Experimental investigation of solar energy-based water distillation using inclined metal tubes as collector and condenser

Abstract

ABSTRACT The solar still utilizes solar energy to produce potable water from brackish water, which may support agricultural and industrial sectors as well as the life of humans and animals. A conventional solar still normally distills an average freshwater of 2 L/m2/day which is not sufficient to meet individual daily demand. As a motivation for productivity enhancement, a new model of solar water distiller has been experimented with under Thailand climatic conditions. Its structure is not like a typical solar still, the low-temperature brackish water was supplied from the water tank to the condenser tubes for condensation rate improvement. After making a turn, the brackish water was heated up in blackened receiver tubes by absorbing solar radiation, which leads to a temperature growth of the feed water. The high temperature of outlet water in the receiver tubes plays a role as an additional heat for brackish water in the basin, which will enhance the temperature of basin water along with the evaporation rate. Various water feed rates and a variety of water depths were studied for their effect on the performance of the proposed solar still. The experimental conditions consisted of 0.5 cm, 1 cm, and 2 cm of water levels and 0.5 L/h and 1 L/h of mass flow rates. As the water level decreased from 2 cm to 0.5 cm, the daily productivity was improved by 34%. Additionally, there is a 28% growth in output as the mass flow rate of feed water declined from 1 L/h to 0.5 L/h. Further remarkably, in comparison with a conventional solar still under the same level of water depth, the daily distillate yield of the proposed model improved double and 58.5% at a water depth of 0.5 cm and 1 cm, respectively.