Determination of performance parameters of infrared dryer to increase drying performance and uniformity of heat distribution

Thin layer drying of agriculture products using an infrared dryer (IR) is one of the interesting and low costs methods. Quality of dried products such as shrinkage, minimum color changes and rehydration ability could be increased if the engineering aspects will be considered in designing of dryer and selection of proper performance parameters. Wavelength of emitters and the distance of infrared radiator from the product are the important designing parameters in IR dryers. These parameters could guaranty the drying uniformity and the maximum temperature on the product surface in continues and batch IR dryer. Due to the lack of the mathematical models and equations usable in IR dryer designing, in this research the designing characteristic of infrared radiators was studied such as the effect of radiators location on the radiation uniformity, drying uniformity and the maximum temperature on the product surface. The study was performed by stabling the infrared wavelength at the range that absorbed by the water content of the radiated foodstuffs. Studied parameters, the horizontal and vertical distance had significant effect on the maximum temperature on the product surface and uniformity of heat distribution. A mathematical model was developed to describe the maximum temperature on the product surface as a function of radiator parameters. RMSE and r values of the model were 2.75 and 0.97, respectively. In order to validate the developed model, the drying kinetic of potatoes and its internal temperature profile was studied by keeping the horizontal and vertical distance of infrared radiators at the recommended value and stabling the infrared wavelength at the range that absorbed by the water content of the radiated foodstuffs. The results showed the good fitness between the experimental and predicted data.