dislocation density significantly increases after SFPB process,which can generate a large number of diffusion channels in the area of the surface of the bond coat.At the initial stage of isothermal oxidation,the diffusion velocity of Al in the bond coat significantly increases,leading to the formation of a layer of stable α-Al2O3 phase.A great number of Cr3＋ positive ions can diffuse via diffusion channels during the transient state of isothermal oxidation,which can lead to the presence of（Al0.9Cr0.1）2O3 phase and accelerate the γ→θ→α phase transformation.Cr3＋ luminescence spectroscopy measurement shows that the residual stress increases at the initial stage of isothermal oxidation and then decreases.The residual stress after isothermal oxidation for 310 h reduces to 0.63 GPa compared with 0.93 GPa after isothermal oxidation for 26 h.In order to prolong the lifespan of TBCs,a layer of continuous,dense and pure α-Al2O3 with high oxidation resistance at the interface between topcoat and bond coat can be obtained due to additional SFPB process.

Integration of Low-level Waste Heat Recovery and Liquefied Nature Gas Cold Energy Utilization

Two novel thermal cycles based on Brayton cycle and Rankine cycle are proposed, respectively, which integrate the recovery of low-level waste heat and Liquefied Nature Gas （LNG） cold energy utilization for power generation. Cascade utilization of energy is realized in the two thermal cycles, where low-level waste heat,low-temperature exergy and pressure exergy of LNG are utilized efficiently through the system synthesis. The simulations are carried out using the commercial Aspen Plus 10.2, and the results are analyzed. Compared with the conventional Brayton cycle and Rankine cycle, the two novel cycles bring 60.94% and 60% in exergy efficiency, respectively and 53.08% and 52.31% in thermal efficiency, respectively.

Atomistic simulation of thermal effects and defect structures during nanomachining of copper

Molecular dynamics （MD） simulations of monocrystalline copper （100） surface during nanomachining process were performed based on a new 3D simulation model. The material removal mechanism and system temperature distribution were discussed. The simulation results indicate that the system temperature distribution presents a roughly concentric shape, a steep temperature gradient is observed in diamond cutting tool, and the highest temperature is located in chip. Centrosymmetry parameter method was used to monitor defect structures. Dislocations and vacancies are the two principal types of defect structures. Residual defect structures impose a major change on the workpiece physical properties and machined surface quality. The defect structures in workpiece are temperature dependent. As the temperature increases, the dislocations are mainly mediated from the workpiece surface, while the others are dissociated into point defects. The relatively high cutting speed used in nanomachining results in less defect structures, beneficial to obtain highly machined surface quality.

Improvement of strength and ductility of Al-Cu-Li alloy through cryogenic rolling followed by aging

To develop an improved approach in achieving an excellent combination of high strength and ductility,the solutionized Al?Cu?Li plates were subjected to rolling at cryogenic and room temperatures,respectively,to a reduction of83%,followed by aging treatment at160°C.The results indicate that Al?Cu?Li alloys through cryogenic rolling followed by aging treatment possess better mechanical properties.Rolling at cryogenic temperature produces a high density of dislocations because of the suppression of dynamic recovery,which in turn promotes the precipitation of T1(Al2CuLi)precipitates during aging.Such high density of T1precipitates enable effective dislocation pinning,leading to an increase in strength and ductility.In contrast,room temperature rolled alloys after aging treatment exhibit lower strength and ductility due to low density of T1precipitates in the grain interior and high density of T1precipitates around subgrain boundaries.

Identification of Superoxide O2^- during KNO3-NaNO2-NaNO3 Salt by Electron UV-Vis Absorption Spectroscopy Thermal Decomposition of Molten Paramagnetic Resonance and

On account of excellent thermal physical properties, molten nitrates/nitrites salt has been widely employed in heat transfer and thermal storage industry, especially in concentrated solar power system. The thermal stability study of molten nitrate/nitrite salt is of great importance for this system, and the decomposition mechanism is the most complicated part of it. The oxide species O2^2- and O2^- were considered as intermediates in molten KNO3-NaNO3 while hard to been detected in high temperature molten salt due to their trace concentration and low stability. In this work, the homemade in situ high temperature UV- Vis instrument and a commercial electron paramagnetic resonance were utilized to supply evidence for the formation of superoxide during a slow decomposition process of heat transfer salt （HTS, 53 wt% KNO3/40 wt% NaNO2/7 wt% NaNO3）. It is found that the superoxide is more easily generated from molten NaNO2 compared to NaNO3, and it has an absorption band at 420-440 nm in HTS which red shifts as temperature increases. The band is assigned to charge-transfer transition in NaO2 or KO2, responsible for the yellow color of the molten nitrate/nitrite salt. Furthermore, the UV absorption bands of molten NaNO2 and NANO3 are also obtained and compared with that of HTS.

Enhanced photocatalytic NO removal and toxic NO2 production inhibition over ZIF‐8‐derived ZnO nanoparticles with controllable amount of oxygen vacancies

The controlled introduction of oxygen vacancies(OVs)in photocatalysts has been demonstrated to be an efficient approach for improving the separation of photogenerated charge carriers,and thus,for enhancing the photocatalytic performance of photocatalysts.In this study,a two‐step calcination method where ZIF‐8 was used as the precursor was explored for the synthesis of ZIF‐8‐derived ZnO nanoparticles with gradient distribution of OVs.Electron paramagnetic resonance measurements indicated that the concentration of OVs in the samples depended on the temperature treatment process.Ultraviolet–visible spectra supported that the two‐step calcined samples presented excellent light‐harvesting ability in the ultraviolet‐to‐visible light range.Moreover,it was determined that the two‐step calcined samples presented superior photocatalytic performance for the removal of NO,and inhibited the generation of NO2.These properties could be attributed to the contribution of the OVs present in the two‐step calcined samples to their photocatalytic performance.The electrons confined by the OVs could be transferred to O2 to generate superoxide radicals,which could oxidize NO to the final product,nitrate.In particular,the NO removal efficiency of Z 350‐400(which was a sample first calcined at 350℃ for 2 h,then at 400℃ for 1 h)was 1.5 and 4.6 times higher than that of Z 400(which was one‐step directly calcined at 400℃)and commercial ZnO,respectively.These findings suggested that OV‐containing metal oxides that derived from metal‐organic framework materials hold great promise as highly efficient photocatalysts for the removal of NO.

Calculation of Equation of State of QCD at Finite Chemical Potential and Temperature

In this paper, using path integral techniques we derive a model-independent formula for the pressure density P（μ, T） （or equivalently the partition function） of Quantum Chromodynamics （QCD）, which gives the equation of state （EOS） of QCD at finite chemical potential and temperature. In this formula the pressure density P（μ, T） consists of two terms： the first term （p（μ, T）｜T=0） is a μ-independent （but T-dependent） constant; the second term is totally determined by G[μ, T]（p, ωn） （the dressed quark propagator at finite μ and finite T）, which contains all the nontrivial μ-dependence. Then, in the framework of the rainbow-ladder approximation of the Dyson-Schwinger （DS） approach and under the approximation of neglecting the μ-dependence of the dressed gluon propagator, we show that G[μ, T]（p,ωn） can be obtained from G[T]（p,ωn ） （the dressed quark propagator at μ= 0） by the substitution ωn →ωn ＋ iμ. This result facilitates numerical calculations considerably. By this result, once C [T] （p, ωn） is known, one can determine the EOS of QCD under the above approximations （up to the additive term p（μ, T）｜T=0）. Finally, a comparison of the present EOS of QCD and the EOS obtained in the previous literatures in the framework of the rainbow-ladder approximation of the DS approach is given. It is found that the EOS given in the previous literatures does not satisfy the thermodynamic relation ρ（μ,T） =δp（μ,T）/δμ｜T.

Optical Fiber Instrument for Single-point Multi-parameter Measurement

A novel kind of optical fiber instrument for two channel measurement of temperature and displacement was developed. Four channel quartz fiber optics were employed to measure two channel signals of temperature and displacement simultaneously, and the operating efficiency of this instrument was greatly improved.