Modelling and simulation of the thermal vapour compression desalination process

A description is given of a steady state mathematical model developed to analyse the single effect thermal vapour compression (TVC) desalination process. The model considered the effects of all thermodynamic losses on the unit thermal performance ratio, the specific heat transfer area and the specific flow rate of the cooling water. The losses contemplated are the boiling point elevation, the non-equilibrium allowance and the temperature depression corresponding to the pressure drop in the demister and during the vapour condensation process. The model also takes into consideration the variation in the physical properties of the sea water with temperature and salt concentration, the effect of fouling factors and the presence of non-condensable gases on the heat transfer coefficients in the evaporator and the condenser. The relationships between the parameters that control the product water cost (e.g. the thermal performance ratio, the specific heat transfer area and the mass flow rate of the cooling water) and important parameters such as the motive steam pressure, the vapour compression ratio and the boiling temperature have been established and presented in detail. (author)