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. •A graphical method for evaluating the thermodynamic feasibility of AVC-MEE systems is proposed.•The method is based on the vapor pressure diagram of absorbent solution and seawater.•The method is revealed to be effective and easy to apply.•The method can provide useful information for further investigation.