Parametric analysis of an air-heated humidification-dehumidification (HDH) desalination system with waste heat recovery

• Air-heated HDH desalination with waste heat recovery is proposed.
• Performance of the desalination system is calculated.
• Second law of thermodynamics is applied to judge the feasibility of the desalination system.
• Sensitivity analysis at different parameters is calculated and presented.

Industrial waste heat is effective to provide power for the desalination system to acquire distilled water. In this paper, exhaust gas is drawn into the plate heat exchangers (PHEs) to heat the circulated humid air within the humidification dehumidification (HDH) desalination unit. Based on the governing equations of the components and the fixed-effectiveness model, key parameters are prescribed to accomplish the performance analysis of the HDH desalination system, and the relevant recovery results of the waste heat are also attained. The simulation results present that the balance condition of the dehumidifier is inaccessible due to a negative specific entropy generation of the dehumidifier in spite of the obtained best performance at such point. It is summarized that high values of the component effectiveness and the initial temperature as well as the vacuum environment are beneficial to raise the performance of the desalination system and reduce the heat transfer surface area for the PHEs. Moreover, the elevation of the top temperature contributes to a slight elevation of the gained-output-ratio (GOR), while the relevant heat transfer surface area of the PHEs increases.