A graphical method for evaluating the thermodynamic feasibility of absorption vapor compression multi-effect thermal desalination systems

A graphical method is developed for evaluating the thermodynamic feasibility of combined absorption vapor compression (AVC) and low-temperature multi-effect evaporation (LT-MEE) desalination systems. The method is based on the diagram showing the relationship among the vapor pressure, temperature and concentration of absorbent solution and seawater. Three commonly used absorbent solutions-LiBr-H2O, LiCl-H2O and CaCl2-H2O, are taken as examples. A five-step procedure is proposed and three systems-a conventional water-only system, a water-refrigeration cogeneration system and an intermediate vapor absorption water-only system, are analyzed for illustration purpose. Requiring only a small amount of information, the method is suitable to be used in the preliminary planning or design phase of an AVC-MEE system. Besides, the method can also give the values or ranges of several important parameters for the AVC-MEE systems being evaluated to be feasible, thus providing useful information for further investigation.