The water is then pulled out of the system by a vacuum pump. Apparently, in order to optimize the efficiency and capacity of vacuum dehydration, it is important to maximize the heat and mass transfer inside the vacuum chamber. Temperature is the driving force for heat and mass transfer. Therefore, the following parameters, such as vacuum pressure, operating temperature, surface area of diffuser, and flow rate, need to be considered. The higher the vacuum, the lower the boiling temperature and the more water that can be vaporised.
Maximum vacuum is preferred for vacuum dehydration.
Water vapor increases pressure in the chamber and further slows the mass transfer of water from a liquid state to a vapor state. The condenser can be located either inside or outside of vacuum chamber. Once a bubble of vapor is created, it becomes a nucleus of further boiling. These droplets are not only isolated from each other, but also prevented from contacting irregular surfaces of the vessel by the continuous oil phase. Interfacial tension between water and oil provides a contractive force for water droplets in oil.