Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9756
T. Sameshima, T. Kikuchi, T. Uehara, T. Arima, M. Hasumi, Tomoyoshi Miyazaki, Go Kobayashi, I. Serizawa
We report a microwave heating system with a carbon heating tube (CHT) made by a 4-mm diameter quartz tube filled carbon particles and Ar gas at 1400 Pa. 2.45-GHz microwave at 200 W was introduced to a 300-dimameter metal cavity, in which 60-mm-long CHT was set at the central position. The numerical simulation with a finite element moment method resulted in the standing wave of the electric field caused by three dimensional Fresnel interference effect with low high electric field intensity ranging from from 1 to 6 kV/m because of effective absorption of microwave power by the CHT. The lowest average electrical field intensity of 5 kV/m in the cavity space was given by the electrical conductivity of carbon ranging from 10 to 55 S/m. The CHT with 55 S/m heated to 1200oC by microwave irradiation at 200 W. This heating method was applied to activate 1.0x1015-cm-2 boron and phosphorus implanted regions in n-type crystalline silicon substrate to fabricate pn junction and solar cells. The CHT heating at 1200oC realized decrease in the sheet resistivity to 146 Ω/sq, decrease in the density of defect states to 1.3x1011 and 9.2x1010 cm-2 for boron (p+) and phosphorus (n+) implanted surfaces, and solar cell characteristic with a conversion efficiency of 15% under illumination of air mass 1.5 at 0.1 W/cm2.
{"title":"MICROWAVE RAPID HEATING SYSTEM USING CARBON HEATING TUBE","authors":"T. Sameshima, T. Kikuchi, T. Uehara, T. Arima, M. Hasumi, Tomoyoshi Miyazaki, Go Kobayashi, I. Serizawa","doi":"10.4995/ampere2019.2019.9756","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9756","url":null,"abstract":"We report a microwave heating system with a carbon heating tube (CHT) made by a 4-mm diameter quartz tube filled carbon particles and Ar gas at 1400 Pa. 2.45-GHz microwave at 200 W was introduced to a 300-dimameter metal cavity, in which 60-mm-long CHT was set at the central position. The numerical simulation with a finite element moment method resulted in the standing wave of the electric field caused by three dimensional Fresnel interference effect with low high electric field intensity ranging from from 1 to 6 kV/m because of effective absorption of microwave power by the CHT. The lowest average electrical field intensity of 5 kV/m in the cavity space was given by the electrical conductivity of carbon ranging from 10 to 55 S/m. The CHT with 55 S/m heated to 1200oC by microwave irradiation at 200 W. This heating method was applied to activate 1.0x1015-cm-2 boron and phosphorus implanted regions in n-type crystalline silicon substrate to fabricate pn junction and solar cells. The CHT heating at 1200oC realized decrease in the sheet resistivity to 146 Ω/sq, decrease in the density of defect states to 1.3x1011 and 9.2x1010 cm-2 for boron (p+) and phosphorus (n+) implanted surfaces, and solar cell characteristic with a conversion efficiency of 15% under illumination of air mass 1.5 at 0.1 W/cm2.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128209683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9870
Willem P. R. Deleu, Vincent Goovaerts, C. Groffils
Microwave technology has come a long way from the sixties when the first microwave ovens were developed. This first generation of microwave ovens uses only microwaves to heat the substrate and with an efficiency of around 63% in converting electrical energy to microwaves, this means 37% of the electric energy is lost as heat. The first improvement to this system “second generation” is using hybrid heating with both microwaves and hot air. The hot air in this case is simply the air used to cool the magnetron and transformers that is blown into the microwave cavity. The 37% of lost energy can thus be reused. The first role of the hot air current is to remove moisture from the cavity to avoid condensation on the (cold) cavity walls. The second role is to insulate the hot product from the cold environment and prevent energy loss. The third role is increasing evaporation speed; this decreases drying time and can also keep the drying temperature low through evaporative cooling. Low drying temperatures are favored in many processes especially with food as it delivers a superior dry product.The “third generation” utilizes an additional heat exchange to further increase the system’s efficiency. The hot (wet) exhaust air is not fully saturated yet so it can be used to preheat the substrate before it enters the microwave cavity. A good example is thawing and preheating frozen starting material. If water cooled magnetrons are used, the hot air is replaced by hot water instead for the heat exchange. Microwave processes are generally much faster resulting in smaller machines and reduced operational area. When designing a microwave process all these factors need to be taken into account to result in the cheapest and most robust process. As heat exchange generally takes a long time, it should only be done to a degree that it does not slow down the microwave process.
{"title":"Hybrid microwave with heat recovery for an efficient drying process","authors":"Willem P. R. Deleu, Vincent Goovaerts, C. Groffils","doi":"10.4995/ampere2019.2019.9870","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9870","url":null,"abstract":"Microwave technology has come a long way from the sixties when the first microwave ovens were developed. This first generation of microwave ovens uses only microwaves to heat the substrate and with an efficiency of around 63% in converting electrical energy to microwaves, this means 37% of the electric energy is lost as heat. The first improvement to this system “second generation” is using hybrid heating with both microwaves and hot air. The hot air in this case is simply the air used to cool the magnetron and transformers that is blown into the microwave cavity. The 37% of lost energy can thus be reused. The first role of the hot air current is to remove moisture from the cavity to avoid condensation on the (cold) cavity walls. The second role is to insulate the hot product from the cold environment and prevent energy loss. The third role is increasing evaporation speed; this decreases drying time and can also keep the drying temperature low through evaporative cooling. Low drying temperatures are favored in many processes especially with food as it delivers a superior dry product.The “third generation” utilizes an additional heat exchange to further increase the system’s efficiency. The hot (wet) exhaust air is not fully saturated yet so it can be used to preheat the substrate before it enters the microwave cavity. A good example is thawing and preheating frozen starting material. If water cooled magnetrons are used, the hot air is replaced by hot water instead for the heat exchange. Microwave processes are generally much faster resulting in smaller machines and reduced operational area. When designing a microwave process all these factors need to be taken into account to result in the cheapest and most robust process. As heat exchange generally takes a long time, it should only be done to a degree that it does not slow down the microwave process.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128646895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9892
René Miguel Guillén Pineda, María Amparo Borrell Tomás, M. Moya, Felipe Laureano Peñaranda Foix, R. Moreno
At present, ZrTiO4 nanopowders are used as a dielectric in the electroceramic field, applications of catalysis, microwave telecommunications devices, pigments, composites, etc. One of the most interesting applications is the potential as structural material and similar applications that require a high thermal resistance. However, all the properties of zirconium titanate are still a subject of interest for the industrial field.12 There are several routes of synthesis of ZrTiO4; among them is the sol-gel method and lyophilization. These methods have been used to make powders or small pieces of zirconium titanate. However, structural applications require materials in large quantities, so it is necessary to identify the differences between the methods of synthesizing and allowing the preparation of powders suitable for the generation of green materials for subsequent sintering.3 To develop a new generation of nanomaterials with microstructural differences it is necessary to innovate in the sintering process. Years ago, the use of conventional oven for sintering material was the usual procedure. Nowadays, non-conventional methods as Microwave sintering (MW) are a bright way to produce high dense materials, using heating rates in reduce dwell times and lower consumption using 70%-80% less energy. 4 This reactive sintering technique achieves excellent mechanical properties, homogeneous microstructure employing lower sintering temperatures. All these energy and economic advantages generate a new vision for the future on ceramic materials and their industrial production. The main objective of this study is to make a comparison of the mechanical properties of the materials synthesized by sol-gel method and lyophilization and sintered by microwaves.
{"title":"Comparison in mechanical properties of zirconium titanate (ZrTiO4) synthetized by alternative routes and sintered by microwave (MW)","authors":"René Miguel Guillén Pineda, María Amparo Borrell Tomás, M. Moya, Felipe Laureano Peñaranda Foix, R. Moreno","doi":"10.4995/ampere2019.2019.9892","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9892","url":null,"abstract":"At present, ZrTiO4 nanopowders are used as a dielectric in the electroceramic field, applications of catalysis, microwave telecommunications devices, pigments, composites, etc. One of the most interesting applications is the potential as structural material and similar applications that require a high thermal resistance. However, all the properties of zirconium titanate are still a subject of interest for the industrial field.12 There are several routes of synthesis of ZrTiO4; among them is the sol-gel method and lyophilization. These methods have been used to make powders or small pieces of zirconium titanate. However, structural applications require materials in large quantities, so it is necessary to identify the differences between the methods of synthesizing and allowing the preparation of powders suitable for the generation of green materials for subsequent sintering.3 To develop a new generation of nanomaterials with microstructural differences it is necessary to innovate in the sintering process. Years ago, the use of conventional oven for sintering material was the usual procedure. Nowadays, non-conventional methods as Microwave sintering (MW) are a bright way to produce high dense materials, using heating rates in reduce dwell times and lower consumption using 70%-80% less energy. 4 This reactive sintering technique achieves excellent mechanical properties, homogeneous microstructure employing lower sintering temperatures. All these energy and economic advantages generate a new vision for the future on ceramic materials and their industrial production. The main objective of this study is to make a comparison of the mechanical properties of the materials synthesized by sol-gel method and lyophilization and sintered by microwaves.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127731509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9836
A. Vodopyanov, A. Samokhin, Nikolay Aleksev, M. Sinayskiy, A. Sorokin, S. Sintsov
Nanoscale tungsten carbide WC powders are of practical interest for the creation of nanostructured hard alloys with enhanced physical and mechanical characteristics, wear-resistant nanostructured coatings, electrocatalysts in fuel cells, metal melt modifiers [1]. An efficient method for producing tungsten carbide nanopowder is a plasma-chemical synthesis of a multi-component powder nanocomposite system W-C in combination with its subsequent heat treatment [2]. Experimental studies have shown the possibility of producing tungsten carbide WC nanopowder by this method. But the transformation of the nanocomposite in the target product is accompanied by an increase in the size of nanoparticles. We assume that this growth is associated with prolonged heating (several hours) in an electric furnace at a temperature of about 1000 ° C. This time is necessary for the complete transformation of the nanocomposite into the target product. The aim of the work was an experimental study of the formation of tungsten carbide nanopowder WC when processing a multi-component powder nanocomposite system W-C in an electromagnetic field with a frequency of 24 GHz. A multipurpose gyrotron system with a nominal power of 7 kW with at a frequency of 24 GHz was used for the experiments. The microwave application system described in [3]. The powders were treated in an argon flow. The experiments were carried varying exposure time and microwave power. The samples of nanopowders obtained in the experiments were analyzed using the following methods: XRD, TEM, SEM, BET, LDA, CEA. It was established that microwave radiation with a frequency of 24 GHz allows heating samples of powders to a temperature of 1100-1200 C almost immediately (after 1-2 s) after switching on. The tungsten carbide WC is formed in a few minutes under the exposure to microwave radiation of the original W-C nanocomposite system. There is only a slight increase in the average particle size from 20 to 30 nm. The investigations showed that the synthesis of tungsten carbide WC under the microwave heating as compared to conventional heating in an electric furnace may be carried out for significantly less time while maintaining the particles in the nanometer range.The work was carried out within the framework of the Program #14 "Physical chemistry of adsorption phenomena and actinide nanoparticles" of the Presidium of the Russian Academy of Sciences.References Z. Zak Fang, Xu Wang, et al. Int. Journal of Refractory Metals & Hard Materials, 2009, 27, 288–299.Samokhin A., Alekseev N., et al. Plasma Chem. Plasma Proc., 2013, 33, 605–616.Samokhin A., Alekseev N., et al. J. Nanotechnol. Eng. Med., 2015, 6, 011008.
{"title":"TUNGSTEN CARBIDE NANOPOWDER SYNTHESIS UNDER THE EXPOSURE OF 24 GHZ GYROTRON RADIATION ON THE NANOCOMPOSITE OF THE W-C SYSTEM OBTAINED IN A THERMAL PLASMA","authors":"A. Vodopyanov, A. Samokhin, Nikolay Aleksev, M. Sinayskiy, A. Sorokin, S. Sintsov","doi":"10.4995/ampere2019.2019.9836","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9836","url":null,"abstract":"Nanoscale tungsten carbide WC powders are of practical interest for the creation of nanostructured hard alloys with enhanced physical and mechanical characteristics, wear-resistant nanostructured coatings, electrocatalysts in fuel cells, metal melt modifiers [1]. An efficient method for producing tungsten carbide nanopowder is a plasma-chemical synthesis of a multi-component powder nanocomposite system W-C in combination with its subsequent heat treatment [2]. Experimental studies have shown the possibility of producing tungsten carbide WC nanopowder by this method. But the transformation of the nanocomposite in the target product is accompanied by an increase in the size of nanoparticles. We assume that this growth is associated with prolonged heating (several hours) in an electric furnace at a temperature of about 1000 ° C. This time is necessary for the complete transformation of the nanocomposite into the target product. The aim of the work was an experimental study of the formation of tungsten carbide nanopowder WC when processing a multi-component powder nanocomposite system W-C in an electromagnetic field with a frequency of 24 GHz. A multipurpose gyrotron system with a nominal power of 7 kW with at a frequency of 24 GHz was used for the experiments. The microwave application system described in [3]. The powders were treated in an argon flow. The experiments were carried varying exposure time and microwave power. The samples of nanopowders obtained in the experiments were analyzed using the following methods: XRD, TEM, SEM, BET, LDA, CEA. It was established that microwave radiation with a frequency of 24 GHz allows heating samples of powders to a temperature of 1100-1200 C almost immediately (after 1-2 s) after switching on. The tungsten carbide WC is formed in a few minutes under the exposure to microwave radiation of the original W-C nanocomposite system. There is only a slight increase in the average particle size from 20 to 30 nm. The investigations showed that the synthesis of tungsten carbide WC under the microwave heating as compared to conventional heating in an electric furnace may be carried out for significantly less time while maintaining the particles in the nanometer range.The work was carried out within the framework of the Program #14 \"Physical chemistry of adsorption phenomena and actinide nanoparticles\" of the Presidium of the Russian Academy of Sciences.References Z. Zak Fang, Xu Wang, et al. Int. Journal of Refractory Metals & Hard Materials, 2009, 27, 288–299.Samokhin A., Alekseev N., et al. Plasma Chem. Plasma Proc., 2013, 33, 605–616.Samokhin A., Alekseev N., et al. J. Nanotechnol. Eng. Med., 2015, 6, 011008. ","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132998662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9761
G. Churyumov, O. Denisov, T. Frolova, Nan-Nan Wang, J. Qiu
For more than 50 years, interest to the microwave heating technology has not weakened. In addition to the traditional areas of its application, which described in detail in [1], recently there has been an expansion of technological possibilities for the use of microwave energy associated with the impact of electromagnetic waves of the microwave range on various materials (sintering of metal and ceramic powders) and media, including plasma [2]. One such new direction is the creation of high-power and environmentally friendly sources of optical radiation on the basis of an electrodeless sulfur lamp with microwave excitation [2, 3]. The purpose of this paper is to the further development of the theory and practice of microwave excitation by the electrodeless sulfur lamps, improvement the energy efficiency during energy conversion into the optical radiation and widening the application of new light sources in real practice. The results of the computer modeling of conversion process of the microwave energy into optical radiation energy are presented. The simulation results are compared with experimental data. It is shown that additional use of the solar panels for the reverse conversion of the optical radiation into DC energy with follow-up its using in the circuits of secondary power supply allows improving the energy efficiency of the light source. References Microwave Power Engineering. Edited by E.C. Okress. V. 1, 2. Academic Press, New York & London. 1968.A.N. Didenko, SVCh-energetika. Teoriya i praktika. – Moscow: Nauka. 2003.- 445 s.G. Churyumov, T. Frolova, “Microwave Energy and Light Energy Transformation: Methods, Schemes and Designs. Microwave Energy and Light Energy Transformation: Methods, Schemes and Designs” // In book “Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing.” Edited by Kok Yeow You, IntechOpen, 2018. pp. 75-91.
{"title":"A HIGH-POWER SOURCE OF OPTICAL RADIATION WITH MICROWAVE EXCITATION","authors":"G. Churyumov, O. Denisov, T. Frolova, Nan-Nan Wang, J. Qiu","doi":"10.4995/ampere2019.2019.9761","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9761","url":null,"abstract":"For more than 50 years, interest to the microwave heating technology has not weakened. In addition to the traditional areas of its application, which described in detail in [1], recently there has been an expansion of technological possibilities for the use of microwave energy associated with the impact of electromagnetic waves of the microwave range on various materials (sintering of metal and ceramic powders) and media, including plasma [2]. One such new direction is the creation of high-power and environmentally friendly sources of optical radiation on the basis of an electrodeless sulfur lamp with microwave excitation [2, 3]. The purpose of this paper is to the further development of the theory and practice of microwave excitation by the electrodeless sulfur lamps, improvement the energy efficiency during energy conversion into the optical radiation and widening the application of new light sources in real practice. The results of the computer modeling of conversion process of the microwave energy into optical radiation energy are presented. The simulation results are compared with experimental data. It is shown that additional use of the solar panels for the reverse conversion of the optical radiation into DC energy with follow-up its using in the circuits of secondary power supply allows improving the energy efficiency of the light source. References Microwave Power Engineering. Edited by E.C. Okress. V. 1, 2. Academic Press, New York & London. 1968.A.N. Didenko, SVCh-energetika. Teoriya i praktika. – Moscow: Nauka. 2003.- 445 s.G. Churyumov, T. Frolova, “Microwave Energy and Light Energy Transformation: Methods, Schemes and Designs. Microwave Energy and Light Energy Transformation: Methods, Schemes and Designs” // In book “Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing.” Edited by Kok Yeow You, IntechOpen, 2018. pp. 75-91.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128430448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9953
M. Celuch, J. Rudnicki, J. Krupka, W. Gwarek
In this work, application of split-post and single-post dielectric resonator to the measurements of surface impedance of microwave susceptors is discussed.
本文讨论了分柱式和单柱式介质谐振器在微波敏感器表面阻抗测量中的应用。
{"title":"Application of dielectric resonators to surface impedance measurements of microwave susceptors","authors":"M. Celuch, J. Rudnicki, J. Krupka, W. Gwarek","doi":"10.4995/ampere2019.2019.9953","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9953","url":null,"abstract":"In this work, application of split-post and single-post dielectric resonator to the measurements of surface impedance of microwave susceptors is discussed.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127078801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9945
J. Gallego, F. Gulisano, Luis Picado, J. Crucho
Over the last ten years the concept of self healing in asphalt mixtures for roads pavements has been reaching great importance due to the fact that this capability allows a material to recuperate original properties after failure. This new generation of asphalt paving materials would allow road agencies to save no renewable resources as aggregates and bitumen, making the road investments more efficient. By the moment, there are two mechanisms to promote self healing in asphalt pavement: the incorporation in the asphalt mixtures of capsules containing a rejuvenating agent, or the heating of the pavement, especially the surface layer, to melt the asphalt binder, that gets liquid and refills the cracks in the material, recuperating a part of its initial structural parameters. Probably the most promising method for the in situ heating of the pavements is the radiation by microwaves. Unfortunately, asphalt mixture components (aggregates and binder) are low sensitive to microwave energy. This is why it may be advantageous to incorporate in the mixture additives to improve the sensibility to the radiation with microwaves. In this investigation two additives were studied: graphene and EAF slag coming from the steel industry. These additives were incorporated at several contents and the efficiency of the heating process was evaluated by the ratio kwh/kg/ºC in order to optimize the content of the additive in the asphalt mixture. Additionally, an evaluation of the electrical conductivity of the asphalt mixture at different contents of additives was carried out to study the possible relation between the conductivity of the mixture and its sensibility to microwave radiation. As a result of the investigation, it seems that microwave radiation can be a real option to promote in situ self healing of asphalt pavements. References J. Gallego, M.A. del Val, V. Contreras, A. Páez. Use of additives to improve the capacity of bituminous mixtures to be heated by means of microwaves, Materiales de Construcción. Vol. 67, Issue 325, January–March 2017, e110. http://dx.doi.org/10.3989/mc.2017.00416 …
在过去的十年中，路面沥青混合料的自我修复概念已经变得非常重要，因为这种能力允许材料在失效后恢复原始特性。这种新一代的沥青铺路材料将允许道路机构节省任何可再生资源，如集料和沥青，使道路投资更有效。目前，有两种机制可以促进沥青路面的自我修复:在沥青混合物中掺入含有回复剂的胶囊，或者加热路面，特别是表层，以熔化沥青粘合剂，从而获得液体并重新填充材料中的裂缝，恢复其初始结构参数的一部分。微波辐射可能是对路面进行就地加热最有前途的方法。不幸的是，沥青混合料成分(集料和粘结剂)对微波能量的敏感性较低。这就是为什么在混合物中加入添加剂以提高对微波辐射的敏感性可能是有利的。本文研究了两种添加剂:石墨烯和来自钢铁工业的电炉炉渣。为了优化沥青混合料中添加剂的含量，采用kwh/kg/ºC的比例来评价加热过程的效率。此外，还对沥青混合料在不同添加剂含量下的导电性进行了评价，以研究其导电性与其对微波辐射敏感性之间的可能关系。研究结果表明，微波辐射可能是促进沥青路面原位自愈的一个真正的选择。参考文献J. Gallego, M.A. del Val, V. Contreras, A. Páez。使用添加剂提高沥青混合料的微波加热能力，Materiales de Construcción。第67卷，325期，2017年1 - 3月，e110。http://dx.doi.org/10.3989/mc.2017.00416…
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Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9776
R. Treviño, A. Orbe, J. Canales, J. Cuadrado, J. Norambuena-Contreras
Nowadays, strengthening and refurbishing of existing structures on urban areas has gained interest in order to reduce costs by avoiding both the use of construction raw materials and the disposal of construction and demolition waste on landfill. Usually, existing structures need to be locally demolished in order to replace either the existing corroded reinforcement or strengthen the existing structure. Among all the existing demolition methods, microwave and induction heating have been proven as a good alternative to generate a local damage with little noise and dust production, which is a desirable feature when structures are in urban areas. However, there is a lack of information about the behaviour of both damaging methods when steel fibre-reinforced concretes are involved. This paper studies the influence of the steel fibre addition on the damaging capacity of both microwave and induction heating demolition methods. For that purpose, mortars containing two different steel fibres (steel fibres used for concrete reinforcement and brass covered steel needles used for mortar reinforcement) were added in three different proportions (0%, 0.5% and 1% by unit volume of mortar) and exposed to up to 10 min of either microwave heating (0.003-0.03 W/mm3, 2.45 GHz) or induction heating (0.016-0.023 W/mm3, 18 kHz). With the aim of evaluating the damage caused by the heating methods, test specimens were visually checked, and mechanical properties were determined via flexural and compressive strength tests. According to the results, mortars exposed to either microwave or induction heating suffered a sudden, violent disintegration without noticing any previous damage on the mortar specimens. Results proved that pressure increment on water-saturated pores caused the failure no matter the fibre type used as a reinforcement. However, for microwave heating, the reflection of microwaves on the fibres tended to concentrate the heating effect on the specimen surface, resulting in higher surface temperatures, but lower damaging potential of the demolition method. Furthermore, similar failure mechanism was observed on oven-dried mortars exposed to microwave heating. Nevertheless, oven dried mortars exposed to induction heating suffered a highly variable, silent and controlled damage, presenting a highly varying quantity of fracture planes that decreased its flexural and compressive strengths by up to 38% and 31%, respectively.
{"title":"Application of microwave and induction heating on fibre-reinforced cementitious materials for the demolition of structures","authors":"R. Treviño, A. Orbe, J. Canales, J. Cuadrado, J. Norambuena-Contreras","doi":"10.4995/ampere2019.2019.9776","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9776","url":null,"abstract":"Nowadays, strengthening and refurbishing of existing structures on urban areas has gained interest in order to reduce costs by avoiding both the use of construction raw materials and the disposal of construction and demolition waste on landfill. Usually, existing structures need to be locally demolished in order to replace either the existing corroded reinforcement or strengthen the existing structure. Among all the existing demolition methods, microwave and induction heating have been proven as a good alternative to generate a local damage with little noise and dust production, which is a desirable feature when structures are in urban areas. However, there is a lack of information about the behaviour of both damaging methods when steel fibre-reinforced concretes are involved. This paper studies the influence of the steel fibre addition on the damaging capacity of both microwave and induction heating demolition methods. For that purpose, mortars containing two different steel fibres (steel fibres used for concrete reinforcement and brass covered steel needles used for mortar reinforcement) were added in three different proportions (0%, 0.5% and 1% by unit volume of mortar) and exposed to up to 10 min of either microwave heating (0.003-0.03 W/mm3, 2.45 GHz) or induction heating (0.016-0.023 W/mm3, 18 kHz). With the aim of evaluating the damage caused by the heating methods, test specimens were visually checked, and mechanical properties were determined via flexural and compressive strength tests. According to the results, mortars exposed to either microwave or induction heating suffered a sudden, violent disintegration without noticing any previous damage on the mortar specimens. Results proved that pressure increment on water-saturated pores caused the failure no matter the fibre type used as a reinforcement. However, for microwave heating, the reflection of microwaves on the fibres tended to concentrate the heating effect on the specimen surface, resulting in higher surface temperatures, but lower damaging potential of the demolition method. Furthermore, similar failure mechanism was observed on oven-dried mortars exposed to microwave heating. Nevertheless, oven dried mortars exposed to induction heating suffered a highly variable, silent and controlled damage, presenting a highly varying quantity of fracture planes that decreased its flexural and compressive strengths by up to 38% and 31%, respectively.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134413981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9894
V. A. Bolotov, S. Tikhov, K. Valeev, V. T. Shamirzaev, V. Parmon
Linear even-carbon-number alpha-olefins (LAO) with four or more carbon atoms are important compounds of high demand in chemical industry as precursors of a wide range of value-added chemicals [1]. LAO are used as co-monomers for polyethylene production, for the production of alcohols (mainly in detergents and plasticizers) and for synthesis of polyalphaolefins (used in synthetic lubricants). Alpha-olefins (C4, C6, C8 and C10) are mainly used to produce poly(vinyl chloride) plasticizers, high-density and linear low-density polyethylene to impart the stress-crack resistance. C10–C14 alpha-olefins can be used to synthesize linear alkylbenzene sulfonates (synthetic detergents). A conventional route to produce alpha-olefins is oligomerization of ethylene. The process provides production of high quality alpha-olefins but is very costly. If not oligomerization, LAO can be produced by thermal cracking of waxy paraffins but the product is not pure and contains numerous internal olefins, dienes and paraffin impurities. The process is conducted in the vapor phase at relatively low cracking temperatures and needs rapid quenching to prevent side reactions such as isomerization or cyclization. In our previous work [2], we showed that the selectivity to alpha-olefins can be increased considerably via catalytic cracking of n-alkanes under selective MW heating of catalysts. In the present work, the general regularities of MW cracking of n-alkanes are presented. Porous ceramic matrix Al2O3/Al composites (ceramometals) and various carbon materials (CM) having high dielectric losses were studied as supports of the catalysts. MW cracking was conducted with n-C16H34 and n-C28H58. The influence particle size and surface morphology of ceramometals and CM on the structural and group composition of the products was studied. It was established that LAO (C2-C23) and n-alkanes (C2-C26) were the main cracking products under selective MW heating of the used supports. The quantitative analysis of the products demonstrated that the liquid-phase process is more selective to alpha-olefins at the MW catalytic cracking than at the convectional thermal cracking. Silica modification of the surface of CM was shown to suppress spark discharge (usually observed at MW heating of CM); hence, the thermal cleavage of C-C bonds on the CM surface but not in the plasma discharge contributes the most to the formation of radicals. It was shown that the selectivity to liquid alpha-olefin could be more than 85 % under MW heating of cermets in region of the E - field node and decrease considerably in the region of H - field node.
{"title":"SELECTIVE FORMATION OF LINEAR ALPHA-OLEFINS VIA MICROWAVE CATALYTIC CRACKING OF LIQUID STRAIGHT-CHAIN ALKANES","authors":"V. A. Bolotov, S. Tikhov, K. Valeev, V. T. Shamirzaev, V. Parmon","doi":"10.4995/ampere2019.2019.9894","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9894","url":null,"abstract":"Linear even-carbon-number alpha-olefins (LAO) with four or more carbon atoms are important compounds of high demand in chemical industry as precursors of a wide range of value-added chemicals [1]. LAO are used as co-monomers for polyethylene production, for the production of alcohols (mainly in detergents and plasticizers) and for synthesis of polyalphaolefins (used in synthetic lubricants). Alpha-olefins (C4, C6, C8 and C10) are mainly used to produce poly(vinyl chloride) plasticizers, high-density and linear low-density polyethylene to impart the stress-crack resistance. C10–C14 alpha-olefins can be used to synthesize linear alkylbenzene sulfonates (synthetic detergents). A conventional route to produce alpha-olefins is oligomerization of ethylene. The process provides production of high quality alpha-olefins but is very costly. If not oligomerization, LAO can be produced by thermal cracking of waxy paraffins but the product is not pure and contains numerous internal olefins, dienes and paraffin impurities. The process is conducted in the vapor phase at relatively low cracking temperatures and needs rapid quenching to prevent side reactions such as isomerization or cyclization. In our previous work [2], we showed that the selectivity to alpha-olefins can be increased considerably via catalytic cracking of n-alkanes under selective MW heating of catalysts. In the present work, the general regularities of MW cracking of n-alkanes are presented. Porous ceramic matrix Al2O3/Al composites (ceramometals) and various carbon materials (CM) having high dielectric losses were studied as supports of the catalysts. MW cracking was conducted with n-C16H34 and n-C28H58. The influence particle size and surface morphology of ceramometals and CM on the structural and group composition of the products was studied. It was established that LAO (C2-C23) and n-alkanes (C2-C26) were the main cracking products under selective MW heating of the used supports. The quantitative analysis of the products demonstrated that the liquid-phase process is more selective to alpha-olefins at the MW catalytic cracking than at the convectional thermal cracking. Silica modification of the surface of CM was shown to suppress spark discharge (usually observed at MW heating of CM); hence, the thermal cleavage of C-C bonds on the CM surface but not in the plasma discharge contributes the most to the formation of radicals. It was shown that the selectivity to liquid alpha-olefin could be more than 85 % under MW heating of cermets in region of the E - field node and decrease considerably in the region of H - field node.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115794663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-15DOI: 10.4995/ampere2019.2019.9822
M. Vinatoru
The literature related to microwave and ultrasound working simultaneously is rather infrequent. The reason is obvious: microwave irradiation is of electromagnetic origin while ultrasound is a mechanical vibration energy. Moreover, the optimal settings for ultrasound propagation throughout a reaction media do not coincide with the conditions required for application of microwaves. Therefore, the challenge is to find a way to best combination of these sources of energy into one apparatus to allow researchers to take advantage of the features of each technology. The oldest paper describing such a combination – microwave and ultrasound is having just 20 years [1] and describe an apparatus which uses a probe system delivering ultrasound through decalin to a vessel holding the reagents dipped in the MW cavity (fig. 1a). Another possibility using a normal MW oven is described by Peng [2] (fig.1b), but this setup is having radiation leakage problems and needs a proper protection. Ragaini et all proposed another type of setup [3] (fig. 1c), not easy to reproduce, but describing calibration and parameters which show an additive increase of thermal energy delivered when MW and US works simultaneous. Insert here uploaded pictures Figure 1. Some MW-US simultaneous setups Few years ago, Cravotto and Cintas [4], disccussed for the first time the potential of using MW and US in sequential or tandem setups. Their paper discuss all possible setups for using mostly glass probe for devlivery of ultrasonic energy or classical setup (fig. 1a). Slowly the concept gain popularity and the paper of Lionelly and Mason [5] prompts to the potential industrial applications, naming the combination of microwave with ultrasound a hybrid technology. The challenge in using this “hybrid technology” is to find a vesatile and reproducible apparatus able to deliver both microwave and ultrasound at a full controlable parameters. In our laboratory we have and use the setup like in the fig. 1a, but the ultrasonic energy is delivered by an ultrasonic cleaning device attached to microwave device (SAIREM Miniflow 200SS). To achieve the above mentioned outcome launched a project to build a device which could work with MW and US in tandem (as Cravotto mentioned [4]) using an US device able to deliver more than a single ultrasonic frequency at a full controlled power. It is our believe that such a device could significantly contribute to MW-US tandem equipment development. Based on our expertise and potential proposed interaction of US with reagents [6] we will investigate the influence (if any) of ultrasound upon MW field. In this paper we will present the earlier results of “Tandem Microwave Ultrasound” energy influence on chemical reagents. References 1. Lagha, A., et al., Analusis, 1999. 27(5): p. 452-457. 2. Peng, Y. and G. Song, Green Chemistry, 2001. 3(6): p. 302-304. 3. Ragaini, V., et al., Ultrasonics Sonochemistry, 2012. 19(4): p. 872-876. 4.
有关微波和超声同时工作的文献很少。原因很明显:微波辐射是电磁源的，而超声波是机械振动能。此外，超声波在整个反应介质中传播的最佳设置与微波应用所需的条件不一致。因此，面临的挑战是找到一种方法，将这些能源最好地结合到一个设备中，使研究人员能够利用每种技术的特点。描述这种微波和超声波结合的最古老的论文只有20年[1]，并描述了一种装置，该装置使用探针系统通过十氢化萘将超声波传递到一个容器中，容器中浸泡着浸在MW腔中的试剂(图1a)。彭[2](图1b)描述了使用普通毫瓦烤箱的另一种可能性，但这种设置有辐射泄漏问题，需要适当的保护。Ragaini等人提出了另一种类型的设置[3](图1c)，不容易重现，但描述的校准和参数表明，当MW和US同时工作时，传递的热能会增加。在这里插入上传的图片图1。几年前，Cravotto和Cintas[4]首次讨论了在顺序或串联装置中使用MW和US的潜力。他们的论文讨论了所有可能的设置，主要使用玻璃探头来传递超声波能量或经典设置(图1a)。慢慢地，这个概念得到了普及，Lionelly和Mason[5]的论文提示了潜在的工业应用，将微波与超声波的结合命名为混合技术。使用这种“混合技术”的挑战是找到一种可重复使用的装置，能够以完全可控的参数传递微波和超声波。在我们的实验室中，我们有并使用如图1a所示的设置，但超声波能量是由附着在微波设备(SAIREM Miniflow 200SS)上的超声波清洗装置传递的。为了实现上述结果，启动了一个项目，建立一个可以与MW和US串联工作的设备(如Cravotto提到的[4])，使用一个能够在完全控制功率下提供多个单一超声波频率的美国设备。我们相信，这种装置可以为MW-US串联设备的发展做出重大贡献。基于我们的专业知识和潜在的US与试剂的相互作用[6]，我们将研究超声波对MW场的影响(如果有的话)。本文将介绍“串联微波超声”能量对化学试剂影响的早期结果。参考文献1 . Lagha, A.等，《分析》，1999。27(5): p. 452-457。2 . 彭旸、宋国光，绿色化学，2001。3(6): p. 302-304。3 . Ragaini, V.等，超声与声化学，2012。19(4): 872-876页。4 . Cravotto, G.和P. Cintas，《化学》，欧洲杂志，2007。13(7): p. 1902-1909。5 . 莱昂内利，C.和T.J.梅森，化学工程与加工:过程强化，2010。49(9): 885-900页。6 . Vinatoru, M.和T.J. Mason，超声波和超声化学，2018。
{"title":"MICROWAVE AND ULTRASOUNDS TOGETHER – A CHALLENGE","authors":"M. Vinatoru","doi":"10.4995/ampere2019.2019.9822","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9822","url":null,"abstract":"The literature related to microwave and ultrasound working simultaneously is rather infrequent. The reason is obvious: microwave irradiation is of electromagnetic origin while ultrasound is a mechanical vibration energy. Moreover, the optimal settings for ultrasound propagation throughout a reaction media do not coincide with the conditions required for application of microwaves. Therefore, the challenge is to find a way to best combination of these sources of energy into one apparatus to allow researchers to take advantage of the features of each technology. The oldest paper describing such a combination – microwave and ultrasound is having just 20 years [1] and describe an apparatus which uses a probe system delivering ultrasound through decalin to a vessel holding the reagents dipped in the MW cavity (fig. 1a). Another possibility using a normal MW oven is described by Peng [2] (fig.1b), but this setup is having radiation leakage problems and needs a proper protection. Ragaini et all proposed another type of setup [3] (fig. 1c), not easy to reproduce, but describing calibration and parameters which show an additive increase of thermal energy delivered when MW and US works simultaneous. Insert here uploaded pictures Figure 1. Some MW-US simultaneous setups Few years ago, Cravotto and Cintas [4], disccussed for the first time the potential of using MW and US in sequential or tandem setups. Their paper discuss all possible setups for using mostly glass probe for devlivery of ultrasonic energy or classical setup (fig. 1a). Slowly the concept gain popularity and the paper of Lionelly and Mason [5] prompts to the potential industrial applications, naming the combination of microwave with ultrasound a hybrid technology. The challenge in using this “hybrid technology” is to find a vesatile and reproducible apparatus able to deliver both microwave and ultrasound at a full controlable parameters. In our laboratory we have and use the setup like in the fig. 1a, but the ultrasonic energy is delivered by an ultrasonic cleaning device attached to microwave device (SAIREM Miniflow 200SS). To achieve the above mentioned outcome launched a project to build a device which could work with MW and US in tandem (as Cravotto mentioned [4]) using an US device able to deliver more than a single ultrasonic frequency at a full controlled power. It is our believe that such a device could significantly contribute to MW-US tandem equipment development. Based on our expertise and potential proposed interaction of US with reagents [6] we will investigate the influence (if any) of ultrasound upon MW field. In this paper we will present the earlier results of “Tandem Microwave Ultrasound” energy influence on chemical reagents. References 1. Lagha, A., et al., Analusis, 1999. 27(5): p. 452-457. 2. Peng, Y. and G. Song, Green Chemistry, 2001. 3(6): p. 302-304. 3. Ragaini, V., et al., Ultrasonics Sonochemistry, 2012. 19(4): p. 872-876. 4. ","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122983116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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