Mechanical vapour recompression is a Gas/ Vapour Compressor which compresses Water Vapour and Polytropic Compression increases Pressure and Temperature of discharged Gas/Vapour.
The secondary steam generated by the evaporator is performed by a mechanically driven compressor to increase its temperature and pressure, and then used for heating the evaporator, and then the pressurized secondary steam is condensed to complete the evaporation process.
Using this phenomena, evaporated vapour from the evaporator compresses to the desired level so that it can be utilized back for Evaporation.