Morphological and biochemical modification of guava processing industrial bio-mass by dielectric barrier discharge atmospheric plasma and effect on yield of bio-materials

Guava pomace, an underutilized industrial byproduct from the guava processing fruit juice industry prone to have a wide range of bioactive and functional metabolites which has not been explored. Dielectric Barrier Discharge Atmospheric (DBDA) plasma is a novel non-thermal technology that has been widely used in the food processing field of research. In this study, the effect of DBDA plasma treatment under different treatment combinations i.e, 25 kV, 30 kV, and 35 kV for 5 min, 10 min and 15 min respectively for each voltage, on modification of morphological and biochemical properties of the guava pomace powder on improving the efficiency of extraction yield of biomaterials have been investigated. The response surface model (RSM) was then constructed using the experimental results of Box–Behnken Design (BBD) to obtain the optimal extraction conditions. The predicted optimal extraction conditions for DBDA plasma treatment as 35 kV for 15 min and solvent extraction conditions were determined as 80 °C for 360 min causing an increment of the oil yield up to 16.54% when extracted using solvent extractor with ethanol as a solvent. These results indicate that the DBDA plasma treatment previous to the extraction step extraction process can contribute to reduce the duration of extraction by 120 min, increasing the oil yield by 42.75% and improving the nutritional quality of the oil. This research helps to develop a novel and economical method for improving the extraction yield of oil and to fully valorizing the guava fruit processing industrial waste into biomaterial

Wpływ naturalnego włókna Gongura roselle na właściwości mechaniczne kompozytów ABS i PLA otrzymanych metodą druku 3D

The influence of the natural Gongura roselle fiber on the tensile and flexural properties as well as on Shore D hardness of acrylonitrile-butadiene-styrene (ABS) and poly (lactic acid) (PLA) was investigated. The composites were printed in fused deposition modeling (FDM) 3D technique. The addition of natural fiber improved the mechanical properties of the tested composites, while the flexural strength, modulus and hardness were better in the case of ABS-based composite. Whereas, PLA-based composites showed higher tensile strength. The influence of the nozzle angle on the mechanical properties of the composites was also investigated. The best results have been obtained when using an angle of 0°.Zbadano wpływ naturalnego włókna Gongura roselle na właściwości mechaniczne przy rozciąganiu i zginaniu oraz twardość Shore’a D akrylonitrylu-butadienu-styrenu (ABS) i poli(kwasu mlekowego) (PLA). Kompozyty otrzymano metodą osadzania topionego materiału (FDM) w technice 3D. Dodatek naturalnego włókna poprawił właściwości mechaniczne badanych kompozytów, przy czym wytrzymałość na zginanie, moduł sprężystości i twardość były lepsze w przypadku kompozytu na osnowie ABS. Natomiast kompozyty na osnowie PLA miały większą wytrzymałość na rozciąganie. Zbadano również wpływ kąta ustawienia dyszy na właściwości mechaniczne kompozytów. Najlepsze wyniki uzyskano stosując kąt 0°

Does Collective Action Sequester Carbon? Evidence from the Nepal Community Forestry Program

Highlights • Presumed open access forests have as little as 34% of those under collective action. • No evidence that Community Forestry Programme forests store more carbon .• Carbon from collective action not conditional on Community Forestry Programme

Steady flow of power law fluids across a circular cylinder

The momentum equations describing the steady cross-flow of power law fluids past an unconfined circular cylinder have been solved numerically using a semi-implicit finite volume method. The numerical results highlighting the roles of Reynolds number and power law index on the global and detailed flow characteristics have been presented over wide ranges of conditions as 5 ≤ Re ≤ 40 and 0.6 ≤ n ≤ 2. The shear-thinning behaviour (n < 1) of the fluid decreases the size of recirculation zone and also delays the separation; on the other hand, the shear-thickening fluids (n > 1) show the opposite behaviour. Furthermore, while the wake size shows non-monotonous variation with the power law index, but it does not seem to influence the values of drag coefficient. The stagnation pressure coefficient and drag coefficient also show a complex dependence on the power law index and Reynolds number. In addition, the pressure coefficient, vorticity and viscosity distributions on the surface of the cylinder have also been presented to gain further physical insights into the detailed flow kinematics

A numerical study of the steady forced convection heat transfer from an unconfined circular cylinder

Forced convection heat transfer from an unconfined circular cylinder in the steady cross-flow regime has been studied using a finite volume method (FVM) implemented on a Cartesian grid system in the range as 10≤Re≤45 and 0.7≤Pr≤400. The numerical results are used to develop simple correlations for Nusselt number as a function of the pertinent dimensionless variables. In addition to average Nusselt number, the effects of Re, Pr and thermal boundary conditions on the temperature field near the cylinder and on the local Nusselt number distributions have also been presented to provide further physical insights into the nature of the flow. The rate of heat transfer increases with an increase in the Reynolds and/or Prandtl numbers. The uniform heat flux condition always shows higher value of heat transfer coefficient than the constant wall temperature at the surface of the cylinder for the same Reynolds and Prandtl numbers. The maximum difference between the two values is around 15-20%

Two-dimensional steady Poiseuille flow of power-law fluids across a circular cylinder in a plane confined channel: wall effect and drag coefficient

The Poiseuille flow of incompressible power-law fluids past a circular cylinder placed midway between two parallel plates has been investigated numerically by solving the continuity and momentum equations using FLUENT (Version 6.2). Extensive results highlighting the roles of the Reynolds number (Re), the power-law index (n), and the blockage ratio (β) on the global and detailed flow characteristics have been presented over wide ranges of conditions (1 ≤ Re ≤ 40, 0.2 ≤ n ≤ 1.9, and 1.1 ≤ β ≤ 4). For a fixed value of the blockage ratio, the drag coefficient increases as the shear-thickening (n > 1) tendency of the fluid increases, whereas shear-thinning (n < 1) fluid behavior shows the opposite dependence. At small Re, this effect is observed to be very strong and it gradually diminishes as Re increases. The effect of Re diminishes for n > 1 with a decrease in β, whereas the dependence becomes stronger for n < 1. Individual drag coefficients also show qualitatively similar dependence on Re, n, and β. In addition, the streamline and pressure profiles have also been presented to provide further physical insights into the detailed kinematics of the flow. The wake size is observed to increase as the flow behavior index (n) decreases. Because of wall effects, the flow separation seems to be delayed in shear-thickening fluids, whereas the opposite trend was observed in shear-thinning fluids. While the pressure profiles are observed to be similar to that for an unconfined flow, the flattening of the pressure curve in the rear portion of the cylinder suggests sluggish pressure recovery due to wall effects. In contrast to an unconfined flow, the front stagnation pressure coefficient values can be negative in magnitude, under certain conditions. The dependence of the pressure coefficient on the flow behavior index intensifies in shear-thickening fluids with a decrease in the blockage ratio

Steady forced convection heat transfer from a heated circular cylinder to power-law fluids

Forced convection heat transfer to incompressible power-law fluids from a heated circular cylinder in the steady cross-flow regime has been investigated numerically by solving the momentum and thermal energy equations using a finite volume method and the QUICK scheme on a non-uniform Cartesian grid. The dependence of the average Nusselt number on the Reynolds number (5≤Re≤40), power-law index (0.6≤n≤2) and Prandtl number (1≤Pr≤1000) has been studied in detail. The numerical results are used to develop simple correlations as functions of the pertinent dimensionless variables. In addition to the average Nusselt number, the effects of Re, Pr and n on the local Nusselt number distribution have also been studied to provide further physical insights. The role of the two types of thermal boundary conditions, namely, constant temperature and uniform heat flux on the surface of the cylinder has also been presented

Forced convection in cross flow of power law fluids over a tube bank

The forced convective heat transfer characteristics for incompressible power-law fluids past a bundle of circular cylinders have been investigated numerically. The cylinder-to-cylinder hydrodynamic interactions have been approximated via a simple cell model. The momentum and energy equations have been solved using a finite difference based numerical method for a range of physical and kinematic conditions. The role of the two commonly used thermal boundary conditions, namely, constant temperature or constant heat flux, on heat transfer characteristics has also been studied. Extensive numerical results elucidating the effect of shear-thinning viscosity on the values of Nusselt number have been obtained for Peclet numbers ranging from 1 to 5000, Reynolds number in the range 1-500, flow behaviour index 1 n 0.5 and three values of voidages, namely, 0.4, 0.5 and 0.6, typical of tubular heat exchangers and tube banks. Under all conditions, varying levels of enhancement in Nusselt number are observed due to shear-thinning behaviour. The surface averaged Nusselt number shows strong dependence on the values of voidage, power-law index, Reynolds and Peclet numbers. The paper is concluded by presenting comparisons with the scant experimental results available in the literature