Economic analysis and experimental investigation of a direct absorption solar humidification-dehumidification system for decentralized water production

Abstract

In the present work, a direct absorption solar humidifier (SH) based closed-air loop open-water loop humidification-dehumidification (HDH) desalination system is investigated experimentally. The selection of air-to-water mass flow ratios for this configuration is unknown. Hence, this work characterizes the impact of feed flowrates and recirculating air flowrates to arrive at an operating state that influences the system efficiency for a determined solar thermal input. Performance curves that directly correlate the system’s Gained output ratio (GOR) against humidity-based normalized gain are proposed to enable site selection and performance estimation. Water flowrate has optimal value for the SH-HDH desalination system highlighting a delicate balance between feed water and air flowrates that allows improved heat and mass transfer in the module while minimizing overall thermal losses. A comparison of the performance of the SH-HDH system with a conventional HDH system showed 18.4% improvement. A novel approach by storing the hot water rejected from SH-HDH configuration during on-sun hours for the off-sun operation was considered. The estimated cost of water produced was ranging from 0.007 to 0.035 USD/liter, depending on received solar irradiation and rainfall at the location. Finally, a comparison of GORsolar, cost of desalination, and productivity of the present system are compared with the literature.