Search

We investigate the MEMS resonant cantilevers for high-performance thermogravimetric analysis (TGA) of chemical decomposition, featuring high accuracy and minimized thermal lag. Each resonant cantilever is integrated with a microheater for sample heating near the free end, which is thermally isolated from the resonance excitation and readout elements at the fixed end. Combining finite element modeling and experiments, we demonstrate that the sample loading region can stabilize within ~11.2 milliseconds in response to a step heating of 500 °C, suggesting a very fast thermal response of the MEMS resonant cantilevers of more than 104 °C/s. Benefiting from such a fast thermal response, we perform high-performance TG measurements on basic copper carbonate (Cu2(OH)2CO3) and calcium oxalate monohydrate (CaC2O4·H2O). The measured weight losses better agree with the theoretical values with 5–10 times smaller thermal lags at the same heating rate, compared with those measured by using conventional TGA. The MEMS resonant cantilevers hold promise for highly accurate and efficient TG characterization of materials in various fields. [ABSTRACT FROM AUTHOR]

The non-isothermal crystallization kinetics of ethylene-tetrafluoroethylene copolymer (ETFE, Fluon®C-88AXP) was studied by using differential scanning calorimetry (DSC). The Jeziorny, Ozawa, Mo, and Kissinger equations have been used to describe the crystallization data. The Ozawa and Kissinger plots show downward curves instead of the linear relationship as predicted. Good linear relationship was obtained using the Jeziorny and Mo equations but no vital model parameters concerned with the crystallization kinetics could be acquired. The integral Avrami equation combining with Hoffman equation has been used to describe the crystallization data through nonlinear regression method and kinetic parameters have been acquired. The fitting quality improves when the thermal lag effect was taken into consideration. Meanwhile, the linearity of the Ozawa and Kissinger analysis is improved greatly and the Ozawa exponent and crystallization activity energy of the copolymer have been obtained. [ABSTRACT FROM AUTHOR]

Accelerating Rate Calorimetry (ARC) is a widely used adiabatic calorimetry technique to evaluate thermo-kinetics of hazardous chemical reactions. Most ARCs rely on measurement of temperature at the external wall of the ARC sphere to evaluate the temperature rise rate, and therefore exothermic reaction rate. We report large temperature gradients between the center and wall for a granulated solid sample tested using an un-stirred ARC that leads to varying spatiotemporal temperature profiles. Such gradients were found to be significantly lowered in organic liquid samples, enabling classifying some granulated solid samples as heat transfer-limited systems. This study reveals that such temperature gradients obviate estimation of representative exothermic reaction rate, manifesting in hazard underestimation through erroneous pressure and apparent conversion profiles. Next, the addition of an inert was demonstrated to reduce the magnitude of such gradients, thereby enabling relatively accurate hazard assessment and offering a potential solution. Lastly, several strategies are outlined to allow researchers to identify and mitigate the influence of gradients during hazard assessment. Researchers must be cognizant of the potential for gradients when analyzing and interpreting ARC data for thermo-kinetic modeling and hazard evaluation. During hazard evaluation, researchers should confirm that no significant gradients exist or find ways to de-sensitize their hazard assessment parameters if gradients exist and cannot be minimized. [ABSTRACT FROM AUTHOR]

We investigate the MEMS resonant cantilevers for high-performance thermogravimetric analysis (TGA) of chemical decomposition, featuring high accuracy and minimized thermal lag. Each resonant cantilever is integrated with a microheater for sample heating near the free end, which is thermally isolated from the resonance excitation and readout elements at the fixed end. Combining finite element modeling and experiments, we demonstrate that the sample loading region can stabilize within ~11.2 milliseconds in response to a step heating of 500 °C, suggesting a very fast thermal response of the MEMS resonant cantilevers of more than 104 °C/s. Benefiting from such a fast thermal response, we perform high-performance TG measurements on basic copper carbonate (Cu2(OH)2CO3) and calcium oxalate monohydrate (CaC2O4·H2O). The measured weight losses better agree with the theoretical values with 5–10 times smaller thermal lags at the same heating rate, compared with those measured by using conventional TGA. The MEMS resonant cantilevers hold promise for highly accurate and efficient TG characterization of materials in various fields.

The opercula of the gastropod Bithynia tentaculata is composed of calcite and exhibits three main thermoluminescence peaks at ∼100, 280 and 360 °C when heated at 0.5 °C.s−1. The two higher temperature peaks can be used for geological and archaeological dating, whilst the lower temperature peak has a lifetime of hours and is only seen after laboratory irradiation. This study explores whether this lower temperature TL peak can be used to assess the reproducibility of laboratory heating of opercula. As found in previous studies, the TL peak at ∼100 °C is seen to consist of at least two signals which have different lifetimes at room temperature. By fixing the interval between irradiation and measurement of the TL signal, the impact of these different lifetimes on the temperature at which the TL peak occurs (T m) can be reduced, and replicate measurements on a single operculum using the same radiation dose yield values of T m within 1 °C. Comparison of different opercula shows variation in T m of 9 °C when heating at 5 °C.s−1, interpreted as primarily arising from variation in thermal lag between the hotplate and the different samples assessed. Reducing the heating rate to 0.5 °C.s−1 reduces the variation in T m between opercula to 2 °C. Imaging the TL emission from opercula using an EMCCD shows spatial variation in heating, and also demonstrates the reduction in variability that can be achieved by using a slower heating rate. Thus, monitoring the position of the TL peak at ∼100 °C can be used to assess thermal reproducibility of TL measurements on calcitic opercula. • A TL peak at ∼100 °C in calcite is a composite of at least 2 first order peaks. • This TL peak can successfully monitor thermal reproducibility. • Thermal lag between the hotplate and opercula may cause variation in peak position. • A slow (0.5 °C.s−1) heating rate reduces the variability in peak position. • Peak position can be used as a rejection criterion to exclude data where thermal lag is too large. [ABSTRACT FROM AUTHOR]

Just like disposal of waste papers by indiscriminate dumping, stabilisation of clay soil using cement or by firing has a potential adverse effect on the environment and public health. Thus, the essence of this work was to investigate the feasibility of chemically modifying clay soils using waste papers in order to solve the disposal problems and also develop clay-based composites suitable for building purposes. Hydrothermally calcined waste paper ash nanomaterial (HCWPAN) was prepared from assorted waste papers and used to separately develop composites with white clay matrix (WCC) and yellow clay matrix (YCC) each at 0 %, 10 %, 20 %, 30 %, and 40 % volumetric proportions of replacement. Three representative samples were developed in each case. Apparent porosity, water absorption, bulk density, sorptivity, thermal conductivity, specific heat capacity, volumetric heat capacity, thermal diffusivity, thermal lag, flaking concentration, flexural strength, and compressive strength were investigated for all the samples. For satisfactory performance during service, the optimum content level of the HCWPAN was found to be 10 % in the samples. Though the WCC sample possessed greater compressive strength (4.029 ± 0.002) MPa than the value (2.895 ± 0.002) MPa obtained for the YCC sample at that level, the latter exhibited greater potential for enhancement of thermal comfort as a walling element in buildings. Also, reductions from 8.98 % to 8.00 % and 13.30 % to 12.575 % were observed in water absorption of the resulting WCC and YCC samples, respectively. From the technical–economic viewpoint, the HCWPAN is a promising material for clay soil modification for building purposes. [ABSTRACT FROM AUTHOR]

• The primary heat dissipation pathway in accelerating rate calorimeter is identified. • The main factors of this heat dissipation are analyzed. • A heat dissipation correction method based on the heat transfer model is proposed. • The validity of the proposed method is verified by numerical simulations and experiments. The accelerating rate calorimeter is a commonly used tool for evaluating thermal hazards. Due to the thermal inertia, the heat dissipation between the reaction system and the furnace, the pure adiabatic condition cannot be achieved. This leads to inaccurate thermodynamic and kinetic results. To systematically study and correct this heat dissipation, numerical simulations and experiments were carried out to investigate the main heat dissipation path and the factors. The results show that convection is the main heat dissipation pathway. The dynamic characteristics of the thermocouple and sidewall have different effects on reactions with different self-heating rates. In addition, a heat dissipation correction method based on the heat transfer model is proposed and validated by simulations and experiments. The simulation and experimental results both show the effectiveness of this correction method. These mean it has a certain significance for the improvement of the accelerating rate calorimeter experimental data processes. [ABSTRACT FROM AUTHOR]

Water or steam injection in oil fields is a common method for enhanced oil recovery in petroleum engineering. The thermoviscous fingering instability is one of the main problems of a complex nature that decreases the efficiency of oil extraction. Actually, oil wells are a porous medium with a level of anisotropy for permeability and diffusion. In this paper, the thermal viscous fingering instability in anisotropic media is investigated using both linear stability analysis and computational fluid dynamics (CFD) simulation. For stability analysis, the growth rate of disturbances is determined by solving quasi-steady-state equations via a shooting method. The CFD simulation is performed by solving the governing equations of heat and mass transfer using a spectral method. It is shown that the longitudinal direction permeability and the transverse direction dispersion have important effects on the instability. The values of the thermal-lag coefficient and the Lewis number have opposite effects on the different types of displacements considered. When porous media are swept using cold fluid, increasing the Lewis number intensifies the level of flow instability. [ABSTRACT FROM AUTHOR]

We revisit Cattaneo's derivation of the equation describing heat transfer and bearing his name, finding a more elaborated model equation, that we will compare with the time‐lagged model. This equation does not comply with the second law of thermodynamics, as well as Cattaneo equation. The latter, however, is known to have provided meaningful results in certain experiments conducted in some liquids and solids at very low temperature. These experiments also match the results given by a nonlinear model proposed by A. Morro and T. Ruggeri in 1988, which instead does meet the laws of thermodynamics. A comparison is made with such a model too. [ABSTRACT FROM AUTHOR]

This paper describes the thermal lag correction for Glider Payload Conductivity Temperature Depth Profiler data with a poor sampling rate. In particular, the thermal lag correction is more vulnerable to the influence of temperature data. According to variations in salinity with depth and the vertical downcast speed of the glider, salinity data are divided into five parts, and a method based on Morison et al. is proposed to determine the correction parameters. At 40–94 dbar and 140–280 dbar, the salinity difference is dominated by the temperature difference. At 94–140 dbar, the salinity difference is immune to the temperature difference and has a greater influence on the thermal lag-induced salinity error correction. After the sectional correction, the accuracy of the typical salinity interval is upgraded from 0.011 to 0.006 psu, which shows the effectiveness of this sectional method on correcting temperature difference. [ABSTRACT FROM AUTHOR]

This paper presents the impact of thermal lag on the progress of different coal types’ gasification by CO2. The analysis was performed using thermogravimetry and numerical modeling. Experiments were carried out at a heating rate of 1–50 Kmin−1 and a temperature ranging from 383 to 1173 K. The developed numerical model enabled the determination of a true sample temperature considering the gasification process to consist of two single-step consecutive reactions. Analysis revealed that the average thermal lag in CO2 is about 11% greater than that in N2, which is related to the properties of CO2 itself and the occurrence of the char–CO2 reaction. The onset temperature of the reverse Boudouard reaction depends on the type of fuel; however, no simple relationship with the coal rank was found. Thermal lag has an impact on the kinetic parameter Aα0.5 describing devolatilization, up to 19.8%, while in the case of the char–CO2 reaction, this influence is expected to be even greater. The performed analysis proved that disregarding thermal lag may significantly hinder the interpretation of the analyzed processes; thus, TG experiments should be carried out with a low heating rate, or at the post-processing stage, a thermal lag model needs to be employed.

In this paper, neural network and genetic algorithm is used to obtain the optimal output power of thermal lag Stirling engine. A neural network is trained and developed using the theoretical data of previous literatures in order to predict the performance of Stirling engine. Input parameters to neural network include angular velocity, thermal resistance, stroke length radius, piston diameter, the volume of heat buffer chamber and the volume of gas chamber, and output parameter includes output power. The accuracy of neural network is evaluated by average square error and regression analysis. Also, genetic algorithm is used for the optimization of the output power of the Stirling engine. The results of present study show that the neural network can be used as an appreciate tool to predict the output power of the thermal lag Stirling engine with a high precision and speed. The main deficiency of thermal lag type of Stirling engines is low output power. However, the optimization of design parameters of thermal lag Stirling engine causes an increase of 86.9% in output power. [ABSTRACT FROM AUTHOR]

Pyrolysis of synthetic or natural polymers is an important process in many industries such as fire safety, thermal recycling, and biomass power generation. The kinetics of pyrolysis is usually studied by thermogravimetric analysis (TGA), which is based on measuring the mass loss of a microscale sample and measuring the temperature of the surrounding fluid during controlled heating. The literature is rich in TGA measurements, which are often assumed to be governed solely by chemical kinetics. Heat and mass transfer effects, however, can occur when the sample mass is too large. Only a few studies in the literature quantify the threshold for the initial mass, above which heat transfer effects are significant. Here, we systematically analyse the role of heat transfer in TGA measurements, review existing formulations, and provide a novel threshold for the maximum sample mass. We focus on the natural polymer cellulose, a surrogate for biomass, and split the problem into heat transfer within the sample (intraparticle) and between the sample and the fluid (interparticle). Using dimensional analysis we derive two upper bound thresholds for the initial sample mass as a function of heating. One threshold is calculated based on interparticle heat transfer and depends on flow and heating conditions as well as material and fluid properties. The other is calculated based on intraparticle heat transfer and depends on heating conditions and material properties. Both thresholds were validated with measurements and previous studies from the literature. Comparing both thresholds shows that the maximum sample mass in a TGA is dictated by interparticle heat transfer and rapidly reduces with heating rate from 1.8 mg at 10 K/min to 0.15 mg at 50 K/min. These results enable the selection of appropriate sample masses and heating conditions in TGA measurements, which in turn will lead to a better understanding of polymer pyrolysis.

Abstract The climatic conditions characterizing the troposphere affect the outdoor activities of the population which, in turn, characterize the anthroposphere. Over the past years recent studies examined a possible analytical definition of the outdoor thermal comfort for different types of population acclimatized to their specific residency area. Thanks to the use of the MOCI (Mediterranean Outdoor Comfort Index: an index used to predict the thermal perception of the Mediterranean population in an outdoor environment), the present study aimed at analyzing the psychophysiological response of a Mediterranean subject with respect to climatic conditions different from the original ones after having experienced a quick change. Indeed, thermal stress and discomfort might affect deeply the ability of the subject to carry out outdoor activities. This condition determines the necessity of possessing useful information to plan the best period to perform a journey in distant places and/or perform useful actions that will make the outdoor activity as much comforting as possible (choosing the proper clothes with the right thermal insulation). For this reason, the worldwide environmental conditions during an average year were examined. To be more specific, this study focused its attention on the editing of seasonal spatial maps with the MOCI level curves and on the temporal analysis of the MOCI values characterizing those 6 different cities (one for each continent) reporting the higher number of foreign arrivals. Highlights • Thermal perception for a Mediterranean normotype in the world. • Use of the Mediterranean Outdoor Comfort Index (MOCI). • Annual hourly distribution of the MOCI in the most visited cities of each continent. • Frequencies and percentiles of the average weekly thermal perception's values. • Mapping of the MOCI seasonal average values in the world. [ABSTRACT FROM AUTHOR]

The thermal and hydrodynamic response of a Sea-Bird unpumped CTD SBE 41, is numerically modeled to assess the biases occurring at the slow flushing rates typical of glider operations. Based on symmetry considerations, the sensor response is approximated by coupling the incompressible Navier-Stokes and the thermal advection-diffusion equations in two dimensions. Numerical results illustrate three regimes in the thermal response of the SBE 41 sensor, when crossing water layers with different thermal signatures. A linear decay in time of the bulk temperature of the conductivity cell is initially found. This is induced by the transit of the inflow through the conductivity cell in the form of a relatively narrow jet. Water masses with new thermal signatures do not immediately fill the sensor chambers, where the cross-section widens. Thermal equilibrium of these water masses is then achieved, in a second regime, via a cross-flow thermal diffusion between the boundary of the jet and the walls. Consequently, the evolution of the bulk temperature scales with the square root of time. In a third regime, the evolution of the bulk temperature depends on the thermal gradient between the fluid and the coating material. This results on an exponential decay of the bulk temperature with time. A comprehensive analytical model of the time evolution of the bulk temperature inside a cell is proposed based on these results. [ABSTRACT FROM AUTHOR]

In the last years, people has become aware of energy saving and thermal comfort requirements for home buildings in hot and cold seasons. In the present study, hybrid multifunctional constructive components made of a reinforced mortar channel filled with cement–soil–sawdust (CL2MSCAL) were evaluated to experimentally determine their thermal performance (thermal conductivity, thermal time lag and decrement factor). The experimental analysis performed in this study was based on dynamic climatology. Measurements of components surface temperature were conducted to determine temperature damping and temperature wave lag. Monthly average temperature and direct solar radiation data of the site was considered. Measurements of real-scale constructive components were conducted on a fully equipped thermal conductive system and thermal chambers (test cells) built for this purpose. Results are compared to concrete components (CCL) that account for approximately 71.6% of the houses built in Mexico and 43.2% in Oaxaca and reinforced mortar (CML) used as prefabricated housing systems. Best results were found for component CL2MSCAL that has a thermal conductivity of 0.81 W·m−1·K−1, a thermal damping of 81.5% (decrement factor of 0.166) and time lag of 7:37 h compared to CCL that present a time lag of 1 h and decrement factor of 0.9. Thus, it is concluded that CL2MSCAL roofing channel components are an alternative for energy saving and thermal comfort. [ABSTRACT FROM AUTHOR]

Knowledge of the kinetic parameters E (thermal activation energy) and s (frequency factor) of charge-trapping defects in the quartz crystal lattice is of paramount importance to assessing the thermal stability of associated luminescence signals used for dosimetry and dating. Since methods proposed for constraining thermoluminescence (TL) kinetics usually make use of the signal response to thermal treatments, accurate temperature control is required to obtain valid E and s values. In an attempt to check the extent to which consistent kinetic parameters could be obtained using routine luminescence measurement equipment, we have investigated three methods (isothermal decay, initial rise and the Hoogenstraaten method) in an inter-comparison study involving eight laboratories using Risø and Freiberg Instruments systems. The target signal was the so-called 110 °C TL peak of a sample of Oligocene coastal dune quartz sand from the Fontainebleau sand formation (France). TL glow curves recorded with heating rates in the range 0.02–5 K s −1 showed peak positions varying up to 60 °C between systems at the highest heating rates, attributed to temperature calibration errors and/or thermal lag. Kinetic parameters derived from the complete data set show a large spread, covering the ranges ∼0.5–1.2 eV and 10 6 –10 17 s −1 for E and s . In most cases, interlaboratory variations exceeded those of replicate measurements within individual laboratories. Signal lifetimes at 20 °C derived from the isothermal decay (∼59 min) and initial rise methods (at low heating rates; ∼60–80 min) most closely match the value directly measured at 20 °C from within two luminescence readers (∼70 min). Finally, we discuss the consequences of these findings for dosimetry and dating using luminescence signals and possible ways to reduce systematic errors in laboratory measurements of kinetic parameters. [ABSTRACT FROM AUTHOR]

Calcitic snail opercula are a promising new material for thermoluminescence (TL) dating with the potential to cover the last ~3 Ma [1]. The ERC-funded Bridging Europe: a Quaternary Timescale for the Expansion and Evolution of Humans (EQuaTe) project aims to produce a secure dating framework for the earliest human occupation and expansion across Europe using this TL signal. Thermal lag is a key consideration for TL measurements and assessing the reproducibility of heating samples during TL measurement is an important but challenging issue. The potential magnitude of the problem is illustrated by Schmidt et al. [2] who reported a variation of ~60°C in the temperature of the "110 °C" TL peak from quartz grains when heating at 5 °C/s. It is unclear what proportion of this variability is due to thermal lag or incorrect calibration of hotplates. Duller et al. [3] showed that across eight different readers it was possible to reduce the variability in the "110 °C" TL peak from quartz to 2°C, and they suggested the temperature at which the TL peak was observed could be used to routinely assess the reproducibility of sample heating during measurement protocols. This relatively simple procedure involves measuring the TL glow curve and fitting the 110 °C TL peak with a Weibull function [see 4] thereby monitoring the peak position during a measurement sequence. The TL signal from calcitic opercula displays one low temperature peak (~100 °C, peak I) and two high temperature peaks (~275 °C and 350 °C, peak II and peak III respectively). Lifetimes of 7.4 x 107 and 1.4 x 1011 years have been reported for peaks II and III [1], and these are the signals that are of value for dating [e.g. 5, 6]. Little work has been published for peak I (~100°C). Here we present our investigation of the low temperature TL peak produced by Bithynia tentaculata opercula, and whether it can be used to investigate thermal lag and monitor temperature during TL measurements. The approach is used to assess the reproducibility of heating between different TL measurements during a single aliquot regenerative dose (SAR) procedure, and also to examine variability in heating between different opercula from a single sample. [ABSTRACT FROM AUTHOR]

This study is attempted to present theoretical solutions for power output of thermal-lag Stirling engine. In this study, a dimensionless nonlinear dynamic model is built. Equation of motion of piston and energy equations for working gases in cold and hot sides are developed and solved by perturbation method. Emphasis of the study is focused on the instability of the thermal-lag phenomenon under various loading and friction damping conditions. Thus, dynamic behavior of the engine with or without friction damping is investigated. The critical curves that separate the stable and unstable zones are plotted. The onset of the thermal-lag oscillation under different loading conditions takes place only when the operating condition is located in the stable zone. The power output of the engine is then evaluated based on the theoretical solutions, and dependence of the power output on influential parameters is investigated. Furthermore, an amplitude equation and a frequency shift equation are presented, and the dynamic characteristics of the engine and the frequency shift can be determined by solving these two equations. [ABSTRACT FROM AUTHOR]

Variations in atmospheric conditions can be important factors influencing temperature dynamics within the active layer of a soil. Solar radiation and air temperature can directly alter ground surface temperatures, while variations in wind and precipitation can control how quickly heat is carried through soil pores. The presence of seasonal snow cover can also create a thermal barrier between the atmosphere and ground surface. This study examines the relation between atmospheric conditions and ground temperature variations on a deglaciated island along the Western Antarctic Peninsula. Ground temperatures were most significantly influenced by incoming solar radiation, followed by air temperature variations. When winter months were included in the comparison, the influence of air temperature increased while solar radiation became less influential, indicating that snow cover reflected solar radiation inputs, but was not thick enough to insulate the ground. When ground temperatures were compared to atmospheric conditions of preceding weeks, seasonal temperature peaks 1.6 m below ground were best related to seasonal air temperature peaks from the previous two weeks. The same ground temperature peaks were best related to seasonal solar radiation peaks of seven weeks prior. This difference was a result of temperature lags within the atmosphere. [ABSTRACT FROM AUTHOR]

• Novel way to determine dynamical thermal lag. • Novel method to obtain specific heat capacity data from fast calorimetry data. • Original use of glass transition to detect and correct static thermal gradients. • Validation of the methods on prototypical organic molecular glass-formers. [Display omitted] Fast scanning calorimetry is an experimental technique very appreciated for its capability of suppressing reorganization processes, thanks to its wide interval of scanning rates, several orders higher than that of conventional calorimeters; nevertheless, drawbacks still exist. In this paper we propose a novel way to estimate the dynamical thermal lag by using the temperatures of maximum slope of the heat flow through the glass transition when we are not in the optimal conditions to apply the existing methods based on a reference material added on both cells of the chip or on the fictive temperature. Moreover, a novel interpretation of the heat flow losses due to the sample depending on the scanning rate sign is provided, in order to rescale the measured specific heat capacity to that from conventional calorimetry. Finally, the use of the glass to liquid transition measured on heating is shown as a new manner to reveal static thermal gradients. [ABSTRACT FROM AUTHOR]

Crystal melting behavior of indium and isotactic polypropylene has been examined by differential scanning calorimetry of heat flux type in terms of the heating rate, $$\beta $$ , dependence. The melting shows the dependence characterized by a power, $$z$$ , of the shift in peak temperature in proportion to $$\beta ^{\text{z}}$$ . The power, $$z$$ , differentiates the melting with and without superheating. For polymer crystal melting, intrinsic nature of the broad melting region with a fractional power, $$z\,\le\,1/2$$ , due to superheating of melting kinetics has been reconfirmed experimentally. On the other hand, the crystal melting of indium, which is supposed to proceed with negligible superheating, showed the shift in peak temperature with the power in the range of $$1/2\,\le\,z \le\,1$$ , depending on sample mass, which is due to instrumental thermal lag predicted by the Mraw's model consisting of lumped elements. The $$\beta $$ dependence is influenced by the thermal lag determined by the thermal contact resistance between the sample pan and the stage, the effect of which has been examined in terms of the dependence on sample mass and the application of silicone grease between the sample pan and the stage. The influence of two different types of the definition of heat flow has also been examined; the simplified one without the time derivative of temperature difference showed an apparent shift in peak temperature at faster scan rates in a similar way as that of thermal lag. [ABSTRACT FROM AUTHOR]

The paper presents the pyrolysis behaviour of eleven different rank solid fuels, carried out using thermogravimetry (TG). Obtained experimental curves were compared with profiles determined using the Single First Order Reaction (SFOR) model and three different approaches of Distributed Activation Energy Model (DAEM). The aim of this work was to develop different models dedicated to pyrolysis, in particular further investigate the interrelation between the activation energy and the pre-exponential factor, its impact on the results quality and attribution with the fuel properties and pyrolysis mechanism. Obtained results showed that the compensation effect, often noted for SFOR, has also occurred for DAEM. Furthermore, analysis indicated an existence of a relationship between the characteristic temperature T iso (and ln( k iso )) and fuel properties. Observed interrelation may be attributed to the change in reaction mechanism. [ABSTRACT FROM AUTHOR]

Ignition and burnout temperatures are important properties of solid fuels for their applications in industry. In this study, the thermogravimetric analyses (TGA) of bamboo and sugarcane bagasse at five different heating rates of 5, 10, 20, 30, and 40 °C min −1 are performed. The intersection method (IM) and deviation method (DM) are employed to approach the ignition temperatures of the two biomass species, while IM and the conversion method (CM) are adopted to analyze their burnout temperatures. In IM and CM, both the ignition and burnout temperatures increase with increasing heating rate, as a consequence of the pronounced thermal lag in biomass particles at high heating rates. The measured ignition temperatures based on DM are lower than those based on IM, and there is no correlation between the temperature and heating rate. The determined burnout temperatures from IM are close to those obtained from CM, while the difference in the burnout temperatures of the two biomass samples is small. The ignition temperatures of the two biomass species measured from IM are between 250 and 300 °C, and their burnout temperatures are close to 500 °C. As a whole, IM is recommended for determining the ignition temperature of biomass, while CM is a feasible and simple route to approach the burnout temperature. The heating rates in TGA between 20 and 30 °C min −1 are suggested because of their accurate and time-saving operations. [ABSTRACT FROM AUTHOR]

Coupled green-building roof system can assess bidirectional heat-flux with indoor space. Two high-rise residential blocks in humid-subtropical Hong Kong, with and without roof building thermal insulation (BTI), were monitored for thermal performance across seasons and weather conditions. Each block had three plots: Sedum and herbaceous Peanut green roofs, plus bare Control. Diurnal heat-flux data were partitioned into daytime and nighttime, and positive and negative fractions. On hot summer-sunny day, Control without BTI facilitates notable daytime influx and nighttime efflux of heat. Sedum augments thermal-mass effect pushing more heat indoor than Control. With balance between transpiration-cooling and heat-sink formation, Peanut registers intermediate heat gain. Adding BTI raises heat-gain and eliminates Control heat-loss, curtails Sedum heat-gain, and maintains Peanut heat-gain. BTI partnering with green roof offer synergistic thermal benefit by increasing thermal mass, thermal capacity and thermal resistance to furnish thermal buffering, thermal lag, and extending heat ingress to nighttime. Lower solar-radiation input on summer-cloudy day significantly trims heat gain at Control, with limited reduction at both green roofs. Summer-rainy day brings further drop in heat gain. For cloudy and rainy scenarios, heat-gain suppression is more notable with BTI. Interpretations for other season-weather conditions and implications of the findings are elaborated. [ABSTRACT FROM AUTHOR]

We present a complete set of freely available MATLAB/Octave scripts called the SOCIB Glider Toolbox ( https://github.com/socib/glider_toolbox ). This new toolbox automates glider data processing functions, including thermal lag correction, quality control and graphical outputs. While the scientific value of the glider platform has been proven, the experience for the glider data user is far from perfect or routine. Over the last 10 years, ocean gliders have evolved such that they are now considered as a core component of multi-platform observing systems and multi-disciplinary process studies; we now have a generic processing system that appropriately complements glider capability. In an ideal world, a simple connection to a glider would provide oceanographic data ready for scientific application in an intuitive, familiar format; the reality has been somewhat different. Up till now users have faced several time-consuming tasks that prevent them from directly and efficiently extracting new oceanographic knowledge from the acquired data. The SOCIB glider toolbox covers all stages of the data management process, including: metadata aggregation, raw data download, data processing, data correction and the automatic generation of data products and figures. It is designed to be operated either in real-time or in delayed mode, and to process data from two of the most widely used and commercially exploited glider platforms, Slocum gliders and SeaGliders. The SOCIB glider toolbox is ready to accelerate glider data integration and promote oceanographic discovery. [ABSTRACT FROM AUTHOR]

A quantitative evaluation has been tried on the thermal lags of a fast-scan (≤10 4 K s −1 ) microchip differential scanning nanocalorimeter (DSC). A thin layer (∼0.2 μm thick) of a standard material of Tin was vapor deposited on a thin film of polyethylene (PE) sample (∼1–10 μm thick), and the thermal lags have been examined by the dependences on the applied heating rate, film mass, and film thickness of the melting onset temperature of Tin on the bottom and top surfaces of PE films put on the sensor stage of nanocalorimeter. Thermal lags are comprised of the instrumental thermal resistance and the temperature gradient in the film. The instrumental thermal lag was detected by the melting of Tin on the bottom of PE films and well explained by the reported value of the thermal resistance of sensor. The temperature gradient in the film was detected by the melting of Tin on the top surface of PE films, and showed the dependence predicted by the modeling of heat transfer in the thickness direction. The influences of thermal lags have also been examined in terms of the heating rate, β , dependence of the shift in melting peak temperature of PE crystals. The power of β z characterizing the β dependence of the shift became larger with increasing film mass and thickness, i.e. with introducing larger thermal lags. When the power is utilized as a fitting parameter, the influence of thermal lags on the melting point extrapolated to zero heating rate could be kept at small level (±1 °C) even for thick films (∼10 μm). Those behaviors have been validated by numerical calculations based on the modeling of fast-scan microchip DSC. [ABSTRACT FROM AUTHOR]