Quantitative Temperature Measurements Research Articles

Spray and Flame Structure of a Generic Injector at Aeroengine Conditions

In support of the development of CFD for aeroengine combustion, quantitative measurements of spray properties and temperature were made. A generic swirling air blast injector was designed and built to produce well defined inlet conditions and for ease of numerical description for the CFD development. The measurements were performed in an optically accessible single sector combustor at pressures of 4 and 10 bar and preheat temperatures of 550 and 650 K, respectively. Jet A-1 was used as fuel. The burner air to fuel ratio was 20 and the pressure loss was set to 3%. Sauter mean diameter profiles and liquid mass flux distributions were generated from the phase Doppler anemometry measurements of the evaporating spray drop sizes and velocities. With planar measurements of Mie scattering and kerosene-LIF, the distribution of kerosene (liquid and vapor phase) was imaged. Temperatures were measured with OH-LIF. The burner was designed with a straight outlet to exhibit lifted flames. Hence initial distributions of size, velocity and density of the spray were measured before it entered the flame. Almost complete prevaporization was seen at least for the four bar flame. Compared with atmospheric investigations, the smaller diameters of the droplets and the small streamline curvature of the configuration led to a more uniform behavior of the spray.

Background-oriented schlieren visualization of heating and ventilation flows: HVAC-BOS

There is an important need for simple methods to visualize and measure whole-field airflow patterns in the HVAC field. The background-oriented schlieren (BOS) method is presented here as an answer to this need—a simple and effective method for visualizing refractive HVAC flowfields in situ. The equipment required is simple, portable, inexpensive, and readily available, thus superseding some previous approaches, including lens-and-grid schlieren techniques that require large fixed installations. For BOS a custom random-dot background pattern is used, and imaging is done by a consumer-grade digital single-lens-reflex (SLR) camera. After covering the principles of BOS, examples are shown of visualized airjets and plumes from heating vents and registers, a space-heater, a teakettle, and a human thermal plume and cough. BOS images of candle plumes are also used to explore several different visualization approaches, equipment arrangements, and image color scales. While current results are purely-qualitative visualizations, quantitative temperature measurements can also be made in certain cases where the flow is approximately two dimensional. Finally, BOS lends itself well to certain HVAC chores, such as the diagnosis of commercial kitchen ventilation airflows.

Quantitative temperature measurement of an electrically heated carbon nanotube using the null-point method

Previously, we introduced the double scan technique, which enables quantitative temperature profiling with a scanning thermal microscope (SThM) without distortion arising from heat transfer through the air. However, if the tip-sample thermal conductance is disturbed due to the extremely small size of the sample, such as carbon nanotubes, or an abrupt change in the topography, then quantitative measurement becomes difficult even with the double scan technique. Here, we developed the null-point method by which one can quantitatively measure the temperature of a sample without disturbances arising from the tip-sample thermal conductance, based on the principle of the double scan technique. We first checked the effectiveness and accuracy of the null-point method using 5 μm and 400 nm wide aluminum lines. Then, we quantitatively measured the temperature of electrically heated multiwall carbon nanotubes using the null-point method. Since the null-point method has an extremely high spatial resolution of SThM and is free from disturbance due to the tip-sample thermal contact resistance, and distortion due to heat transfer through the air, the method is expected to be widely applicable for the thermal characterization of many nanomaterials and nanodevices.

Fluoranthene laser-induced fluorescence at elevated temperatures and pressures: implications for temperature-imaging diagnostics

The objective of this study is to develop a quantitative measurement of temperature from fluoranthene fluorescence under conditions with elevated temperatures and pressures. Absorption and fluorescence of fluoranthene are studied in a pressure and temperature range of 0.1–4 MPa and 473–873 K for the two excitation wavelengths of 266 and 355 nm. The influence of thermodynamic parameters such as pressure, temperature and gas composition is characterized in a high-pressure and high-temperature facility. When increasing the pressure, the vibrational relaxation mechanisms are favored, which involves an increase of the fluorescence quantum yield. Concerning the temperature effect, the fluorescence decreases with increasing temperature, this is explained by efficient radiative mechanisms of intersystem crossing. The quenching effect is strongly efficient in air, with a fluorescence evolution described by the Stern–Volmer relation. Over the temperature range studied, the fluorescence quantum yield decreases exponentially by two orders of magnitude. From the temperature dependence of fluoranthene fluorescence in different ambient gases for 266 and 355 nm excitation, the potential temperature measurements in homogeneously and inhomogeneously seeded systems are suggested: the single-color detection technique, the single-excitation two-color detection technique and the dual-excitation wavelength technique.

A Clinical Investigation into the Relationship between Increased Periwound Skin Temperature and Local Wound Infection in Patients with Chronic Leg Ulcers

Increased local temperature is a classic sign of wound infection, and its quantitative measurement has the potential to assist with assessment and diagnosis of chronic deep wound and surrounding skin infection at the bedside. Evidence supporting such use in chronic wound care is very limited. This clinical pilot study was conducted in an attempt to quantify the relationship between increased periwound skin temperature and wound infection, as well as validate use of a handheld infrared thermometer for the wound care practitioner. Using a cross-sectional design, 2 groups of participants were recruited from a chronic wound clinic: without wounds (n = 20) and with chronic leg ulcers (n = 40). Participant and wound characteristics were documented. All skin temperatures were documented using a handheld infrared thermometer under consistent environmental conditions within the clinic. Data analysis was based on the difference (Delta) in skin temperature (in degrees Fahrenheit) between a target or wound site and an equivalent contralateral control site. Wound infection was identified using the combination of a validated assessment tool and clinical judgment. Supplemental semiquantitative bacterial swabs were collected from all wounds. Descriptive statistics were analyzed using the chi-squared calculation. A Pearson r calculation of test-retest skin temperature data collected from nonwounded participants initially determined reliability of the infrared thermometer. Correlation of increased periwound skin temperature to wound infection was determined by calculation of a 1-way analysis of variance. The infrared thermometer was found to be reliable (r = 0.939, P = .000 at a 95% confidence interval). A statistically significant relationship between increased periwound skin temperature and wound infection was identified (F = 44.238, P = .000 at a 95% confidence interval). Neither patient nor wound characteristics were significantly different between the participants with noninfected or infected wounds. The results of this study demonstrate that incorporating quantitative skin temperature measurement into routine wound assessment provides a timely and reliable method for a wound care practitioner to quantify the heat associated with deep and surrounding skin infection and to monitor ongoing wound status. Study limitations may reduce transferability of these findings to wound types other than chronic leg ulcers. Further research is needed to support and strengthen these results.

Non-invasive tissue temperature measurements based on quantitative diffuse optical spectroscopy (DOS) of water

We describe the development of a non-invasive method for quantitative tissue temperature measurements using Broadband diffuse optical spectroscopy (DOS). Our approach is based on well-characterized opposing shifts in near-infrared (NIR) water absorption spectra that appear with temperature and macromolecular binding state. Unlike conventional reflectance methods, DOS is used to generate scattering-corrected tissue water absorption spectra. This allows us to separate the macromolecular bound water contribution from the thermally induced spectral shift using the temperature isosbestic point at 996 nm. The method was validated in intralipid tissue phantoms by correlating DOS with thermistor measurements (R = 0.96) with a difference of 1.1 ± 0.91 °C over a range of 28–48 °C. Once validated, thermal and hemodynamic (i.e. oxy- and deoxy-hemoglobin concentration) changes were measured simultaneously and continuously in human subjects (forearm) during mild cold stress. DOS-measured arm temperatures were consistent with previously reported invasive deep tissue temperature studies. These results suggest that DOS can be used for non-invasive, co-registered measurements of absolute temperature and hemoglobin parameters in thick tissues, a potentially important approach for optimizing thermal diagnostics and therapeutics.

The basics and issues of Thermochromic Liquid Crystal Calibrations

Thermochromic Liquid Crystals (TLCs) have been widely used by researchers in heat transfer and fluid flow communities as a thermal imaging tool for mapping surface and spatial temperature distributions. In order to utilize TLCs for quantitative temperature measurements, calibration is first necessary to determine the colour–temperature relationship of TLCs. This paper is aimed to provide novice and intermediate users of TLCs with a review on the basics and issues pertaining to calibrations of TLCs, particularly for surface thermography. A general overview of TLCs, the basic elements of a TLC calibration rig, and the common calibration methods of TLCs are described. The crucial issues associated with calibrations of TLCs, namely, imaging, colourimetry, illumination, hysteresis, film thickness and aging, and the methods used to compensate for these effects are discussed. This paper is intended to provide useful information to novice and intermediate users of TLCs, particularly on TLC calibrations.

Thermographic Monitoring of Aluminium Foaming Process

A novel method for measuring the temperature distribution and evolution of metal foams in the molten state is proposed. Foamable AlSi9 precursor material containing 0.6 wt% TiH2 was foamed, kept at high temperatures and solidified while its temperature distribution was monitored by a thermographic camera. Free foaming and foaming inside a closed mould were carried out and direct and screened IR monitoring have been tested. Different heating conditions were applied giving rise to homogeneous and inhomogeneous temperature distributions. The effect of oxidation was studied on a piece of pure aluminium for reference purposes. The error sources of the measured temperature were analysed. Direct monitoring of foams was shown to be associated to serious problems with quantitative temperature measurement, while screened monitoring yielded promising and accurate quantitative results.

Heat Transfer Characterizations of Heat Pipe in Comparison With Copper Pipe

The article presents some significant experimental data for studying the heat transfer behavior of heat pipe, which will further help the cooling efficiency improvement of the heat pipe cooler. It is well known that the heat pipe owns the extreme large heat conductivity and is often integrated with cooling plates for CPU cooling. The heat pipe uses special heat transfer techniques to obtain extremely large heat conductivity, which are the inside liquid evaporation for heat absorption and the inside microstructural capillarity for condensation. These special techniques yield the instant heat transfer from the heat source to the remote side directly, but the special heat transfer behavior is changed due to the integration with cooling plates. The destroyed heat transfer behavior of the heat pipe causes the cooling efficiency of the heat pipe cooler to be not able to reach a predicted good value. To improve the cooling efficiency of the heat pipe cooler we recover the original heat transfer behavior of the heat pipe integrated with cooling plates. This work first built a CPU simulator in accordance with the ASTM standard for heating the heat pipe, then uses the color schlieren technique to visualize the sequent heat flux nearby the heat pipe and the infrared thermal camera for quantitative temperature measurements synchronously. The result shows that the heat flux first appears at the opposite side from the heat source and there exhibits also the highest temperature. This is different from the heat transfer behavior of the copper pipe. Another very interesting result is that the heat flux of the cooling plate nearest to the heat source is first viewed than the others, which is similar to the integration with the copper pipe.

Quantitative scanning thermal microscopy using double scan technique

Although scanning thermal microscope has shown the highest spatial resolution in local temperature and thermophysical property measurement, its usefulness has been severely limited due to difficulties in quantitative measurement. We propose a double scan technique that measures temperature only from the heat transfer through the tip-sample contact by the subtraction of the signal due to the heat transfer through the air. A rigorous theoretical model for this technique is derived. The effectiveness of the double scan technique in quantitative temperature measurement is demonstrated experimentally.

516 赤外線分光放射温度計の開発(一般セッション)

The earlier infrared sensing, two-colored technique, was further discussed for developing a more general method of measuring temperature quantitatively under near-ambient conditions. The three-colored technique for quantitative temperature measurement is newly proposed by applying three kinds of infrared filters simultaneously. The respective filters concerned have selective wavelength band several μm in width in the range of 7〜14μm. The applicability was confirmed using numerical simulation to allow a parametric study of how the result varies for different values of emissivity corresponding to the individual infrared filters. The new method has a feature which allows quantitative temperature measurement for target surfaces at each picture element without presuming any emissivity, reflectively and ambient conditions, so that it may be useful across various medical or engineering disciplines.In this survey, we investigated the measurement error experimentally, and the adaptability was evaluated in terms of the surround disturbance and directional characteristics on the technique.

An experimental study of unsteady natural convection in a reservoir model cooled from the water surface

The general characteristics of unsteady natural convection flow in a reservoir model cooled from the water surface are presented in this paper. Flow visualization was carried out using thermo-chromic liquid crystals, and quantitative temperature measurements were conducted using a PIT (particle image thermometry) technique. The experimental photographs clearly show different stages of the flow development including the growth of a thermal boundary layer below the water surface, the onset of convective instabilities, and further flow development. The present results indicate that the convective motions in reservoirs induced by night-time cooling have a significant impact on water quality and transport of nutrients and pollutants.

905 自動車生産工程向け赤外線分光放射温度計の開発

The multi-colored technique for quantitative temperature measurement is proposed by combining several kinds of infrared filters. The respective filters concerned have selective wavelength band several ,u m in width in the range of 2-13 L m. The applicability is confirmed using numerical simulation to allow a parametric study of how the result varies for different values of emissivity corresponding to the individual infrared filters. An experimental investigation is also performed to evaluate the measurement error and the adaptability of the technique. This method has a feature which allows quantitative temperature measurement for target surfaces at each picture element without presuming any emissivity, reflectively and ambient conditions, so that it may be useful across various medical or engineering disciplines.

C113 2色レーザー誘起蛍光法を用いたマイクロ電気泳動における温度分布の可視化(温度計測)

"2-Color Laser-induced Fluorescence" (2C-LIF) is a novel quantitative temperature measurement method in micro fluidic flow. In a conventional method (1-Color LIF), the undesirable spatio-temporal noise could prevent from quantitative measurement, which is originated from unstable excitation light intensity and channel configuration. In contrast, 2C-LIF can eliminate the undesirable influence using a ratio-metric technique with two fluorescence images, because fluorescence intensities can be approximately a linear function of the excitation light. Therefore, it can obtain quantitative temperature distribution, thus simplify temperature calibration in micro channel. In this study, 2C-LIF was applied to micro-electrophoretic flow, and then local Joule heating by loading high electric field could be visualized according to complicated channel configuration. Consequently, the spatial intensity error could be reduced to about 95% as compared with 1-Color LIF image. The temperature distribution in microchannel was quantitatively measured with high resolution 0.12×0.12μm, temperature sensitivity 1.51%/K with accuracy ±0.45%/K.

CARS spectroscopy of CH 4 for implication of temperature measurements in supercritical LOX/CH 4 combustion

Experimental and theoretical investigations of coherent anti-Stokes Raman spectroscopy of CH 4 have been carried out. Experimental spectra were measured in a heated high-pressure test cell and compared with numerical simulations. Good agreement was obtained for the temperature and the pressure dependence of CARS spectra in the ranges 300–1100 K and 0.1–5.0 MPa. The observed dependencies provide useful guidance for CARS thermometry, allowing quantitative measurements of temperature in high-pressure combustors. Application of multiplex CH 4 CARS thermometry for single-shot measurements in a LOX/CH 4 combustion at high pressure was demonstrated at supercritical conditions (5.6 MPa).

Effects of a volcanic plume on thermal imaging data

Ground‐based thermal imaging is becoming an increasingly important tool for volcano surveillance, however the impact of volcanic plumes on quantitative measurements of surface temperature has not been previously evaluated. Here we use a radiative transfer model to simulate gas (primarily H2O and SO2) and aerosol absorptions over the path between a thermal camera and a heat source on Stromboli volcano, Italy. A FTIR spectrometer was used to quantify path amounts of gases likely to be encountered when making thermal measurements of the active craters. We find that when using a camera sensitive from 7.5 to 13 μm, underestimates of ∼400 K may be produced when viewing a source with an actual temperature of 1200 K. Cameras that operate between 3 and 5 μm are somewhat less susceptible to these errors.

QUANTITATIVE MEASUREMENTS OF SPECIES AND TEMPERATURE IN A DME-AIR COUNTERFLOW DIFFUSION FLAME USING LASER DIAGNOSTIC METHODS

A diffusion flame of dimethyl ether (DME) and air in a counterflow burner has been investigated experimentally by means of different laser-based methods. Quantitative measurements of temperature, O2 concentration, and OH concentration have been carried out using dual broadband rotational coherent anti-Stokes Raman Spectroscopy (CARS), Rayleigh scattering and laser-induced fluorescence (LIF). Furthermore a qualitative formaldehyde profile has been measured using LIF. The measured profile has been compensated for fluorescence signal quenching and the Boltzmann distribution to obtain a representative qualitative formaldehyde profile for the flame.

Spatially resolved temperature measurement in microchannels

Non-intrusive local temperature measurement in convective microchannel flows using infrared (IR) thermography is presented. This technique can be used to determine local temperatures of the visualized channel wall or liquid temperature near this wall in IR-transparent heat sinks. The technique is demonstrated on water flow through a silicon (Si) microchannel. A high value of a combined liquid emissivity and substrate overall transmittance coupled with a low uncertainty in estimating this factor is important for quantitative temperature measurement using IR thermography. The test section design, and experimental and data analysis procedures that provide increased sensitivity of the detected intensity to the desired temperature are discussed. Experiments are performed on a 13-mm long, 50 μm wide by 135 μm deep Si microchannel at a constant heat input to the heat sink surface for flow rates between 0.6 and 1.2 g min−1. Uncertainty in fluid temperature varies from a minimum of 0.60°C for a Reynolds number (Re) of 297 to a maximum of 1.33°C for a Re of 251.

5027 マイクロ電気泳動流れにおける温度分布計測(S51-2 マイクロ・ナノスケールの熱流体現象とその応用(2),S51 マイクロ・ナノスケールの熱流体現象とその応用)

"2-Color Laser-induced Fluorescence" (2-C LIF) is a novel quantitative temperature measurement method in microfluidic flow. A conventional method (1-Color LIF) measurement causes spatial random error which depends on spatio-temporal distribution of excitation light intensity. In contrast, the proposed method can cancel the undesirable influence using a ratio-metric technique with two fluorescence images, because fluorescence intensity can be approximately a linear function of the excitation light intensity. Therefore, it is possible to measure the temperature distribution quantitatively and simplify temperature calibration. In this paper, we represent the application of this method for micro-electrophoretic flow. We applied to calibrate between the temperature and ratio value which is calculated by dividing the Rhodamine B fluorescence image with the Rhodamine 110 fluorescence image. As a result, spatial intensity error can be reduced to about 90% as compared with 1-Color LIF image. We visualized temperature distribution in micro-electrophoreticwith high resolution 0.24μm×0.24μm and sensitivity 1.32%/K.

Quantitative temperature measurements in high-pressure flames with multiline NO-LIF thermometry

An accurate temperature measurement technique for steady, high-pressure flames is investigated using excitation wavelength-scanned laser-induced fluorescence (LIF) within the nitric oxide (NO) A-X(0, 0) band, and demonstration experiments are performed in premixed methane/air flames at pressures between 1 and 60 bars with a fuel/air ratio of 0.9. Excitation spectra are simulated with a computational spectral simulation program (LIFSim) and fit to the experimental data to extract gas temperature. The LIF scan range was chosen to provide sensitivity over a wide temperature range and to minimize LIF interference from oxygen. The fitting method is robust against elastic scattering and broadband LIF interference from other species, and yields absolute, calibration-free temperature measurements. Because of loss of structure in the excitation spectra at high pressures, background signal intensities were determined using a NO addition method that simultaneously yields nascent NO concentrations in the postflame gases. In addition, fluorescence emission spectra were also analyzed to quantify the contribution of background signal and to investigate interference in the detection band-width. The NO-LIF temperatures are in good agreement with intrusive single-color pyrometry. The proposed thermometry method could provide a useful tool for studing high-pressure flame chemistry as well as provide a standard to evaluate and validate fast-imaging thermometry techniques for practical diagnostics of high-pressure combustion systems.