| dc.description.abstract |
There is no living thing on earth that can sustain itself without water. Humans need pure drinking water to lead a healthy life. Adults must drink about 2-3 liters of water daily to keep fit. In the time of natural disasters, environmental accidents, or desert areas, getting pure drinking water can be a significant problem. However, water is available in the air, and in such times of emergency, water can be extracted from the air by the condensation process of moisture. In this study, a prototype was developed to harvest water from the air to condense about 2-3 liters of water within six hours. The TEC-12706 model Peltier device was selected from available models as a thermo-electric cooler, requiring a 12V DC power supply. It had cold and hot surfaces which were attached with fins. Proper fin size and air flow rate were optimized to maximize the water condensation rate at the cold surface. Experimentation revealed that a cold side fin of 4 cm × 4 cm size with a 5.9 × 10-3 m3/sair flow rate gave the best yield of water condensation. The hot side heat exchanger was also investigated, and it was found that the fan-assisted finned heat exchanger rejected heat more effectively, which also gave a better performance on the cold side. A single TEC set was found to condense a maximum of 25 ml/h of water at 95% RH, so 24 TEC sets were required to harvest the desired amount of water. For multiple TECs, their orientation for series and parallel configurationswas investigated by simulation and experiments. It was found that parallel orientation gave the best result. So, it was chosen for a compact modular concept with eight TEC sets placed with parallel airflow configurations. Fin sizes and airflow rates for a module of eight TECs were optimized through an experimental process. It was recorded that after 30 minutes of transient period, a TEC attained a steady temperature, resulting in a constant moisture condensation rate. It was also studied that the water condensation rate is proportional to the ambient RH. Condensation rate ranges from 10 ml/h to 25 ml/h when ambient RH ranges from 50% to 95% with a tropical range of dry bulb temperature. In the case of running the setup with a renewable energy supply, about 6.8 square meters of solar panels would be required to supply about 1.2 kW power to run the complete setup, which could harvest about 3 liters of water in 6 hours of daytime. A 12V DC battery could back up the prototype in case of the absence of solar power. It was found that the complete setup with three modules having 24 TECs could run by two 100Ah pb-Acid DC batteries in parallel for about an hour without compromising the performance of the water condensation rate. About 2.5 kWh of electrical energy was required to harvest 1 liter of water. In the end, harvested water was tested in the laboratory to ensure its safety for drinking. The prototype developed could have applications as post-disaster drinking water management equipment. |
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