温度计量技术进展近况

近年来，在把ITS－90更方便地传递到工作用温度计，温度测量仪表采用信息技术和特殊工业场合测温应用方面均取得了一些进展。本文介绍了国内外温度技术在这些方面进展的状况。对温度定点，校验器，热电偶和热电阻测温，辐射测温，光纤测温和信息时代自动化系统中的温度检测仪表的重要进展分别作了介绍。     

Cryogenic thermometry with a common diode: Type BAS16

Cryogenic test experiments often require a large number of temperatures to be monitored. In order to reduce cost, we investigated the feasibility of low-cost common diodes. We chose the Philips BAS16 diode in a type SOT23 package. By means of Stycast 2850FT, these diodes were glued into alumina holders. In total, 20 sensors were assembled and tested. With an excitation current of 100 μA and considering a temperature range from 50 K to room temperature, a quadratic least-squares-fit was obtained: T = 486.1 − 363.7V − 38.3V². All sensors agreed with this fit within an error of 1.3 K.     

Recent advances in coherent anti-Stokes Raman scattering spectroscopy: Fundamental developments and applications in reacting flows

Coherent anti-Stokes Raman scattering (CARS) spectroscopy is widely used for measuring temperature and species concentration in reacting flows. This paper reviews the advances made over the last twelve years in the development and application of CARS spectroscopy in gas-phase reacting flows. The advent of high-power nanosecond (ns) lasers and off-the-shelf compact picosecond (ps) and femtosecond (fs) lasers is enabling the rapid expansion of the application of single-shot or high-bandwidth CARS spectroscopy in a way that would have been quite unimaginable two decades ago. Furthermore, compact ps lasers are paving the way for the development of a fiber-based CARS system for use in harsh environments. The objective of this paper is to provide an overview of recent progresses in ns-, ps-, and fs-CARS spectroscopy for gas-phase thermometry and species-concentration measurements since the second edition of A.C. Eckbreth's book entitled Laser Diagnostics for Combustion Temperature and Species, which was published in 1996. During the last two decades, four encompassing issues have driven the fundamental development and application of CARS spectroscopy in reacting flows: 1) measurement of temperature and concentration of multiple species with one CARS system, 2) extension of the application of traditional ns-CARS to challenging reacting flow environments, 3) performance of nonresonant background-free and collision-free measurements in high-pressure reacting flows, and 4) measurement of temperature and species concentration at high bandwidth, typically 1 kHz or greater, to address the instability and transient phenomena associated with turbulent reacting flows in the combustors and augmentors of modern propulsion systems. This review is focused on identifying and discussing the recent results of gas-phase CARS spectroscopy related to the four issues mentioned above. The feasibility of performing high-bandwidth CARS spectroscopy with one laser beam as well as the potential of tailored fs lasers for thermometry and species-concentration measurements in gas-phase reacting flows are also discussed.     

Effect of processing parameters on structural,morphological and optical Y2O3:Yb3+/Ho3+ powders characteristics

Rod-like and flake-like up-converting Y₂O₃:Yb³⁺/Ho³⁺ particles which are composed of nanoparticles with size less than 100 nm, are prepared by a simple hydrothermal processing at 473 K (3 h) followed by additional thermal treatment at 1373 K (3 and 12 h). The effect of precursor pH value on the formation of Y₂O₃:Yb³⁺/Ho³⁺ is followed through X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Structural refinement confirms formation of the cubic bixbyte structure (S.G. Ia-3) with the non-uniform accommodation of dopants at C₂ and S₆ cationic sites. Under 978 nm laser excitation, strong green (530–570 nm) up-conversion is observed in all samples. The emission shows a decrease in intensity with an increase in external temperature, indicating FIR (fluorescence intensity ratio) based temperature sensing behavior of 0.52% for the ⁵F₄ → ⁵I₈/⁵S₂ → ⁵I₈ transitions.     

Development of Nanoscale Temperature Measurement Technique Using Near-field Fluorescence

A nanoscale thermal system design, especially for the precise measurement of the temperature distribution in microfabricated devices using novel nanomaterials such as carbon nanotubes and fullerene has become increasingly important along with the development of nanotechnology. A new approach has been proposed toward an optical nanoscale temperature measurement method using near-field optics and fluorescence thermometry, namely, Fluor-NOTN (fluorescent near-field optics thermal nanoscopy). The topographic image and temperature dependence of a fluorescently modified sample, excited by near-field light, are simultaneously monitored. In this article, the temperature dependence of Cy3 fluorescent dye is verified near room temperature (298–308 K). A Cy3 mono-dispersed sample of a permalloy (Ni₈₁Fe₁₉) wire heater, 500 nm in width and 100 nm in thickness, is designed and fabricated. A localized temperature gradient of ΔT = 4 K within a submicron distance from the heater was successfully detected by near-field fluorescence with 100 nm spatial resolution.     

Fast grain boundary: A FORTRAN-77 program for calculating the effects of retrograde interdiffusion of stable isotopes

Exchange of stable isotopes between coexisting minerals is recognized widely as an important factor in the interpretation of stable isotope geochemistry of plutonic and high-grade metamorphic rocks. Where retrogression has occurred without major recrystallization events, the rate limiting step for stable isotope exchange will be diffusion. The mathematics of diffusion are well known for many problems, but no analytical solution, including that for closure temperature, adequately describes the complex and highly variable controls of rate and mass balance that will dominate many diffusion processes in rocks. We have implemented a model describing diffusional exchange for rocks in which grain boundary diffusion is sufficiently rapid that a representative volume of rock (typically millimeter to centimeter) is able to have mutual equilibration of all grain boundaries for the time scale of cooling. This Fast Grain Boundary model explicitly links intracrystalline diffusion rates and abundances of all minerals in a rock, and allows study of the impact of rock type on stable isotope thermometry, retrogression, and zonation.The FORTRAN-77 program for the Fast Grain Boundary model presented here can be used with a personal computer to solve typical problems in minutes. Input includes the grain size(s), model abundance(s), diffusion coefficient, and fractionation factor for each constituent mineral, and a cooling rate for the rock. Output includes the diffusion profile and integrated (bulk) composition of every mineral in a rock, as well as the apparent temperatures that would be observed by applying bulk-mineral stable isotope thermometry to such a rock.     

Ferroelectric,upconversion emission and optical thermometric properties of color-controllable Er3+-doped Pb(Mg1/3Nb2/3)O3-PbTiO3-Pb(Yb1/2Nb1/2)O3 ferroelectrics

The (0.98-x)(0.6Pb(Mg_1/3Nb_1/3)O₃-0.4PbTiO₃)-xPb(Yb_1/3Nb_1/3)O₃-0.02Pb(Er_1/2Nb_1/2)O₃ ((0.98-x)(PMN-PT)-xPYN:Er³⁺) ceramics were prepared through a solid-state reaction method. The phase structure, piezoelectric response, ferroelectric performance and upconversion emission of the ceramics were systematically investigated. The phase structure, the electrical and optical properties are strongly related to the content of PYN. The optimized piezoelectric response and upconversion emissions of the ceramics were achieved near x = 0.12, which locates in the morphotropic phase boundary (MPB) composition. Furthermore, the temperature sensing behaviors of the resultant compounds based on the thermally coupled levels of ²H_11/2 and ⁴S_3/2 of Er³⁺ ions in the temperature range of 133–573 K were studied by utilizing the fluorescence intensity ratio technique. Additionally, the thermal effect, which is induced by the laser pump power, of the studied ceramics is also investigated and the produced temperature is enhanced from 268 to 348 K with the pump power rising from 109 to 607 mW.     

Dihydropyridine derivatives as controllers for production of hydrogen during zinc dissolution

Two of dihydropyridine derivatives, namely, 4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (DPCN) and 4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carboxamide (DPCA) were evaluated as controllers for H₂ production during the dissolution of Zn in dilute HCl. Different chemical (thermometry, gravimetry, and gasometry) and electrochemical (potentiodynamic polarization and impedance) techniques were used. SEM and optical profilometry surface investigations for some corroded and un-corroded Zn samples were carried out to describe the Zn surface during the dissolution process. The rate of H₂ production was found to increase with the immersion time and temperature and was lowered by the inhibitor. The potentiodynamic data proved that DPCN and DPCA inhibit the dissolution of Zn according to a mixed-type mechanism.     

Evaluation of sensor materials for ultrasonic thermometry In coal gasification systems

The success of ultrasonic thermometry, in coal gasification systems depends on the selection of approprzate sensor materzal(s) that can withstand the hostile environment exhibit good. acoustic sen~itivity to temperature and show long-term stability or reproducibility of acoustic properties in the environment. Six candidate materials SS 310, Incoloy 800, sapphire, alumina, spinel and chrome oxide - were selected based on pilot-plant. experience and laboratory studies of materials performance in coal galasification environments. They were exposed in two simulated coal gasification environment, Westinghouse low-Btu (British thermal unit) at 871°C for 15 hand Texaco medium-Btu at 982°C for 15 h. The physical and acoustic properties of the materzals before and after exposure to the gasification environments are presented, together With a discussion on the long-term performance predictions of the materials for ultrasonic thermometry.     

Ethanol flame structure investigated by molecular beam mass spectrometry

The oxidation of ethanol was studied in low-pressure, premixed flat flames using molecular beam mass spectrometry (MBMS) in combination with electron impact ionization (EI) and resonance-enhanced multiphoton ionization (REMPI). Flame temperature profiles were measured by laser-induced fluorescence (LIF) of seeded NO. Two ethanol/oxygen/argon flames with stoichiometries of ?=1.00 and ?=2.57 were investigated at 50 mbar by EI-MBMS. Profiles of a variety of stable and radical species were measured as a function of height above the burner. The benzene profile in the fuel-rich ethanol flame was obtained by REMPI-MBMS. The same technique was used to determine the dependence of the benzene concentration on the ethanol/propene ratio in low-pressure flames with blended fuels (propene/ethanol/oxygen/argon). The C/O ratio of all blends was kept constant at C/O=0.773 or C/O=0.600. Ethanol addition ranged from 0 to 15% for flames with C/O=0.773, and from 0 to 100% for flames with C/O=0.600. In both data sets, a decrease of the benzene concentration with increasing ethanol percentage was observed. Qualitative information on some other aromatic species with higher mass was also obtained.