Physical and chemical characteristics of water in a microwave field and mass transfer during the drying of dense textiles

Abstract

Microwave drying provides economic advantages based on optimised energy consumption and productivity deriving from the changes in physical and chemical properties of water in a microwave field: heating rate, as influenced by chemical composition, volume, the presence of the heat transformer; volume expansion, vapour pressure, rH, evaporation rate and the evaporation parameter – all measured in relation to temperature, time and power. For example, in the case of felt, energy consumption is reduced from 4-6 kWh in classical drying to 1.7-2.3 kWh during microwave drying per 1 kg of dried water. In addition, the drying period is shortened from 200-400 min. in classical drying to 60- 140 min. in microwave drying. Thus, based on drying time alone, productivity increases 3 to 4 times. Each material subjected to a drying process is characterised by typical energy consumption and productivity levels.