Heat transfer and friction factor of Therminol liquid phase heat transfer fluid in a ribbed tube

Experiments and simulations on flow and heat transfer behavior of Therminol-55 liquid phase heat transfer fluid have been conducted in a ribbed tube with the outer diameter and inner diameter 25.0 and 20.0 mm,pitch and rib height of 4.5 and 1.0 mm.respectively.Experimental results show that the heat transfer and thermal performance of Therminol-55 liquid phase heat transfer fluid in the ribbed tube are considerably improved compared to those of the smooth tube.The Nusselt number increase with the increase of Reynolds number.The increase in heat transfer rate of the ribbed tube has a mean value of 2.24 times.Also,the pressure drop results reveal that the average friction factor of the ribbed tube is in a range of 2.4 and 2.8 times over the smooth tube.Numerical simulations of three-dimensional flow behavior of Therminol-55 liquid phase heat transfer fluid are carried out using three different turbulence models in the ribbed tube.The numerical results show that the heat transfer of ribbed tube is improved because vortices are generated behind ribs,which produce some disruptions to fluid flow and enhance heat transfer compared with smooth tube.The numerical results prove that the ribbed tube can improve heat transfer and fluid flow performances of Therminol liquid phase heat transfer fluid.

Optimization of dual electrolyte and characteristic of micro-arc oxidation coating fabricated on ZK60 Mg alloy

Micro-arc oxidation （MAO） process was carried out in a dual electrolyte system of NaAlO 2 and Na 3 PO 4 to develop compact, smooth and corrosion-resistant coatings on ZK60 Mg alloy by single factor experiments. The microstructural characteristics of coatings were investigated by X-ray diffractometry （XRD） and scanning electron microscopy （SEM） coupled with energy dispersive X-ray spectroscopy （EDS）. Test of mass loss was conducted at a 3.5% NaCl solution to assess the resistance to corrosion. The effect of every element in the dual electrolyte system on voltage—time responses during MAO process and the coating characteristic were also analyzed and discussed systematically via single factor experiments. The results reveal that the main components of NaAlO 2 and Na 3 PO 4 as well as additives of NaOH, NaB4O7 and C6H5Na3O7 demonstrate different effects on MAO process and coating characteristics. By means of single factor experiments, an optimized dual electrolyte system was developed, containing 17.5 g/L NaAlO 2, 5.0 g/LNa3 PO4, 5.0 g/L NaOH, 3.0 g/L NaB4O7 and 4.2g/LC6H5Na3O7 .

Optimization of tensile strength for new type acetone-urea-formaldehyde furan resin using uniform design

In this study,the 24 h tensile strength of new type acetone-urea-formaldehyde furan resin (nitrogen content 3%) was investigated by uniform design optimization.Four independent variables such as acetone:formaldehyde molar ratio (mol/mol),solution pH value,reaction temperature (℃) and reaction time (min) were considered in the experiments.U13(134) uniform design was employed and the equation of 24 h tensile strength model was obtained after 13 experimentations.The 24 h tensile strength was optimized by applying single factor experiments and stepwise non-linear regression analysis.Minitab (Minitab 15 trial version) and MATLAB (R2010a trial version) were used for data analysis.The t-value and p-value indicate that the major impact factors include the interaction effect of solution pH value and reaction temperature (X2X3),the linear terms of acetone:formaldehyde molar ratio (X1),reaction time (X4) followed by the square effects of acetone/formaldehyde molar ratio (X1X1).The optimized results were achieved with the acetone:formaldehyde molar ratio (mol/mol) at 3:1,solution pH value at 6.0,reaction temperature at 70℃,and reaction time at 140 min,respectively.This method can not only significantly reduce the number and cost of the tests,but also provide a good experimental design strategy for the development of furan resin.The investigation shows that the predicted results of 24 h tensile strength are consistent well with the experimental ones.

Extraction of Flavonoids from Leaves of Coix lacryma-jobi L.

[Objectives] To extract the flavonoids from leaves of Coix lacryma-jobi L. [Methods] Ethanol extraction method was adopted,spectrophotometry was used,and single factor experiment and orthogonal experiment were carried out to study the effects of ethanol percentage,extraction temperature,solid-to-liquid ratio and extraction time on the extraction of total flavonoids from leaves of C. lacryma-jobi L.[Results] The order of 4 factors influencing the extraction of flavonoids from leaves of C. lacryma-jobi L. was: solid-to-liquid ratio > extraction time > ethanol percentage > extraction temperature. When the extraction temperature was 70℃,the extraction time was 1. 5 h and the solid-liquid ratio was 1: 10,the ethanol percentage was 60%,the extraction effect was the best,extraction of flavonoids was 0. 107 5 mg/m L.[Conclusions] This study is expected to provide a theoretical basis for further development and utilization of C. lacryma-jobi L.

Research and Optimization of Foshou Yam and Honey Nutritional Can by Response Surface Methodology

[Objectives]This study was conducted to screen best process parameters for making Foshou yam and honey can.[Methods]The Foshou yam produced from Wuxue was used as a raw material to prepare Foshou yam and honey nutritional can by combining Foshou yam with honey through screening,pre-cooking,filling,exhausting,cooling and other technical processes.The optimum technology parameter of Foshou yam and honey nutritional can was studied through single factor tests and response surface optimization.[Results]The optimum technical parameters of Foshou yam and honey nutritional can were citric acid concentration 0.1%,amount of edible salt 0.1%,cooking time 14 min and honey concentration 26%.Under these conditions,the final sensory score was 90.20.The prepared can was not only rich in nutrition,but also had good flavor and taste.[Conclusions]This study provides reference for the development and utilization of Foshou yam and the research and development of functional food.

Optimization of Liquid Seed Medium for Grifola frondosa

In this paper,the liquid seed medium of Grifola frondosa was optimized by single factor and orthogonal experiments using the shake flask culture method.The single factor experiments results showed that soybean powder and maltose were the optimal nitrogen and carbon sources,and MgSO4 was the optimal inorganic salt.The orthogonal experiment results showed that the optimal combination of liquid seed culture medium for Grifola frondosa was:20%potato,0.75%soybean powder,5%maltose,0.1%KH2PO4,0.05%MgSO4,0.001%VB1.Using the optimized medium,shaking culture for 10 d under the inoculum amount of 5%,the temperature of 28℃,and the rotation speed of 150 r/min,the dry weight of mycelium exceeded 1.3228 g/100mL.