Gypsum board drying is among the most energy-intensive industrial processes, consuming 13 to 35 TWh per year in Sweden. A standard 3 m² board takes 24 kWh to produce, two thirds of it for drying, heat conventionally supplied by a gas-fired burner. The evaporated water then leaves the plant as humid exhaust.
MVR4G-DRY replaces the burner with an integrated mechanical vapour recompression heat pump. Seven steam compressors recompress that vapour in stages, delivering seven temperature levels up to 210°C at a lift of 160°C, beyond the 140 to 180°C typical of industrial MVR systems. The recovered heat passes through a tube condenser and heat exchanger to raise the temperature of the drying air, which in turn dries the boards. An additional n-pentane heat pump recovers further heat from the exhaust.
The 10.5 MWth system achieves a COP of at least 2.3 and cuts specific energy consumption from 0.778 to below 0.389 kWh per kg of water evaporated, an energy saving of over 50%. Working fluids are water/steam (R718) and n-pentane (R601), both natural and non-PFAS. The demonstration runs on a live production line at Knauf’s Åhus plant, advancing the system from TRL6 to TRL8.








