Investigation of a solar energy driven and hollow fiber membrane-based humidification–dehumidification desalination system

Abstract

A solar energy driven and membrane-based air humidification–dehumidification desalination (MHDD) system is proposed. A test rig is designed and constructed to investigate the performance of the system. The test rig consists of a U-tube evacuated solar collector, a heat storage water tank, a membrane-based humidifier (hollow fiber membrane module) and a dehumidifier (a fin-and-tube heat exchanger). A theoretical model for the whole system simulation is developed and validated. Performance indices of the system, such as the specific water production rate on the basis of unit area of membrane (SWR), specific electric energy consumption on unit volume of water production (SEC), coefficient of performance (COP) and electric coefficient of performance (COPE) are investigated. The effects of various parameters including the saline water flow rate, the air flow rate and the packing fraction of the membrane module, etc., on system performance are examined. It indicates that solar energy accounts for 92.0% of the energy consumption by the whole system. Sensible heat losses account for most of the energy losses from the system. High-purity water is produced by this system at a SWR of 25.88kgm−2d−1, a SEC of 19.23kWh/m3, a COP of 0.75 and a COPE of 36.13. The feasible operating parameters investigated are: hot saline water flow rate, 236L/h for per unit area of membrane; air flow rate, 25m3/h for per unit area of membrane; module packing faction, 30%.