Conveyor-Belt Dryers with Tangential Flow for Food Drying: Development of Drying ODEs Useful to Design and Process Adjustment

Abstract

The mathematical investigation presented in this paper concerns the conveyor-belt dryer with tangential flow operating in co-current. This dryer is bigger than the continuous through-circulation conveyor dryer but has the advantage of better preserving the organoleptic and nutritional qualities of the dried product. In a previous work a mathematical modeling of the conveyor-belt dryer with tangential flow was carried out to offer guidelines for its optimized design. The last of those design guidelines indicated the need for an optimized adjustment of the dryer to ensure the constant maintenance of the final moisture content of the product. The fast and very precise measurement of the moisture content as the first step in the feedback chain was therefore necessary. Considering the difficulty of this type of measurement, two specific ordinary differential equations (ODEs) were obtained with the mathematical investigation of this work. Their solution became a relationship between the final moisture content of the product, the outlet air temperature, and other quantities that could be easily implemented in an automatic dryer control system. Therefore, the fast and accurate and much less expensive measurement of the temperature of the air leaving the dryer, owing to the relationship found, replaces the measurement of moisture content for the adjustment system. The experimental verification of the relationship highlighted the need to introduce a modification by which the relationship was finally validated.

Improving the Design and Operating Parameters of the Belt Conveyor for Working With Heavily Impure Grain Crops

“…Fig. 5 Scheme of the Petkus Gigant seed cleaning machine [29] The Petkus Gigant grain cleaning machine consists of: grain receiving hopper (1); feed rollers (2); flaps (3); aspiration channels (4, 10); deposition chambers (5,9); air gates (6,8); fan (7); trier cylinder (11); tray (12); brush (13); lower and upper sieves (14,15); cleaner (16). In concordance with the scheme, the grain mixture with impurities is decanted, located in the departments of the device as follows: light impurities (I, III); fine grain with impurities (II); large impurities (IV); grain of airlattice purification (V); short impurities (VI).…”

“…The latest belt conveyors are characterised by low operating costs, high reliability, and safety. Friso evaluated the belt conveyor, which is one of the most popular transport vehicles, due to its high performance, simplicity of design, low energy consumption, reliability, and ability to transport loads at high speed over long distances [11].…”

Prototype of an Innovative Vacuum Dryer with an Ejector System: Comparative Drying Analysis with a Vacuum Dryer with a Vacuum Pump on Selected Fruits

“…Carrying out the average based on the masses of water to be evaporated when the moisture is higher than Wc and when it is lower than Wc, an average thermal energy value of 2578 kJ is obtained if the final moisture W 2 is 20% [57][58][59].…”

Mathematical Modelling of Rotary Drum Dryers for Alfalfa Drying Process Control

“…In the first zone, long L I−C , the moisture content X of the product is higher than the critical content X C ; therefore, the temperature T P is constant and equal to the wet-bulb temperature T WB [17,18].…”

“…The diagram is completed with the identification of an elemental area dA of the product, which can be defined as the infinitesimal length dz of the drum multiplied by a quantity f, which is the sum of the perimeters of the sections of the product elements present in the generic section of the drum, as shown in Figure 3. In the first zone, long LI − C, the moisture content X of the product is higher than the critical content XC; therefore, the temperature TP is constant and equal to the wet-bulb temperature TWB [17,18].…”