Human-powered Desalination Unit

Abstract

The objective of this research is to design a human-powered desalination unit that can provide safe drinking water for a typical household in developing countries. Currently more than 800,000 children younger than 5 years die every year from diarrhea diseases, which are mainly (>80%) caused by unsafe drinking water and lack of sanitation. The hypothesis of our study is that a human-powered machine operating on a Mechanical Vapor Compression (MVC) cycle can provide economically- and technologically-affordable drinking water without the use of expensive RO membranes. Thermodynamic analysis for human-powered MVC cycle with minimized pressure difference, and small surface area is conducted. The design space included the following limitations: (i) only one compressor and only pump could be used, (ii) evaporation mass ratio was less than 0.7, and (iii) the water had to reach the minimum temperature required to inactivate bacteria, viruses, and protozoa. The effects of the concentration of salt in the waste brine were considered. The flow rate of clean water generated was calculated as a function of the required heat exchanger surface area; the primary cost factor in the design; as well as the compressor isentropic efficiency. The point of maximum efficiency in term of mass flow rate per unit surface area was calculated.