Study on Heating Uniformity of Pt-Rh Alloy Bushing for Producing Flexible Glass

The numerical simulation for temperature distribution of Pt-Rh alloy bushing was carried out using a thermal-electric module in ANSYS Workbench finite element analysis software.The effects of side wall thickness,plug thickness,the angle of two side walls and electrode structure on the uniformity of temperature distribution were investigated.Meanwhile,the contrastive analysis results of bushing with and without glass melt were discussed.The simulation results show that,when the homogeneous glass melt flows through bushing,the temperature difference between the center and both ends of bushing is decreased significantly,but the temperature distribution at both ends of bushing is still affected by heating non-uniformity of bushing.Compared with side wall thickness,plug thickness and the angle of two side walls,electrode structure plays a greater role in adjusting heating uniformity of bushing.

Developing a screw conveyor in radio frequency systems to improve heating uniformity in granular products

Radio frequency(RF)treatments have been increasingly studied due to the rapid heating,deep power penetration depth and high energy efficiency.However,the major challenges for commercial RF applications are non-uniform and run-away heating.The purpose of this study was to improve RF heating uniformity in three granular products(soybean,corn,and peanut)using a custom-made screw conveyor with sample movement and mixing.The results showed that soybean,corn and peanut samples in the screw conveyor were RF heated in a similar heating rate under the selected electrode gap and screw rotation speed,and the variations between the highest and lowest temperatures in the three samples were all clearly reduced as compared to the stationary treatments.The RF heating uniformity index was also reduced for soybean,corn,and peanut during and after the RF treatment.Therefore,the screw conveyor could improve RF heating uniformity due to stable,continuous,uninterrupted movement and mixing of samples.The small-scale screw conveyor used in RF systems would provide a solid basis for further large-scale industrial applications.

New strategy for improving heating uniformity and insect mortality in radio frequency treated mung beans

Radio frequency(RF)heating is usually used to control insects while maintaining the quality of harvested grains.Different packaging conditions may influence RF heating uniformity,insecticidal efficacy,product quality,and energy efficiency.An RF unit was used for conducting thermal treatments to evaluate the heating uniformity,the mortality of Rhizopathy dominica,the main quality attributes of mung beans under four packaging conditions,and the energy efficiency.The results show that after the aluminum foil sheet was added at the top or bottom side of bags,the RF heating uniformity was improved.The mortality of Rhizopathy dominica in mung beans was 100%for vacuum-packaged bags added with aluminum sheets on the bottom side and ordinarily sealed bags.The fastest cooling rate was observed in vacuum-packaged bags with aluminum foil sheets added at the top side.The energy efficiency of the RF system for treating mung beans in Packaging A,B,C,and D were 54.8%,56.0%,53.6%,and 54.8%,respectively.The effective RF treatment protocol was developed using vacuum-packaged bags with aluminum sheets added at the bottom side,54℃hot air assisted RF treatment under an electrode gap of 13.5 cm for 5 min,holding for 6 min,and placing bags upward for cooling.The suitable packaging condition could be explored for developing practical RF disinfestation treatments.

Evaluation of a heating block system for accurate temperature-time controlled pasteurization treatments on various foods

For simulating real pasteurization treatments using hot air,hot water,radio frequency and microwave heating,a unique experimental heating block system(HBS)was developed.The stability and uniformity of sample temperatures and heating rates in HBS were determined for studying the thermal resistance of food-borne pathogens.A computer simulation model was also developed to analyze the behavior of thermal process in HBS.The results showed that the required heating rates with various set-temperatures and holding times could be easily and precisely achieved in eight selected food materials.Thermocouple and thermal imaging data showed that the good sample heating uniformity in six cells of HBS was achieved.The real temperature-time histories obtained by radio frequency energy could be approximately done in HBS by setting a number of linear regression curves.The HBS can help in more precisely characterizing the heat resistance of pathogens in foods to further develop pasteurization processes.

Transverse Flux Induction Coil for Uniform Bar Heating Excluding Edge

This work particularly focuses on compensating Joule heat in under-heated areas occurred when thin steel bar is(<20 mm)heated by transverse flux induction heater(TFIH).The under-heated areas take place in range of 50~150 mm from the both edges,so Transverse Flux Induction Coil(TFIC)including a magnetic core is proposed and optimized to supplement this fault.The solutions on the electromagnetic field are obtained numerically by commercial code MAXWELL 3D software from ANSYS Corp.and then,verified experimentally by pilot-scale tests,in which the TFIH was manufactured with a nominal power of 100 kW at a fundamental frequency of 1 kHz.Ultimately,TFIC having geometrically the optimized magnetic core made the heating pattern U-shaped,so could supply a desirable temperature profile for the rolling process.