High Thermal Parameters Research Articles

The effect of the inlet steam superheat degree on the non-equilibrium condensation in steam turbine cascade

Due to the high steam velocity and low thermal parameters at the turbine's final stage, steam generates non-equilibrium condensation and forms a large number of small droplets during the process of pressure expansion. The wet steam mixed with droplets impinges on the turbine blades, endangering turbine operation safety and reducing turbine work efficiency. This article modifies the non-equilibrium condensation control equation and embeds it into the numerical simulation software to make the numerical calculation results more accurate. By modifying the inlet steam superheat in the classical experiments, the condensation characteristics of wet steam in Moses–Stein nozzles and Dykas cascades are studied. The results show that increasing inlet superheat can effectively suppress the generation of non-equilibrium condensation and reduce outlet liquid mass fraction. The minimum supercooling temperature of non-equilibrium condensation is only related to the working fluid characteristics (the steam model used in this article is around 20 K). When the inlet superheat of the cascade is large, the rapid condensation region is mainly near the suction surface. In contrast, when the superheat is low, the rapid condensation zone is mainly near the pressure surface. The condensation location is mainly affected by the intensity of internal condensation shock waves in the cascade. Increasing inlet superheat not only increases the shock wave intensity but also decreases the shock wave angle in the passage. When the inlet temperature increases by 20 K, the heat efficiency of the cascade increases by about 1%.

Innovative bases of technology of autonomous transportation of perishable cargo

Transportation of perishable goods is a special type of transportation that has great social significance and has an impact on the health of the population. The correct choice of transportation technology and vehicle ensures the preservation of the quality of the transported perishable cargo due to compliance with the required temperature conditions, which in turn ensures compliance with food safety requirements. This article is devoted to the development of scientifically sound recommendations for the selection of new cooling systems for perishable goods by rail and technology parameters, including requirements for specialized vehicles, compliance with which will provide conditions for maintaining the quality of cargo throughout the entire transportation. The subject of research is to ensure the possibility of changing the composition of the gas environment of vehicles for the transportation of perishable goods due to re-equipment. The aim of the work is to develop the principles of technology for autonomous transportation of perishable foodstuffs, namely, ensuring high thermal parameters of vehicle enclosing structures; autonomous operation of installations during PG transportation with the simplest and most reliable implementation; achieving maximum efficiency of the equipment used in terms of generating thermal energy or energy spent on cooling when using non-energy-intensive methods organization of mass exchange of air inside the cargo area. Through analysis and theoretical studies, the possibility of joint operation of the gasifier and the heater was confirmed, the single-line nitrogen supply scheme was adjusted. Due to the use of modern methods and devices for cooling (heating), a reduction in costs for the transportation of products is guaranteed. The result of the work is confirmation of the possibility of joint operation of the gasifier and the heater under real conditions of transportation of fruit and vegetable products by rail.

Growth and characterization studies of 3-aminobenzene sulfonic acid single crystal for thermal application

We report the growth and characterization of 3-Amino benzene sulfonic acid (3-ABSA) of an organic single crystal for the first time under slow evaporation technique. The presence of characteristics vibrational groups and molecular structure were established by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) studies. The lower ultraviolet ray absorption edge was found to be 220 nm with a broad transmission window was observed in the visible region. The mechanical strength of grown crystal was assessed, and it belongs to soft material category. However, high thermal stability and other thermodynamic parameters were calculated using thermogravimetric (TGA) and differential thermal analyses (DTA). Therefore, the dielectric behavior of grown crystal was measured at various frequencies and temperature. The Kurtz powder second harmonic generation displays the second harmonic generation behavior of material and its efficiency is 0.55 times that of KDP were discussed in detail.

Entropy generation analysis for peristalsis of magneto Jeffrey materials

This article communicates peristalsis of Jeffrey material in curved geometry. Here, material has temperature-dependent thermal conductivity and viscosity. Mathematical modeling of an inclined magnetic field in curved configuration has been presented in this article. Irreversibility effects have been analyzed through entropy generation. Slip conditions are entertained both for velocity and thermal fields. Problem is first reduced in wave frame and then lubrication approach has been utilized. Numerical solution of dimensionless problem is obtained and important parameters of curiosity are examined. It is noticed that velocity enhances for higher viscosity whereas temperature decreases for higher thermal conductivity coefficient. Velocity of the flow is maximum for inclination of magnetic field to be zero and it is minimum for [Formula: see text] Heat transfer parameter enhances both for thermal conductivity parameter and Hartmann number. Temperature is high for curved configuration when compared with straight channel. It is observed that entropy remains unchanged in center of the channel and it is maximum near the channel walls. Entropy generation decays near the channel walls by higher viscosity and thermal conductivity parameters. However, entropy is more for higher inclination of magnetic field.

A new species of Lepidophyma (Squamata: Xantusiidae) from San Luis Potosí, México, with notes on its physiological ecology.

In recent years, there has been an increase in the descriptions of members of the lizard genus Lepidophyma. Herein, we describe a new species of Lepidophyma from the Huasteca Potosina region of Mexico, previously confused with L. gaigeae, from which it differs in lacking parietal spot, among other characteristics. We inferred its phylogenetic position and provide information on its thermal and hydric physiology, as well as on some other aspects of natural history. Molecular and morphological data supported the independent taxonomic status of the new species, indicating its placement as the sister taxon of L. gaigeae and a wide morphological separation between these species. Lepidophyma lusca sp. nov. has a diurnal-crepuscular activity period and occurs at lower elevations than L. gaigeae. Also, the new species differ from its sister taxon in its physiology, as reflected by its tendency toward higher thermal parameters and water loss rates. With the description of L. lusca sp. nov., the number of species in the genus Lepidophyma rises to 21.

Experimental Determination of the Influence of Shape on the Heat Transfer Process in a Crushed Granite Storage Bed

The article presents the problem of modelling the charging of a constant-phase bed storage in the first hours of the process. The places of errors in the heat transfer calculations for the packed beds were indicated. Granite in the shape of spheres and crushed rocks, with a characteristic dimension of 50 mm, was used for the experimental tests. The material was subjected to tomographic examination and then used as a storage material. The charging process was carried out for three flow rates: 0.006, 0.008 and 0.010 m3/s. After three hours of testing, the temperature of the outlet air for the granite sphere as the storage material was the same as for the granite crushed rock. However, the biggest differences occurred after 1 h of charging. They were equal to: 40.4% for the flow rate of 0.006 m3/s, 22.0% for the flow rate of 0.008 m3/s, and 18.5% for the flow rate of 0.010 m3/s. The differences were greater than the uncertainty of the measurements. As a result, different temperatures of the storage material were obtained. After three hours, they were equal to: 25.2%, 12.3% and 8.6% for the lowest, medium, and highest airflow, respectively. The conducted heat transfer analysis and the relationship Nu = f(Re) was determined. The influence of the calculated and actual surface of the crushed rock on the heat exchange process was explained. For all the tested air flow rates through the bed, higher thermal parameters were obtained for the crushed rock than for the sphere. The maximum differences in the Nu number were: 222.6%, 151.4% and 161.3% for the flow of 0.006, 0.008 and 0.010 m3/s, respectively. This means that the description of the heat exchange process in the piled beds would require a parameter that takes into account the geometry of the storage material.

Experimental Investigations on Wavefront Distortion of LD-Pumped Neodymium-Doped Silica-Glass Rod with High Thermal Shock Parameter

The characterization of a laser diode (LD)-pumped neodymium-doped silica glass (NDSG) laser is here described. The gain performance and wavefront distortion were measured, and the thermal toughness and uniformity distribution of the material were experimentally observed. At a pumping frequency of 1 Hz and energy 7.79 J, a small-signal gain of 1.16 was measured, and the wavefront distortion reached 2.67 λ (wavelength λ = 1053 nm). At a pumping frequency of 25 Hz with 194 W power, the NDSG was still not cracked, which is consistent with its high thermal shock parameter. However, the material uniformity was relatively poor. These results indicate good prospects for the application of NDSG lasers at high energy and high repetition frequency, but the gain performance, uniformity, and other aspects affected by the manufacturing process need to be improved.

Spitzer Observations of Interstellar Object 1I/‘Oumuamua

Abstract 1I/‘Oumuamua is the first confirmed interstellar body in our solar system. Here we report on observations of ‘Oumuamua made with the Spitzer Space Telescope on 2017 November 21–22 (UT). We integrated for 30.2 hr at 4.5 μm (IRAC channel 2). We did not detect the object and place an upper limit on the flux of 0.3 μJy (3σ). This implies an effective spherical diameter less than [98, 140, 440] m and albedo greater than [0.2, 0.1, 0.01] under the assumption of low, middle, or high thermal beaming parameter η, respectively. With an aspect ratio for ‘Oumuamua of 6:1, these results correspond to dimensions of [240:40, 341:57, 1080:180] m, respectively. We place upper limits on the amount of dust, CO, and CO2 coming from this object that are lower than previous results; we are unable to constrain the production of other gas species. Both our size and outgassing limits are important because ‘Oumuamua’s trajectory shows non-gravitational accelerations that are sensitive to size and mass and presumably caused by gas emission. We suggest that ‘Oumuamua may have experienced low-level post-perihelion volatile emission that produced a fresh, bright, icy mantle. This model is consistent with the expected η value and implied high-albedo value for this solution, but, given our strict limits on CO and CO2, requires another gas species—probably H2O—to explain the observed non-gravitational acceleration. Our results extend the mystery of ‘Oumuamua’s origin and evolution.

Experimental and analytical determination of water vapour transmission properties of recyclable insulation material

The article presents the results of preliminary research related to the development of a new solution for thermal insulation of external walls from the inside. The innovative material solution is based on a recyclable material (re-expanded polystyrene) combined with cement, creating a light concrete with high thermal and moisture parameters. Preliminary research included the determination of the basic features of the European Assessment Document (EAD). The paper presents the determination of diffusion parameters based on the model of water vapor transport in a porous material. The main assumption of the authors was to develop a material whose diffusion resistance coefficient was close to 6–7 [–]. The solution would ensure free flow of water vapor in brick walls insulated from the inside and it does not lead to thermal or moisture disturbances. The main aim of the article is to demonstrate the great potential of using recycling materials in construction.

Simultaneous retrieval of high temperature thermal conductivities, anisotropic radiative properties, and thermal contact resistance for ceramic foams

Open-cell ceramic foams exhibit outstanding thermal, mechanical and exchange properties that make them widely used in various industrial areas with high temperature hostile environments. Deficiency in reliable high temperature thermal properties as well as interface contact attributes brings demanding challenges to precise design and optimization of foams in conditions of usage. Aiming at this problem, the present paper interests in the determination of multiple high temperature thermal parameters for description of conduction and radiation transports taken place within the material as well as contact behaviors between ceramic foams, by inverse identification technology. The thermal contact effect arising from introduction of thermocouples in temperature measurements for ceramic foams was modelled in a new thermal model. On basis of the renewed heat transfer model, three categories of thermal parameters, i.e. conductive properties, anisotropic radiative properties, and thermal contact resistance, were simultaneously reconstructed from a simple and rapid transient thermal measurements. The reliability of the estimated thermal parameters was discussed by comparison with experimental measurements and literature data. It was found that the proposed inverse model demonstrates good behavior to determine critical thermal properties information as well as thermal resistance effect.

An improvement of soil temperature simulations on the Tibetan Plateau.

The simulation of soil temperature on the Tibetan Plateau (TP) plays a dominant role in the performance of both global climate and numerical weather forecast models. To improve the simulation of soil temperature on the TP, the Johansen soil thermal conductivity parameterization scheme was introduced into Community Land Model 3.5 (CLM3.5) and Regional Climatic Model 4 (RegCM4). The improved CLM3.5 and RegCM4-CLM were utilized to conduct offline and regional simulation experiments on the TP. Comparison of the new and old schemes revealed that CLM3.5 provides high thermal conductivity parameters of mineral soil solid on the TP. The Johansen scheme is more practical for the TP than the soil thermal conductivity parameterization in CLM3.5. The simulation of soil temperature and liquid water content was improved in offline experiment. The improved parameterization scheme can also reduce the simulation error of soil temperature in winter throughout the entire TP.

Enhanced mid-infrared 2.7 μm luminescence in low hydroxide bismuth-germanate glass and optical fiber co-doped with Er3 +/Yb3 + ions

In this article, low hydroxide bismuth-germanate glasses doped with Er3+ and co-doped with Er3+/Yb3+ ions have been synthesized. The fabricated host was characterized by high thermal stability parameter (ΔT=125°C), high transmittance in mid-infrared region and low maximum phonon energy (724cm−1). In order to reduce OH− ions impact on the transmittance value at the band of 3.1μm, the modified synthesis process has been conducted in low vacuum conditions (50–70mbar). The wide transmittance window from 0.515 to 5.5μm has been determined in terms of optical parameters. Luminescent properties of Er3+ ions indicated increase of luminescence intensity at the wavelength of 2.7μm (4I11/2→4I13/2) under 980nm laser diode excitation resulting from OH− reduction. Simultaneously, the addition of ytterbium to glass system has increased emission intensity in mid-infrared band due to Yb3+→Er3+ energy transfer. According to mid-infrared luminescence measurements, molar ratio of co-dopants in developed glass matrix for the maximum emission intensity has been determined. Glass characterized by the highest mid-IR emission intensity has been used as the active core of produced optical fiber.

Geochemical evidence of organic matter source input and depositional environments in the lower and upper Eagle Ford Formation, south Texas

Late Cretaceous source rocks in the south Texas Eagle Ford Formation were characterized based on geochemical features of the Iona-1 core, which penetrates the lower and upper Eagle Ford Formation. This set of immature samples provides a detailed record of the variation of organic matter (OM) sources across different depositional facies. Our results show that organic matter rich shales are dominated by marine Type II kerogen. Lower Eagle Ford (LEF) contains high-sulfur kerogen (Type II-S) with S/C>0.04, and a minor contribution of terrestrial OM is evident in the upper Eagle Ford (UEF). Combined geochemical data from Iona-1 core samples based on bulk geochemical rock properties, residual oil chromatography and biomarker analyses reveal that the total organic carbon content and extractable bitumen content in the LEF are higher than in the UEF; redox-sensitive biomarkers demonstrate that sulfur-rich photic-zone anoxia/euxinia developed in the LEF and that persistent oxygenation occurs during deposition of the UEF. Sulfur-rich kerogen in the LEF, in turn, generates medium/high sulfur-containing oils (up to 2.6%). As a consequence of the elevated sulfur contents in the LEF, oil/bitumen generation initiated earlier and at lower maturity levels than in the UEF. High levels of anomalous 22S/(22S+22R) homohopane ratios and 20S 5α,14α,17α-steranes have been observed in the LEF interval, which is controversial because of the low maturity level indicated by most bulk geochemical thermal maturity parameters, including Tmax-calculated %Ro (∼0.45) and Ts/(Ts+Tm), as well as C29Ts/(C29Ts+C29) hopane and C29ββ/(ββ+αα) sterane ratios. These anomalously high thermal maturity parameters are more likely caused by enhanced isomerisations due to high organic-sulfur content under reducing depositional environments in the LEF rather than by thermal maturation. Hypothetical diagenetic pathways for the sulfurisation of homohopanoids and steroids are proposed to explain their abnormal isomerisations in the LEF.

Definitive radiotherapy plus regional hyperthermia for high-risk and very high-risk prostate carcinoma: Thermal parameters correlated with biochemical relapse-free survival

Purpose: The aim of this study was to assess the efficacy of definitive radiotherapy (RT) plus regional hyperthermia (HT) and investigate the potential contribution of HT to clinical outcomes in patients with prostate carcinoma. Materials and methods: Following our institution’s treatment protocol, HT was combined with RT to improve clinical outcomes in selected patients with high-risk or very high-risk prostate cancer. Data from 82 patients treated with RT plus HT and 64 patients treated with RT alone were retrospectively analysed. Results: Median follow-up duration was 61 months. The 5-year biochemical disease-free survival (bDFS) rate for the 82 patients treated with RT plus HT was 78%, whereas bDFS for the 64 patients treated with RT alone was 72%; this difference was not significant. Among the 75 patients treated with RT plus HT who underwent intra-rectal temperature measurements, higher thermal parameters were significant prognostic indicators of improved bDFS by univariate analysis. A higher CEM43 °CT90 thermal parameter and a T stage of T1–2 were significant prognostic factors based on multivariate analysis. The 5-year bDFS rates for the 40 patients with a higher CEM43 °CT90 and the 64 patients treated with RT alone were significantly different, whereas 5-year bDFS for the 35 patients with a lower CEM43 °CT90 and the 64 patients treated with RT alone were not. Conclusions: The addition of HT with higher thermal parameters to RT may improve bDFS for patients with high-risk or very high-risk prostate cancer. These findings also demonstrate the importance of careful selection of treatable patients with higher thermal parameters.

Seismicity and shallow slab geometry in the central Vanuatu subduction zone

AbstractThe Vanuatu arc in the southwest Pacific Ocean is one of the world's most seismically active regions, with almost 39 magnitude 7+ earthquakes in the past 43 years. Convergence rates are around 90–120 mm/yr along most of the arc, but drop to 25–43 mm/yr in the central section, probably due to the subduction of the d'Entrecasteaux ridge. We characterize the slab geometry and tectonic state in this central section by analyzing data from a 10 month deployment of 30 seismometers over this section. We located more than 30,000 events (all less than magnitude 5.5), constructed an improved 1‐D velocity model, calculated focal mechanisms and cluster geometries, and determined the 3‐D geometry of the interplate seismogenic zone. The seismogenic zone has a shallow bulge in front of the d'Entrecasteaux ridge, which could be explained by the ridge's buoyancy contributing to the uplift of the fore‐arc islands. The seismogenic zone extends to ~45 km depth, significantly below the 26–27 km depth of the fore‐arc Moho, indicating that the upper mantle wedge is not significantly serpentinized, which is consistent with the relatively high thermal parameter of the subducting plate. The maximum width of the seismogenic zone is 80 km, indicating an upper earthquake magnitude limit of Mw 7.85 ± 0.4, assuming standard rupture zone aspect ratios. The data also reveal a double seismic zone, 20 to 30 km below the seismogenic zone, which is presumably caused by flexure of the downgoing plate.

Conjugated heat and electrophysical characteristics of K-phase films on electrode walls of the channel of an aluminum-hydrogen MHD generator at high thermal and electric parameters

The utilization of aluminum as an intermediate energy carrier with subsequent production of high-temperature hydrogen in reactions of hydrothermal oxidation makes it possible to build high-performance thermal-power cycles with an MHD generator, with a real prospect for their utilization in emergency and high-peak power plants [1]. One of the main problems of efficient operation of an MHD generator channel is the deposition of K-phase in the form of conducting melt films of Al2O3 on the fire surface of MHDG channel walls. As this takes place, there are leakage currents through the melt films in the induced transversal and Hall fields, which are accompanied by Joule heat-evolution. The peculiarities of formation, flow, and thermal regime of such a film on the fire walls of MHDGs in the induced Hall and transversal fields were studied in this connection, as well as the peculiarities of current flow with regard to temperature dependencies of the conduction and the viscosity of the Al2O3 melt. The results of investigation make it possible to estimate the influence of such films on aluminum-hydrogen MHDG performance.

Thermal and electrical relaxation studies in Li (4+ x) Ti xNb 1− xP 3O 12 (0.0 ≤ x ≤ 1.0) phosphate glasses

A new superionic conducting transparent phosphate glasses with composition Li (4+ x) Ti x Nb 1− x P 3O 12 (0 ≤ x ≤ 1.0) were prepared by rapid melt quenching. As quenched samples were characterized by X-ray powder diffraction, differential scanning calorimetric and Fourier transform infrared spectroscopy studies. These glasses were found to have high thermal stability parameter and Li 4NbP 3O 12 has been found to have high glass forming ability. Electrical properties of the present glasses were studied by impedance and dielectric spectroscopy in the frequency range 10 Hz–3 MHz in the temperature range 323–523 K. Arrhenius behavior has been observed for all the glass in conductivity, dielectric loss and conductivity relaxation and their activation energies are explained and reported.

Structural, dielectric, impedance and optical properties of CaBi 2B 2O 7 glasses and glass-nanocrystal composites

Optically clear glasses were fabricated by quenching the melt of CaCO 3–Bi 2O 3–B 2O 3 (in equimolecular ratio). The amorphous and glassy characteristics of the as-quenched samples were confirmed via the X-ray powder diffraction (XRD) and differential scanning calorimetric (DSC) studies. These glasses were found to have high thermal stability parameter ( S). The optical transmission studies carried out in the 200–2500 nm wavelength range confirmed both the as-quenched and heat-treated samples to be transparent between 400 nm and 2500 nm. The glass-plates that were heat-treated just above the glass transition temperature (723 K) for 6 h retained ≈60% transparency despite having nano-crystallites (≈50–100 nm) of CaBi 2B 2O 7 (CBBO) as confirmed by both the XRD and transmission electron microscopy (TEM) studies. The dielectric properties and impedance characteristics of the as-quenched and heat-treated (723 K/6 h) samples were studied as a function of frequency at different temperatures. Cole–Cole equation was employed to rationalize the impedance data.

Ambi-site substitution of Mn in lanthanum germanate apatites

A neutron diffraction study at 4 K of the Mn doped lanthanum germanate apatite-type oxide ion conductor of nominal starting composition “La 9.5Mn 0.5(GeO 4) 6O 2.75” is reported. The structure was refined in space group P6 3/ m, although high thermal displacement parameters were observed for the oxide ion sites (particularly O3, and O4). Reduced thermal displacement parameters were obtained by splitting the O3 site, and allowing the O4 oxygen to move off site, which may indicate local regions of lower symmetry within the structure. In addition, the data suggested ambi-site substitution of Mn, with it being present on both the Ge site and the La site. Assuming no change in La:Mn:Ge ratio, a composition of La 9.18Mn 0.28(GeO 4) 5.8(MnO 4) 0.2O 2 was determined. As such there are nominally no interstitial oxide ions, but rather cation vacancies on the La site. Therefore, the high conductivity for this sample is most likely related to the introduction of Frenkel-type defects at higher temperature, as previously proposed for other apatite-type systems containing vacancies on the La site.

Inkommensurabel modulierte Kristallstrukturen und Phasenumwandlungen – Die Verbindungen SrPt2As2 und EuPt2As2

AbstractModulated Crystal Structures and Phase Transitions – The Compounds SrPt2As2 and EuPt2As2The new compounds SrPt2As2 (a = 4.482(1), b = 4.525(1), c = 9.869(2) Å) and EuPt2As2 (a = 4.435(2), b = 4.467(2), c = 9.784(3) Å) have been prepared by reaction of the elements at 1050 °C. Satellite reflections observed in X‐ray diffraction experiments on single crystals revealed that both compounds have modulated crystal structures at room temperature. The average structures can be derived from the CaBe2Ge2 type and described in the orthorhombic space group Pmmn (Z = 2) with splitted positions for half the Pt and As atoms. Based on the average structure of SrPt2As2, the modulated structure has been solved and refined using the (3+1)‐dimensional superspace group Pmmn(α00)0s0 and a modulation vector q = 0,62·a*. The modulation appears in the layers of the PtAs4 tetrahedra with occupational and displacive components. The other atoms are also slightly affected by the modulation. With increasing pressure, SrPt2As2 undergoes a phase transition at about 60 kbar. The crystal structure of the high pressure phase (HP‐SrPt2As2: a = 9.752(2), b = 4.398(1), c = 8.727(2) Å, β = 90.34(3)°; 66(5) kbar) is a monoclinic variant (P21/c; Z = 4) of the tetragonal CaBe2Ge2 type known from EuPt2Ge2. Band structure calculations reveal that a Peierls‐distortion within the Pt square nets is a reason for the structural instabilities in SrPt2As2. The satellite reflections of EuPt2As2 become weaker with increasing temperature and disappear above 200 °C. The high temperature phase (HT‐EuPt2As2: a = 4.464(1), c = 9.832(1) Å; 350 °C) crystallizes with the CaBe2Ge2 type (P4/nmm; Z = 2). High thermal displacement parameters of the Pt and As atoms of the PtAs4 tetrahedra cover the effects of the modulation at room temperature. Several analogous compounds were studied by X‐ray diffraction resulting in the following lattice parameters: a = 4.564(1), c = 10.021(2) Å for BaPt2As2, a = 4.603(2), c = 10.565(2) Å for SrPt2Sb2, a = 4.630(2), b = 4.683(2), c = 10.389(3) Å for EuPt2Sb2, and a = 4.458(1), c = 9.823(2) Å for SrIr2As2.