Multi-objective optimization and economic study of energy-efficient hybrid silica gel adsorption/HDH/AC cogeneration system

Over the past century, integrated adsorption desalination (AD) systems have gained significant interest as sustainable solutions to the increasing global freshwater demand. Although many hybrid AD systems are presented, ample energy efficiency improvement still exists by integrating humidification de-humidification (HDH) and air conditioning (AC) for water production and thermal comfort cogeneration. In this regard, a comprehensive mathematical model is developed to evaluate key performance metrics for two AD/HDH/AC proposed system configurations. Additionally, multi-objective optimization is employed to identify optimal operating conditions. The results reveal that the hybrid system (Scheme #2) demonstrates high productivity and GOR. At a heating water temperature of 50 °C, it produces up to 181.4 kg/h of water with a maximum GOR of 3.74. This productivity increases to 216.2 kg/h with a GOR of 1.69 under maximum output conditions. For Scheme #1, maximum productivity is 115 kg/h at a GOR of 1.67, while the peak GOR is 3.86 at 65 kg/h. The specific cost per kilogram of water (SCPW) varies between $0.015 and $0.0165, depending on the operating conditions. Key parameters affecting system performance include chilled and heating water temperatures, flow rates, and the mass ratio of the humidifier. The findings show that integrating AC with HDH and AD provides superior performance, offering dual benefits of thermal comfort and water desalination.