Enhanced extraction of essential oil from Cinnamomum cassia bark by ultrasound assisted hydrodistillation

Cinnamon essential oil with many bioactivities is an important raw material for the production of various chemicals,and the conventional hydrodistillation(HD)for cinnamon oil extraction always require a longer extraction time.In this work,ultrasound-assisted hydrodistillation extraction(UAHDE)technique was employed to enhance the extraction efficiency of essential oils from cinnamon barks.The parameters with significant effects on the essential oil extraction efficiency(ultrasound time,ultrasound power,extraction time,liquid–solid ratio)were optimized,and the proposed UAHDE was compared with the conventional HD extraction in terms of the extraction time,extraction yield,and physicochemical properties of extracted oils.Compared to the HD extraction,the UAHDE resulted in a shorter extraction time and a higher extraction yield.Using GC–MS analysis,the UAHDE provided more valuable essential oil with a high content of the vital trans-cinnamaldehyde compounds compared with the HD.Scanning electron micrograph(SEM)confirmed the efficiency of ultrasound irradiation for cinnamon oil extraction.In addition,the analysis of electric consumption and CO_(2) emission shows that the UAHDE process is a more economic and environment-friendly approach.Thus,UAHDE is an efficient and green technology for the cinnamon essential oil extraction,which could improve the quantity and quality of cinnamon oils.

Constructal entransy optimizations for insulation layer of steel rolling reheating furnace wall with convective and radiative boundary conditions

Based on the entransy dissipation extremum principle for thermal insulation process,the constructal optimizations for a plane insulation layer of the steel rolling reheating furnace wall with convective and radiative boundary conditions are carried out by taking the minimization of entransy dissipation rate as optimization objective.The optimal construct of the plane insulation layer is obtained.The results show that for the convective heat transfer boundary condition,the optimal constructs of the insulation layer obtained based on the minimizations of the entransy dissipation rate and heat loss rate are obviously different.Comparing the optimal construct obtained based on the minimization of the entransy dissipation rate with that based on the minimization of the heat loss rate,the entransy dissipation rate is reduced by 5.98%,which makes the global thermal insulation performance of the insulation layer improve.For the combined convective and radiative heat transfer boundary condition,compared the insulation layer having an increasing thickness with that having constant thickness and a decreasing thickness,the entransy dissipation rates are reduced by 16.59%and39.72%,respectively,and the global thermal insulation performance of the insulation layer is greatly improved.There exits an optimal constant coefficient a2;optwhich leads to the minimum dimensionless entransy dissipation rate of the insulation layer.The difference between the optimal constant coefficients a2;optobtained based on the minimizations of the entransy dissipation rate and the maximum temperature gradient of the insulation layer is small.This makes the corresponding thermal stress obtained based on the minimum dimensionless entransy dissipation rate also be small,and the global thermal insulation performance and thermal safety of the insulation layer are improved simultaneously.The results obtained can provide some guidelines for the optimal designs of the insulation layers.

The optimal configuration of reciprocating engine based on maximum entransy loss

A class of two-heat-reservoir heat engine model with heat leakage,finite heat capacity high-temperature source and infinite heat capacity low-temperature heat sink,is researched with the finite-time thermodynamic theory and the entransy theory.The optimal configuration based on the minimum entropy generation and the maximum entransy loss under the given cycle is searched,which are compared with the optimal configuration based on the maximum output work,and all the heat transfer in the model is assumed to obey the Newton’s law.The results show that,for the infinite heat capacity high-temperature source,the optimal configuration does not change whether heat leakage exists or not;however,for the finite hightemperature reservoir,the optimal configuration is different among which based on the minimum entropy generation,the maximum entransy loss,and the maximum output work when the heat leakage exists.

Optimization of the power, efficiency and ecological function for an air-standard irreversible Dual-Miller cycle

This paper establishes an irreversible DualMiller cycle (DMC) model with the heat transfer (HT) loss, friction loss (FL) and other internal irreversible losses. To analyze the effects of the cut-off ratio (ρ) and Miller cycle ratio (rM) on the power output (P), thermal efficiency (η) and ecological function (E), obtain the optimal popt and optimal rMopt, and compare the performance characteristics of DMC with its simplified cycles and with different optimization objective functions, the P,η and E of irreversible DMC are analyzed and optimized by applying the finite time thermodynamic (FTT) theory. Expressions of P,η and E are derived. The relationships among P,η, E and compression ratio (ε) are obtained by numerical examples. The effects of ρ and rM on P,η, E, maximum power output (MP), maximum efficiency (MEF) and maximum ecological function (ME) are analyzed. Performance differences among the DMC, the Otto cycle (OC), the Dual cycle (DDC), and the Otto-Miller cycle (OMC) are compared for fixed design parameters. Performance characteristics of irreversible DMC with the choice of P,η and E as optimization objective functions are analyzed and compared. The results show that the irreversible DMC engine can reach a twice-maximum power, a twicemaximum efficiency, and a twice-maximum ecological fiinction, respectively. Moreover, when choosing E as the optimization objective, there is a 5.2% of improvement in η while there is a drop of only 2.7% in P compared to choosing P as the optimization objective. However, there is a 5.6% of improvement in P while there is a drop of only 1.3% in rj compared to choosing as the optimization objective.

壮族师公戏中傩面具的艺术特征和功能

在演出过程中使用傩面具是传统壮族师公戏的重要特点,作为一种特殊的艺术符号,傩面具在壮族传统文化中发挥着重要功能,具有丰富的象征意义。本文通过对师公戏傩面具的历史及存世现状的梳理,来分析现代师公戏傩面具的艺术特征及其社会功能。