Local Temperature Measurements Research Articles

Applications of a remote sensing-based two-source energy balance algorithm for mapping surface fluxes without in situ air temperature observations

The two-source energy balance (TSEB) model uses remotely sensed maps of land–surface temperature (LST) along with local air temperature estimates at a nominal blending height to model heat and water fluxes across a landscape, partitioned between dual sources of canopy and soil. For operational implementation of TSEB, however, it is often difficult to obtain representative air temperature data that are compatible with the LST retrievals, which may themselves have residual errors due to atmospheric and emissivity corrections. To address this issue, two different strategies in applying the TSEB model without requiring local air temperature data were tested over a typical Mediterranean agricultural area using a set of high-resolution multispectral airborne remote sensing images. Alleviating the need for accurate local air temperature data as input, these two approaches estimate the surface-to-air temperature gradient that drives the sensible heat flux by directly exploiting the information available in the image. The two approaches include: 1) a scene-based internal calibration (TSEB-IC) procedure that estimates air temperature over a well-watered and fully vegetated pixel in the LST image, and 2) a disaggregation scheme (DisALEXI) that uses air temperature estimates from a time-differential coupled TSEB-atmospheric boundary layer model of atmosphere–land exchange (ALEXI). A comparison of the air temperatures modeled by TSEB-IC and DisALEXI with in situ weather station observations shows good agreement, with average differences on the order of 1K, comparable with the uncertainties in the remotely sensed surface temperature maps. Surface fluxes estimated by each method agree well with micro-meteorological measurements acquired over an olive orchard within the aircraft imaging domain. In comparison with fluxes generated with TSEB using local measurements of air temperature, instantaneous fluxes from these alternative methods show good spatial agreement, with differences of less than 10Wm−2 across the domain. Finally, a sensitivity analysis of the three models, performed by introducing artificial errors into the model inputs, demonstrates that the DisALEXI and TSEB-IC approaches are relatively insensitive to errors in absolute surface temperature calibration, while turbulent fluxes from TSEB applications using local air temperature measurements show sensitivity of approximately 30Wm−2 per degree temperature perturbation. This highlights the value of both internal calibration and time-differential estimation of the surface-to-air temperature gradient within a surface energy balance framework.

Local temperature measurement of 1 bar gas in a TEM nanoreactor

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Infra-red thermography of laminar heat transfer during early thermal development inside a square mini-channel

Infra-red thermography (IRT) has been employed to experimentally scrutinize the thermo-hydrodynamics of very early part of hydrodynamically fully developed, but thermally developing, internal laminar flow of water (850⩾Re⩾100) in a mini-channel of square cross-section (5mm×5mm; aspect ratio=1.0; Dhyd 5mm). The channel is machined on that face of an aluminum substrate whose dimensions are 11mm×140mm; the total width of the substrate being 45mm. A constant heat flux boundary condition is provided on the substrate face which is opposite to that on which the mini-channel is machined. Thus, the mini-channel receives heat from three sides; the fourth side being covered by an insulating poly-carbonate material. IRT provides non-intrusive and high-resolution spatial measurement of local wall temperature in the streamwise direction. By assuming a one-dimensional heat transfer model in the transverse direction, the local value of heat flux and therefore the Nusselt number, in the thermally developing region, can be estimated. Moreover, a 3D conjugate heat transfer numerical model, exactly corresponding to the real experimental conditions, has also been developed. The conjugate effects in the experiment arising due to the substrate, as well as the high heat transfer coefficient in the early thermal development zone, are analyzed. The errors and discrepancy in the in situ boundary conditions which may creep in due to such effects, especially in the estimation of transport coefficients in the developing flow region, are scrutinized and delineated. It is concluded that experimental estimation of local heat flux is a primary requirement for minimizing the errors in estimating local Nusselt number in developing flows. This in turn, necessitates the use of non-intrusive field measurement techniques, such as IRT.

Study on the mechanism of the oxidation of soot on Fe2O3 catalyst

The present paper deals with the mechanism of the soot oxidation on Fe2O3 catalyst. The catalytic oxidation of soot is essential for the regeneration of diesel particulate filters already applied for vehicles and working machines. A series of mechanistic studies were conducted including systematic variation of reaction conditions, isotopic labelling (18O2) and local temperature measurements by using an IR camera. These investigations provided knowledge on the transfer of oxygen from the gas-phase to catalyst and soot, the heat distribution on the surface of the catalyst/soot mixture and the effect of crucial parameters on the kinetics, i.e. heating rate, contact mode (tight vs. loose) and catalyst/soot ratio. From these examinations the following insights were derived: (1) Lattice oxygen of Fe2O3 is drastically involved in the soot oxidation by migration from the bulk to the soot. Therefore, the ratio of catalyst/soot directly affects the total amount of oxygen transported from catalyst to soot. (2) In another route, oxygen is “pumped” from the gas-phase via the Fe2O3 surface to the soot. (3) The oxygen transfer from Fe2O3 to soot mainly occurs by physical contact points. (4) The local temperature in the catalyst/soot mixture strongly depends on the amount and heat capacity of the catalyst, respectively, i.e. the catalyst acts as a temperature buffer. Thus, an optimum ratio of catalyst/soot exists reflecting a compromise of high number of contact points (high catalyst mass) and low heat capacity (low catalyst mass).Consequently, a global reaction mechanism of the catalytic soot oxidation on Fe2O3 was suggested. This mechanism implies the formation of oxygen defect sites as a result of the oxygen transfer to the soot. These defect sites are refilled either by migration of surface oxygen and re-oxidation by gas-phase oxygen, respectively, or by bulk oxygen. The resulting oxygen deficiency of the bulk is balanced by migration of oxygen from the surface or sub-surface.

Composite materials with embedded photonic crystal fiber interferometric sensors

A feasibility study of smart composite materials with embedded photonic crystal fiber (PCF) sensors for measurements of local and average strain and temperature is presented in this paper. For this purpose a composite material sample with embedded fiber sensors is fabricated and characterized. For temperature independent local strain measurements a short length PCF modal interferometer is utilized, while for an average strain measurement a polarization maintaining PCF Sagnac interferometric sensor is used. The strain and temperature sensitivities of a buffer coated and a buffer stripped PM-PCF Sagnac fiber loop mirror sensors are measured in free space and compared to those for similar sensors embedded in the composite material. It is found that the Sagnac interferometer with an acrylate coated PCF embedded in the composite material shows the same response as the one in free space while the unbuffered PCF Sagnac interferometric sensor which is temperature insensitive in free space shows significant temperature sensitivity when embedded in the composite material sample. A fiber Bragg grating array is also embedded in the composite material for comparison of the strain and temperature measured by the PCF modal interferometers. The results obtained in this study demonstrate that PCF sensors are a feasible technology that can be adapted for composite material strain measurement.

Conjugate heat transfer characterization in cooling channels

Cooling technology of gas turbine blades, primarily ensured via internal forced convection, is aimed towards withdrawing thermal energy from the airfoil. To promote heat exchange, the walls of internal cooling passages are lined with repeated geometrical flow disturbance elements and surface non-uniformities. Raising the heat transfer at the expense of increased pressure loss; the goal is to obtain the highest possible cooling effectiveness at the lowest possible pressure drop penalty. The cooling channel heat transfer problem involves convection in the fluid domain and conduction in the solid. This coupled behavior is known as conjugate heat transfer. This experimental study models the effects of conduction coupling on convective heat transfer by applying iso-heat-flux boundary condition at the external side of a scaled serpentine passage. Investigations involve local temperature measurements performed by Infrared Thermography over flat and ribbed slab configurations. Nusselt number distributions along the wetted surface are obtained by means of heat flux distributions, computed from an energy balance within the metal domain. For the flat plate experiments, the effect of conjugate boundary condition on heat transfer is estimated to be in the order of 3%. In the ribbed channel case, the normalized Nusselt number distributions are compared with the basic flow features. Contrasting the findings with other conjugate and convective iso-heat-flux literature, a high degree of overall correlation is evident.

The effect of rainstorms on adult Anopheles funestus behavior and survival

We describe the effect that the passage of a cold front, with a subsequent heavy rainstorm ten days later, had on a population of Anopheles funestus mosquitoes collected exiting houses or in light-traps from a village in southern Mozambique. Temperature effects explained 40% (r=0.634; p <0.001) of the variation in numbers of males collected and 19% of the variation in gravid females collected (r=0.437; p=0.033). The age structure of mosquitoes varied according to distance from the breeding site (χ(2) = 64.1, df 6, p <0.001). The proportion of parous insects that were caught in the light-traps with sacs (χ(2) = 6.33, d.f. 2, p=0.042) and young insects that had mated before being collected (χ(2) = 13,3, d.f. 2, p=0.001) were reduced on the night of the rain but this effect was short lived. It is concluded that the effect of rain on mosquito populations depends on the kind of water body used for larval development.

Effect of Urban Catchment Composition on Runoff Temperature

AbstractUrban runoff adversely impacts cold-water stream environments due to sporadic fluxes of thermally enriched runoff. This adversely impacts tourism in regions that support trout and salmon streams. Research on storm water control measures (SCMs) has shown that meeting the 21°C trout threshold is not consistently feasible with current SCM technologies. Thus, it is important to consider other factors in storm water temperature management, such as catchment characteristics. Median and maximum runoff temperatures from a shaded parking lot were consistently lower than those from a nearby unshaded lot. This suggests the need to implement a tree canopy cover in trout-sensitive catchments. A light-colored chip seal pavement was compared to a traditional hot-mix asphalt pavement; the light-colored chip seal produced median storm water temperatures that were 1.4°C lower than the standard hot-mix asphalt. It was shown that runoff temperature measurement location is critical when evaluating SCM performance, and...

Local heat transfer coefficient for pool boiling of R-134a and R-123 on smooth and enhanced tubes

The current paper presents experimental investigation of nucleate pool boiling of R-134a and R-123 on enhanced and smooth tubes. The enhanced tubes used were TBIIHP and TBIILP for R-134a and R-123, respectively. Pool boiling data were taken for smooth and enhanced tubes in a single tube test section. Data were taken at a saturation temperature of 4.44°C. Each test tube had an outside diameter of 19.05mm and a length of 1m. The test section was water heated with an insert in the water passage. The insert allowed measurement of local water temperatures down the length of the test tube. Utilizing this instrumentation, local heat transfer coefficients were determined at five locations along the test tube. The heat flux range was 2.5–157.5kW/m2 for the TBIIHP tube and 3.1–73.2kW/m2 for the TBIILP tube. The resulting heat transfer coefficient range was 4146–23255W/m2.°C and 5331–25950W/m2.°C for both tubes, respectively. For smooth tube testing, the heat flux ranges were 7.3–130.7kW/m2 and 7.5–60.7kW/m2 for R-134a and R-123, respectively; with resulting heat transfer coefficient ranges of 1798.9–11,379W/m2.°C and 535.4–3181.8W/m2.°C. The study provided one of the widest heat flux ranges ever examined for these types of tubes and showed significant structure to the pool boiling curve that had not been traditionally observed. Additionally, this paper presented an investigation of enhanced tubes pool boiling models.

A possibility of local measurements of ion temperature in a high-temperature plasma by laser induced ionization

A new diagnostic for local measurements of ion temperature and drift velocity in fusion plasmas is proposed in the paper. The diagnostic is based on laser induced ionization of excited hydrogen and deuterium atoms from the levels which ionization energy less than the laser photon energy. A high intensive laser beam ionizes nearly all the excited atoms in the beam region resulting in a quench of spontaneous line emission of the appropriate optical transitions. The measurements of the quenching emission have been used in the past for local measurements of hydrogen atom density in tokamak plasma. The idea of the new diagnostic is spectral resolution of the quenching emission. The measured spectrum relates directly to the velocity distribution of the excited atoms. This distribution is strongly coupled to the distribution of the hydrogen atoms at the ground state.So, the spectral resolution of quenching emission is a way of local measurements of the temperature and drift velocity of hydrogen atoms in plasma. The temperature of hydrogen atoms is well coupled to the local ion temperature as long as the mean free path of the atoms is shorter than the ion gradient length in plasma. In this case the new diagnostic can provide local measurements of ion temperature in plasma. The paper considers technical capabilities of the diagnostic, physical restrictions of its application and interpretation of the measurements.

A review of the tolerability of the candidate TB vaccine, MVA85A compared with BCG and Yellow Fever vaccines, and correlation between MVA85A vaccine reactogenicity and cellular immunogenicity

BackgroundThe development of a new, more effective vaccine against tuberculosis (TB) for use in healthy and HIV-infected adults, children and infants, remains a global health priority. MVA85A is a candidate tuberculosis vaccine designed to enhance immunity to the existing vaccine, Bacillus Calmette-Guerin (BCG). MVA85A entered clinical trials in 2002 and has now progressed to Phase IIb proof-of-concept efficacy trials in infants and HIV-infected adults in Africa. MethodsA detailed analysis was conducted of the cumulative safety data of intradermal delivery of MVA85A in 112 healthy adult subjects in a series of open label, single arm, non-controlled, Phase I safety and immunogenicity clinical trials in the UK. The trials differed with respect to previous mycobacterial exposure, vaccine regime and dose. Objective safety measures (local reaction size and body temperature) were evaluated for correlations with adaptive antigen-specific immune responses. ResultsAll subjects in the combined mid-dose group developed a local reaction, of which 92% were mild, 8% were moderate and no reactions were severe. Around 90% of subjects in each group reported at least one systemic adverse event, most commonly headache, myalgia, malaise, feeling feverish, fatigue and arthralgia. Of all systemic adverse events in the combined mid-dose group, 96% were mild, 3% were moderate and 1% were severe (but none of these were judged to be vaccine-related). Pre-vaccination mycobacterial exposure did not affect the adverse event profile. The size of local reaction and frequency of systemic adverse events increased with MVA85A vaccine dose. There were no documented fevers in the low-dose group, whilst 3% of subjects in the combined mid-dose group and 21% in the high-dose group had documented fevers. Peak local reactions were larger after a second poxvirus vaccination, but other local and systemic adverse events were comparable to a single MVA85A vaccination. No severe systemic AEs or serious adverse events in any group were judged to be vaccine-related. Local AEs compared favourably to BCG vaccine-induced local AE and systemic AEs after MVA85A vaccination were comparable to those after the live viral Yellow Fever vaccine in similar populations. There were no correlations found between local reaction size or body temperature and adaptive immune responses (measured by ex vivo interferon gamma Enzyme Linked Immunospot). ConclusionsThe candidate TB vaccine, MVA85A has been safely administered to over 100 healthy adults in the UK. Intradermal vaccination with MVA85A induced a transient, superficial reaction local to the injection site and mild short-lived viral symptoms. The local and systemic AE profile of MVA85A vaccination was comparable to published data of other intradermal vaccines and live viral vaccines respectively. Local reaction sizes and body temperature measurements did not correlate with the adaptive cellular immune response to MVA85A.

Simulation and Implementation of an Attractiveness based On-Demand Routing Algorithm for Wireless Sensor Networks

A sensor network with an on-demand data centric routing strategy is presented. The routing between the sensor nodes and the data sink(s) (base station/s) is based on attractiveness-metric (Pa) gradients for the data forwarding decisions within the network. The performance of Pa based routing was simulated by the multi-agent simulation tool NetLogo and compared with the popular and widely used Dynamic Source Routing (DSR) algorithm. Additionally, to test the long term stability and the performance of the Pa based routing algorithm, several sensor nodes for local temperature and humidity measurement were placed in wine yards to monitor the risk of downy mildew infection.

Probing for inclusions in heat conductive bodies

This work deals with an inverse boundary value problem arising from the equation of heat conduction. Mathematical theory and algorithm is described in dimensions 1--3 for probing the discontinuous part of the conductivity from local temperature and heat flow measurements at the boundary. The approach is based on the use of complex spherical waves, and no knowledge is needed about the initial temperature distribution. In dimension two we show how conformal transformations can be used for probing deeper than is possible with discs. Results from numerical experiments in the one-dimensional case are reported, suggesting that the method is capable of recovering locations of discontinuities approximately from noisy data.

The effects of temperature and hydrodynamics on the crystallization fouling under cross flow conditions

Crystallization fouling experiments were performed in a channel for a cross flow of hot saturated sodium sulphate (Na2SO4) solution over a pipe containing cold water. The heat transfer coefficient and fouling thermal resistance were determined from measurements of local surface temperature and the thickness of the crystalline fouling layer. A systematic assessment of the asymptotic variation of these parameters with time was obtained for a range of hot salt solution Reynolds number based on pipe diameter (RehD) of 165–485, salt solution bulk temperature of 30 °C–50 °C, and cold water (at 5 °C) Reynolds number in the pipe (Rec) of 7500–25000. It was found that the temperature of the salt solution has a large effect on the fouling rate. Increasing the pipe surface temperature decreases the crystallization fouling rate. Increasing the hot solution Reynolds number, via the velocity, decreases the fouling thermal resistance, while increasing the cold water Reynolds number, via the velocity, decreases the fouling thermal resistance, but at the same time it increases the fouling layer thickness. The crystallization process that applies here was found to be under activation control (i.e. chemical kinetic control) so that the mass transport of salt plays only a minor role.

Key Issues in Microscale Temperature Sensing with Thermocouple Array

Precise local temperature measurement is important for research on failure analysis of integrated circuits, micro/nano-fluidics, chemistry reactions in confined geometry, biological and biochemical reactions, etc. Thermocouple arrays are believed powerful for local temperature sensing at the microscale with high spatial, temporal, and temperature resolutions. And, as a passive device, a thermocouple array can often be embedded in a complicated solid device, providing real-time temperature information of critical regions of the device. In this work, we will discuss in detail some key issues of temperature sensing at the microscale by using thermocouple arrays, in terms of material, fabrication, calibration, measurement, time-resolvable mapping, and potential application.

Local temperature measurements on nanoscale materials using a movable nanothermocoupleassembled in a transmission electron microscope

A nanoscale thermocouple consisting of merged Cu and Cu–Ni tips is developed for localtemperature measurements on advanced nanomaterials by using a probing technique in ahigh-resolution transmission electron microscope (TEM) equipped with a double probescanning tunneling microcopy (STM) unit. The fabricated nanothermocouple works as theso-called T-type thermocouple and displays a quick response and high spatialand thermal resolutions. A generated thermoelectromotive force which reflectsrapid temperature changes controlled by electron beam intensity alternations on ametal nanoelectrode proves the technique’s usefulness for high-precision localtemperature measurements. The developed method demonstrates the effectivenesswhile also measuring temperature changes in Joule heated multi-walled carbonnanotubes (CNTs) and in a modeled electrical conductive composite nanosystem.

Low Mass Quality Flow Boiling in Microtubes at High Mass Fluxes

In this article, an experimental study on boiling heat transfer and fluid flow in microtubes at high mass fluxes is presented. De-ionized water flow was investigated over a broad range of mass flux (1000 kg/m2s–7500 kg/m2s) in microtubes with inner diameters of ∼ 250 μm and ∼685 μm. The reason for using two different capillary diameters was to investigate the size effect on flow boiling. De-ionized water was used as working fluid, and the test section was heated by Joule heating. Heat transfer coefficients and qualities were deduced from local temperature measurements. It was found that high heat removal rates could be achieved at high flow rates under subcooled boiling conditions. It was also observed that heat transfer coefficients increased with mass flux, whereas they decreased with local quality and heat flux. Moreover, experimental heat flux data were compared with partial boiling correlations and fully developed boiling correlations. It was observed that at low wall superheat values, there was only a small inconsistency between the experimental data and the conventional partial boiling prediction method of Bergles, while the subcooled and low quality fully developed boiling heat transfer correlation of Kandlikar could fairly predict experimental results at high wall superheat values.

Statistical analysis of turbulent thermal free convection over a horizontal heated plate in an open top cavity

An experimental study of the thermal field established, over a horizontal heated plate (1000 × 500 × 12 mm 3) in an open top cavity, of aspect ratio Γ = 2 has been conducted by means of local temperature measurements as a function of distance from the wall. The working fluid was air at atmospheric pressure and the imposed temperature conditions correspond to Rayleigh numbers (Ra) of order 10 8. Temperature measurements were accomplished on the centerline over the plate using a fine thermocouple ( d = 0.025 mm). The thermal boundary layer thickness was estimated close to 2.0 mm. Distributions of mean and rms temperatures are presented and discussed along with the corresponding skewness and flatness distributions. The dependence of skewness and flatness factors of the overall probability density function (PDF) of an intermittent random process is illustrated. Based on these results the form of the temperature PDFs over the plate is discussed. It is shown that the exponential form of the distributions observed in the present experiments, as in several experiments in hard turbulence, is compatible with the intermittent presence of fluid structures with different origin and past history, which did not have the time to become homogenized. Power spectra density results at the same locations indicate the presence of a characteristic angular frequency ω p , whereas secondary peaks observed at higher frequencies provide further support to the concept of an intermittent process and the presence of fluid structures with different past history.

O 2 rotational temperature measurements by coherent microwave scattering from REMPI

This Letter reports non-intrusive local rotational temperature measurements of molecular oxygen, based on coherent microwave scattering (Radar) from Resonance Enhanced Multi-Photon Ionization (REMPI) in air and in pure oxygen with subsequent analysis of the rotational state distribution. Rotationally resolved 2 + 1 REMPI spectra of molecular oxygen (C 3Π ( v = 2) ← X 3Σ ( v′ = 0)) at different temperatures have been obtained by Radar REMPI. Rotational temperatures have been determined from the Boltzmann plots of various experiments. The overall measurements have an accuracy of ∼60 °C in the pure oxygen and ∼50 °C in the room air, with experiments conducted up to 500 °C.

Local temperature measurements in turbulent rotating Rayleigh-Bénard convection

We present local temperature measurements of turbulent Rayleigh-Bénard convection with rotation about a vertical axis. The fluid, water with Prandtl number about 6, was confined in a cell with a square cross section of 7.3×7.3 cm(2) and a height of 9.4 cm. Temperature fluctuations and boundary-layer profiles were measured for Rayleigh numbers 1×10(7)<Ra<5×10(8) and Taylor numbers 0<Ta<5×10(9). We present statistics of the temperature field measured by a single thermistor located along the vertical centerline of the cell or by an array of thermistors distributed laterally from that centerline. The statistics include the mean temperature, standard deviation, skewness, and the probability distribution functions at various locations in the cell, especially near and inside the thermal boundary layer. The effects of rotation on these quantities are discussed including the presence of a rotation-dependent mean vertical temperature gradient, the negative skewness of temperature fluctuations in the boundary layer, and the horizontal homogenization of temperature.