Thermodynamic and economic investigation of a humidification dehumidification desalination system driven by low grade waste heat

This paper focuses on the thermodynamic and economic investigation of a humidification dehumidification desalination system (HDDS), using waste exhaust gas to heat the humid air. In accordance with the principles of the mass and energy conservation, thermodynamic analysis of the HDDS is first completed, and the heat and mass transfer (HMT) areas for the waste heat recovery exchanger, packing-bed humidifier and plate type dehumidifier, are obtained. Finally, the economic performance of the HDDS is also calculated. The research results state clearly that the top values of the water production and GOR arrive at 289.32 kg h(-1) and 3.06 at the dehumidification balance conditions, while the maximum total investment of the air-heated HDDS is calculated as 112.55 x 10(3) The influence laws from the variation of the dehumidification effectiveness, minimum enthalpy difference during humidification, top temperature and temperature of the waste heat source are different and complicated, especially on the unit cost of water production, which is determined with the thermodynamic and economic performance considered simultaneously. It can be concluded that the elevation of the thermodynamic performance, mainly referring to the aspect of water production, will raise the corresponding cost of the air heated HDDS, which is mainly composed of the investment of the dehumidifier area.