Experimental parametric investigation of waste heat powered humidification dehumidification system for production of freshwater from wastewater

In this study, the performance of a novel humidification dehumidification (HDH) system powered by waste heat for the production of freshwater from domestic wastewater is investigated experimentally. The waste heat rejected from the domestic air conditioning unit is utilized as the process air for powering the HDH system. The influence of the major parameters such as process air temperature, humidity ratio, wastewater flow rate and coolant liquid flow rate were evaluated to identify the optimum conditions for maximum freshwater productivity. Further, the humidification potential of cellulose paper and Polyvinyl Chloride (PVC) humidifier materials were evaluated comparatively to identify the effective humidifier material for maximum productivity. Experimental results indicated that the maximum achievable yield is about 7.1 kg/h with the use of cellulose material for an optimum flow condition of 0.5 m(3)/h and 0.9 m(3)/h in humidifier and dehumidifier units respectively. Further, the maximum freshwater productivity, gained output ratio (GOR) and cost of freshwater production are 4.7 kg/kWh, 1.27 and $0.0409/kg respectively. A significant decrement in the contaminants were identified during water quality analysis and the obtained results indicated that the developed HDH system could be utilized for local production of freshwater with competent use of waste heat and wastewater simultaneously.