scholarly journals Theoretical and experimental drying of a cylindrical sample by applying hot air and infrared radiation in an inert medium fluidized bed

2012 ◽  
Vol 29 (2) ◽  
pp. 231-242 ◽  
Author(s):  
B. Honarvar ◽  
D. Mowla
Author(s):  
Naret Meeso ◽  
Adisak Nathakaranakule ◽  
Thanid Madhiyanon ◽  
Somchart Soponronnarit

The applied strategy of far-infrared radiation in paddy drying is divided into two main processes with some overlapping, namely, series and combined drying processes. The first comprises fluidized-bed drying, far-infrared radiation, tempering and ambient air ventilation as well as transport of paddy, and the latter is the combination of far-infrared radiation and hot-air convection in fluidization technique. The changes of average moisture content, grain temperature and milling quality in each paddy drying process are presented together with mathematical models. The experiments showed that series drying process was more effective to apply in the aspects of paddy drying and milling qualities than combined drying process. Due to less effectiveness in combined drying process, heat and mass transfer models, only series drying process were developed. The simulation results indicated that the models were capable of satisfactorily predicting the simultaneous average moisture contents and grain temperatures of a paddy grain as compared with the experimental results.


Author(s):  
Kyrylo Kostogryz ◽  
Yu. I. Khvastukhin ◽  
A. M. Tsyupyashuk

Today many industries now use the dryer as a part of grain-drying process even during wet and dry seasons. This helps in reducing spoilage and wastage of paddy. Mostly the available industrial dryers are expensive to purchase and to maintain its smooth functioning. This study therefore is a step to design a simple Plug flow fluidized dryer that can lead to introduce small scale dryers to paddy process industry. The Plug flow fluidized bed dryers are designed and fabricated in this study consists of the drying chamber, hot air distributer plate, hot air inlet and exit system, paddy entry and exit system, fluidization chamber unit with temperature control unit and the centrifugal fan. The evaluation of dryer is based on drying time and reduction in moisture content and outlet temperature of paddy on quality parameters. Dryer dimensions are very important to analyze heat and mass transfer analysis of the Plug flow fluidized bed drying process of paddy grains. It was found d that heat and mass transfer properties of paddy grains in fluidized bed dryer was decreases as the time of drying passes and very rapid at the start of drying. The model present here predicts about dryer dimensions along safe zone of rough rice moisture content with other parameters. Simulation results show a good agreement between the simulation model and the existing simulation models


2018 ◽  
Vol 33 (4) ◽  
pp. 581-591
Author(s):  
Aron Tysén ◽  
Hannes Vomhoff ◽  
Lars Nilsson

Abstract The use of infrared radiation for heating the web in the through air drying process was investigated in lab scale. The hypothesis was that infrared radiation should be a more efficient method to transfer drying energy to the wet web compared to hot air, but that a certain air flow is still required as a transport medium for the evaporated water. A trial program comprising handsheets made of two types of bleached chemical pulps, five grammages (15, 22, 30 and 60 g/m²), and dried with five radiator power levels was performed on a lab scale through air drying equipment. Drying times of the samples were determined from temperature data recorded with an infrared camera. The use of infrared radiation shortened drying times, especially for low grammage samples. The shortening of the drying time ranged between 10 and 45 %. The most substantial shortenings were obtained for the lowest grammages and the highest radiator power level. However, the increase of power did not linearly shorten drying time. After an initial shortening at the lowest power level, the positive effect of the IR heating decreased as the power was further increased.


2015 ◽  
Vol 651-653 ◽  
pp. 1003-1008 ◽  
Author(s):  
Bart Buffel ◽  
Marijke Amerijckx ◽  
Martijn Hamblok ◽  
Bart van Mieghem ◽  
Frederik Desplentere ◽  
...  

The present study addresses the difficulties in heating thermoplastic sheets for ther-moforming applications. In industrial environments, the sheets are heated in a contact free method by means of convective hot air ovens and infrared radiation. In this study the temperature evolution at the outer surface as well as the core of thermoplastic sheets as a function of time is measured by means of thermocouples. These measurements reveal significant through thickness temperature dif-ferences which need to be resolved before high quality products can be made. The temperature dif-ferences can be decreased by decreasing the radiative power. This is however not acceptable in in-dustry since it lowers the number of produced parts per unit of time.In order to gain insight in the time-temperature relationship during the heating phase, a finite differ-ence model is developed. The model clearly shows the constantly changing through thickness tem-perature distribution and can be used as a tool by the thermoforming industry to optimize the pro-duction process.


Sign in / Sign up

Export Citation Format

Share Document