Temperature Plots Research Articles

Simulation study of fuel spray dynamics in a constant volume combustion chamber

ABSTRACT The OpenFOAM computational fluid dynamics code was used to investigate the performance characteristics of spray jet in a constant volume combustion bomb. The total duration of fuel spray was approximately 1.25 × 10 − 3 second, and the total mass of fuel sprayed was 6.0 × 10 − 6 kilogram. The results show that there was a positive and somewhat positive qualitative correlation between the profiles of the number of parcels and the mass flow rate of the injected fuel at between 0 ≤ t ≤ 4.4 × 10 − 4 second. Furthermore, at between 9.1 × 10 − 4 ≤ t ≤ 1.3 × 10 − 3 the number of parcels experienced a sharp rise while the injected mass flow rate was decreasing, see Figure 6. The results of the present study show that the spray droplet sizes vary from 0.25 \\mum to 150 \\mum which were found to be reasonably representative of measurement data that are usually observed at the top dead centre position of internal combustion engine test bed experiments. Furthermore, the results of the study show the contour plots of pressure and temperature. The pressure rise varies from the initial value of 50 bar to 75 bar at the end of combustion while the temperature rose from 550 ∘ K to its final value of 2800 ∘ K . The specific details of the results from this study are summarised in the conclusion section.

CO2 solubility and diffusivity in poly(vinyl acetate) studied using the PC-SAFT and free volume theory

Poly (vinyl acetate) (PVAc) is a polymer used in various industrial applications, and the quantitative determination of CO2 solubility and diffusion coefficient is important for designing foaming processes involving supercritical CO2. In this study, these two physical properties were obtained experimentally and theoretically using the perturbed chain–statistical associating fluid theory (PC–SAFT) and free volume theory at temperatures between 353 K and 473 K and pressures up to 20 MPa. CO2 solubility increased almost linearly with pressure and could be correlated with the PC–SAFT equation of state and binary interaction parameter kij within the average relative deviation of 2.1%. Furthermore, the fitted plot of kij versus temperature can be used to predict CO2 solubility at lower temperatures. The diffusion coefficient of CO2 in PVAc was experimentally determined from CO2 sorption curves. Its value increased with increasing CO2 solubility and temperature, which was consistent with the free volume theory.

Heat exchange modeling between the air flow and the metro ventilation shaft lining in the conditions of St. Petersburg, Russia

Icing of the injection layer in underground tunnels and ventilation shafts leads to wear, destruction of supporting structures and flooding. In St. Petersburg the air temperature in winter can drop to -25 ° C, what can lead to these phenomena in the subway facilities. The article presents the modeling results of a viscous three-dimensional air flow, heat and mass transfer of a metro ventilation shaft in the Ansys CFX program. A numerical model of the ventilation shaft and the surrounding soil consisting of five layers has been developed: air; foam glass concrete; prefabricated cast-iron tubing lining; injection layer; soil massif. The parameters of the computational grid and the boundary conditions of the problem are specified. Two models of the ventilation shaft with an axial length of 1 m and 10 m were built. Temperature plots are constructed for three tasks, where the injection layer consists of water, wet clay soil and average between water and wet clay soil. The choice of overall thermal and technical characteristics of the thermal insulation material during the reconstruction of the existing ventilation shafts in three different sealing space conditions is confirmed.

Micelle Formation of Dodecanoic Acid with Alkali Metal Counterions.

Alkali series with different atomic numbers affect the physicochemical properties of aqueous solutions. The micellar properties of aqueous solutions of dodecanoate as surfactants were measured by changing the counterions (C12-Na, C12-K, C12-Rb, and C12-Cs). A plot of Krafft temperature vs. alkali metal atomic number showed a downward convex curve, with its minimum temperature (20°C) in the C12-K system. By contrast, a plot of the critical micelle concentration (CMC) vs. alkali metal atomic number exhibited an upward convex curve with the maximum CMC (25.6 mmol L-1) at C12-K. Furthermore, the minimum surface tension (γ min ) of the solution at the CMC increased with increasing atomic number (C12-Na ≈ C12-K < C12-Rb < C12-Cs). The size of the dodecanoate micelles decreased with increasing atomic number. The ionization degree of the micelles also increased with increasing atomic number of the alkali metal. Small-angle X-ray scattering (SAXS) measurements revealed that alkali dodecanoate micelles formed spherical to ellipsoidal structures. In addition, micelles from the shell region showed large electrostatic repulsion, judging from the shape of the spectrum in the higher Q -1 region. From the measurement results of the solubilization of naphthalene into the micelles, the size of the micelles corresponded to the maximum solubilization quantity of naphthalene.

Study of dust properties nearby pulsar J0302+2252 using Iris, Akari and wise surveys

A search of dust structures nearby the pulsar J0302+2252 in IRIS, AKARI, and WISE surveys were performed using Skyview Observatory (http://skyview.gsfc.nasa.gov). The physical properties have been studied at 60µm &amp; 100µm in the IRIS survey, 90µm &amp; 140µm in the AKARI survey, and 12µm &amp; 22µm in the WISE survey at right ascension (R.A.) (J2000)=03h 02m 31.99s and Declination (Decl.) (J2000)=+ 220 52m 12.10s . In this work, we have studied the physical properties such as Dust color temperature, Planck’s function, Visual extinction, and Mass profile of the dust using the data reduction software ALADIN v11. The dust color temperature is found to be 22.271 ± 0.261K in IRIS, 22.343 ± 0.939 K in AKARI, and 278.74 ± 0.067 K in WISE. Also, the dust mass is found to be 2.286 × 1027 kg (1.149 × 10-3 M⊙ ) in IRIS, 8.800 ×1026 kg (0.416× 10-3 M⊙ ) in AKARI and 5.220 ×1025 kg (0.026 ×10-3 M⊙ ) in WISE. The average visual extinction is found to be 1.372 ×10-13 mag. In IRIS, 4.970 ×10-14 mag. In AKARI and 1.673 ×10-15 mag. In WISE. The dust color temperature and dust mass distribution show a very good agreement with Gaussian. The Contour plots of dust color temperature and dust mass show inverse relation between them in all three bands IRIS, AKARI, and WISE.

Surface stabilisation of the high-spin state of Fe(II) spin-crossover complexes.

Temperature dependent X-ray photoemission spectroscopy (XPS) has been employed to examine the Fe 2p and N 1s core levels of the studied Fe(II) spin crossover (SCO) complexes of interest, namely: Fe(phen)2(NCS)2, [Fe(3-Fpy)2{Ni(CN)4}], and [Fe(3-Fpy)2{Pt(CN)4}]. The changes in the Fe 2p core-level spectra with temperature indicate spin state transitions in these SCO complexes, which are consistent with one's expectations and the existing literature. Additionally, the temperature dependence of the binding energy of the N 1s core-level provides further physical insights into the ligand-to-metal charge transfer phenomenon in these molecules. The high-spin fraction versus temperature plots reveal that the surface of each of the molecules studied herein is found to be in the high-spin state at temperatures both in the vicinity of room temperature and below their respective transition temperature alike, with the stability of the high-spin state of these molecules varying with the choice of ligand.

Comparative Study of Dust Properties around White Dwarf PG 1225-079 in IRIS, AKARI and WISE Data

In this work, dust properties around the White Dwarf PG 1225-079 located at RA (J2000): 12h 27m 47.35s, DEC(J2000): -08° 14’ 37.97” is studied extensively using the publicly available data from Improved Reprocessing of IRAS Survey (IRIS), AKARI infrared survey and Wide field Infrared Survey Explorer (WISE). The bipolar dust structure hardly resolved in IRIS (60 μm and 100 μm) is clearly resolved in AKARI (90 μm and 140 μm) and WISE (12 μm and 22 μm) images. The dust color temperature and dust mass are calculated from the infrared flux density. The average value of dust color temperature in isolated dust structure is 27.57 K for IRIS (I1). For isolated upper and lower dust clouds the average temperatures are; 22.64 K and 22.63 K for AKARI (A1 and A2), 295.34 K and 296.85 K in WISE (W1 and W2) data. A wide range of temperatures suggests the bipolar dust structure is dynamically active. The mass of dust is found to be 3.44 × 1025 kg in IRIS (I1), 1.82 × 1026 kg and 5.89×1026 kg in two bipolar regions in AKARI (A1 and A2) and 1.12 ×1026 kg and 1.14×1026 kg in WISE (W1 and W2). A good relation is found between the infrared flux in all survey data with r2 value 0.83 in IRIS (I1) and more than 0.90 in AKARI (A1, A2) and WISE (W1, W2) data. SIMBAD database explore some sources including Supernova Remnants nearby the dust which might be the progenitor of dust as well as the contributor of energetic radiation. The Gaussian modeling of temperature is found to be deviated from normal shape. The contour plot of dust color temperature and dust mass shows non uniform variation among the IRIS, AKARI and WISE survey. The relation between infrared flux, dust color temperature and dust mass within the dust clouds are presented.

Implementing a sol-gel route to adjust the structural and dielectric characteristics of Bi and Fe co-doped BaTiO3 ceramics

The present work explores the impact of Fe insertion on the physical properties of Ba0.95Bi0.05Ti1-xFexO3 (x = 0.025, 0.050, and 0.075) prepared via sol gel method. The resulting samples crystallize in the tetragonal structure with space group P4mm and their morphological features point out the variation of the microstructure with Fe content. In turn, the dielectric constant versus temperature plot reveals the existence of two transition phases: the first one is ferroelectric-paraelectric transition phase (TF-P) and the second one is ferroelectric orthorhombic - ferroelectric tetragonal phase (TO-T). Analysis of conductivity curves using Jonscher’s augmented equation (for x = 0.025) and Jonscher’s power law (for x = 0.075) suggests the Non-Overlapping Small Polaron Tunneling (NSPT) model as a conduction mechanism.

Convective enhancement of microalgae slurry in continuous tubular reactors for biocrude production during hydrothermal liquefaction

Continuous hydrothermal liquefaction (HTL) reactor is promising in the large-scale production of biocrude from microalgae biomass. To optimize the temperature distribution and biocrude yield of microalgae slurry, the convection of microalgae slurry is enhanced through adjusting flow rate (1 – 24 mL/min) and inserting twist tapes (twist ratio: 3 – 10) in the flow channel, respectively. A computational fluid dynamics (CFD) model integrated HTL kinetics of microalgae biomass is proposed to simulate the contour plots of temperature and biocrude yields at the heating temperature from 523 to 623 K. Comparing to increasing flow rate, the swirl flow induced by the twist tape can significantly increase the convective heat transfer coefficient from 669 to 1707 W·m−2·K−1, while the conversion rate of biocrude from 0.188 to 0.298 g·L-1·s−1 at 8 mL/min and 623 K. As the enhancement factor of convective heat transfer coefficient h /h0 is higher than 2, the biocrude yield YBC of microalgae slurry appears obvious increasing by the enhancing convective heat transfer. This investigation provides the insights to optimize the flow channel of tubular reactors for the optimization of HTL conversion of microalgae biomass.

MHD and Thermal Slip Effects on Viscous Fluid over Symmetrically Vertical Heated Plate in Porous Medium: Keller Box Analysis

The heat transfer characteristics along the non-magnetized shapes have been performed in various previous studies numerically. Due to excessive heating, these mechanisms are less interesting in engineering and industrial processes. In the current analysis, the surface is magnetized, and the fluid is electrically conducting, which is responsible for reducing excessive heating along the surface. The main objective of the present work is to analyze convective heat transfer analysis of viscous fluid flow with thermal slip and thermal radiation effects along the vertical symmetric heated plate immersed in a porous medium numerically. The results are deduced for viscous flow along a magnetized heated surface. The theoretical mechanism of heat and magnetic intensity along a vertical surface is investigated for numerical analysis. The nonlinear-coupled partial differential equations (PDEs) for the above viscous fluid flow mechanism with the symmetry of the conditions normal to the surface are transformed and then converted into non-similar formulations by applying appropriate and well-known similarity transformations for integration and solutions. The final non-similar equations are numerically integrated by employing the Keller box method. The discretized algebraic equations are plotted graphically and numerically on the MATLAB R2013a software package. The main finding of the current analysis is to compute physical quantities such as velocity graph, magnetic field graph, and temperature plot along with their slopes, that is, skin friction, magnetic intensity, and heat transfer for different parameters included in the flow model. First, the velocity graph, magnetic field graph, and temperature graph are obtained, and then their slopes are analyzed numerically along the vertical magnetic surface. It is noticed that fluid velocity is increased at lower magnetic force, but minimum velocity is noticed at maximum magnetic force. It is worth mentioning that with the increase in magnetic force, the magnetic energy increases, which extracts the kinetic energy of the fluid and causes the above-said behavior. Furthermore, the current issues have significant implications for the polymer industries, glass fiber production, petroleum production, fiber spinning, plastic film production, polymer sheet extraction, heat exchangers, catalytic reactors, and the production of electronic devices.

Temperature-Dependent Density and Magnetohydrodynamic Effects on Mixed Convective Heat Transfer along Magnetized Heated Plate in Thermally Stratified Medium Using Keller Box Simulation

The heat transmission properties along the non-magnetized geometries have been numerically obtainedby various researchers. These mechanisms are less interesting in engineering and industrial processes because of excessive heating. According to current studies, the surface is magnetized and the fluid is electrically conductive, which helps to lessen excessive surface heating. The main objective of the current analysis is to numerically compute the temperature-dependent density effect on magnetohydrodynamic convective heat-transfer phenomena of electrical-conductive fluid flow along the vertical magnetized and heated plate placed in a thermally stratified medium. For the purpose of numerical analysis, the theoretical process governing heat and magnetic intensity along a vertical magnetic plate is examined. By using suitable and well-known similarity transformations for integration, the non-linear coupled PDEs for the aforementioned electrical-conductive fluid flow mechanism are changed and subsequently converted into non-similar formulation. The Keller Box method is used to numerically integrate the final non-similar equations. The MATLAB software program plots the transformed algebraic equations graphically and quantitatively. The behavior of the physical quantities such asvelocity graph, magnetic field graph, and temperature plot along with their slopes that arerate of skin friction, the rate of heat transfer, and the rate of magnetic intensity for different parameters included in the flow model. The novelty of the current work is to compute the magneto-thermo analysis of electrically conducting flow along the vertical symmetric heated plate. First, we secure the numerical solution for steady part and then these results are used to find skin friction, heat transfer, and magnetic intensity. In the current work, the fluid becomes electrically conducing due to a magnetized surface which insulates heat during the mechanism and reduces the excessive heating. The results are excellent and accurate because they are satisfied by its given boundary conditions. Additionally, the current problems have a big impact on the production of polymer materials, glass fiber, petroleum, plastic films, polymer sheets, heat exchangers, catalytic reactors, and electronic devices.

Elucidating the phase transitions of decanoic-acid crystal by XRD, Raman, group theory and Gibbs energy analyses combined with DFT calculations

This research reports a series of phase transitions in the decanoic-acid (DA) crystal under low-temperature conditions, which were elucidated by XRD, Raman scattering and DFT calculations in a dimer of DA in the C form (monoclinic structure). The first phase change was noticed within the 210–190 K interval duly characterized as a transition of second-order type, as indicated by Gibbs energy behavior, suggesting that the monoclinic structure (P21/c) of the crystal is not changed. The second change was observed nearly 110–90 K, whose transition is first-order type occurring from the C form to an A form (triclinic), possibly belonging to the P1 space group. This new polymorphic phase was duly predicted through DFT calculations. According to Gibbs energy behavior, the third phase change (∼30–10 K) is proposed to be a transition from the A form to a new polymorphic phase that probably is a first-order transition, likely associated with a change from the P1 space group to P-1. Furthermore, group theory and wavenumber vs temperature plots’ analyses corroborated the phase transitions undergone by DA crystal. In addition, anharmonicity effects in several Raman bands’ behavior were noticed during the cooling. A correct assignment for the Raman and IR modes via DFT calculations at room-temperature conditions is also provided herein.

Experimental investigation of plant family extracts as gas hydrate inhibitors in an offshore simulated environment

This study experimentally investigates the use of Meliaceae Family Extract (MFE), Annonaceae Family Extract (AFE) and the Extracts Hybrid (EH) of both plants as inhibitors of gas hydrate were compared with conventional Monoethylene glycol (MEG). 1 to 3 wt% of the inhibitors were screened on a hydrate mini flow-loop. Different plots of pressure and temperature against time, final and initial pressure against time indicate that MFE, AFE and EH outperformed MEG at different weight concentrations. At 1 wt%, MFE exhibited an outstanding inhibition efficiency of 64.65%, whereas AFE, EH and MEG record 57.58%, 58.59% and 54.55%. MFE gave an improved performance at 1 wt% compared to the other three inhibitors. At 2 wt%, the optimum efficiency was recorded by AFE with an inhibition efficiency of 72.73% while EH, MFE and MEG were 69.70%, 50.51% and 59.60%. MEG performed slightly better at 3 wt% with inhibition efficiency of 71.72% than MFE and EH with inhibition efficiency of 70.71% while AFE performed the least at 68.69%. EH generally performed better, it is locally sourced and gotten from plant families which makes it less expensive and environmentally friendly unlike MEG, which is expensive and toxic to the environment.

Stereo-Recognition of Hydrogen Bond and Its Implications for Lignin Biomimetic Synthesis.

The hydrogen bond (H-bond) is essential to stabilizing the three-dimensional biological structure such as protein, cellulose, and lignin, which are integral parts of animal and plant cells; thus, stereo-recognition of the H-bond is extremely attractive. Herein, a methodology combining the variable-temperature 1H NMR technique with the density functional theory was established to recognize the underlying H-bonding patterns in lignin diastereomers. This method successfully classified the intramolecular and intermolecular H-bonds with slope values varying between 50.2-201.5 and 221.9-655.4, respectively, from the natural logarithm of the hydroxyl proton chemical shift versus the inverse of the temperature plot. Moreover, this slope was found to be correlated with the interaction distance between the H-bond donor and acceptor. Finally, it was proposed that the stereo-preferential formation of the β-O-4 structure (erythro vs threo form) during lignin biomimetic synthesis was probably influenced by their intramolecular H-bonding patterns, thus making it easier to reach thermodynamic equilibrium.

Bardeen solution with a cloud of strings

In this paper we present a Bardeen solution surrounded by a cloud of strings fluid. We show how this model has the same event horizon characteristic as the Bardeen solution, however, the parameter of the strings make the solution singular at the origin. We also analyze the solution from a thermodynamic point of view. We calculate the system's state function, enthalpy; the temperature; and the other potentials; as a function of entropy. By analyzing the thermodynamic coefficients, we show that the solution presents three distinct phases, two of which are stable and one unstable. These three phases could be best visualized using a plot of Gibbs free energy versus temperature. In the end, we calculate the critical exponents and find that they are the same as those found in Van der Walls theory.

Approximate climate analysis for assessing the suitability of Indian climate zones for hydroponic fodder applications

Hydroponic fodder has been proposed as a novel low-tech solution to India’s fodder scarcity. Hydroponic fodder can reduce water requirements by up to 95% and use up to 70% less land due to their vertically scalable nature. The short crop cycles of approximately 7 days yields a seed to feed ratio of 1:8. This study analyses the external environmental weather conditions in Indian climate zones, assessing their suitability for the application of hydroponic fodder solutions. The weather of each climate zone was approximated by a representative city through parameter selection and optimisation by three-dimensional Euclidean distance minimisation. Simulation and analysis were carried out on the Rhinoceros software platform with the Grasshopper and LadyBug plug-ins. Hourly temperature plots, sun-path diagrams and psychrometric charts with modified predicted mean vote polygons superimposed were generated for each climate zone. The ambient weather suitability of the following representative cities was simulated to be as follows: Ahmedabad (86.70%), Kolkata (81.86%), Bengaluru (94.07%), Lucknow (73.23%) and Srinagar (30.85%). A cost benefit analysis was buttressed by a sensitivity analysis with respect to the selling price of green fodder. A preliminary cash flow analysis yielded a discounted payback period of 4 months for direct fodder sales and 20 months for sale of livestock products as a co-benefit of green fodder production.

Colossal dielectric response and complex impedance analysis of LaFeO3 ceramics

The present investigations mainly focused on the colossal dielectric response and complex impedance analysis of LaFeO3 ceramics. The studied sample was prepared by a citrate gel method. Structural and microstructural properties are analyzed from the XRD pattern and SEM micrograph. The anomalies in the dielectric constant versus temperature plots are analyzed on the basis of polarization induced by the Maxwell-Wagner mechanisms and ferromagnetic interaction between the Fe[Formula: see text] ions driven by the oxygen vacancy mediated Fe[Formula: see text]–V[Formula: see text] –Fe[Formula: see text] exchange interaction A giant dielectric permittivity in the order of [Formula: see text]105 was observed in the sample even at the room temperature for 100 Hz. The colossal dielectric constant in LaFeO3 is mainly driven by the internal barrier layer capacitor (IBLC) formation. The formation of IBLC was explained on the basis of highly insulating grain boundary and less resistive/semiconducting grain, which was confirmed from both the resistance and capacitance of grain and grain boundary from the impedance analysis. The non-Debye-type relaxation process associated with the grain and grain boundary effect was investigated from the broad and asymmetric relaxation peak. The relaxation time for both the grain and grain boundary effect was also calculated. In addition to this, we have also analyzed the normalized bode plot of imaginary part of impedance and electrical modulus which suggests the relaxation process dominated by the short-range movement of charge carriers.

Temperature Profiles of Sunlight-Exposed Surfaces in a Desert Climate: Determining the Risk for Pavement Burns.

Plentiful sunlight and high temperatures in desert climates cause burn injuries from contact with sun-exposed surfaces. The peak temperature, times, and surfaces of greatest risk are not well described. This work recorded temperature measurements of six materials in a desert climate. Surface temperatures of asphalt, brick, concrete, sand, porous rock, and galvanized metal were measured throughout the summer, along with ambient temperature, and sunlight intensity. Samples were placed in both shade and direct sunlight for evaluation of sunlight effect. Seventy-five thousand individual measurements were obtained from March to August 2020. Maximum recorded temperatures for sunlight-exposed porous rock were 170°F, asphalt 166°F, brick 152°F, concrete 144°F, metal 144°F, and sand 143°F, measured on August 6, 2020 at 2:10 pm, when ambient temperature was 120°F and solar irradiation 940 W/m2. Sunlight-exposed materials ranged 36 to 56°F higher than shaded materials measured at the same time. The highest daily temperatures were achieved between 2:00 and 4:00 pm due to maximum solar irradiance. Contour plots of surface temperature as a function of both solar irradiation and time of day were created for all materials tested. A computational fluid dynamics model was created to validate the data and serve as a predictive model based upon temperature and sunlight inputs. This information is useful to inform the public of the risks of contact burn due to sunlight-exposed surfaces in a desert climate.

Comparison of combustion characteristics of four strut injectors with that of three strut injectors by numerically investigating doubly-dual cavity-based scramjet combustor

A numerical investigation has been conducted using 2D RANS (Reynolds Averaged Numerical Solution) equation and SST k- ω turbulence model in a cavity-based scramjet combustor with a doubly-dual cavity and hydrogen-fuelled, to study the performance and combustion characteristics of three struts and four struts injection. Fluid flow characteristics of four-strut injectors were compared with that of three-strut injectors. The reason for better performance output from four strut injection is understood and discussed briefly. Compared with the three-strut injector configuration, the formation of recirculation regions and vortices are enhanced in the four-strut injector system affecting shock wave interactions (shock-shear, shock-shock layer). Due to increased levels of shock layer interaction, and lower presence of oxygen, there was a better mixing of the fuel which resulted in improvement in combustion when four strut injectors were introduced. The intensity of combustion also increased which is evident from static temperature plots.

Dynamics of MHD Convection of Walters B Viscoelastic Fluid through an Accelerating Permeable Surface Using the Soret–Dufour Mechanism

The MHD convective Walters-B memory liquid flow past a permeable accelerating surface with the mechanism of Soret-Dufour is considered. The flow equation constitutes a set of partial differential equations (PDEs) to elucidate the real flow of a non-Newtonian liquid. The radiation thermo-physical parameters were employed based on the use of Roseland approximation. This implies the fluid employed in this exploration is optically thick. Utilizing suitable similarity terms, the flow equation PDEs were simplified to become total differential equations. The spectral homotopy analysis method (SHAM) was utilized to provide outcomes to the model. The SHAM involves the addition of the Chebyshev pseudospectral approach (CPM) alongside the homotopy analysis approach (HAM). The outcomes were depicted utilizing graphs and tables for the quantities of engineering concern. The mechanisms of Soret and Dufour were separately examined. The imposed magnetism was found to lessen the velocity plot while the thermal radiation term elevates the temperature plot because of the warm particles of the fluid.