scholarly journals Simulation and Analysis of Oleic Acid Pretreatment for Microwave-Assisted Biodiesel Production

Processes ◽  
2018 ◽  
Vol 6 (9) ◽  
pp. 142 ◽  
Author(s):  
Weiquan Ma ◽  
Tao Hong ◽  
Tian Xie ◽  
Fengxia Wang ◽  
Bin Luo ◽  
...  
Keyword(s):  
Porous Media ◽  
Oleic Acid ◽  
Microwave Heating ◽  
Rapid Heating ◽  
Experimental System ◽  
Biodiesel Production ◽  
Heating Process ◽  
Acid Pretreatment ◽  
High Loss ◽  
Heating Efficiency

Oleic acid needs to be heated when it is utilized for biodiesel production, but, as a low-loss solution, oleic acid is difficult to heat by microwave. An efficient heating method for oleic acid is designed. A high loss material porous media is placed in a quartz tube, and a microwave directly heats the porous medium of the high loss material. The oleic acid flows through the pores of porous media so that the oleic acid exchanges heat during this process and rapid heating of oleic acid is achieved. A coupling model, based on the finite element method, is used to analyze the microwave heating process. The multiphysics model is based on a single mode cavity operating at 2450 MHz. An elaborate experimental system is developed to validate the multiphysics model through temperature measurements carried out for different flow velocities of oleic acid and different microwave power levels. The computational results are in good agreement with the experimental data. Based on the validated model, the effects of different sizes, porosities, and materials on microwave heating efficiency are analyzed.

scholarly journals Research on Electromagnetic Sensitivity Properties of Sodium Chloride during Microwave Heating

2020 ◽  
Vol 39 (1) ◽  
pp. 54-62
Author(s):  
Hua Chen ◽  
Junjiang Chen ◽  
Weijun Wang ◽  
Huan Lin
Keyword(s):  
Sodium Chloride ◽  
Electric Field ◽  
Water Content ◽  
Heating Rate ◽  
Microwave Heating ◽  
Resonant Cavity ◽  
Relative Dielectric Constant ◽  
Heating System ◽  
Heating Process ◽  
Heating Efficiency

AbstractThe multimode resonant cavity is the most common cavity. The material often shows on selective heating performance during the heating process due to the effect of microwave heating having a closely relationship with the electromagnetism parameters. This paper is based on finite difference time domain method (FDTD) to establish the electromagnetic-thermal model. The electromagnetic sensitivity property parameters of sodium chloride including relative dielectric constant, loss angle tangent and water content of sodium chloride is studied during the heating and drying process. The heating rate and the electric field distribution of sodium chloride, at the different water content, were simulated with the electromagnetic characteristic parameters changing. The results show that with the electromagnetic sensitivity property parameters varying, the electric field strength, heating rate and steady-state temperature of the heating material will all have a variety in the cavity. Some measures are proposed to improve the heating efficiency and ensure the stability of the microwave heating system in the industrial application.

scholarly journals Technical Feasibility of Biodiesel Production From Waste Cooking Oil: Comparison Between Electric Heating and Microwave Heating Process

2021 ◽  
Author(s):  
Wenjing Li ◽  
Guangming Li ◽  
Fan Wang ◽  
Haochen Zhu ◽  
Wenzhi He ◽  
...  
Keyword(s):  
Activation Energy ◽  
Microwave Heating ◽  
Electric Heating ◽  
Waste Cooking Oil ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Heating Process ◽  
Cooking Oil ◽  
High Heat Transfer ◽  
Wide Range

Abstract Base-catalyzed transesterification and conversion of waste cooking oil (WCO) into biodiesel is a renewable energy production technology with a wide range of applications. The most commonly used heating method is electric heating (EH). Microwave heating (MW) has the characteristics of high heat transfer efficiency and short preheating time, and has recently received attention in this field.This study compared effects of the alkali-catalyzed transesterification reaction of WCO under EH and MW processes. The maximum biodiesel yield of EH process appeared when the reaction temperature is 60 °C, the reaction time is 30 min, the molar ratio of alcohol to oil is 6:1, and the catalyst concentration is 1.0%, up to 93.4%. The maximum biodiesel yield obtained from MW technique is 80.66%, under the condition of 200W, 5min, 1wt. % KOH and the methanol/oil molar ratio of 9:1. The activation energy for CH and MW process are found to be 6 768 J·mol-1 and 503.4 J·mol-1, respectively. Microwave heating greatly reduced the activation energy of the reaction, as well as transesterification yield. Compared with other biodiesel producing process, EH process in this study has the advantages of high speed and low production cost, while biodiesel yield is slightly insufficient. This is likely due to the small amount of un-removed moisture contained in the WCO.

scholarly journals Mechanistic and Machine Learning Modeling of Microwave Heating Process in Domestic Ovens: A Review

Foods ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2029
Author(s):  
Ran Yang ◽  
Jiajia Chen
Keyword(s):  
Machine Learning ◽  
Microwave Heating ◽  
Power Efficiency ◽  
Rapid Heating ◽  
Food Products ◽  
Ease Of Use ◽  
Heating Process ◽  
Mechanistic Models ◽  
Model Accuracy ◽  
Major Drawback

The domestic microwave oven has been popularly used at home in heating foods for its rapid heating rate and high power efficiency. However, non-uniform heating by microwave is the major drawback that can lead to severe food safety and quality issues. In order to alleviate this problem, modeling of microwave heating process in domestic ovens has been employed to simulate and understand the complicated interactions between microwaves and food products. This paper extensively reviews the mechanistic models with different geometric dimensions and physics/kinetics that simulated the microwave heating process. The model implementation and validation strategies related to the model accuracy and efficiency are also discussed. With the emergence of the machine learning technique, this paper also discusses the recent development of hybrid models that integrate machine learning with mechanistic models in improving microwave heating performance. Besides, pure machine learning models using only experimental data as input are also covered. Further research is needed to improve the model accuracy, efficiency, and ease of use to enable the industrial application of the models in the development of microwave systems and food products.

scholarly journals Laboratory and Numerical Investigation of Microwave Heating Properties of Asphalt Mixture

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 146 ◽  
Author(s):  
Haopeng Wang ◽  
Yue Zhang ◽  
Yi Zhang ◽  
Shuyin Feng ◽  
Guoyang Lu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Microwave Heating ◽  
Laboratory Tests ◽  
Steel Slag ◽  
Asphalt Mixture ◽  
Electromagnetic Properties ◽  
Heating Process ◽  
Heating Efficiency ◽  
Finite Element Software ◽  
Laboratory Test Results

Microwave heating is an encouraging heating technology for the maintenance, recycling, and deicing of asphalt pavement. To investigate the microwave heating properties of asphalt mixture, laboratory tests and numerical simulations were done and compared. Two types of Stone Mastic Asphalt (SMA) mixture samples (with basalt aggregates and steel slag aggregates) were heated using a microwave oven for different times. Numerical simulation models of microwave heating of asphalt mixture were developed with finite element software COMSOL Multiphysics. The main thermal and electromagnetic properties of asphalt mixture, served as the model input parameters, were measured through a series of laboratory tests. Both laboratory-measured and numerical simulated surface temperatures were recorded and analyzed. Results show that the replacement of basalt aggregates with steel slag aggregates can significantly increase the microwave heating efficiency of asphalt mixture. Numerical simulation results have a good correlation with laboratory test results. It is feasible to use the developed model coupling electromagnetic waves with heat transfer to simulate the microwave heating process of asphalt mixture.

Usefulness of Foundry Tooling Materials in Microwave Heating Process

2013 ◽  
Vol 58 (3) ◽  
pp. 919-922 ◽  
Author(s):  
K. Granat ◽  
B. Opyd ◽  
D. Nowak ◽  
M. Stachowicz ◽  
G. Jaworski
Keyword(s):  
Electromagnetic Field ◽  
Microwave Heating ◽  
Loss Factor ◽  
Perturbation Technique ◽  
Resonant Cavity ◽  
Precise Determination ◽  
Heating Process ◽  
Basic Criterion ◽  
Measurement Results ◽  
Heating Technology

Abstract The paper describes preliminary examinations on establishing usefulness criteria of foundry tooling materials in the microwave heating technology. Presented are measurement results of permittivity and loss tangent that determine behaviour of the materials in electromagnetic field. The measurements were carried-out in a waveguide resonant cavity that permits precise determination the above-mentioned parameters by perturbation technique. Examined were five different materials designed for use in foundry tooling. Determined was the loss factor that permits evaluating usefulness of materials in microwave heating technology. It was demonstrated that the selected plastics meet the basic criterion that is transparency for electromagnetic radiation.

Nitrogen and Sulfur Co-doped Fluorescent Carbon Dots for the Detection of Morin and Cell Imaging

2018 ◽  
Vol 15 (1) ◽  
pp. 47-55
Author(s):  
Xuebing Li ◽  
Haifen Yang ◽  
Ning Wang ◽  
Tijian Sun ◽  
Wei Bian ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Fluorescent Probe ◽  
Fluorescence Intensity ◽  
Carbon Dots ◽  
Cell Imaging ◽  
Water Soluble ◽  
Heating Process ◽  
X Ray ◽  
Doped Carbon Dots ◽  
Co Doped

Background: Morin has many pharmacological functions including antioxidant, anticancer, anti-inflammatory, and antibacterial effects. It is commonly used in the treatment of antiviral infection, gastropathy, coronary heart disease and hepatitis B in clinic. However, researches have shown that morin is likely to show prooxidative effects on the cells when the amount of treatment is at high dose, leading to the decrease of intracellular ATP levels and the increase of necrosis process. Therefore, it is necessary to determine the concentration of morin in biologic samples. Method: Novel water-soluble and green nitrogen and sulfur co-doped carbon dots (NSCDs) were prepared by a microwave heating process with citric acid and L-cysteine. The fluorescence spectra were collected at an excitation wavelength of 350 nm when solutions of NSCDs were mixed with various concentrations of morin. Results: The as-prepared NSCDs were characterized by transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The fluorescence intensity of NSCDs decreased significantly with the increase of morin concentration. The fluorescence intensity of NSCDs displayed a linear response to morin in the concentration 0.10-30 μM with a low detection limit of 56 nM. The proposed fluorescent probe was applied to analysis of morin in human body fluids with recoveries of 98.0-102%. Conclusion: NSCDs were prepared by a microwave heating process. The present analytical method is sensitive to morin. The quenching process between NSCDs and morin is attributed to the static quenching. In addition, the cellular toxicity on HeLa cells indicated that the as-prepared NSCDs fluorescent probe does not show obvious cytotoxicity in cell imaging. Our proposed method possibly opens up a rapid and nontoxic way for preparing heteroatom doped carbon dots with a broad application prospect.

scholarly journals Properties and Developments of Combustion and Gasification of Coal and Char in a CO2-Rich and Recycled Flue Gases Atmosphere by Rapid Heating

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Zhigang Li ◽  
Xiaoming Zhang ◽  
Yuichi Sugai ◽  
Jiren Wang ◽  
Kyuro Sasaki
Keyword(s):  
Coal Gasification ◽  
Radiative Heat ◽  
Arrhenius Equation ◽  
Rapid Heating ◽  
Volatile Matter ◽  
Heating Process ◽  
Mass Ratio ◽  
Coal Oxidation ◽  
Transfer Condition ◽  
Coal Temperature

Combustion and gasification properties of pulverized coal and char have been investigated experimentally under the conditions of high temperature gradient of order 200°C·s−1by a CO2gas laser beam and CO2-rich atmospheres with 5% and 10% O2. The laser heating makes a more ideal experimental condition compared with previous studies with a TG-DTA, because it is able to minimize effects of coal oxidation and combustion by rapid heating process like radiative heat transfer condition. The experimental results indicated that coal weight reduction ratio to gases followed the Arrhenius equation with increasing coal temperature; further which were increased around 5% with adding H2O in CO2-rich atmosphere. In addition, coal-water mixtures with different water/coal mass ratio were used in order to investigate roles of water vapor in the process of coal gasification and combustion. Furthermore, char-water mixtures with different water/char mass ratio were also measured in order to discuss the generation ratio of CO/CO2, and specified that the source of Hydrocarbons is volatile matter from coal. Moreover, it was confirmed that generations of CO and Hydrocarbons gases are mainly dependent on coal temperature and O2concentration, and they are stimulated at temperature over 1000°C in the CO2-rich atmosphere.

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