Investigation of a water desalination method via a humidification-dehumidification process using HVAC technology
Potable water is becoming a scarce resource in many arid regions of the world. An experimental unit was designed and constructed to examine and characterize the production capabilities of a humidification-dehumidification (HDH) desalination process. An HDH cycle offers a viable, technologically light, alternative for producing fresh water from brackish water because the low relative humidity air is infused with water vapor through evaporation by means of conventional heating, ventilation and air conditioning (HVAC) components. The evaporation process effectively separates salts and suspended solids from the brackish feed-water. Desalinated water is subsequently recovered by extracting the water vapor from the moist air through condensation. The study used CELdek™ cellulose evaporative media (CEM) varied from 4.0" to 16.0" for air flow rates of 400, 600, 800 and 1000 CFM. Two system configurations were tested, single and two-stage, where each stage was comprised of a heating and humidification process. Water production for single stage experiments varied from 0 - 10.82 lbw/hr for 4.0" and 16.0" CEM thicknesses, respectively, at 1000 CFM. Similarly, at 1000 CFM, two-stage experiments' water production varied from 4.22 - 17.94 lb w/hr, for 4.0" and 16.0" CEM thicknesses, respectively. Analyses of the data indicate that the HVAC-HDH process investigated is highly inefficient because the system's values of performance (PR) and gained output ratios (GOR) are below 1.0. Moreover, the experimental system would require a solar pond size of 0.27 acre to adequately provide all thermal energy requirements, mitigating the need for conventional power sources. Water samples from the prototype unit's production had a mean conductivity of 19±2 μS/cm, establishing the system's effectiveness for desalinating water.
Cornejo, Juan Antonio, "Investigation of a water desalination method via a humidification-dehumidification process using HVAC technology" (2012). ETD Collection for University of Texas, El Paso. AAI1518193.