IR Heating Research Articles

The simulation of carbon material structure based on polyacrylonitrile obtained under IR heating

Since recently an economically efficient method including IR heating has been used for the synthesis of polymer based functional carbon nanocrystalline materials. One of the most widely used polymers having a broadest range of physicochemical properties and various applications is polyacrylonitrile (PAN). Under IR heating PAN undergoes chemical and structural transformations and a polyconjugated system forms with an increase in heating intensity. However, there are still no data on the quantitative and qualitative effects of carbon, nitrogen, hydrogen or metal atoms on the structural stability and configuration of the PAN based carbon material.We have for the first time determined using the MNDO semiempirical quantum chemical model for a carbon material (CM) structure based on heat treated polyacrylonitrile (PAN) that an increase in the N content from 14 to 18 atoms in CM monoatomic layers C46N14H10, C44N16H12, and C42N18H14 and in the H content from 12 to 22 atoms in CM monoatomic layers C44N16H12 and C44N16H22 leads to a decrease in the binding energy (Eb) from 7.40 and 7.12 to 6.88 and 6.25eV, respectively, and to an increase in the difference between the maximum and minimum bond length (Δl), between the maximum and minimum valence angle (Δθ), and between the maximum and minimum local charge (Δq) from 0.176 Е, 12.0°, and 0.487 to 0.238 Е, 20.8°, and 0.613, respectively, and promotes curving of the CM structure. Quantum chemical simulation results are confirmed by the element analysis of the CM specimens and FeNi3/C nanocomposite. When the IR heating temperature was increased from 30 to 500°С, the concentrations of N (СN) and H (СH) in the CM and in the FeNi3/C nanocomposite decreased from 27 to 18 and 10wt% and from 6 to 1 and 0.5wt%, respectively.

ChemInform Abstract: Neutron Powder Diffraction Study of Ba3ZnRu2‐xIrxO9 (X: 0, 1, 2) with 6H‐Type Perovskite Structure.

AbstractPolycrystalline samples of the triple perovskites Ba3ZnRu2‐xIrxO9 (x = 0, 1, 2) are prepared by calcination of stoichiometric amounts of BaCO3, ZnO, RuO2, and Ir (900 °C, 12 h) and subsequent heating in O2 atmosphere (1150 °C, 72 h).

Formation Features of Hybrid Magnetic Materials Based on Polyphenoxazine and Magnetite Nanoparticles

Hybrid metal-polymer nanocomposite materials based on polyphenoxazine (PPhOA) and Fe3O4 nanoparticles were obtained for the first time via two methods: in situ oxidative polymerization of phenoxazine (PhOA) in an aqueous solution of isopropyl alcohol with nanoparticles of Fe3O4 being present; chemical transformations of PPhOA subjected to IR heating at 400–450 °С in the presence of FeCl3·6H2O in an inert atmosphere. Obtained hybrid Fe3O4/PPhOA nanomaterials were characterized by means of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption spectrometry (ААS), elemental analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), as well as by vibrating sample magnetometry. The chemical structure, phase composition, magnetic and thermal properties of obtained nanocomposites were investigated in relation to the synthesis conditions.

Radiant Heating and Tempering Treatmentsfor Improving Rate of Moisture Removalduring Drying of Shelled Corn

<abstract> <b><i>Abstract. </i></b> Radiant heating holds great potential to improve the drying rate of freshly-harvested, high moisture content (MC) grain. The effectiveness of the process when combined with tempering steps for drying corn has not been elucidated. This study evaluated the effects of various process parameters during radiant heating and tempering treatment of corn to determine the percentage point of moisture removed and relative energy requirements. Freshly-harvested corn at initial moisture contents (IMCs) of 20%, 24% and 28% wet basis (w.b.) were used in the study. The corn was heated using an IR energy source equipped with catalytic IR emitters to surface temperatures of 50°C, 70°C, and 90°C. The IR treatments were performed with the corn kernels at product-to-emitter-gap (PEG) sizes of 110, 240, and 430 mm which corresponded to measured IR intensities of 10.84, 2.83 and 2.15 kW m^-2. Following the IR treatments, the samples were tempered for 2, 4, and 6 hours at 50°C, 70°C, and 90°C. The study evaluated the implications of one- and two-pass IR heating and tempering treatments. The rate of corn kernel surface temperature rise depended on the PEG size and IMC. The longest duration corresponded to the largest PEG (430 mm) size and IMC (28%), and vice versa. At a PEG size of 430 mm, IR heating durations of 110, 122, and 140 s were required to raise the surface temperature of the corn kernels at IMCs of 20%, 24%, and 28% (w.b.) and ambient conditions (26°C) to 90°C, respectively. IR heating of corn at IMC range of 20% to 28% and at PEG size of 430 mm to surface temperatures ranging from 50°C to 90°C resulted in 0.9 to 3.2 and 1.5 to 5.2 percentage point reduction in MC, for one- and two-pass treatments, respectively. The longer the tempering duration the more moisture was removed from the corn kernels. One-pass IR heating of corn kernel at IMC of 28% and PEG size of 430 mm to surface temperature of 90°C, and tempering at 50°C, 70°C, and 90°C for 6 h, resulted in 4.2, 4.7 and 5.2 percentage points and 7.2, 8.7, and 8.6 percentage points of moisture removed for one- and two-pass treatments, respectively. The significant and rapid moisture removals by the IR and tempering treatments provide for justification to optimize and scale-up the practices for corn drying.

Hybrid materials based on polyphenoxazine and copper nanoparticles

It is shown that, during the IR heating of polyphenoxazine in the presence of copper acetate monohydrate Cu(OOCCH3)2 · H2O in an inert atmosphere at a temperature of 250–450°C, the dehydration of phenyleneamine structures accompanied by the formation of conjugated bonds C=N and the reduction of Cu2+ to Cu0 by the evolving hydrogen followed by the formation of copper nanoparticles occur simultaneously. As a result, a nanostructured hybrid composite material, in which Cu nanoparticles are dispersed in the polymer matrix, is formed. The material shows thermal stability, and Cu nanoparticles have diameters of 5–40 nm.

A pilot scale electrical infrared dry-peeling system for tomatoes: Design and performance evaluation

A pilot scale infrared dry-peeling system for tomatoes was designed and constructed. The system consisted of three major sections including the IR heating, vacuum, and pinch roller sections. The peeling performance of the system was examined under different operational conditions using tomatoes with different cultivars and sizes. Three lines of tomatoes were heated and processed at the same time at a residence time of 125 s and achieved a percentage of fully peeled tomatoes of 85%, a peeling yield of 82%, and an average thickness of peeled tomato skin of 0.75 mm. When tomatoes were loaded as a single line, the required heating time was reduced to a range from 80 to 100 s, depending of tomato size, for achieving the same level of peeling percentage and yield. The presence of the vacuum section could achieve cracks in 100% of the tomatoes after IR heating. The peeled products from IR heating had high firmness and appealing surface integrity, which indicated desirable quality characteristics. Because the dry-peeling is a chemical- and water-free process, residuals of tomato skins after IR peeling could be easily utilised as value-added by-products.

A 35-&lt;inline-formula&gt;&lt;tex-math&gt;${\mu} \hbox{m}$&lt;/tex-math&gt;&lt;/inline-formula&gt; Pitch IR Thermo-Mechanical MEMS Sensor With AC-Coupled Optical Readout

A thermo-mechanical MEMS detector with 35-μm pixel pitch is designed, fabricated, and characterized. This fabricated design has one of the smallest pixel sizes among the IR thermo-mechanical MEMS sensors in the literature. The working principle of the MEMS detector is based on the bimaterial effect that creates a deflection when exposed to IR radiation in the 8–12-μm waveband. The nanometer level out of plane mechanical motion is observed in response to IR heating of the pixel, which is detected by a diffraction grating-based optical readout. Performance of MEMS sensor arrays with optical readout have been limited by a large DC bias that accompanies a small AC signal. We developed a novel optical setup to reduce the DC term and the related noise using an AC-coupled detection scheme. Detailed noise characterization of the pixel and the readout system is reported in this paper. The noise equivalent temperature difference of our detector is measured as 216 mK using f /0.86 lens with the AC-coupled optical readout. Finally, we obtained a thermal image using a single MEMS pixel combined with a scanning configuration. Despite the reduced pixel size, the measured noise levels are comparable to the state-of-the-art thermo-mechanical IR sensors.

Metalcarbon Nanocomposites Based on Pyrolysed Polyacrylonitrile

The electronic structure and geometry of metal − carbon nanocomposites based on the pyrolyzed poliacrylonitril (PPAN) with Cu, Si, Fe, Co, Ni atoms using the DFT method have been theoretically studied. The effect of nitrogen on the stability of PPAN and its conductivity has been determined. The electrophysical properties and structure of metal nanocomposites have been studied using the XFA method. The composites have been produced by IR heating. We suggest that metal − carbon nanocomposites form due to the special processing of the (PAN − MeR) samples. Metal nanoparticles are regularly dispersed in the nanocristalline matrix of PPAN. The conductivity of this metal − carbon nanocomposites has an activation character and varies from10 − 1 to 10 3 Om/sm depending on synthesis temperature ( T = 600—900 ° С). The results of theoretical and experimental research are in good agreement.

Metal–carbon nanocomposites based on pyrolysed polyacrylonitrile

The electronic structure and geometry of metal−carbon nanocomposites based on pyrolyzed polyacrylonitrile (PPAN) with Cu, Si, Fe, Co and Ni atoms using the DFT method have been theoretically studied. The effect of nitrogen on the stability of PPAN and its conductivity has been determined. The electrophysical properties and structure of metal nanocomposites have been studied using the XFA method. The composites have been produced by IR heating. We suggest that metal−carbon nanocomposites form due to the special processing of the (PAN−MeR) samples. Metal nanoparticles are regularly dispersed in the nanocrystalline matrix of PPAN. The conductivity of these metal−carbon nanocomposites has an activation character and varies from 10−1 to 103Om/cm depending on synthesis temperature (T=600–900°С). The results of theoretical and experimental research are in a good agreement.

국내 현장중온재생공법의 프리히터 개발을 위한 기초연구

PURPOSES : To design a pre-heater for warm in-place recycling equipment, three different heating systems were evaluated to determine their thermal efficiency. METHODS: In this study, a wheel-tracking specimen was used to measure the inner temperature as a function of the heating system. The inner temperature of the specimen was measured with a data logger at the surface, and at depths of 1cm, 2cm, 3cm, 4cm, and 5cm. To evaluate the thermal efficiency, the researchers used three different types of equipment, namely, IR, a heating wire, and a gas burner. RESULTS: The IR heating system exhibits a higher level of performance than the others to achieve the target temperature at a depth of 5cm in the specimen. The gas burner system was capable of heating the surface to a temperature of up to . The other types, however, cannot heat the surface up to 600. The thermal efficiencies were measured based on the laboratory conditions. CONCLUSIONS: To find the most effective system for application to the development of a pre-heater for warm in-place recycling, various systems (IR, heating wire, gas burner) were examined in the laboratory. As a result, it was found that the hot plate of a gas burner system provides the highest temperature at the surface of the asphalt but, of all the systems, the IR system provides the best internal temperature increase rate. Furthermore, a gas burner can age the asphalt binder of the surface layer as a result of the high temperature. However, the gas burner cannot attain the target temperature at 5cm. The IR system, on the other hand, is effective at increasing the internal temperature of asphalt.

Experimental and numerical investigation of 3D gas flow temperature field in infrared heating reflow oven with circulating fan

This study presents the experimental and numerical analysis of the thermal process for laboratory scale desktop lead-free reflow oven and discusses a 3D CFD model of radiation heating with forced-air convection from circulating stainless steel fan. The experiments were carried out to determine the temperature boundary condition of infrared heating element. In addition, the RPM of the rotating fan was measured using HT50 tachometers. To validate the spatial temperature of the oven, a set of industrial standard thermocouples was employed in various positions. The device was accessed throughout all stages of temperature reflow profile. The profile setting of the oven is in accordance to standard JSTD-020D. The desktop reflow oven was then numerically simulated using the computational model and the advanced user-defined functions (UDFs) were developed to model the thermal profile. The study reveals the temperature distribution of the desktop reflow oven is dependent on the air circulation in the oven at various positions. The temperature contour and air circulation in the oven chamber were demonstrated in the numerical simulation. The experimental and simulation results are useful for further improvement of temperature uniformity within the oven chamber for a convective IR heating reflow oven. The temperature results show a satisfactory agreement with both experiment and simulation.

THE STRUCTURAL FEATURES OF A NANOCOMPOSITE FeNi3/C OBTAINED UNDER AN IR HEATING

The structural features of a nanocomposite FeNi3/C synthesized from a solution FeCl3•6H2O/NiCl2•6H2O/polyacrylonitrile (PAN)/dimethyl formamide (DMF) with CFe=CNi=5; 10; 20; 25 mas. % under an IR heating are studied by a combination scattering (CS), a scanning electron microscopy (SEM), and an X−ray phase analyses (XPA). It is determined that as the IR heating temperature grows from 500 to 700 °С, the FeNi3 nanoparticle size increases from about 15 to 60 nm; amorphous, microcrystalline, and nanocrystalline graphite−like carbon phases (the halo in the XPA spectrum at 2θ ≈ 8÷32°) that are characterized by more intensive band D (ν =1340÷1358 cm−1) than the band G (ν =1560÷1596 cm−1) in the CS spectrum are formed; from the data of a SEM and a CS (the G peak, ν =1596 см−1), the possibility of the graphene structure generation is suggested at 600 and 700 °С; the peak in the area of 1120 cm−1 and the high intensity of the CS spectrum in the region of 1430—1480 cm−1 reveal the formation of polymer−destruction intermediate products at the interface of nanoparticles FeNi3.

THE SIMULATION OF CARBON MATERIAL STRUCTURE BASED ON POLYACRYLONITRILE OBTAINED UNDER IR HEATING

We have for the first time determined using the MNDO semiempirical quantum chemical model for a carbon material (CM) structure based on heat treated polyacrylonitrile (PAN) that an increase in the N content from 14 to 18 atoms in CM monoatomic layers C46N14H10, C44N16H12, and C42N18H14 and in the H content from 12 to 22 atoms in CM monoatomic layers C44N16H12 and C44N16H22 leads to a decrease in the binding energy (EB) from 7,40 and 7,12 to 6,88 and 6,25 eV, respectively, and to an increase in the difference between the maximum and minimum bond length (∆l), between the maximum and minimum valence angle (∆θ), and between the maximum and minimum local charge (∆q) from 0,176 Е, 12,0°, and 0,487 to 0,238 Е, 20,8°, and 0,613, respectively, and promotes curving of the CM structure. Quantum chemical simulation results are confirmed by the element analysis of the CM specimens and FeNi3/C nanocomposite. When the IR heating temperature was increased from 30 to 500 °С, the concentrations of N (СN) and H (СH) in the CM and in the FeNi3/C nano-composite decreased from 27 to 18 and 10 wt. % and from 6 to 1 and 0.5 wt. %, respectively.

Chemical structure and mechanical properties of glow discharge polymer films and deuterated glow discharge polymer films

Taking advantage of low pressure plasma chemical vapor deposition technology, the hydrocarbon glow discharge polymer (GDP) and deuterated glow discharge polymer (D-GDP) films were fabricated by glow discharge polymerization technology. The deposition rates, the chemical structures and mechanical properties of films were studied by FTIR spectra, surface profiler and nano-indentation. The results show that the deposition rate of GDP/D-GDP almost linearly increases with the increase of gas flow, the deposition rate of GDP films is higher than that of D-GDP films. The cross-link degree of D-GDP films is lower than that in GDP films. The D-GDP films might be more favorable for IR heating on the DT ice of ICF target. The mechanical property of GDP is better than that of D-GDP.

Snowpack-climate manipulation using infrared heaters in subalpine forests of the Southern Rocky Mountains, USA

Effects of infrared heaters on snow accumulation, snowmelt, and snow–atmosphere energy exchange were examined at Niwot Ridge, Colorado (CO) and compared to a naturally warmer, but otherwise similar subalpine site in the Valles Caldera National Preserve, New Mexico (NM). Observed snow accumulation was 30% lower on average and snow melted out 16 days earlier in the heated plots compared to the controls. Soil temperature during snowmelt was 3°C greater on average and soil moisture was 4% lower on average in heated plots compared to controls. In NM, snow accumulation was 23% lower, snow melted 23 days earlier, soil temperature was 0.6°C greater, and soil moisture was 13% lower on average relative to CO controls. In order to estimate differences in energy and mass balance fluxes at the snow–atmosphere interface in control versus warmer plots, the 1-D, physically based snowmelt model, SNOWPACK, was used. Model results indicated that heaters alter radiative, turbulent and mass fluxes by amounts comparable to the differences between CO and NM fluxes. The proportion of the energy flux associated with latent heat exchange during snowmelt was 9–27% of the total energy flux in heated models and 19–22% of NM models compared to 3–7% in control models. Thus, sublimation loss to the atmosphere was greater in both experimentally and naturally warmer cases relative to the control case. We conclude that IR heaters can provide alterations to the timing and magnitude of snow accumulation and snowmelt consistent with conditions observed at a warmer analog site and with climate and hydrology model projections. Impacts of IR heating on energy partitioning and sublimation should be considered when designing manipulations of the snowpack, as reductions in snowmelt water may alter biological or ecological processes.

A magnetic metal/polymer nanocomposite material based on poly(diphenylamine) and Fe3O4 nanoparticles

It was discovered that IR heating of poly(diphenylamine) in the presence of FeCl3•6H2O in an inert atmosphere at 300–700 °C produces a metal polymer nanocomposite with Fe3O4 nanoparticles dispersed in polymer matrix. This is achieved by condensation of crystalline diphenylamine oligomers with evolution of hydrogen that promotes iron reduction. The formation of Fe3O4 nanoparticles was confirmed by X-ray powder diffraction. The magnetic and thermal properties of the Fe3O4—poly(diphenylamine) nanocomposite were examined. This nanocomposite material shows superparamagnetism and thermal stability.

Thermal diffusivity of TBC: Results of a small round robin test and considerations about the effect of the surface preparation and the measuring approach

Among the techniques used to measure the thermal diffusivity of TBC, the Laser Flash is a standard. Nonetheless, this technique shows two main limitations related to the size and the well-defined geometry of the specimens. Furthermore the most reliable data can be typically obtained only on freestanding coatings. On the contrary, other photothermal and thermographic techniques in reflection configuration (the same side is heated and temperature detected) can overcome these limitations. One aspect, only partially studied in the literature, is common to most of the photothermal and thermographic techniques. It concerns the effect of the blackening coating used for guaranteeing the absorption of the heating radiation just within a very shallow outer layer and to make opaque the TBC in the sensitivity range of the IR detector/camera.For this purpose, an inter-laboratory round robin has been promoted for comparing the thermal diffusivity in dependency of the blackening layer deposition technique, the TBC microstructure (in particular porous APS, columnar EB-PVD and PS-PVD™) and the three different experimental set-ups in terms of spectral range and frame rate of the IR cameras, heating source and data reduction.

Simplifying Electrothermal Dynamics of 15-Ah Prismatic Li-Ion Batteries

A simply coupled electrochemical and thermal model is validated and presented for a 15 Ah large format prismatic lithium iron phosphate cell. Understanding the thermal response of lithium-ion cells is essential because it would allow the batteries to be operated more efficiently. Two important issues regarding the thermal response are "cold start" and "thermal runaway."[1] Use of a validated simulation can aid in enhancing the performance and safety of these batteries.To minimize the number of essential parameters, the simplest models are carefully chosen to depict the battery responses. At least two physical models are necessary for describing an electrochemical system: an electrochemical model and a local energy balance. For the electrochemical model, we select the Newman and Tobias model, which provides an analytic solution with an assumption that the ion concentration gradient is negligible.[2] For the energy balance [3,4], three different heat sources are necessary to match our experimental data: (1) Joule heating of the cell materials (simple IR heating), (2) an additional Joule heating generated by the interfacial resistance between electrode and electrolyte, and (3) the reaction heating from reversible entropy change. Joule heating is always exothermic; however, the reversible heat depends on the electrochemical reaction and can be endothermic or exothermic.Even though the minimal physics are chosen for simplicity, the number of physicochemical parameters in the completed model was more than ten; however, the number could be decreased to five after rigorous dimensional analysis. Therefore, not only do these parameters suggest important factors for the battery response, but they also help to control the battery in efficient ways, since this test shows that many parameters have the same effect in the electrical/thermal response. Comparison to target experimental data characteristics of the battery (Fig. 1) allows iterations of the dimensionless parameters to increase accuracy through multidimensional Newton-Raphson method. Finalized parameters will guide simulations to help control the battery in efficient ways.[1] T. M. Bandhauer, S. Garimella, and T. F. Fuller, Journal of The Electrochemical Society 158, R1 (2011).[2] J. S. Newman and C. W. Tobias, 109(12), 1183 (1962).[3] D. Bernardi, E. Pawlikowski, and J. Newman, J. Electrochem. Soc. 132, 5 (1985).[4] J. Newman and K. E. Thomas-Alyea, Electrochemical Systems, 3rd ed. Wiley, 2004.

Performances of infrared emitters applied to the porous thin materials drying

Drying of solids is one of the oldest and most common unit operations found in diverse processes. In this paper the drying of hygroscopic textile materials is discussed. The authors have previously investigated the drying kinetic of different fabrics dried by a hot air jet. In this paper a comparison between the convective and electric IR drying is made. In particular two fabrics with fibers which show a different hygroscopic behaviour are analysed: wool and cellulose/cotton. Unlike the convective drying, IR drying is weakly affected by the radiation properties and by the hygroscopic behaviour of the two fabrics. This is likely due to a better diffusion of the heat flux, which is constant over the entire drying surface in the case of IR heating, and produces unexpected results on the nondimensional kinetic parameter (characteristic curve). Wool shows a complete different characteristic curve if dried with IR or with convective flow. The better performances have been reached with MW emitter, but it has been observed that this advantage decreases with the distance of the source from the surface to be dried.

An investigation of the temperature variations in Neptune’s upper stratosphere including a July 2008 stellar occultation event

We extracted physical atmospheric parameters from a 23 July 2008 single-chord stellar occultation of the star USNO-B1.0 0759-0739128 (I-band magnitude of 12.60) by Neptune using a light curve model fitting technique. We observed the occultation using the Agile CCD camera mounted on the Astrophysical Research Consortium 3.5m telescope at Apache Point Observatory. We found isothermal temperatures of 116.5± 12.0K and 154.0±13.0K for the immersion and emersion light curve profiles, respectively. We compare the stratospheric temperatures derived from the 2008 occultation to published temperatures of Neptune at similar atmospheric pressures derived from previous stellar occultations observed in the 1980s, and from long-term photometric measurements made routinely since the 1983–1990 occultation campaign. No obvious long-term temporal variation in stratospheric isothermal temperature is present. Fluctuations in the fitted isothermal temperature values, on the order of 20K, is evident. We explore several hypotheses to explain the observed temperature variability of Neptune’s stratosphere, including seasonal variability, variations in the Lyman-α flux received at Neptune due to the 11-year solar cycle, diurnal variations, varying insolation due to heliocentric variability, IR and UV heating by hydrocarbons, aerosol precipitation, inertia-gravity wave dissipation, and effects due to atmospheric tidal perturbations by Triton. We investigate the effects of these mechanisms on the gradual temporal changes of Neptune’s stratospheric temperature and conclude that local variations in stratospheric temperature during each event, on the order of 20K, are dominated by viscous dissipation of inertia-gravity waves.