THEORETICAL DESCRIPTION OF THE EXPLOSIVE EVAPORATION WATER IN AN EXTRUDER TO A VACUUM CHAMBER

Abstract

Today, products manufactured on the basis of raw materials of plant origin using thermoplastic extrusion produced a lot, ranging from breakfast cereals and ending animal feeds. Of all the macrostructures porous is of greatest interest in the production of functional additives to bakery products. For extrudates porous macrostructure use short uncooled die at the exit of the melt through a die is a sharp release of pressure that leads to explosive evaporation of water and formation of a porous macrostructure. When determining the characteristics of the explosion the greatest difficulties arise when considering the transition process fluid in a superheated state followed by a detonation of boiling liquid. When liquid evaporates much of the heat energy spent in the overheating of the liquid is converted into mechanical energy of compression and the kinetic energy of moving liquid-vapor mixture, due to which a porous structure. In addition to the explosive evaporation of free water moisture content of the extrudate is reduced by drying by convective mass transfer. Based on the equation of Fick’s first law, the ideal gas law and the theory of similarity was calculated convective mass transfer of moisture in the atmospheric conditions of extrusion and the application of the vacuum chamber of the extruder. The rate of evaporation of moisture from the extruded product by using the vacuum chamber is increased about 30 times that justify its use for increasing the drying rate of the extrudate and increases its porosity due to explosive evaporation of water at an increased pressure gradient between the chambers.