Design and Evaluation of a Combined (Humidification-Dehumidification) System to Extract Fresh Water from the Air in the Arid Area

摘要

Surface cooling water harvesting from air represents an alternative way to provide new potable water sources. In this study, an Extracting Water Machine (EWM) is fabricated, which is a device that can convert water vapor directly into usable and even drinkable water. This study was conducted to evaluate the quantity, chemical quality, and power consumption of condensed water, particularly in areas where the relative humidity is less than 30 %, with an abundance of non-fresh water (i.e., wells, marshes, and others). Three operating strategies were proposed during February, March, April, and May; the experiments were conducted every hour on a particular day of each month for each test using actual climate data of Nasiriya, Iraq in 2020. In the first test, the device operated in dehumidification mode and the ambient air passed directly to the surface of the cooling coil; it has found that the daily condensed water and energy consumption for the four consecutive months under consideration were (16.82, 4.58, 3.93, 4.23) L/day and (0.525, 1.86, 2.175, 2.13) kWh/L, respectively. In the second test, the device also operated on the dry mode, and the air passed through the evaporative cooler and then to the evaporator coil. The results were (36.418, 26.01, 20.895, 19.2) L/day and (0.530, 0.443, 0.550, 0.555) kWh/L respectively. In the last one, the device was run on the cooling mode using an evaporative cooler. The obtained water amounts were (31.93, 38.53, 31.03, 32.29) L/day with (0.530, 0.443, 0.550, 0.555) kWh/L energy consumption for February, March, April, and May. The results indicate the second and third tests are useful under the prevailing climatic conditions. Analysis carried out on the obtained water revealed that some parameters including total dissolved solids and electrical conductivity were within the World Health Organization standard for drinking water.