Simultaneous production of cooling and freshwater by an integrated indirect evaporative cooling and humidification-dehumidification desalination cycle

Abstract

Cooling and freshwater represent two fundamental demands in hot and arid regions. This paper reports the integration of an indirect evaporative cooler (IEC) and a humidification-dehumidification desalination cycle (HDH) for the simultaneous production of cooling and freshwater. To take full advantage of system integration, the purge air from IEC is supplied to HDH to promote water productivity. A pilot IEC unit is firstly designed and tested to achieve the temperatures and humidity of the outlet air steams. Results reveal that the IEC unit is able to cool down the supply air to below 25 °C under different outdoor conditions, and the purge air temperature is also 5–10 ℃ lower than the intake air temperature. Employing the IEC purge air as the working air, the HDH cycle is then investigated analytically. Under the operation ranges considered, the freshwater productivity and gain-output ratio (GOR) are 25–125 L/hr and 1.6–2.5, respectively, which are higher than other HDH configurations operating under the same conditions. Finally, the performance of the combined IEC-HDH system is evaluated. The overall coefficient of performance (COP) and Second-law efficiency are found to be 2.1–2.5 and 3–26%, respectively. Further improvement of efficiency can be achieved by integrating with adsorption or vapor compression refrigeration cycles.