Establishing the model for predicting the moisture and velocity in the critical point during drying of green masonry products

Abstract

The aim of this study was to establish the model for predicting the moisture and velocity in the critical point during drying of green masonry products. The raw material was first dried at a temperature of 60°C, and then after cooling to room temperature, was milled down using perforated rolls mill. Milled material was identified and subject to further classical preparation, which precedes the fom1ation on the vacuum presses. Thus prepared sample carried the name .. sample A. The staning raw material was mechanically activated for 30 minutes. Thus prepared sample carried the name- sample B. Laboratory samples 120x50xl4 mm were formed in a laboratory extruder under a vacuum of 0.8 bar. These samples were used in further experimental work. Drying process was monitored and all process parameters such as: temperature, relative humidity of the drying air, weight changes, linear shrinkage, temperature of the surface and in the centre of test samples were recorded continually. Two mathematical models, based on multi factorial experimental design technique, were set up . The first describes the moisture and the second one the velocity value of the samples B in the critical point as a function of temperature , relative humidity and the velocity of the drying medium.