Single-effect thermal vapor-compression desalination process: Thermal analysis

A mathematical model is developed to analyze a single-effect thermal vapor- compression (TVC) desalination process. The model considers the effect of v arious thermodynamic losses on the system preformance ratio, the specific h eat transfer area, and the specific flow rate of cooling water. The losses contemplated are the boiling-point elevation, the nonequilibrium allowance, and the temperature depression corresponding to the pressure drop in the d emister and during the vapor-condensation process. The model takes into con sideration the dependence of the physical properties of the seawater an tem perature and salt concentration. In addition, the model considers the effec ts of the fouling factors and the presence of noncondensable gases on the h eat transfer coefficients in the evaporator and the condenser. The system p erformance is analyzed in terms of parameters controlling the cost of produ ct water which include the performance ratio, the specific heat transfer ar ea, and the specific flow rate of cooling water. The performance ratio is f ound to have values close to 2 at low boiling temperature, low compression ratio, and high pressure for the motive steam. On the other hand, the speci fic heat transfer area and the specific cooling-water flow, rate are found to decrease at higher boiling temperatures, higher compression ratios, and lower pressures for the motive steam.