In this paper, the problem of free convection boundary layer flow on a horizontal circular cylinder in a nanofluid with viscous dissipation and constant wall temperature is investigated. The transformed boundary layer equations are solved numerically using finite difference scheme namely the Keller-box method. Numerical solutions were obtained for the reduced skin friction coefficient, Nusselt number and Sherwood number as well as the velocity and temperature profiles.The features of the flow and heat transfer characteristics for various values of the Brownian motion parameter, thermophoresis parameter, Lewis number and Eckert number were analyzed and discussed.
Analyzed the effects of thermal radiation, chemical reaction, heat gener-
ation/absorption, magnetic and electric fields on unsteady flow and heat transfer of
nanofluid. The transport equations used passively controlled. A similarity solution is
employed to transformed the governing equations from partial differential equations to
a set of ordinary differential equations, and then solve using Keller box method. It was
found that the temperature is a decreasing function with the thermal stratification due to
the fact the density of the fluid in the lower vicinity is much higher compared to the upper
region, whereas the thermal radiation, viscous dissipation and heat generation enhanced
the nanofluid temperature and thermal layer thickness.
Zeolite socony mobil-5 (ZSM-5) is a common catalyst used for biomass pyrolysis. Nevertheless, the quantitative information on the catalytic behavior of ZSM-5 on biomass pyrolysis is absent so far. This study focuses on the catalytic pyrolysis phenomena and mechanisms of biomass wastes using ZSM-5 via thermogravimetric analyzer and pyrolysis-gas chromatography/mass spectrometry, with particular emphasis on catalytic level identification and aromatic hydrocarbons (AHs) formation. Two biomass wastes of sawdust and sorghum distillery residue (SDR) are investigated, while four biomass-to-catalyst ratios are considered. The analysis suggests that biomass waste pyrolysis processes can be divided into three zones, proceeding from a heat-transfer dominant zone (zone 1) to catalysis dominant zones (zones 2 and 3). The indicators of the intensity of difference (IOD), catalytic effective area, catalytic index (CI), and aromatic enhancement index are conducted to measure the catalytic effect of ZSM-5 on biomass waste pyrolysis and AHs formation. The maximum IOD occurs in zone 2, showing the highest intensity of the catalytic effect. The CI values of the two biomass wastes increase with increasing the biomass-to-catalyst ratio. However, there exists a threshold for sawdust pyrolysis, indicating a limit for the catalytic effect on sawdust. The higher the catalyst addition, the higher the AHs proportion in the vapor stream. When the biomass-to-catalyst ratio is 1/10, AHs formation is intensified significantly, especially for sawdust. Overall, the indexes conducted in the present study can provide useful measures to identify the catalytic pyrolysis dynamics and levels.
Bacteria exist widely in a diversity of natural environments. In order to survive adverse conditions such as nutrient depletion, biochemical and biological disturbances, and high temperature, bacteria have developed a wide variety of coping mechanisms. Temperature is one of the most important factors that can enhance the expression of microbial proteins. This study was conducted to investigate how outer membrane proteins (OMPs) of the bacterium Shigella flexneri respond to stress, especially during fever when the host's body temperature is elevated.
This study investigates thermal natural convective heat transfer in a nanofluid filled-non-Darcian porous and wavy-walled domain under the local thermal non-equilibrium condition. The considered cavity has corrugated and cold vertical walls and insulated horizontal walls except the heated part positioned at the bottom wall. The transport equations in their non-dimensional model are numerically solved based on the Galerkin finite-element discretization technique. The dimensionless governing parameters of the present work are the nanoparticle in volume concentration, the Darcy number, number of undulations, modified heat conductivity ratio, dimensionless heated part length, and location. Comparisons with other published theoretical and experimental results show good agreement with the present outcomes. The findings indicate that the heater length, its position, and the waves number on the side vertical walls as well as the nanoparticles concentration can be the control parameters for free convective motion and heat transport within the wavy cavity.
The heat and mass transfer of steady magnetohydrodynamics of dusty Jeffrey fluid past an exponentially stretching sheet in the presence of thermal radiation have been investigated. The main purpose of this study is to conduct a detailed analysis of flow behaviour of suspended dust particles in non-Newtonian fluid. The governing equations hav been converted into dimensionless form, and then solved numerically via the Keller-box method. The expression of Sherwood number, Nusselt number and skin friction have been evaluated, and then displayed in tabular forms. Velocity, temperature and concentration profiles are presented graphically. It is observed that large value of dust particles mass concentration parameter has reduced the flow velocity significantly. Increase in radiation parameter enhances the temperature, whereas the increment in Schmidt number parameter reduces the concentration.
The control effects on the convection dynamics in a viscoelastic fluid-saturated porous medium heated from below and cooled from above are studied. A truncated Galerkin expansion was applied to balance equations to obtain a four-dimensional generalized Lorenz system. The dynamical behavior is mainly characterized by the Lyapunov exponents, bifurcation, and isospike diagrams. The results show that within a range of moderate and high Rayleigh numbers, proportional controller gain is found to enhance the stabilization and destabilization effects on the thermal convection. Furthermore, due to the effect of viscoelasticity, the system exhibits remarkable topological structures of regular regions embedded in chaotic domains.
Basa catfish is a good source for fish oil extraction, which was believed to have good thermo-oxidative stability because of its similar fatty acid composition to that of palm olein (PO). The thermo-oxidative stability of PO, basa catfish oil (FO), and palm olein-basa fish oil blend (PO-FO; ratio 1:1) was evaluated after 75 frying cycles. No significant difference was observed in p-anisidine value, TOTOX value, conjugated trienes, monomeric oxidized triacylglycerols, and free fatty acids concentration after frying. Moreover, compared to PO, FO exhibited lighter color, lower acid value, conjugated dienes, polymerized triacylglycerol, and total polar content. The PO-FO blend also demonstrated a more favorable frying stability compared to the other two frying systems. These findings indicated that FO could be proposed as a promising alternative to common PO, and its blending with other vegetable oils at an appropriate ratio might improve the overall oil frying quality for future industrial applications.
Coral reef research has predominantly focused on the effect of temperature on the breakdown of coral-dinoflagellate symbioses. However, less is known about how increasing temperature affects the establishment of new coral-dinoflagellate associations. Inter-partner specificity and environment-dependent colonization are two constraints proposed to limit the acquisition of more heat tolerant symbionts. Here, we investigated the symbiotic dynamics of various photosymbionts in different host genotypes under "optimal" and elevated temperature conditions. To do this, we inoculated symbiont-free polyps of the sea anemone Exaiptasia pallida originating from Hawaii (H2), North Carolina (CC7), and the Red Sea (RS) with the same mixture of native symbiont strains (Breviolum minutum, Symbiodinium linucheae, S. microadriaticum, and a Breviolum type from the Red Sea) at 25 and 32 °C, and assessed their ITS2 composition, colonization rates, and PSII photochemical efficiency (Fv/Fm). Symbiont communities across thermal conditions differed significantly for all hosts, suggesting that temperature rather than partner specificity had a stronger effect on symbiosis establishment. Overall, we detected higher abundances of more heat resistant Symbiodiniaceae types in the 32 °C treatments. Our data further showed that PSII photophysiology under elevated temperature improved with thermal pre-exposure (i.e., higher Fv/Fm), yet, this effect depended on host genotype and was influenced by active feeding as photochemical efficiency dropped in response to food deprivation. These findings highlight the role of temperature and partner fidelity in the establishment and performance of symbiosis and demonstrate the importance of heterotrophy for symbiotic cnidarians to endure and recover from stress.
This paper presents the temperature characteristics of silicon nanowire transistors (SiNWTs) and examines the effect of temperature on transfer characteristics, threshold voltage, I(ON)/I(OFF) ratio, drain-induced barrier lowering (DIBL), and sub-threshold swing (SS). The (MuGFET) simulation tool was used to investigate the temperature characteristics of a transistor. The findings reveal the negative effect of higher working temperature on the use of SiNWTs in electronic circuits, such as digital circuits and amplifiers circuits, because of the lower I(ON)/I(OFF) ratio, higher DIBL, and higher SS at higher temperature. Moreover, the ON state is the optimum condition for using a transistor as a temperature nano-sensor.
CaCu3Ti4O12 was synthesized starting from a solution of TiO2 to which Ca and Cu nitrates were added. Due to the differences in the solubilities of the Ca, Cu and Ti, initial variations from ideal stoichiometry and a high solution pH was necessary to obtain stoichiometric CaCu3Ti4O12 precipitates. As precipitated samples were amorphous with CuO phases observed after drying of the precipitates at 300 oC. CaCu3Ti4O12 phases were observed after heat treatment at 1000 oC. XRD studies show the presence of CuO and TiO2 in addition to the CaCu3Ti4O12 for non stoichiometric samples. Observations under the SEM show the presence of Cu rich and Ti rich phases in addition to the CaCu3Ti4O12.
The drying of Piper betle Linn (betel) leaf extract using a lab scale spray dryer was simulated using Computational Fluid Dynamics (CFD). Three different turbulent models (standard k-ε, RNG k-ε and realizable k-ε) were used in the present study to determine the most suitable model for predicting the flow profile. Parametric studies were also conducted to evaluate the effect of process variables on the final moisture content. Four different initial droplet sizes (36, 79, 123 and 166 μm) were tested with four sets of combination of hot air temperature (140 and 160°C) and feed rate (4, 9.5 and 15 ml/min). It was found that standard k-ε is the most suitable turbulent model to predict the flow behaviour Moreover, the lowest final moisture content present in samples was obtained at 140°C and a feed rate of 15.0 ml/min.
A study has been conducted on pink guava juice (PGJ) fouling deposit. Several ex-situ experimental rigs were set-up to obtain PGJ fouling deposit, while the best ex-situ experimental rig was also selected. PGJ was heated at 93°C and its fouling deposit was obtained after 1 hour of heating. Then, it was used for the ex-situ cleaning study at 1 litre min-1, at several temperatures (70, 80 and 90°C), and in some chemical concentrations (1.6 v/v% of Maxiclean CP6 or 0.325 % OH-; 1.8 v/v% of Maxiclean CP6 or 0.369 % OH-; 2.0 v/v% of Maxiclean CP6 or 0.44 % OH-). The best cleaning combinations were investigated. Carbohydrate is the main content in the fouling deposit. The morphology of the deposit was studied using SEM and it showed an aggregated structure. The cleaning process improved as the temperature increased with the increasing of the chemical solution concentration. The shortest cleaning time was 40 minutes, for cleaning using 2.0 v/v % of Maxiclean CP6 (0.44 % OH-) at 90°C.
This paper discuss thermal comfort studies of an under air conditioning in hot and humid climate which at one of the higher institution in East Coast of Malaysia. Indoor thermal environment is important as it affects the health and productivity of building occupants. The paper reports on an experimental investigation of indoor thermal comfort characteristics under the control of air conditioning. Firstly, the well known Fanger’s thermal comfort model was simplified for the current experimental investigation. This is followed by reporting the experimental results of indoor thermal comfort characteristics under the control of temperature, with eight different of temperatures which are 22oC to 29oC. Finally, indoor thermal comfort was merely affected by the increment ventilation and outdoor climate. PMV value was higher when near from the window because of the effects of the wall radiations and the metabolic heat.
Extract of mengkudu was heated using a bench-top tube heat exchanger at 30, 50, 70 and 90 o C for 0, 5, 10 and 15 min residence time. The treated mengkudu extract was then measured for pH, L * , a * , b * color parameters, clarity, viscosity and total polyphenol content. Results show that heating using temperature of 30 to 90 o C for 5 to 15 mins significantly (p
The microstructure, tensile fracture and creep fracture of as-cast beta phase contained γ-TiAl with nominal composition of Ti-48Al-4Cr (at.%) was investigated. The effect of beta phase on tensile and creep strength was determined from fracture analysis. Tensile test were performed at room temperature whereas constant load tensile creep test were performed at temperature 800 0 C and initial stress of 150MPa. Initial as-cast microstructure, microstructure and fracture surface after tensile and creep test were examined using scanning electron microscopy technique. Analysis shows brittle fracture after room temperature tensile test whereas ductile fracture after high temperature creep test. The role of beta phase was discussed. It is concluded that beta phase is sensitive to temperature and detrimental at both room and high temperature.
This study analysed mixed convection heat transfer for thermally developing flow in a side heated square duct with varying inclination angles. The test section consists of one-side heated isothermal wall and three adiabatic walls. The inclination angle varied from 00C, and heat flux ranging from 252 W/m2C to 100o30o 858 to 1788 and the wall surface emissivity was considered to be 0.05 and 0.85. Flow visualizations were carried out to obtain the flow structure of natural convection and mixed convection for three inclination angles. The variation of surface temperature along the length of the test section was studied to calculate the convective Nusselt number. The result showed that the heat transfer enhancement and convective Nusselt number was significantly affected by the variations of inclination angle, flow velocity, Reynolds number, and the surface radiation. It was also observed that the increase in the inclination angle improved convection rate and hence significantly enhanced heat transfer. to 200, with hot wall temperature ranging from to 872 W/m2
In this paper, the problem of steady laminar boundary layer flow of an incompressible viscous fluid over a moving thin needle is considered. The governing boundary layer equations were first transformed into non-dimensional forms. These non-dimensional equations were then transformed into similarity equations using the similarity variables, which were solved numerically using an implicit finite-difference scheme known as the Keller-box method. The solutions were obtained for a blunt-nosed needle. Numerical computations were carried out for various values of the dimensionless parameters of the problem which included the Prandtl number Pr and the parameter a representing the needle size. It was found that the heat transfer characteristics were significantly
influenced by these parameters. However, the Prandtl number had no effect on the flow characteristics due to the decoupled boundary layer equations.
XRF analysis was done on a local zircon samples and the result shows it has a high Fe, Th and U content. The high Fe content in Malaysian zircon had made the mineral to be classified as of a low-grade zircon. Presence of Fe in this mineral may be resulted from clay mineral coating found on the zircon surface. Chemical leaching technique was used for the removal of this Fe and the study also shows that a 600 o C heat pretreatment stage is important for the effectiveness of this process. Other parameters studied are the HCl concentration, leaching temperature and time. By using the optimum leaching parameters, the Fe content had been reduced to 0.049% and thus qualified it to be categorised as a premium grade zircon.
Linear stability analysis was used to investigate the onset of Marangoni convection in a two-layer system. The system comprised a saturated porous layer over which was a layer of the same fluid. The fluid was heated from below and the upper free surface was deformable. At the interface between the fluid and the porous layer, the Beavers-Joseph slip condition was used and in the porous medium the Darcy law was employed to describe the flow. Predictions for the onset of convection were obtained from the analysis by the perturbation technique. The effect of surface deformation and depth ratio, z (which is equal to the depth of the fluid layer/depth of the porous layer) on the onset of fluid motion was studied in detail.