Performance Investigation of a novel direct contact membrane distillation unit with air bubble injection

This study proposes, develops, and evaluates a novel air-assisted direct contact membrane distillation (DCMD) unit incorporating a dual vapor condensation mechanism to enhance productivity and energy efficiency. Unlike previous studies focusing solely on an air bubble injection to improve heat and mass transfer, this research introduces an external bubble column dehumidifier to recover vapor from the air-saturated feed stream, achieving a secondary condensation process. The innovative design mitigates fouling and scaling, improves thermal efficiency, and enhances distillate flux. Experimental results demonstrate an 18% increase in condensate flux, a 7% reduction in specific thermal energy consumption, and a 7% increase in the gained output ratio compared to conventional DCMD systems. The air injection also contributes over 150% to flux improvement by reducing concentration and temperature polarization effects. This advancement establishes a practical and scalable solution for sustainable water desalination under different conditions including feed salinity, feed temperature and flowrate, coolant flowrate and temperature, and air injection flowrate.