Description of process and heat pump demonstrator:
A closed loop heat pump will be integrated in the tunnel dryer at the production site of Wienerberger in Uttendorf, Austria. It is a continuous dryer, where the shaped clay products (green bricks) with a moisture content of around 30% are dried to 2-4%, which is the maximum moisture that is allowed in the firing process in the kiln. In the tunnel dryer, bricks are dried in a counter-current flow of air. Drying air is heated by heat exchanger surfaces, which are supplied with hot water from a heat recovery cycle and are located inside the tunnel. The heat pump will also use the heat recovery cycle as the heat source. The heat pump will provide hot water up to 160°C to heat the drying air. The hot air is fed into the outlet zone of the tunnel dryer, where the highest temperatures are required. The heat pump will act as a booster for the heat recovery cycle.
This heat pump demonstrator includes piston compressors (HBC 511) developed by Viking Heat Engines. They are based on a proven, heavy-duty design developed in collaboration with the world's largest engine design company, AVL. The compressor is engineered to operate at very high pressures and internal temperatures (>160°C). It is compatible with all common refrigerants of the 3rd and 4th generations e.g. HFOs like OpteonMZ (HFO 1336mzz-Z) from Chemours as used in the demonstrator. It has an internal oil circuit with oil filter and preheater and very low internal friction through exclusive use of low-friction bearings. The piston compressor also has an efficient integrated water-cooled synchronous motor (PMM) and reaches a high isentropic and volumetric efficiency over a broad range of operating conditions by utilizing a variable speed operation. For its lubrication, a novel lubricant is provided by FUCHS.
The heating capacity of the heat pump demonstrator will be around 400 kW. The heat pump demonstrator replaces a natural gas burner and shall lead to end energy savings of up to 84% and reductions in CO₂ emissions of about 80%.