Gas Temperature Measurements Research Articles

Ammonia emissions and dry deposition in the vicinity of dairy farms

We conducted the first research in the Czech Republic to measure ventilation and ammonia (NH 3 ) emission rates in a naturally ventilated animal building (dairy farm) during a five-day measurement period in June, combined with a three-month (May-July) monitoring of NH 3 concentration and dry deposition at 12 locations along horizontal gradients from the dairy farm up to the distance of 400 m. Passive diffusion-tube samplers were used to measure monthly NH 3 concentrations. Moisture (H 2 O) balance was used to determine ventilation rates of the dairy farm. Continuous measurements of gas concentrations (NH 3 ), temperature and relative humidity inside and outside the building were performed. The air exchange rate was 4.8 h –1 and the emission rate was 43.2 NH 3 g cow –1 d –1 for building. The emission rate was 126% of what was obtained using emission factors from the Czech national inventory (34.2 g cow –1 d –1 ). NH 3 concentrations and dry deposition fluxes decreased exponentially with distance from the dairy farm. Between May and July, mean predicted dry deposition fluxes ranged from 0.28 to 0.03 µg NH 3 m –2 s –1 at a distance of 50 and 400 m from the source, respectively. Dry NH 3 deposition over the nearest 400 m from the source accounted for 11.5% of daily emissions. The results confirm the short-range dispersion of NH 3 emitted from a point source found in other studies, but it may not be the same in other situations, since dispersion of NH 3 is dependent on the surrounding land-cover and on the number of animals in a barn.

An ATCA Survey of H i Absorption in the Magellanic Clouds. I. H i Gas Temperature Measurements in the Small Magellanic Cloud

Abstract We present the first results from the Small Magellanic Cloud portion of a new Australia Telescope Compact Array H i absorption survey of both of the Magellanic Clouds, comprising over 800 hr of observations. Our new H i absorption line data allow us to measure the temperature and fraction of cold neutral gas in a low-metallicity environment. We observed 22 separate fields, targeting a total of 55 continuum sources, against 37 of which we detected H i absorption; from this we measure a column-density-weighted mean average spin temperature of = 150 K. Splitting the spectra into individual absorption line features, we estimate the temperatures of different gas components and find an average cold gas temperature of ∼30 K for this sample, lower than the average of ∼40 K in the Milky Way. The H i appears to be evenly distributed throughout the SMC, and we detect absorption in 67% of the lines of sight in our sample, including some outside the main body of the galaxy (N H i cm−2). The optical depth and temperature of the cold neutral atomic gas show no strong trend with location spatially or in velocity. Despite the low-metallicity environment, we find an average cold gas fraction of ∼20%, not dissimilar from that of the Milky Way.

Dynamic transport and reaction behaviour of high-pressure gases in high-rank coal

This paper presents the results obtained through continuous and simultaneous measurements of gas flow, temperature and coal deformation during high-pressure gas injection in high-rank coal samples, obtained from the South Wales coalfield (UK). The results demonstrate that CO2 flow rates experience an initial decline due to internal coal swelling, followed by the flow rate recovery and global coal swelling. As the flow of high-pressure CO2 induces measurable temperature drop within the sample related to the Joule-Thomson cooling, the changes induced by the variations in thermal state of the system are associated with abrupt shift in coal response to reactive gas flow. However, subsequent injections of He and N2 show that the changes induced by CO2 sorption on coal permeability to gases are irreversible. This work demonstrates the importance of considering the coupled reactive gas and heat transport, and consequent coal deformation mechanisms while assessing the storage potential of coal seams.

CPFD simulation of petcoke and SRF co–firing in a full–scale cement calciner

Computational particle fluid dynamics (CPFD) simulation is carried out to study the effect of petcoke and solid recovered fuel (SRF) co–firing in a full–scale cement calciner. The simulations are conducted using the Multi–Phase Particle–In–Cell (MP–PIC) approach with the Barracuda Virtual Reactor® 17.3.1 solver. The results from the CPFD simulation are compared with extensive field measurements of gas temperature and composition at several points in different calciner cross–sections. In the simulation, the SRF particles are divided into three components of plastic, biomass, and inert. The plastic particles go through drying, melting and decomposition while the conversion of biomass particles involves drying, devolatilization, and char oxidation. The predicted concentrations of O2 and CO2 are in good agreement with the measurements, while the gas temperature is overpredicted, especially in the lower calciner vessel. However, the trends of changes in the gas temperature are well–captured. The converted fuel fraction and calcination factor are predicted with an acceptable degree of accuracy. The simulation results show that large biomass particles in SRF tend to leave the calciner without complete conversion. Furthermore, a recirculation pattern for SRF particles is observed in the lower calciner vessel and the conical section, leading to high conversion degree of this fuel.

Spectroscopic study of CO2 and CO2–N2 mixture plasma using dielectric barrier discharge

Nowadays, increasing concentration of CO2 in the atmosphere is a major threat for the environment and is a main reason for global warming. Variation in gas temperature and dissociation of CO2 into its by-products (CO and O) in a home-made dielectric barrier discharge (DBD) reactor have been reported as a function of discharge parameters, i.e., applied voltage and gas flow rate. To estimate the dissociation fraction of CO2 in the DBD reactor, the optical emission actinometry technique is employed in which 5% N2 is used as an actinometer. Emission lines of the Angstrom band of CO at 451.09 nm (B1∑ +v′=0−A1π, v″=0) and the 2nd positive system of N2 at 337.01 nm (C3πuv′=0−B3πg,v″=0) are used for actinometry measurements. To estimate the rate coefficients used in actinometry measurements, gas temperature is measured using the Boltzmann plot technique, from the rotational spectra of the Q-branch of the Angstrom band CO (0–1). To avoid discrepancy in gas temperature measurements, rotational temperature of the 2nd positive system, the N2 (0–1) band, is also measured. For this, synthetic spectra have been fitted over the experimentally recorded spectrum of the N2 (0–1) band. A slight difference in gas temperature has been noted for the Angstrom band of CO and the 2nd positive system of nitrogen. Conversely, an increasing trend in the dissociation fraction of CO2 with an increase in the applied voltage is noted. About 34% dissociation fraction is achieved for 10 kV applied voltage at a flow rate of 25 SCCM. With an increase in the gas flow rate (25–200 SCCM), a decrease in the dissociation fraction of CO2 from 34% to 11% is noted.

Application of Semi-automatic Program for Gas Temperature Measurement in Atmospheric Pressure Plasmas Using a Synthetic Diatomic Molecular Spectrum Method

Application of Semi-automatic Program for Gas Temperature Measurement in Atmospheric Pressure Plasmas Using a Synthetic Diatomic Molecular Spectrum Method

Numerical Investigation on Metrological Fidelity of a Shielded Thermocouple Probe and the Effects of Geometrical Parameters

Abstract Proper design optimization and precise error characterization of temperature sensing-elements are rudimentary in the field of high accuracy gas temperature measurements. The intricate flow structures and heat transfer mechanisms related to a shielded thermocouple probe are studied in this paper using computational fluid dynamics and conjugate heat transfer (CFD/CHT) simulation tools. Owing to the probe’s novel geometry, it was a pre-requisite to characterize the metrological fidelity of the probe and the steady-state errors were determined from the simulations. The influence of certain geometrical parameters on the error characteristics of the probe was also investigated. The characteristic variation of the metrological fidelity of the probe with respect to those geometrical parameters should facilitate the optimization of the probe design.

Numerical model for the determination of the reduced electric field in a CO2 microwave plasma derived by the principle of impedance matching

Three dimensional electromagnetic modelling of a free-standing CO2 microwave plasma has been performed, by describing the plasma as a dielectric medium. The relative permittivity and conductivity of the medium are parametrised. The waveguide geometry from the experiment, including the tuner, is put into the model, knowing that this corresponds to maximum power transfer of the microwave generator to the plasma under plasma impedance matching conditions. Two CO2 plasma discharge regimes, differing mainly in pressure, input power and temperature, have been studied. The model’s validity has been checked through study of materials of known conductivity. From measurements of the neutral gas temperature and the plasma electron density profile, the reduced electric field is determined. From the parametrisation of the dielectric properties, a range for the effective electron-neutral collision frequency for momentum transfer is estimated. The results for the reduced electric field and the range of the electron neutral collision frequency obtained, are consistent as verified by simulations using BOLSIG+. In addition, from this comparison it is possible to narrow down the range of the collision frequencies, and to estimate the electron temperature. The reduced electric field lies between 80 and 180 Td for the relatively low pressure, low input power, the so-called ‘diffuse’ regime. For the relatively high pressure, high input power (‘contracted’) regime it lies between 10 and 60 Td. The normalised collision frequency lies between 1.6 and 2.3 for the diffuse regime, while for the contracted regime it lies between 2 and 3. The electron temperature ranges from 2 to 3 eV for the diffuse regime, and from 0.5 to 1 eV for the contracted regime.

Oxygen atom kinetics in CO2 plasmas ignited in a DC glow discharge

Oxygen atom densities were measured in situ in a CO2 glow discharge, at pressures between 0.2 and 5 Torr (26.7–666.6 Pa). Two measurement techniques were compared, namely optical emission actinometry (using Ar as the actinometer) and high-resolution two-photon absorption laser induced fluorescence normalised to Xe, and were found to give consistent results. The variation of the atomic oxygen density with gas pressure shows two different regimes with a transition around 1 Torr. Measurements of the O atom loss frequency under plasma exposure showed that this behaviour is caused by a change in the O atom loss mechanisms, which are dominated by surface processes in our experimental conditions. The corresponding recombination probabilities on Pyrex γO are found to vary with the gas temperature near the wall for a constant surface temperature, similarly to what has recently been obtained in pure O2. However, the measured values are more than two times lower than γO obtained in a O2 plasma in similar conditions. The O atom densities are also compared to the dissociation fraction of CO2 determined by infra-red absorption. The obtained CO and O densities show different behaviour as a function of the energy input. The simultaneous measurement of gas temperature, electric field, O, CO and CO2 densities and O atoms loss frequency in the same conditions provides an ideal set of constraints for validating CO2 plasma kinetic models.

Analysis of the heat transfer for processes of the cylinder heating in the heat-treating furnace on the basis of solving the inverse problem

This paper presents results of experimental test concerning heating of a cylinder in the furnace for heat and thermochemical treatment. Tests were conducted for heating up to temperature of 550 °C, what corresponds to nitriding processes. Calculation model including Chebyshev polynomials enabling determination of temperature distribution in the cylinder is presented.Two variants of calculation model were examined; they differ in terms of the assumed boundary condition. Analysis of regularization of the solution to the inverse problem done by the change of time step (self-regularization) was made. Based on the solution of the non-linear inverse problem for the heat equation and on the gas temperature measurement read from the furnace retort, temperature distributions on the boundary of the cylinder, combined radiation convection heat transfer coefficients (CHTC) and heat flux on the surface of the cylinder were calculated. Due to a great variability of temperature for the processes under consideration, the calculation model includes the variation of the heat conduction coefficient and of the specific heat of the material the cylinder is made of depending on temperature change. Five heating processes differing in parameters of heating rate were analysed. Impact of measurement errors on distributions of temperature on the edge of the cylinder and of the CHTC was determined. Obtained temperature distributions in the element were verified by a check measurement. Maximal error of the obtained results did not exceed 0.5%. Data presented herein give practical knowledge enabling supervising the temperature distribution in the cylindrical element being processed. These problems are of crucial meaning for processes of heat and thermochemical treatment due to formation of proper surface and subsurface layers.

DTF내 미분탄의 탈휘발 거동 해석 및 실험

Devolatilization behavior of pulverized coal in a drop tube furnace (DTF) has been calculated with the measured gas temperature and velocity. The particle temperature and velocity were calculated from the energy and momentum equations of particle by using the fourth order Runge-Kutta method. The volatile evolved from the particle along with the reactor tube was also calculated varying the wall temperature of reaction tube as well as the particle diameter. The optimal kinetic parameters of subbituminous coal were obtained from the volatile evolution data of the devolatilization experiment in the DTF by error minimization.

Study on simultaneous sensing of gas concentration and temperature in one-dimensional photonic crystal

Based on the mixed effects of the defect mode and interface state, a one-dimensional (1D) photonic crystal (PC) structure used for simultaneous gas concentration and temperature measurement is proposed. Using multiple physical field numerical module of the finite element method, the reflection spectrum with two relatively independent peaks is formed. And the wavelengths of the reflection peaks can be shifted when the concentration of the gas filled in the photonic crystal and environment temperature are changed. The defect layer thickness, metal layer thickness and period of photonic crystal are optimized. Taking the toluene as temperature-sensing medium, and the mixture of air and ethylene as gas-sensing medium, the relationships between the reflection peaks and related physical quantities are studied. Gas concentration and temperature can be measured by analyzing the relative shift of position of two reflection peaks in reflection spectrum. The results show that gas sensitivity is 500pm/1% ranging from 0% to 3% and its Q factor is 471.4. Temperature sensitivity is 88.7 pm/°C ranging from −20 °C to 70 °C and its Q factor is 415.7. The structure is simple, highly sensitive, and dual-parameter sensing. The study has reference value for simultaneously detecting harmful gas leakage and temperature in the polluted environment.

A method for natural gas forecasting and preliminary allocation based on unique standard natural gas consumption profiles

The paper reports on the development of unique standard gas consumption profiles for the end gas consumers and the preparation of a method for the implementation of the developed profiles for forecasting and preliminary gas allocation. Four years of gas consumption and temperature measurements were used to develop eight types of consumption profiles for 17 gas consumer groups, which were grouped according to their professional activity. As an alternative to the exponential, Gompertz or logistic model functions, frequently used in gas consumption model developments, the sigmoid model function is implemented and model constants for the eight types of profiles are developed based on the knowledge of the temperature independent portion of the gas consumption and separate treatment of workdays/weekends. Based on these profiles, a method was developed for the preliminary allocation of the gas consumption. The developed profiles and the gas consumption allocation method were validated on the available set of gas consumption data for the Slovenian gas market, proving the sigmoid model function based gas consumption allocation as an accurate and viable means of gas consumption forecasting.

Effect of Firefighting Intervention on Occupant Tenability during a Residential Fire

This study examines the impact of firefighting intervention on occupant tenability to provide actionable guidance for selecting firefighting tactics that are based upon empirical rather than anecdotal evidence. Twelve fire experiments were conducted utilizing a full-sized residential structure to assess the impact of firefighting tactics on occupant exposure. Six groups of firefighters, recruited from fire departments throughout the country, participated in two experiments each. Two attack tactics were examined: (1) interior attack—water applied from the interior while a search team searched for simulated trapped occupants, and (2) transitional attack—exterior water application before transitioning to the interior while a search team searched for simulated trapped occupants. Gas concentration and temperature measurements were analyzed using a fractional effective dose (FED) approach to determine the impact of firefighter tactics on the exposure for potential trapped occupants. Water application by the fire attack teams resulted in a rapid drop in temperatures throughout the structure, followed shortly afterward by a decrease in the FED rate. There was no significant difference between the magnitude of the temperature decrease or the time until the inflection point in the FED curve between transitional attack and interior attack. As the removal time for the occupant increased, the toxic exposure to the occupant increased, despite the decreasing FED rate due to suppression. Occupant tenability analysis showed that the most threatened occupants are not always closest to the seat of the fire, while occupants near the fire but behind closed doors may have received a low exposure. As such, the results emphasized the need for rapid removal of occupants and coordination of suppression and ventilation tactics to limit toxic exposures.

2D mid-infrared laser-absorption imaging for tomographic reconstruction of temperature and carbon monoxide in laminar flames

This manuscript presents the design and initial application of a mid-infrared laser-absorption-imaging (LAI) technique for two-dimensional (2D) measurements and tomographic reconstruction of gas temperature and CO in laminar flames. In this technique, the output beam from a quantum-cascade laser (QCL) is expanded, passed through the test gas, and imaged in 2D using a high-speed mid-infrared camera. The wavelength of the QCL is scanned across the P(0,20) and P(1,14) transitions of CO near 4.8 μm at 50 Hz to provide 2D measurements of path-integrated gas temperature and CO column density across over 3,300 lines-of-sight simultaneously. This enabled the first sub-second (0.1 s), high-resolution (140 μm), 2D laser-absorption measurements and tomographic reconstruction of flame temperature and CO mole fraction using mid-infrared wavelengths. Prior to entering the test gas, the beam was reflected off two diffusers spinning at 90,000 RPM (≈9400 rad/s) to break the laser coherence and prevent diffraction-induced image artifacts. This technique was validated with measurements of CO in an isothermal jet and then demonstrated in laminar, partially premixed, oxygen-ethylene flames despite large background emission from soot and combustion products.

Measurement of Gas Temperature and Concentration Based on TDLAS

The measurement of gas temperature and concentration in combustion process has always been an important part of research. Based on the application of tunable diode laser technology in gas detection, the molecular absorption spectroscopy system was established and the concentration and temperature of water vapor were measured. Based on the spectral parameters in the latest HITRAN 2016 database, a group of programs have been compiled, which adopt the form of VOIGT function and consider frequency shift caused by pressure and temperature and . The spectral absorbance of H2O was obtained by the computer program. Based on the scanning range of the laser, the spectral lines of water vapor molecule near 1392 nm were screened to obtain the suitable pairs of spectral lines for measuring temperature and concentration. The pairs of spectral lines were validated as gas temperature measurements at high temperature by numerical simulation. TDLAS system is built independently, and TDLAS technology is used to measure the gas concentration field and temperature field in an experimental way. It is of great significance for TDLAS technology in gas monitoring.

Measurement of the gas temperature of neutrals in reactive plasmas by moderate-resolution OES

Measurements of gas temperature (Tg) in the low-temperature high-density plasma of SF6 containing gas mixes were performed by OES technique. The translational temperature of plasma in the ICP discharge was measured by the method of small addition of nitrogen to the fluorine containing plasmas. Moderate resolution compact spectrometer was applied to get partially resolved rotational spectra of 2+ system of the molecular nitrogen. It is shown that Tg can reach up to 1300 K, weakly depends on investigated pressure range and linearly depends on RF power in the discharge. The absolute value of the temperature differs significantly for different tested plasmas of N2, and SF6/N2. Various aspects of the effect of Tg parameter in plasma on the processes of plasma etching of semiconductor microstructures are discussed.

Oxygen (3P) atom recombination on a Pyrex surface in an O2 plasma

The recombination of O (3P) atoms on the surface of a Pyrex tube containing a DC glow discharge in pure O2 was studied over a wide range of pressure (0.2–10 Torr) and discharge current (10–40 mA) for two fixed surface temperatures (+50 °C and +5 °C). The recombination probability, γ, was deduced from the observed atom loss rate (dominated by surface recombination) determined by time-resolved optical emission actinometry in partially-modulated (amplitude ∼15%–17%) discharges. The value of γ increased with discharge current at all pressures studied. As a function of pressure it passes through a minimum at ∼0.75 Torr. At pressures above this minimum γ is well-correlated with the gas temperature, Tg, (determined from the rotational structure of the O2 (b1Σg+, v = 0) → O2(X3Σg−, v = 0) emission spectrum) which increases with pressure and current. The temperature of the atoms incident at the surface was deduced from a model, calibrated by measurements of the spatially-averaged gas temperature and validated by radial temperature profile measurements. The value of γ follows an Arrhenius law depending on the incident atom temperature, with an activation energy in the range 0.13–0.16 eV. At the higher surface temperature the activation energy is the same, but the pre-exponential factor is smaller. Under conditions where the O flux to the surface is low γ falls below this Arrhenius law. These results are well explained by an Eley–Rideal (ER) mechanism with incident O atoms recombining with both chemisorbed and more weakly bonded physisorbed atoms on the surface, with the kinetic energy of the incident atoms providing the energy to overcome the activation energy barrier. A phenomenological ER model is proposed that explains both the decrease in recombination probability with surface temperature as well as the deviations from the Arrhenius law when the O flux is low. At pressures below 0.75 Torr γ increases significantly, and also increases strongly with the discharge current. We attribute this effect to incident ions and fast neutrals arriving with sufficient energy to clean or chemically modify the surface, generating new adsorption sites. Discharge modeling confirms that at pressures below ∼0.3 Torr a noticeable fraction of the ions arriving at the surface have adequate kinetic energy to break surface chemical bonds (>3–5 eV).

Identification of damages in the inlet air duct of a diesel engine based on exhaust gas temperature measurements

The temperature of the exhaust gas of a diesel piston engine, measured in the characteristic control sections of its thermo-flow system, can be a valuable source of diagnostic information about the technical condition of the elements limiting the working spaces thus separated, including the turbocharging system, but also its fuel supply system and replacement of the medium. In standard marine engine measurement systems equipped with an impulse turbocharging system, the exhaust gas temperature is measured at the outlet of individual cylinders and before and after the turbocharger turbine, using traditional thermocouples with high measurement inertia (time constant of tenths of a second and more). This means that for further diagnostic analyses, the average value of the periodically changing temperature of the exhaust stream leaving individual engine cylinders, the exhaust stream in the collective duct feeding the turbine and the exhaust stream in the exhaust duct of the turbine is used. This article proposes a new approach to the issue of diagnostic informationiveness of the exhaust gas temperature of a diesel engine, extending its observations with the dynamics of changes in the duration of one working cycle. The aim of the tests carried out on the laboratory stand of Farymann Diesel engine type D10 was to determine the diagnostic relations between the loss of permeability of the inlet air channel filter baffle and selected standards of the quick-changing signal of the exhaust gas temperature. On the basis of the calculations carried out, the following dynamic features of the recorded signal were determined: maximum amplitude of instantaneous exhaust gas temperature values (peak-to-peak value), its rate of increase and decrease, and the specific enthalpy of exhaust gases within one engine work cycle. Comparative analysis of numerical data characterizing the recorded quick-changing exhaust gas temperature courses clearly indicates obvious thermodynamic and energy consequences of partial loss of flow capacity of the air channel supplying the combustion chamber of the test engine. A further development of the experimental test programme is foreseen in order to determine a diagnostic matrix to support the diagnostic inference about the technical condition of the diesel engine on the basis of measurements and analysis of the quick-changing exhaust gas temperature.

Optical clumped isotope thermometry of carbon dioxide

Simultaneous analysis of carbon dioxide isotopologues involved in the isotope exchange between the doubly substituted 13C16O18O molecule and 12C16O2 has become an exciting new tool for geochemical, atmospheric and paleoclimatic research with applications ranging from stratospheric chemistry to carbonate-based geothermometry studies. Full exploitation of this isotope proxy and thermometer is limited due to time consuming and costly analysis using mass spectrometric instrumentation. Here, we present an all optical clumped CO2 isotopologue thermometer with capability for rapid analysis and simplified sample preparation. The current development also provides the option for analysis of additional multiply-substituted isotopologues, such as 12C18O2. Since the instrument unambiguously measures all isotopologues of the 12C16O2 + 13C16O18O rightleftharpoons 13C16O2 + 12C16O18O exchange, its equilibrium constant and the corresponding temperature are measured directly. Being essentially independent of the isotope composition of the calibration gas, an uncalibrated working reference is sufficient and usage of international calibration standards is obsolete. Other isotopologues and molecules can be accessed using the methodology, opening up new avenues in isotope research. Here we demonstrate the high-precision performance of the instrument with first gas temperature measurements of carbon dioxide samples from geothermal sources.