Improving microwave heating efficiency of asphalt concrete by increasing surface magnetic loss of aggregates

2018 ◽  
Vol 21 (4) ◽  
pp. 950-964 ◽  
Author(s):  
Wei Liu ◽  
Shengyue Wang ◽  
Xingyu Gu
Keyword(s):  
Microwave Heating ◽  
Asphalt Concrete ◽  
Magnetic Loss ◽  
Heating Efficiency

scholarly journals The Prospect of Microwave Heating: Towards a Faster and Deeper Crack Healing in Asphalt Pavement

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 507
Author(s):  
Shi Xu ◽  
Xueyan Liu ◽  
Amir Tabaković ◽  
Erik Schlangen
Keyword(s):  
Microwave Heating ◽  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Heating Time ◽  
Porous Asphalt ◽  
Heating Efficiency ◽  
Healing Effect ◽  
Uneven Heating ◽  
Porous Asphalt Concrete

Microwave heating has been shown to be an effective method of heating asphalt concrete and in turn healing the damage. As such, microwave heating holds great potential in rapid (1–3 min) and effective damage healing, resulting in improvement in the service life, safety, and sustainability of asphalt pavement. This study focused on the microwave healing effect on porous asphalt concrete. Steel wool fibres were incorporated into porous asphalt to improve the microwave heating efficiency, and the optimum microwave heating time was determined. Afterwards, the microwave healing efficiency was evaluated using a semi–circular bending and healing programme. The results show that the microwave healing effect is largely determined by the steel fibre content and the mix design of the porous asphalt concrete.. Besides, the uneven heating effect of microwave contributes to an unstable damage recovery in the asphalt mixture, which makes it less efficient than induction heating. However, microwaves exhibited the ability to penetrate further into the depth of the test specimen and heat beneath the surface, indicating deeper damage recovery prospects.

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.

Evaluation of Self-Healing Performance of Asphalt Concrete for Macrocracks via Microwave Heating

2020 ◽  
Vol 32 (9) ◽  
pp. 04020248 ◽  
Author(s):  
Hongzhou Zhu ◽  
Hai Yuan ◽  
Yufeng Liu ◽  
Shiping Fan ◽  
Yongjie Ding
Keyword(s):  
Microwave Heating ◽  
Asphalt Concrete ◽  
Self Healing

Microwave-Assisted Chemistry: a Closer Look at Heating Efficiency

2009 ◽  
Vol 62 (3) ◽  
pp. 236 ◽  
Author(s):  
Richard Hoogenboom ◽  
Tom F. A. Wilms ◽  
Tina Erdmenger ◽  
Ulrich S. Schubert
Keyword(s):  
Microwave Heating ◽  
Microwave Power ◽  
Large Scale ◽  
Small Scale ◽  
Passive Heating ◽  
Conductive Heating ◽  
Heating Efficiency ◽  
Medium Scale ◽  
Microwave Assisted ◽  
Demineralized Water

Nowadays, microwave heating has evolved into a common tool for chemists based on its numerous advantages over conventional conductive heating. Surprisingly, the efficiency of microwave-assisted heating is still rather unexplored. In this contribution, we report our investigations concerning the heating efficiency of a variety of solvents including polar and apolar substances. Moreover, the effects of adding salt or passive heating elements on the microwave heating efficiency will be addressed. Finally, the heating efficiency of demineralized water is discussed at different volumes and with different microwave power levels in both monomode and multimode microwave synthesizers, demonstrating maximum average heating efficiencies of 10% for small-scale vessels (5 mL), 20% for medium-scale (50 mL), and 30% for large-scale microwave heating (400 mL).

scholarly journals Induction Heating and Healing Behaviors of Asphalt Concretes Doped with Different Conductive Additives

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Hechuan Li ◽  
Jianying Yu ◽  
Quantao Liu ◽  
Yuanyuan Li ◽  
Yaqi Wu ◽  
...  
Keyword(s):  
High Temperature ◽  
Induction Heating ◽  
Asphalt Concrete ◽  
Healing Rate ◽  
Steel Fiber ◽  
Steel Slag ◽  
Rest Period ◽  
Self Healing ◽  
Heating Efficiency ◽  
Conductive Additives

It is consensual that the self-healing property of asphalt concrete can repair the damage inside it during high temperature and rest period. In order to not affect the traffic, the rest period of asphalt pavement is very short and uncontrollable; so, it is necessary to obtain enough high temperature in a limited time to achieve higher healing efficiency of asphalt concrete. The purpose of this paper is to study the induction heating efficiency and healing behaviors of asphalt concretes doped with different conductive additives. Steel fiber, steel grit, and steel slag were added to asphalt mixtures as conductive additives to prepare induction healing asphalt concretes. The steel grit and steel slag were added to replace the aggregates of corresponding particle size by equal volume to ensure the consistency of asphalt concrete volume, which can avoid degrading the performance of asphalt concrete due to the change of porosity. The induction heating efficiency and healing rate of asphalt concrete were quantified by infrared camera and three-point bending-healing experiment, respectively. The results showed that the thermal properties of asphalt concrete changed with the addition of different conductive additives. The asphalt concrete with steel fiber had the best induction heating property. While steel slag had extremely weak induction heating speed, the better thermal insulation property of the asphalt concrete with steel slag resulted in a higher induction healing rate. It was suggested to add steel slag to induction healing asphalt concrete to improve the healing rate.

scholarly journals Application of Conductive Materials to Asphalt Pavement

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Hai Viet Vo ◽  
Dae-Wook Park
Keyword(s):  
Carbon Fibers ◽  
Asphalt Concrete ◽  
Thermal Testing ◽  
Snow Melting ◽  
Heating Efficiency ◽  
Preservation Method ◽  
Concrete Body ◽  
Conductive Additives ◽  
The Impact ◽  
Actual Test

Snow-melting pavement technique is an advanced preservation method, which can prevent the forming of snow or ice on the pavement surface by increasing the temperature using an embedded heating system. The main scope of this study is to evaluate the impact of conductive additives on the heating efficiency. The electrical resistivity and thermal conductivity were considered to investigate effects of conductive additives, graphite, and carbon fibers on the snow-melting ability of asphalt mixtures. Also, the distribution of the conductive additives within the asphalt concrete body was investigated by microstructural imaging. An actual test was applied to simulate realistic heating for an asphalt concrete mixture. Thermal testing indicated that graphite and carbon fibers improve the snow-melting ability of asphalt mixes and their combination is more effective than when used alone. As observed in the microstructural image, carbon fibers show a long-range connecting effect among graphite conductive clusters and gather in bundles when added excessively. According to the actual test, adding the conductive additives helps improve snow-melting efficiency by shortening processing time and raising the surface temperature.

scholarly journals Microwave Deicing Efficiency: Study on the Difference between Microwave Frequencies and Road Structure Materials

2018 ◽  
Vol 8 (12) ◽  
pp. 2360 ◽  
Author(s):  
Longting Ding ◽  
Xuancang Wang ◽  
Wengang Zhang ◽  
Shuai Wang ◽  
Jing Zhao ◽  
...  
Keyword(s):  
Finite Element ◽  
Simulation Model ◽  
Microwave Heating ◽  
Asphalt Concrete ◽  
Great Influence ◽  
Microwave Frequency ◽  
Concrete Surface ◽  
Cement Concrete ◽  
Microwave Frequencies ◽  
The Difference

A method of deicing using microwave heating is proposed to make scientific and economical road deicing in a cold area, and to make up for deficiencies in the existing methods for melting snow and ice. This paper proposes to define microwave deicing efficiency as the heating rate of a concrete surface when heated to 0 °C (the efficiency of deicing is equal to the difference divided by heating time, which is between 0 °C and the initial temperature at the junction of ice and concrete). Based on the mechanism of microwave heating and deicing, a method combining the finite element simulation model with indoor experiments was proposed to study the deicing efficiency of microwaves, and the effects of different microwave frequencies and different road structure materials on microwave deicing efficiency were analyzed. The results show that the microwave frequency and road structure materials have a great influence on microwave deicing. For asphalt concrete, the ice melting efficiency of 5.8 GHz is 4.31 times that of 2.45 GHz, but the heating depth is less than that of 2.45 GHz. At 2.45 GHz, the melting efficiency of cement concrete is 3.89 times that of asphalt concrete. At 5.8 GHz, the melting efficiency of cement concrete is 5.23 times that of asphalt concrete. Through the consistency of the simulation and experimental results, the validity of the simulation model based on the finite element theory is verified. The results provide theoretical guidance and a practical basis for future applications of microwave deicing.

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 Modelling microwave heating of an oil palm mesocarp

2018 ◽  
Vol 240 ◽  
pp. 01017 ◽  
Author(s):  
Ming Law ◽  
Jessie Chang
Keyword(s):  
Moisture Content ◽  
Microwave Heating ◽  
Oil Palm ◽  
Electromagnetic Waves ◽  
Oil Quality ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Heating Efficiency ◽  
Heating Model ◽  
Palm Fruits

An oil palm mill often uses steam in sterilization and fruit detachment processes. Consequently, a large amount of wastewater is produced. To reduce the wastewater, microwave (MW) heating of oil palm fruits has been studied and positive results were reported in open literature. Nevertheless, MW heating of oil palm fruits requires proper control to avoid overheating, which deteriorates the oil quality. MW heating efficiency depends not only on the electromagnetic strength, but also on the complex permittivity of oil palm fruits. This study reports the MW heating model of an oil palm mesocarp. The three-dimensional model solved Maxwell’s Electromagnetic waves equation, diffusion equation of moisture content, and heat conduction equation. The model was validated with mesocarp’s experimental data of moisture content and temperatures. The electromagnetics, moisture, and temperature distributions of the mesocarp were studied. The simulation results showed that the volumeand surface-averaged temperature were similar, thus the surface temperature might be used as a good approximation to the volumetric temperature. Besides, the model also showed that radiation and convection were the main heat loss mechanisms. This validated model can be used for designing a microwave heating reactor for oil palm fruits.

scholarly journals In Search of the Driving Factor for the Microwave Curing of Epoxy Adhesives and for the Protection of the Base Substrate against Thermal Damage

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2240
Author(s):  
Satoshi Horikoshi ◽  
Yuhei Arai ◽  
Nick Serpone
Keyword(s):  
Microwave Heating ◽  
Thermal Damage ◽  
Driving Factor ◽  
Heating Efficiency ◽  
Microwave Curing ◽  
Epoxy Adhesives ◽  
Ionic Intermediates ◽  
Electrically Charged ◽  
Base Substrate ◽  
Lower Heating

This study used controlled microwaves to elucidate the response of adhesive components to microwaves and examined the advantages of microwave radiation in curing epoxy adhesives. Curing of adhesives with microwaves proceeded very rapidly, even though each component of the adhesive was not efficiently heated by the microwaves. The reason the adhesive cured rapidly is that microwave heating was enhanced by the electrically charged (ionic) intermediates produced by the curing reaction. In contrast, the cured adhesive displayed lower microwave absorption and lower heating efficiency, suggesting that the cured adhesive stopped heating even if it continued to be exposed to microwaves. This is a definite advantage in the curing of adhesives with microwaves, as, for example, adhesives dropped onto polystyrene could be cured using microwave heating without degrading the polystyrene base substrate.

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