Investigation of the effect of Al2O3/water nanofluid on the performance of a thermoelectric cooler to harvest water from humid air

Abstract

One of the sources of fresh water, especially in desert and water-scarce areas is atmospheric air. Cooling the moist air and lowering its temperature to the dew point leads to the condensation of present water. This research used a thermoelectric cooler system to obtain water from humid air. Al₂O₃/water nanofluid was used to take the heat from the hot side of the thermoelectric cooler. Using a lab setting, the convective heat transfer coefficient of various nanofluid concentrations was determined. According to the findings, for high Reynolds numbers, the heat transfer coefficient of the nanofluid is between 5000 and 7000 W m⁻² K⁻¹. The effect of some parameters, such as velocity and humidity of the inlet air as well as the nanofluid concentration, on the amount of harvested water was studied experimentally and numerically. The results showed that increasing air humidity led to an increase in the amount of water obtained and the system's performance coefficient. The maximum amount of extracted water at a relative humidity of 20% and air temperature of 35 °C was obtained at 51.3 ml h⁻¹ at the inlet air velocity of 1.4 m s⁻¹ and using a nanofluid of 5 wt%. The velocity of inlet air had a significant effect on the performance coefficient of the system. Increasing the velocity from 1.1 to 1.6 m s⁻¹ increased the COP by about 30%. In general, the research results showed that thermoelectric coolers could be used as portable devices to extract fresh water from the air, even with low humidity.