Values Of Gr Research Articles

Germination of soybean seeds after low-temperature storage and its dependence on weather and climate conditions in the places of reproduction of accessions

Background. Soybean (Glycine max (L.) Merr.) is a microbiotic whose seeds quickly lose germination in uncontrolled conditions at room temperatures. This determines the need to preserve accessions in special conditions. Low temperature storage (LTS) allows to maintain high seed germination ability, but not for all accessions. Therefore, it is relevant to assess the results of LTS at the VIR Genebank and to make an attempt to determine the best geographical conditions for growing plants and harvesting seeds that will be subjected to LTS. Materials and methods. The work was carried out on 312 soybean accessions from the VIR collection, originating from almost the entire area of soybean cultivation. The accessions used in the research were reproduced at three VIR experiment stations (ES), namely Adler ES, Kuban ES (Krasnodar Territory) and the Far East ES (Primorsky Territory). The seeds were harvested in 1999 to 2017 and stored in sealed foil laminated bags at –10°C from 2002 to 2021. The accessions were removed from LTS and germination assessed in 2022. Results. At the beginning of LTS, seed germination (Gi) ranged from 12 to 100% (averaging 79.1%), while that after LTS (Gr) ranged from 1 to 97% (57.8% on average). The retention of germination ability was expressed as the germination index (GI = Gr / Gi), which ranged from 0.02 to 1.73 (an average of 0.72). All the indicators of germination in the range of up to 20 years of LTS were not associated with the duration of LTS and with the number of years before LTS (0.5-4 years in our research). The climatic conditions characteristic of the place of reproduction had a significant impact on Gi and Gr, but not on GI. The average Gi of seeds obtained at the Adler ES and Kuban ES did not differ significantly (77.4% and 75.7%), while that of seeds harvested at the Far East ES was significantly higher (84.0%). Gr of the accessions from the Far East ES (64.3%) was also greater than that of accessions from the Kuban ES (52.2%) and Adler ES (57.2%). The excessively high sum of temperatures above 10°C (recorded in some years at all stations) reduced Gi, Gr but had little effect on GI. The highest values of Gi, Gr, and GI were demonstrated by the accessions maturing in 101-120 days. Additionally drying of the most late-ripening accessions (later than 140 days) in sheaves under an awning yielded seeds with high germination ability and good LTS tolerance. Conclusion. The seeds from different places of reproduction of accessions differed in germination before and after LTS, and, on an average, the highest values were demonstrated by the seeds harvested at the Far East ES, where the temperature regime is closer to the optimal one for soybeans. The seed germination index showed relative independence from the conditions of reproduction of accessions, including the climate and weather conditions, as well as the initial germination ability and LTS duration.

Mathematical Solutions of Free Convection Flow of Casson Fluid in Channel with Accelerated Plate

Mathematical Solutions of Free Convection Flow of Casson Fluid in Channel with Accelerated Plate

Research on the Temperature Variation Law during the Nitrogen Pre-Cooling Process in LNG Unloading Pipelines

In order to study the temperature change law of a nitrogen pre-cooling LNG unloading pipeline, a three-dimensional numerical simulation of an LNG pipeline with a bellow expansion bend was conducted using Fluent software (2020 R2). This simulation involved progressively controlling the nitrogen injection temperature and flow rate. The results show that increasing the nitrogen flow rate can improve the pre-cooling rate and reduce the top–bottom temperature difference of the pipeline, but there is an optimal value. Under the same nitrogen injection velocity conditions, it was found that smaller pipe diameters result in smaller temperature differences between the top and bottom of the pipeline. However, due to the reduced cooling capacity of the nitrogen injection, this leads to a decrease in the pre-cooling rate. The top–bottom temperature difference of the pipeline is mainly related to the strength of the natural convection in the pipeline. The stronger the natural convection, the greater the temperature difference between the top and bottom. Gr and Gr/Re2 reflect the relative magnitude of the natural convection intensity and forced convection intensity in the pipe. The larger the Gr and Gr/Re2, the stronger the natural convection. Therefore, Gr and Gr/Re2 are positively correlated with the top–bottom temperature difference, and the variation trend of the top–bottom temperature difference can be judged by the values of Gr and Gr/Re2.

MHD flow of third-grade fluid through a vertical micro-channel filled with porous media using semi implicit finite difference method

This study examines the complex dynamics of an incompressible, electrically conducting third-grade fluid (TGF) flow through a vertical micro-channel that is filled with porous media. The research utilizes asymmetrical convective cooling, a transverse magnetic field, and exothermic reactions to introduce a comprehensive model. The viscosity of the fluid, which is determined by the Naham-type law, changes significantly with temperature. Additionally, the convective heat transfer rates, which govern the asymmetric convective cooling at the surfaces of the micro-channel, are modeled using Newton's law of cooling, and Modified Darcy law is used to address the porous medium effect. To solve the complex system of nonlinear partial differential equations, we employ computational solutions derived from reliable and efficient finite difference methods (FDM). The method is tested for different time-steps and mesh sizes and it is found that the algorithms reliably produce the same results. Our investigation includes an evaluation of both spatial and temporal convergence of the FDM scheme. The study present qualitative discussions of graphical results, that highlight the impact of various flow parameters integrated into the system. The velocity and temperature profiles increases for higher values of thermal Grashoff number Gr and Reynolds number Re while opposite effect is noticed for increasing values of Hartman number M.

Development of simultaneous antioxidant and visual pH‐sensing films based on guar gum loaded with Aronia melanocarpa extract

SummaryAnthocyanins have attracted increasing attention for different packaging systems due to having functional features such as biocompatibility, antioxidative activity, visible colour response at varying pH values. In this study, the extract of Aronia melanocarpa as anthocyanins source was incorporated into guar gum films to take advantage of both antioxidant and pH responsive attributes. Aronia addition did not affect the thermal stability of guar gum films. Radical scavenging activity of the films (%) was measured by 2,2‐Diphenyl‐1‐picrylhydrazyl (DPPH) assay, and aronia added films exhibited very strong antioxidant activity (up to 85%). The colour of aronia solution varied from pink to brown with pH ranging from 1 to 13. Similarly, when the films were immersed in buffer solutions at different pH values, the visual colour varied from pink to brownish yellow. ΔE values of GR_AR_3 (guar gum films having the highest aronia concentration) ranged between 23.31 and 40.62 at pH 1–13. This result proved colour change of the films can be even detected by untrained consumers. Furthermore, the films were found to be very sensitive to ammonia vapour. Aronia incorporated guar gum films could be suggested as both antioxidant films to prevent foods oxidation from oxidation and promising intelligent films to monitor the deterioration of foods.

Investigation of Williamson nanofluid in a convectively heated peristaltic channel and magnetic field via method of moments

The study of Williamson nanofluid under peristaltic pumping is conducted in this work. The model equations are developed using the magnetic field and convection effects, and consequently, a nonlinear system of ordinary differential equations is achieved. Then, the residual method based on a linearly independent set of functions known as method of moments is implemented and portrayed as the results under the parameters’ variations. The model results revealed that the peristaltic pumping can be controlled by increasing the values of Gr and Gc; however, the dual effects of the directed magnetic field on the movement of Williamson fluid are examined. The heat transfer augmentation is observed for a stronger Brinkman number and it is higher toward the channel walls. Similarly, the thermophoretic effect and Brownian motion of the particles highly affect the concentration of Williamson nanofluid.

Mixed convective and radiative heat transfer of LiF-BeF2-ThF4-UF4 in a vertical circular tube

Molten salts are promising fluids for applications involving heat transfer and thermal energy storage. The buoyancy effect and radiative heat transfer effect are frequently ignored in previous studies that concentrate on forced convective heat transfer of molten salts. However, these effects might not be negligible, particularly for laminar flows of optically semi-transparent fluids, such as molten salts. Therefore, this study tries to understand the heat transfer characteristics of molten salts, including mixed (forced and natural) convective heat transfer and radiative heat transfer. A two-dimensional axisymmetric model is created in STAR-CCM+ for assisting (buoyancy-assisted) laminar flows of LiF-BeF2-ThF4-UF4 (67.5–20.0–12.0–0.5 mol%) in a 5-m long, 15-mm-inner-diameter vertical circular tube. The effects of several non-dimensional parameters on the velocity, temperature, and Nusselt number are examined, including the Reynolds number (Re¯=2.0×102to1.8×103), Grashof number (Gr¯=3.1×103to5.4×104), optical thickness (τ=0.1τ0to10τ0, τ0 = 0.27, 2.11, and 446.47 for the three bands λI = 0.10 to 3.36 µm, λII = 3.36 to 5.42 µm, and λIII = 5.42 to 100.00 µm, respectively), and emissivity (ε=0.0to1.0). A flow regime map is also suggested to assess the radiative heat transfer effect in molten salts. Our analysis demonstrates that: (1) the predicted results in this study deviate from published experimental data by 14.5 to 45.1 % without taking the buoyancy effect and radiative heat transfer effect into account, however, these differences are dramatically decreased to 10.1 to 17.4 % while considering the buoyancy effect or 7.5 to 14.7 % while considering the buoyancy effect and radiative heat transfer effect; (2) the radiative heat transfer effect tends to mitigate the buoyancy effect, but their net effect enhances heat transfer; (3) the buoyancy effect factor fbuoy and thermal radiation effect factor frad are, respectively, up to 38.5 % and 19.5 % under the conditions investigated, illustrating the need to evaluate the two effects for molten salts; (4)fbuoy becomes larger for smaller values of Re¯, τ, and ε, and larger values of Gr¯ and non-dimensional axial location x/Di. frad becomes larger for smaller values of Re¯ and larger values of Gr¯, τ, ε, and x/Di; and (5) the flow regime map provided in this study aids in determining whether the radiative heat transfer effect in molten salts is negligible.

ЭКСПЕРИМЕНТАЛЬНОЕ МОДЕЛИРОВАНИЕ ТЕПЛООБМЕНА В ТЕПЛОВЫДЕЛЯЮЩИХ СБОРКАХ БЫСТРЫХ РЕАКТОРОВ В АВАРИЙНЫХ РЕЖИМАХ В УСЛОВИЯХ ЕСТЕСТВЕННОЙ КОНВЕКЦИИ

The results of experimental studies of heat transfer carried out at the State Research Center RF - IPPE on models of fuel assemblies in cores and screens of fast reactors BOR-60, BN-350, BN-600, BN-800 (the relative pitch of the fuel element simulators varied in the range 1.04≤s/d≤1.24) with natural and mixed convection of liquid metal coolants, which are the basis for the development of design codes. Model fuel assemblies of fast reactors contain 37 fuel elements (fuel rod simulators) located in a triangular lattice and enclosed in a hexagonal cover. The elements were heated with nichrome heaters, which ensure a constant heat flux on the inner surface of the elements and along the length of the heat generation. The central, lateral and corner elements are rotary. On their surface, 12 chromel-alumel thermocouples each in covers made of X18H9T steel (diameter of the cover 0.8-0.5 mm, diameter of thermoelectrodes 0.2 mm) are embedded, measuring the coolant temperature in the collectors of the models, as well as in each cell at the exit from the bundles. The spacing of the elements is carried out using wire coils; variants of smooth fuel rod simulators are also used. Experimental studies on model fuel assemblies revealed regularities in the formation of temperature fields in fuel elements and coolant. Natural convection manifests itself in the region of low velocities, promotes fluid mixing between channels, leveling the uneven heating of the coolant in the cross section of the fuel assembly, and reduces the azimuthal non-uniformity of the temperature of the wall fuel elements in the fuel assembly. The results of experimental studies show that the effect of natural convection manifests itself in the range of Pe<10 (Re<2000) numbers in gratings with relative steps (s/d<1.05) and in wide bundles (s/d<1.3 to a greater extent in bundles of smooth fuel rods in comparison with bundles of ribbed fuel rods. The introduction of displacers into the peripheral channels of a fuel assembly does not fundamentally change the nature of the temperature field in a fuel assembly as compared to the version of the geometry of a fuel assembly without displacers. An attempt was made to generalize the experimental data using the Gr*Pr criterion, where Gr* is the modified Grashof number calculated from the local heat flux on the heat exchange surface and the axial coordinate measured from the beginning of heat generation. In the dependences DTwmax = f(Gr*Pr2) at Pe<100 or ribbed side elements and Pe<10 for smooth side elements, two regions of DTwmax change in the Gr*Pr2 growth function are observed - first, DTwmax ncreases to a certain “limiting” value characteristic for fixed Pe, and then - a drop in DTwmax at large values of the parameter Gr*Pr2. As the Peclet number increases, the “limiting” value of DTwmax hifts to the region of larger values of Gr*Pr2; and at Pe=370 or ribbed elements and Pe=26.5; 100 or smooth elements, the limiting value of DTwmax is not achieved in the investigated range of the Gr*Pr2 parameter variation. For smooth side elements, the limiting values of DTwmax are approximately the same for different Pe numbers and amount to DTwmax≈10.

Entropy generation and heat transfer analysis in power-law fluid flow: Finite difference method

In this article entropy generation analysis for unsteady laminar free convection flow of power-law fluid is investigated. Fluid flow is in the presence of thermal radiation and magnetic field. The flow and heat transfer are governed by coupled system of PDE's. System of partial differential equation (PDE's) governs the continuity, momentum and energy equations. Using suitable dimensionless parameters, the system of PDE's is transformed into dimensionless form. Numerical computations made employing finite difference method (FDM). This method converts the nonlinear PDE 's to simple algebraic equations and by using variational technique the approximate solution is obtained technique. Impacts of important flow variables on velocity, skin friction and Nusselt number are shown graphically. Skin friction and Nusselt number are discussed for different pertinent flow variables. Velocity, temperature, entropy and Bejan number variations through important variables are discussed in the form of graphs. The obtained results show that velocity decays against Re, Ha and Pr. Temperature is enhanced for higher values of Re, Ec, Tr and Gr. For higher estimation of Ec entropy of the system enhance while show opposite behavior for the Bejan number. Entropy of system boosts for strong magnetic field.

A methodology to integrate melt pool convection with rapid solidification and undercooling kinetics in laser spot welding

In laser spot welding because of small melt pool and short process duration, the welding process takes place rapidly with high cooling rates. As a result the analysis of solidification in laser spot welding becomes challenging. The solidification takes place generally with non-equilibrium kinetics involving undercooling and recalescence. In this work, a methodology for handling the rapid solidification in laser spot welding is developed by solving the coupled transient conservation equations of mass, momentum and energy. Undercooling and recalescence are coupled with the melt pool convection and heat transfer using an interface tracking algorithm which predicts the rapidly evolving interface temperature and interface speed. The melt pool result is first validated with the published results. Thereafter, the effect of undercooling is investigated by presenting a detailed comparison of results obtained from the rapid (non-equilibrium) solidification model and the conventional (equilibrium) solidification model. The results conclude that undercooling and recalescence have profound effect on melt pool dimension, temperature, solidification time and melt pool convection. The rapid solidification behavior is delineated further with the help of solidification parameters, such as interface temperature, solidified thickness, temperature gradient (G) and solidification rate (R). The weld microstructure is estimated using the combined values of GR and G/R.

Utilization potential of Glutograph in wheat breeding programs and the influence of genotype and environment on bread wheat quality

AbstractBackground and objectivesGlutograph is a relatively new instrument to determine the stretch (GS) and relaxation (GR) properties of wheat gluten. The aims of this research were to determine heritability values of GS and GR and to investigate the effects of genotype and environment on some quality parameters and yield. The relationship between Glutograph parameters and other traits was also investigated by using correlation and biplot analyses.FindingsWide ranges of variability values were observed among both genotypes and environments for Glutograph parameters and other investigated characteristics. Genotype was found to be the most significant source of variation (~69%), and high heritability values (~0.95) were calculated for Glutograph parameters. Glutograph parameters had strong relationships with gluten index (GI) and Alveograph deformation energy (W) based on correlation and biplot analyses. Biplot analysis performed on 24 genotypes and nineteen traits demonstrated that especially eight genotypes had similar responses for GS, GI, grain protein content, Alveograph elasticity index, W, and Zeleny sedimentation values.ConclusionGlutograph could be a beneficial quick screening test especially in early stages of breeding programs for improving the baking quality of wheat.Significance and noveltyThe high heritability values indicate that Glutograph has a great potential for evaluation of gluten quality, especially in breeding programs.

Entropy Analysis for boundary layer Micropolar fluid flow

This paper reports entropy generation analysis of radiative micropolar fluid flow in porous medium. The mathematical model depicting convective boundary layer flow due to a vertically moving infinite plate bounding the porous medium on one side is solved numerically. An implicit finite difference method together with Gauss elimination method is used. The numerically computed velocity and temperature fields are employed to analyze entropy. The plots for entropy generation number for various sets of parameters are drawn. It is found that entropy generation number Ns decreases with increasing values of heat sink parameter Q and radiation parameter N whereas it increases with increasing values of Grashoff number Gr, Brinkman number Br. The Bejan number shows pronounced variations for the parameters entering into the problem.

Non-linear convection flow of micro polar nanofluid past an isothermal sphere

In this study, steady laminar two dimensional boundary layer flow of non-linear convection micropolar nanofluid over an isothermal sphere is examined. The mathematical developing for the flow problem has been made. By means of appropriate similarity transformation and dimensionless variable, the governing non-linear boundary value problems were reduced into combined high order non-linear ordinary differential equations. Then, solution for velocity, microrotation, temperature and concentration has been obtained numerically. The equations were calculated using method bvp4c from matlab software for various quantities of main parameters. The influences of diffident parameters on skin friction coefficient, wall duo stress coefficient the Nusselt number, Sherwood number as well as the velocities, temperature, and concentration are analyzed and discussed through the tables and plotted graphs. A comparison with previous paper obtainable in the literature has been performed and an excellent agreement is obtained. The finding results indicate the raise in either the values of thermal Grashof number Gr or Brownian motion parameter Nb or Schmidt number Sc allows to bringing down the kinematic viscosity of the fluid causes improve the temperature profile distribution within the boundary layer. On the other hand, it can be diminished by the growth in either the value of solutal Grashof number Gm or solutal non linear convection parameter s which agrees to enlarge fluid density.

Effect of dietary vitamin B 6 supplementation on growth and intestinal microflora of juvenile golden pompano ( Trachinotus ovatus )

In order to investigate the dietary vitamin B6 (VB6) requirement for juvenile golden pompano, an experiment of six different diets with six dietary VB6 levels (0, 3.75, 7.47, 10.6, 13.7 and 18.5 mg/kg) was conducted. The results indicated that the content of dietary VB6 significantly increased weight gain rate (WGR), specific growth rate (SGR) and feed conversion ratio (FCR; p < 0.05). Golden pompano fed diet containing 7.47 mg/kg VB6 achieved the maximum ALT, AST, GPx, hepatic VB6 concentrations as well as the minimum MDA, however, the ALT, AST, GPx and hepatic VB6 concentrations decreased while MDA increased with a further increase in dieatry VB6. The highest values of GR and POD occurred at the 10.6 and 13.7 mg/kg dietary VB6 (p < 0.05) respectively. A diet supplemented with 7.47 mg/kg VB6 increased intestinal Na+, K+-ATPase, Chymotrypsin, γ-glutamyl transpeptidase, creatine kinase and amylase activities (p < 0.05). The relative abundance of Tenericutes and Bacteroidetes decreased while Proteobacteria and Firmicutes improved with an increase in dietary VB6 levels up to 7.47 mg/kg. Quadratic regression analysis on WGR, hepatic VB6 concentrations, AST and ALT indicated that the optimum dietary VB6 levels for juvenile golden pompano were 8.84–9.28 mg/kg.

Theoretical and numerical study on high frequency vibrational convection: Influence of the vibration direction on the flow structure

Thermal convection induced simultaneously by horizontal temperature gradient and vibration in a rectangular cavity filled with molten silicon is investigated numerically and theoretically. The time averaged equations of convection are solved in the high-frequency vibration approximation. The Chebyshev spectral collocation method and a Newton-type method based on the Frechet derivative are used in the numerical solution of the streamfunction formulation of the incompressible Navier-Stokes equations. Validation by comparison with previous studies has been performed. Different values of the Grashof number Gr and vibrational Grashof number Grv and all the possible orientations of the vibrations are considered. Numerical results show that depending on the vibration direction, the flow can be amplified or damped, with even the possibility of flow inversion which can occur between critical vibration angles α1 and α2. A general theoretical expression is derived relating these critical angles and the ratio of vibrational to buoyant convection parameters, Grv/Gr. A very good agreement between the theoretical and numerical results is obtained.

Natural convection heat transfer in a power-law fluid from a heated rotating cylinder in a square duct

Laminar natural convection heat transfer in a power-law fluid from an isothermal rotating cylinder placed coaxially in a square duct has been studied numerically over the following ranges of conditions: Grashof number (10⩽Gr⩽103); Prandtl number (0.72⩽Pr⩽100); power-law index (0.2⩽n⩽1.5) and non-dimensional rotational velocity (0⩽S⩽4). The spatial variation of the velocity and temperature fields are visualised in terms of the streamline and isotherm patterns, and temperature and vertical velocity at a few locations, respectively. Indeed, a range of flow patterns including twin-celled and single-celled recirculating regions can be observed depending upon the relative strengths of the buoyancy-induced and forced flow. The rate of heat transfer is described in terms of the distribution of the local Nusselt number over the surface of the cylinder together with its surface averaged value. As expected, the mean Nusselt number shows a positive dependence on the both Grashof and Prandtl numbers irrespective of the values of the power-law index and rotational velocity. For a non-rotating cylinder (S = 0), shear-thinning fluid behaviour promotes heat transfer, whereas shear-thickening viscosity impedes it with reference to that in Newtonian fluids otherwise under identical conditions. For the case of a rotating cylinder (S≠0), the rotation has positive influence on the rate of heat transfer at low values of the Grashof or Rayleigh number (Ra<500) irrespective of the type of fluid behaviour, i.e., shear-thinning or shear-thickening or Newtonian. However, at high values of the Grashof or Rayleigh numbers, the gradual increase of rotation of the cylinder first lowers the rate of heat transfer, and then increases it for shear-thickening (n > 1) and Newtonian fluids (n = 1). On the other hand, a reverse trend is seen for shear-thinning fluids. These non-monotonous trends in the overall heat transfer stem from the interactions between the rate of variation of the fluid viscosity and the temperature gradient on the surface of the cylinder. Therefore, a prudent choice of the operating conditions and the fluid behaviour can be used to regulate the rate of heating or cooling from a rotating cylinder. Finally, the present values of the average Nusselt number are correlated in order to facilitate the interpolation of the present results for the intermediate values of Gr, Pr, S and n and/or the estimation of heat transfer duty in a new application.

Control of the NADPH supply and GSH recycling for oxidative stress management in hepatoma and liver mitochondria

To unveil what controls mitochondrial ROS detoxification, the NADPH supply and GSH/GSSG recycling for oxidative stress management were analyzed in cancer and non-cancer mitochondria. Therefore, proteomic and kinetomic analyses were carried out of the mitochondrial (i) NADPH producing and (ii) GSH/GSSG recycling enzymes associated to oxidative stress management. The protein contents of the eight enzymes analyzed were similar or even higher in AS-30D rat hepatoma mitochondria (HepM) than in rat liver (RLM) and rat heart (RHM) mitochondria, suggesting that the NADPH/GSH/ROS pathway was fully functional in cancer mitochondria.The Vmax values of IDH-2 were much greater than those of GDH, TH and ME, suggesting that IDH-2 is the predominant NADPH producer in the three mitochondrial types; in fact, the GDH reverse reaction was favored. The Vmax values of GR and GPx were lower in HepM than in RLM, suggesting that the oxidative stress management is compromised in cancer mitochondria. The Km values of IDH-2, GR and GPx were all similar among the different mitochondrial types.Kinetic modeling revealed that the oxidative stress management was mainly controlled by GR, GPx and IDH. Modeling and experimentation also revealed that, due to their higher IDH-2 activity and lower GPx activity presumably by acetylation, HepM (i) showed higher steady-state NADPH levels; (ii) required greater peroxide concentrations to achieve reliable steady-state fluxes and metabolite concentration; and (iii) endured higher peroxide concentrations without collapsing their GSH/GSSG ratios. Then, to specifically prompt lower GSH/GSSG ratios under oxidative stress thus compromising cancer mitochondria functioning, GPx should be re-activated.

Experimental study on structural models of coal macrolithotypes and its well logging responses in the Hancheng area, Ordos Basin, China

Coal macrolithotype (bright, semi-bright, semi-dull, and dull coals) controls the heterogeneity of coal physical properties in the coalbed methane (CBM) reservoir. However, few scholars carried out the work aiming at the compositional-based macrolithotype analysis of coal reservoirs. In this work, the Hancheng area, Ordos Basin, China, was taken as an example to understand the macrolithotype difference, establish the structural models of macrolithotypes, and then evaluate the responses of advanced well loggings (the natural gamma-ray spectroscopy (NGS), formation microresistivity image (FMI), and cross-dipole array acoustic (XMAC) loggings). Results show that, from the bright to dull coal, the coal density, ash yield, and mineral content increase while the vitrinite content and pore-fracture development degree decrease gradually. The dull and semi-dull coals usually are found in touch with the mudstone (roof, floor, and parting) while the bright or semi-bright coal occurs as an interlayer between them. In the structural models of macrolithotypes for the CBM reservoir, the fracture model couples the artificial and macrofractures controlled by the tectonic stress field as well as the microfracture mainly restricted by the coal macrolithotypes; the pore model shows multilevel pores with gradually decreasing pore size, namely the protogenetic (plant tissue and intergranular pores) and secondary (gas and intermolecular pores) pores; and the pore-fracture relation model is characterized by the multilevel communication between the pores and fractures. Of all the three advanced logging responses of macrolithotypes, the NGS and XMAC show a good consistency with the natural gamma (GR) and interval transit time (AC) loggings since the former was derived from the latter essentially, respectively. But using FMI to identify macrolithotypes is error-prone due to the strong coal heterogeneity around the wellhole. From the bright to dull coal and mudstone, the values of thorium, kalium, uranium elements and GR (or GR without uranium) increase while those of AC including the longitudinal, transverse, and Stoneley waves decrease gradually.

A Computational Study on Mixed Convection Heat Transfer in an Inclined Rectangular Channel under Imposed Local Flow Modulation

Numerical investigation of mixed convection heat transfer in an inclined 2D rectangular channel provided with partially heated bottom wall and a constant low temperature upper wall has been performed. The heated section of the bottom wall i.e. the heaters are maintained with constant heat flux and separated from each other by adiabatic segments. A fully developed parabolic velocity profile at constant low temperature is induced at the inlet. To enhance the heat transfer from the heaters, local flow field in the channel is modulated by placing circular cylinders rotating in counterclockwise direction (aiding flow) above each heater along the channel centerline. The fluid and the thermal fields within the rectangular channel are governed by the two-dimensional Navier-Stokes and Energy equations that have been solved by adapting Galerkin finite element method. The governing parameters of the present problem such as Reynolds number (Re) and Grashof number (Gr) are varied in the range of 1 ≤ Re ≤ 100 and 103 ≤ Gr ≤ 105. Air has been considered as working fluid having a Prandtl number, Pr = 0.71. In addition to these governing parameters, the inclination angle of the channel (α) and the speed ratio (ξ) that is the ratio of peripheral speed of the rotating cylinder and the maximum inlet flow velocity is also varied in the range of 0° ≤ α ≤ 90° and 0.5 ≤ ξ ≤ 2.0 respectively. The thermal and the fluid fields are visualized via the isotherm and the streamline plots. The efficacy of local flow modulation with rotating cylinder for heat transfer enhancement has been estimated in terms of normalized average Nusselt number over the heaters as Nu/Nunc, where Nu and Nunc represents the average Nusselt number with and without flow modulation respectively. Results obtain in the present study reveals that, for very weak flow (Re = 1), flow modulation results in lower heat transfer particularly at lower values of Gr on the contrary for moderate and higher values of Re (10, 100), flow modulation has been found to result in higher heat transfer particularly at lower values of Gr. For example, at Re = 100 and α= 0°, about 32% to 55% enhancement in heat transfer has been obtained for 103≤ Gr ≤ 105. Variation in heat transfer enhancement through flow modulation has also been noticed for different channel inclination angle (α) for various system configurations.Journal of Chemical Engineering, Vol. 30, No. 1, 2017: 43-50

Unsteady MHD Mixed Convection inside L-shaped Enclosure in the Presence of Ferrofluid (Fe3O4)

Mixed convection has been one of the most interesting topics of research in the field of heat transfer for many years. In the present study, unsteady MHD mixed convection heat transfer inside a heated L-shaped enclosure filled with Fe3O4water has been investigated numerically. Lid-motion is introduced by the top wall to induce forced convection. For pure mixed convection (Ri = 1), Grashof number (Gr = 103 - 105) and time (τ) are varied, whereas the solid volume fraction of nanofluid (φ = 0.1) and Hartman number (Ha = 25) are kept constant. Results have been presented in terms of isotherm lines, streamlines, average Nusselt (Nu) number and average temperature (θay). The obtained results show that MHD causes significant effects on heat transfer rate. Interestingly, natural convection is more effective in this case of mixed convection as higher values of Nu are obtained for higher values of Gr.