Enhanced drying – heat-pumps, moisture monitoring, drying kinetics

Industrial drying is an energy-intensive process due to the high energy input required for water evaporation. Conventional industrial air-drying uses fossil fuels to heat the air that dries the products. The exhaust air, which is not dry enough for a new drying process, still contains useful heat that can be recovered by a heat pump. This environmentally sustainable solution reduces the dependence on fossil fuels, provides significant economic savings - especially given the recent increase in energy prices – and mitigates CO2-emissions. Yet, the integration of a heat pump requires a re-evaluation of the temperature levels that affect drying conditions and product moisture content, which can be monitored and result in an additional energy savings by eliminating the need to over-dry products. It is also necessary to study the effects of altered drying conditions in the laboratory before applying them directly in the industrial dryer. The drying kinetics of the products in question should be determined with a measuring device that can establish the temperature, humidity, and velocity profile of the air in the laboratory drying chamber. This contribution introduces enhanced industrial drying by presenting a concept for heat pump integration, a concept and device for product moisture measurement, and mainly, a newly developed prototype laboratory dryer for continuous study of drying kinetics of large samples. This work was carried out as part of the EDDY – Enhanced Drying, FFG project number 880778. EDDY is a subproject of NEFI – New Energy for Industry, a flagship region funded by the Climate and Energy Funds Austria.