Performance evaluation of a multi-stage humidification compression with heat recovery based on mathematical modeling

A solar multi-stage desalination plant based on humidification compression with a heat recovery section was proposed in this study. Unlike conventional multi-stage plants, in this plant, water was reheated in the energy recovery section before entering the next humidifiers. The plant consisted of three packed columns (humidifiers), a polytropic compressor and three heat exchangers for energy recovery. A mathematical model was established to evaluate the impact of several operating parameters on the plant performance. The model was numerically solved, and a good conformity was found between the experimental data and numerical results. Average absolute error values of 2.12%, 0.25% and 0.38% were found for the outlet air humidity, outlet water temperature and outlet air temperature, respectively. In addition, the gained output ratio (GOR) and performance ratio (PR) for the proposed plant were found to be higher than those of conventional plants. In addition, higher inlet water temperature and lower pressure ratio and water-to-air mass flow ratio enhanced the GOR. On the other hand, the variation of pressure ratio had no significant influence on the PR, but higher inlet water temperature and lower water-to-air mass flow ratio increased the PR.