Design and Fabrication of an Atmospheric Water Generator Based on Vapor Compression Refrigeration Cycle

Abstract

Water generation from the atmosphere is an environmentally friendly alternative and a sustainable process to extract pure and fresh water. An atmospheric water generator (AWG) is a device that uses dehumidification to generate potable water out of moisture present in the air. The moisture or humidity present in the air is cooled below the dew point temperature and as a result, water vapor is condensed into water droplets. The collected water droplets are filtered and re-mineralized to produce fresh and potable drinking water. Using these principles, we have designed and fabricated a prototype system for extracting clean drinking water from atmospheric air using a vapor compression refrigeration cycle. An AWG is fabricated by using a secondhand window air conditioning unit with a capacity 18000 Btu/h. The device consists of an air filter, compressor, condenser, throttling device, and cooling coils. In addition, the device utilizes the dehumidified cool air to cool the condenser and improves its effectiveness considerably. During two operating days, the system was able to collect 5800 mL. Initially it was employed for two days starting from 12 noon, on October 3, 2020 to 12 noon, October 5th 2020. After that, the AWG was employed for two more days, staring from 12:30 pm, October 5th 2020 to 12 noon, October 7th 2020. During this run, 4100 mL of water was collected. It was found that the quality of collected water from the AWG was on par with that of normal drinking water. The quality of the collected water was assessed by an Oakton PC 450 waterproof portable meter with a combination probe and calibration system. The instantaneous temperature and relative humidity values are represented on the psychrometric chart to understand the possibility of water generation and are shown in results and discussions. During the aforementioned trial between 12:30 pm, October 5th 2020 and 12 noon, October 7th 2020, temperature and relative humidity readings were recorded.