Parametric analysis of efficient desalination by coupling the fuel cell exhaust and humidification-dehumidification

Humidification-dehumidification desalination is simple and can avoid membranes. However, it has a high energy consumption especially when assigned a dedicated energy source. This research proposes to serially couple the cathode airflow of a proton exchange membrane fuel cell directly to open loop humidification-dehumidification desalination, which recycles the waste heat of the fuel cell and additionally, the water vapor generated by the electrochemical reaction. A combined experiment and simulation approach is carried out to analyze the system. Several experimental trials involving different amounts of packing materials are carried out to assess the trade-off between higher humidification efficiency and increasing resistance against airflow. Then, after model validation via the experiment, simulation studies are carried out. Results reveal that an airflow rate-specific fuel cell output power of over 40 kJ/kg is recommended to ensure the exhaust gas is over 65°C and has a relative humidity of under 20 %, which are proper conditions for humidification-dehumidification desalination. Moreover, although increasing the packing material increases the humidification efficiency, it also impacts the airflow rate and heat exchange rate, which results in a worsening desalination rate. Finally, the experiment demonstrated a maximum desalination rate of 1.13 kg/h when the seawater temperature is 35°C.