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.

Numerical simulation analysis on multi-layer low-temperature heating method of asphalt pavement in hot in-place recycling

Asphalt mixture pavement reheating is one of the important steps in hot in-place recycling(HIR).To improve the heating speed of asphalt pavement in HIR,based on the numerical analysis model of asphalt mixture heating process,a new multi-layer low-temperature heating method(MLHM)was proposed.Considering input heat flux,the thermal capacity and thermal resistance of asphalt mixture,the heat transfer model was established based on energy conservation law.By heating the asphalt mixture in layers,it changes the situation that the heat energy can only be input from the upper surface of the asphalt mixture pavement.Through the simulation of the heating method of asphalt mixture in the existing technology,the result shows that the existing heating methods lead to serious aging or charring of the asphalt mixture.By MLHM,the upper and the bottom of the asphalt mixture are heated at the same time,and the heating temperature is lower than other heat methods,which not only reduces the heating thickness and increases the heating area of the asphalt mixture pavement,but also improves the heating speed,saves the energy resource and ensures the heating quality.Especially,by MLHM,the heating uniformity is better and speed is faster.

A new method for uniform local heating deep in body using ultrasound phased-array system

A new method for targeted heating of deep tissue was developed by using an ultrasound phased-array system which can generate various multiple loci patterns by electronically changing its amplitude or phase pattern. This method involves using a technique of combining switching and rotating of multiple foei patterns to create a uniform temperature over tissue volumes in various size. Using this method, the target tissue deep in the body can be heated to a specified temperature, which gives conditions for thermo-sensi- tive liposomes release. A simulation study for a 108-element, spherically sectioned array was performed to determine an optimal heating scheme from a set of multiple focus fields which were produced by inputting different combinations of phases and amplitudes. Comparisons of a static multiple foei field, the switched fields and the switched-rotated fields indicated that the technique of combining switching and rotating of multiple foei patterns has advantages of both lowering the peak temperature and evening the temperature distribution. The simulation results also show that the therapeutic heating zones in various size （ Φ5mm ～40mm） with uniform temperature distributions can be obtained employing the combined method. These results offer significant data for desisting thermotherapy equipment for tumor-specific drug release with thermo-sensitive liposomes.

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.

Local Non－Similarity Solution of Coupled Heat－Mass Transfer of a Flat Plate with Uniform Heat Flux in a Laminar Parallel Flow

The coupled heat and mass transfer problem of gas flow over a UHF flat plate with its wall coated with sublimable substance has been solved by local non-similarity method. Considerations have been given also to the effect of non-saturation of the sublimable substance in the oncoming flow and the normal injection velocity at the surface. Analytical results are given for local Nusselt and Sherwood numbers at the various locations.

Analytical Solution of Coupled Laminar Heat-Mass Transfer in a Tube with Uniform Heat Flux

Analytical solution is obtained of coupled laminar heat-mass transfer in a tube with uniform heat flux.This corresponds to the case when a layer of sublimable material is coated on the inner surface of a tube with its outer surface heated by uniform heat flux and this coated material will sublime as gas flows throught the tube.