Study on the Characteristics of a Natural Vacuum Desalination System Using Solar Energy as Energy Sources

Abstract— The characteristics of a natural vacuum solar desalination unit is studied. A prototype of natural vacuum solar desalination consists of solar collector, evaporator and condenser as the main components has been designed and fabricated. The collected heat in the 3 m2 solar collector is transferred into the evaporator using a transfer fluid system flowed by a pump powered by solar cell. The objective is to explore the characteristics of fresh water production of the natural vacuum solar desalination. The prototype is tested by exposing the unit to solar irradiance on a top roof of a building in Medan city of Indonesia. The experiments are carried out from 8.00 WIB to 16.00 WIB local time. The results show that the prototype can produce fresh water from 0.87 liters to 1.47 liters per day. The characteristics of fresh water production rate can be divided into five different periods. The first period is initial period or the period without fresh water production. The second period is first rising rate, where the main driving force for desalination is solar irradiation. The third period is constant production rate. The fourth period is second rising production rate, where the main driving force for desalination is ambient temperature. And the final period is falling production rate. The thermal efficiency of the system is relatively low which varies between 6.95% and 8.69%. Those facts suggest that the present prototype is far from efficient. Thus, several modifications are needed to improve the performance of the system. Index Term— Solar Energy; Desalination; Natural Vacuum; Seawate