Proceedings 17th International Conference on Microwave and High Frequency Heating最新文献

{"title":"SINTERING OF MLCC’S BARIUM TITANATE WITH MICROWAVES","authors":"J. Aguilar-Garib, Osvaldo Tijerina-García, Javier Garza-Guajardo","doi":"10.4995/ampere2019.2019.9919","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9919","url":null,"abstract":"A comparison of microwave and conventional, in an electric resistance furnace, sintered layers of dielectric base barium titanate (BaTiO3) of the kind employed for multilayer ceramic capacitors (MLCC) was performed. Two kinds of samples were used for each processing method; the layers alone without electrodes, and the green MLCC with the layers and electrodes interdigitated. Samples were exposed to microwaves for 20 minutes and heated up to 1050°C and 1150°C for sintering in a crucible with graphite that acted as reduction agent and microwave susceptor. Conventional sintering was performed in the same arrangement but lasted 120 minutes since it was found that 20 minutes was not enough time to achieve sintering. Heating rate in both cases was 10 °C/min. It was observed that the layers without the electrodes achieve about the same densification for both processes, while in the case of the green MLCC’s the results were variable, ranging from sample that became dust, to cracked samples and some well sintered ones. At least in the microwave case, it is possible that the variability of the results is due to the importance of the location of the sample in the cavity that in turn affects the electric field pattern, especially because the presence of the  electrodes that can cause overheating around them.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"25 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":"116770716","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}

{"title":"A COMPARATIVE STUDY OF MICROWAVE AND BARRIER DISCHARGE PLASMA FOR THE REGENERATION OF SPENT ZEOLITE CATALYSTS","authors":"G. Bond, A. Halman, H. Eccles, R. Mao, S. Pollington, P. Hinde, V. Demidyuk, A. Gkelios","doi":"10.4995/ampere2019.2019.9936","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9936","url":null,"abstract":"Due to their acid characteristics and pore structure, which can induce high product selectivity; zeolite catalysts are used extensively in industry to catalyse reactions involving hydrocarbons.  However, these catalysts can suffer from deactivation due to cracking reactions that result in the deposition of carbon leading to poisoning of the acid sites and blocking of the pores [1].  Depending upon the reaction and the particular catalyst involved this deactivation may take place over several months or even years but in some cases occurs in minutes.  Therefore, zeolite catalysts are frequently reactivated / regenerated.  This generally involves a thermal treatment involving air which results in oxidation of the carbon [2].  However, the oxidation of carbon is highly exothermic, and if not carefully controlled, results in the generation of exceedingly high localized temperatures which can destroy the zeolite structure and result in subsequent loss of catalyst activity.  More conservative thermal treatments can result in incomplete regeneration and again a catalyst displaying inferior activity. This paper explores the use of non-thermal plasma which had been either generated using microwaves or via a barrier discharge to regenerate spent zeolite catalysts.  The catalyst, H-mordenite, was tested for the disproportionation of toluene (Figure 1) using conventional heating.  The spent catalyst was then regenerated using a plasma or conventional thermal treatment before having its activity re-evaluated for the toluene disproportionation reaction as previous.           Fig. 1. Reaction Scheme for Toluene Disproportionation.   Interestingly, not only is plasma regeneration highly effective but also catalysts can be regenerated in greatly reduced times.  There is an additional advantage in that plasma regeneration can impart physical properties that result in a zeolite that is resistant to further deactivation.  However, the results are highly dependent upon the experimental conditions involved for plasma regeneration.   References Wu J, Leu L., Appl. Catal., 1983; 7:283-294. M. Guisnet and P. Magnoux, Deactivation of Zeolites by Coking. Prevention of Deactivation and Regeneration. In: Zeolite Microporous Solids: Synthesis, Structure, and Reactivity. E.G. Derouane, F Lemos, C. Naccache, F. Ramôa Ribeiro, Eds. Pages 437-456. Springer 1992.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"23 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":"115737858","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}

{"title":"High Efficiency Microwave Flow Chemistry Towards Synthesis of Functional Materials and Pharmaceutical Cores","authors":"J. Barham, Y. Norikane, H. Egami, Y. Hamashima","doi":"10.4995/ampere2019.2019.9860","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9860","url":null,"abstract":"Microwave (MW) heating benefits organic synthesis by affording higher product yields in shorter time periods than conventional heating, yet it suffers from poor scalability and is limited to polar solvents in typical batch mode reactors. Herein, we report a microwave flow reactor using a solid-state semiconductor MW generator. The tunable, single-mode MW heating allows high efficiency, scalable organic synthesis, rapid reaction optimization and is applicable to non-polar solvents (o-Xylene and CPME can be rapidly heated to ca. 260 oC). Auto-frequency tuning compensates for changes in the microwave absorption properties (permittivity, epsilon) with increasing temperature, affording excellent temperature and process control. This technology unlocked unprecedented g/h productivity of C60/fullerene-indene monoadduct (IC60MA) and facilitated a novel, transition metal-free amide-styrene coupling reaction for synthesis of amide-containing pharmaceutical cores in up to 65 g/h (Figure 1). An ortho-Claisen rearrangement reaction was rapidly optimised.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"66 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":"116508231","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}

{"title":"H2-reduction Behavior of FeS-CaO Mixture during Microwave Heating","authors":"A. Amini, K. Ohno, T. Maeda, K. Kunitomo, K. Kashimura","doi":"10.4995/ampere2019.2019.9755","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9755","url":null,"abstract":"Microwave irradiation is an energy-efficient and a rapid-heating method to decrease the activation energy of chemical reactions via both thermal and non-thermal effects of microwave photons 1). Recently, hydrogen-reduction during microwave heating has been proposed for magnetite reduction to combine the advantages of microwave irradiation and using H2 as a reducing agent during iron production 2). In the present study, as a novel idea, the traditional microwave heating system was equipped with thermobalance to investigate the kinetics of H2-reduction of FeS-CaO mixture (FeS(s) + CaO(s) + H2(g) = Fe(s) + CaS(s) + H2O(g)) under microwave heating at 2.45 GHz to further mitigate CO2 emission and prevent SO2 release during iron production from a sulfide mineral. Microscope observations revealed that the un-reacted core model can be employed for such a kinetic study. Linearity (R2) of different rate-controlling mechanisms after a 10-minute reduction reaction demonstrated that the gas diffusion in micropores of reduced metallic Fe is a dominant rate-controlling mechanism while the interfacial chemical reaction is progressed rapidly. This is attributed to extraordinary effects of microwave irradiation on speeding up the chemical reactions 3), while the formation of Fe shell on the surface of FeS/FeO particles decreases the accessibility of gas to un-reacted parts, resulting in a lower rate of gas diffusion in micropores. Moreover, the diffusion coefficients (De) at 460, 570, and 750 °C were calculated from the plot of the gas diffusion, as illustrated in Fig. 1, wherein the X is reduction degree: where Wi (g) is the initial weight of the sample, Wt (g) is the weight of the sample after treatment for t seconds, Wht (g) is the weight change of the sample owing to the dehydration reaction, and WO (-) is the stoichiometric weight ratio of oxygen in the sample, which is 0.111. Consequently, the activation energy of 22.3 kJ.mol-1 was attained from the Arrhenius equation for the hydrogen-reduction reaction of FeS-CaO mixture under microwave heating.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"28 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":"132282200","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}

{"title":"SOLID-STATE MICROWAVE PROCESSOR FOR FOOD TREATMENT","authors":"Marco Fiore, N. D. Modugno, Francesco Pellegrini, Mariagrazia Roselli","doi":"10.4995/ampere2019.2019.9862","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9862","url":null,"abstract":"Uneven heating and hot spots, irregular matching conditions and deterioration of organoleptic qualities are typical drawbacks of magnetron-based food processing with microwave radiation. The proposed “Kopernicook” modular architecture, based on multiple solid-state generators governed by a distributed software platform, allows highly accurate parametric control, full customization of radiation patterns and dynamic self-regulating workflows. The first results, validated with industrial applications, show great flexibility of operation, optimal energy consumption and different ideas for future developments in terms of radiation patterns and feedback-triggered algorithms aimed at maximally efficient processes.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"18 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":"133071870","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}

{"title":"Microwave Annealing of Powder Metals without Sintering","authors":"Radovan Bureš, M. Fáberová, M. Dilýová","doi":"10.4995/ampere2019.2019.9949","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9949","url":null,"abstract":"  ","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"19 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":"128418493","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}

{"title":"MICROWAVE TREATMENT OF MATERIALS IN LOW PRESSURE","authors":"Parosa Ryszard, Andrzej Brożyński, P. Grzeskowiak, K. Kowalczyk, Marek Natoński, P. Zietek, Janusz Żytkiewicz","doi":"10.4995/ampere2019.2019.9625","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9625","url":null,"abstract":"Ryszard Parosa, Andrzej Brożyński, Piotr Grześkowiak, Krzysztof Kowalczyk, Marek Natoński, Piotr Ziętek and Janusz Żytkiewicz PROMIS-TECH Poland Keywords: microwave treatment, low pressure heating, microwave drying Uniquely favourable characteristics of biological product can be obtained through the use of the microwave method in vacuum heating process. Microwave-vacuum drying is superior to other methods in terms of dried products' structure, flavour, colour and biological active compounds contents. But applications of such a methods seems to be much wider: drying of fruits and vegetables for consumption, drying of herbs for extraction of valuable biological compounds, for modification of seed structure (sunflowers seeds, pumpkin seeds), for pasteurisation etc. A universal system was designed for testing such processes in laboratory scale and several industrial scale system have been developed. Process of thermal treatment can be carried out with plastic drum installed inside of multi-mode microwave cavity and cavity which is connected by microwave line with reflectometer and circulator - to microwave generator. In laboratory unit generator 2.45 GHz with controlled power (from 50W to 800W) was applied. System was equipped with vacuum pump with pressure control and is controlled by computer. Most important technical parameters, like: microwave power, time of treatment, pressure inside of drum, temperature of steam – are controlled and  recorded. Laboratory scale unit is shown below.     Basing on laboratory scale test several technologies in industrial scale was developed. Industrial scale unit equipped with 8 generators of 3 kW (2.45 GHz) was constructed and for last 8 years has been successfully used for “production” of crispy chips which are now popular in Polish marked. Exemplary industrial scale installation is shown in photo below.  Multi – drum microwave drier.   Two cavity microwave  industrial drier    Another system for modification od seed is now constructed – ordered by big industrial producer of batons and sweet snacks. Process will be carried our inside of dielectric drum in low pressure and reactor will be equipped with 8 generators of 3 kW (2.45 GHz). Treatment time will be reduced to 3-4 minutes and next material (seeds) will be cooled down. Last project which now realized is connected with drying of wood flour applied in composite material production. System will work continuously with two airlocks and with  dielectric drum and will be connected with 4 microwave generators (3 kW, 2.45 GHz). In next step planed installation will be equipped with microwave high power generator ca. 60 kW with frequency 915 MHz. ","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"74 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":"122145227","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}

{"title":"SUBCRITICAL HYDROTHERMAL CONVERSION (SHC) PROCESS SUPPORTED BY MICROWAVES","authors":"Parosa Ryszard","doi":"10.4995/ampere2019.2019.9626","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9626","url":null,"abstract":"Ryszard Parosa PROMIS-TECH, Poland Subcritical Hydrothermal Conversion (SHC) process can be used for utilization of wet biomass with recovery of energetic gases and diesel-like fluids. Process is carried out in high pressure (over 200 Barr) and wet biomass is heated up to 350°C. In our research we have apply microwave system to heat wet biomass in high pressure vessel – with control of the most important process parameters like temperature, pressure, microwave power and reflection coefficient. In the first stage process was tested with use of small metallic vessel connected to microwave line (rectangular waveguide) by special ceramic window. Microwave generator 2.45 GHz with controlled output power in range of 200 W to 3 kW was applied. Sewage sludges with moisture content up to 60% were heated by microwaves to temperature from 250°C to 350°C with pressure ca 300 Barr. After heating by 15 - 20 minutes inside of vessel fluid like oil was obtained with solid particles in form of carbon black. Fluid after separation of water contains hydrocarbons – with  biodiesel structure. The similar process with conventional heating by metallic walls of vessel needs much longer time – about 40 minutes, and higher energy consumption.In the next stage a semi-industrial system was designed with process reactor in form of ceramic tube located inside of metallic cavity with two single mode microwave radiators connected to microwave generators of 2.45 GHz and with output power 3 kW (CW) each.Heating process is provided in stop/flow system: biomass inside of high pressure cavity is heated by microwaves to adjusted temperature (280 -350°C) and product is transported by heat exchanger to separator. At the same time next portion of biomass is injected to the cavity. During the process reflected microwave power was recorded. When treated material was in very high pressure, close to subcritical state, specific fluctuations of reflected power level ware observed.  Water in subcritical condition lose polar structure and dielectric constants change, but in the hydrothermal conversion process another chemical compounds are formed (for example diesel like hydrocarbons) and treated material still effectively absorb microwaves. In the described system ca 60 – 80 kg of wet biomass (with 50 – 55% of water) was treated and ca 8 – 15 kg of diesel – like fluid was obtained. Basing on the preliminary results a new industrial scale system was designed and actually is under construction. In industrial scale installation a microwave heating system of 60 kW, 915 MHz is planned, with two radiators installed along ceramic tube.  Estimated efficiency of the system is in range of 200 to 400 kg of biomass treated in hour. ","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"33 4 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":"123461604","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}

{"title":"Experimental Investigations of Microwave Effects on Rock Breakage Using SEM Analysis","authors":"Khashayar Teimoori, F. Hassani, A. Sasmito, Ali Madiseh","doi":"10.4995/ampere2019.2019.9647","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9647","url":null,"abstract":"Preconditioning of hard rocks by microwave energy has recently been considered a potentially effective technology in mechanical rock breakage for civil and mining engineering. To obtain the amount of mechanical damage that a single-mode microwave treatment produces in rocks, it is necessary to analyze and evaluate the thermal cracking process by microwave heating at different power levels, exposure times, and distances from the antenna. The current study employs the scanning electron microscopy imaging technique to capture images from surfaces of irradiated rock specimens and to compare them with a nontreated specimen. To evaluate and quantify the amount of cracking (i.e. crack density, crack size, etc.) in a rock specimen after microwave irradiation with different microwave input operating parameters, the following steps were evaluated. First, several experiments of single-mode microwave treatments with different operating parameters were performed on rectangular specimens of basalt. Then, cylindrical core samples with a dimension of r = 0.5 cm, h = 2cm, were drilled from the center of the irradiated specimens and prepared for image processing. The results of the present study show that there are significant differences between the number of microcracks present in samples irradiated at different power levels and distances from the antenna. Also, longer exposure times result in more severe cracks.","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":"129983319","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}

{"title":"GENERALISATION AND EVALUATION OF MACROSCOPIC MODELS FOR MICROWAVE SUSCEPTORS IN CONTACT WITH HEATED FOODS","authors":"M. Celuch, K. Wilczyński, M. Olszewska-Placha","doi":"10.4995/ampere2019.2019.9847","DOIUrl":"https://doi.org/10.4995/ampere2019.2019.9847","url":null,"abstract":"Introducing a thin conductive layer into a finite-mesh (as inherent in e.g. finite difference time domain (FDTD) and finite element (FEM) methods) typically requires a dedicated equivalent macroscopic model allowing for computationally effective and accurate electromagnetic (EM) and thermal simulations. Thin conductive layers, such as microwave susceptors, characterised by their surface resistance (Rs), are adequately represented with a dielectric surrogate layer of higher thickness and proportionally scaled conductivity, maintaining the value of Rs. Systematic evaluation of macroscopic models of microwave susceptors used for enhancing the heating efficiency of microwavable food packages has been reported in [1]. Our studies therein focus on validity, accuracy and practical application limits of the proposed macroscopic models of thin metallic layers, in terms of power dissipated in susceptor placed in free space and irradiated by EM wave, at all angles of incidence. In this work we extend our studies to real-life simulation scenarios, in which microwave susceptor is in contact with food. We first consider a four-layer model as in Fig. 1(left) and conduct both analytical and numerical conformal FDTD calculations. The accuracy and application limit of the macroscopic model are investigated for all incidence angles and both, TE and TM polarisations of the impinging EM wave, for different foods. We aim to determine a range of optimum, in terms of power dissipated in the susceptor, values of the susceptor’s surface resistance in all those cases. The results of our canonical calculations with the four-layer model of Fig.1(left) are validated in the 3D FDTD modelling scenario of Fig.1(right), representative of a real-life domestic oven. While for normal incidence our results are in overall agreement with some of the previously published observations [2], they are formalised and generalised to constitute reliable guidelines for microwave oven and food packaging designers and manufacturers. We also show cases where some of the earlier rule-of-the-thumb guidelines fail.","PeriodicalId":277158,"journal":{"name":"Proceedings 17th International Conference on Microwave and High Frequency Heating","volume":"13 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":"126308697","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}