Performance investigation of a reverse osmosis desalination system powered by solar dish-Stirling engine

Abstract

Solar desalination is a promising technology to reduce the costs and environmental impact associated with the use of fossil fuel resources. Currently, almost all reverse osmosis (RO) desalination technologies powered by solar thermal energy are based on organic Rankine cycle (ORC) systems. Considering the significant advantages of the Stirling cycle in the utilization of solar energy, in this paper we present a RO desalination system powered by a solar dish-Stirling (DS) engine; a detailed parametric analysis based on finite-time thermodynamics is carried out to evaluate the water productivity as well as the energy and exergy efficiency of the system. The water productivity monotonically increases with increasing absorber temperature, while the optimal absorber temperature for maximum energy and exergy efficiency ranges from 1100 to 1300 K. Linear correlations are found between the optimal working fluid temperature of the source side and the maximized water productivity, energy/exergy efficiency, and average absorber temperature. The water productivity and energy/exergy efficiencies show an initial increase followed by a decrease with increasing sink side temperature. Among these properties, the stagnation point for maximum water productivity is found at a higher sink side temperature.

Keywords

• Solar desalination
• Reverse osmosis
• Dish-Stirling
• Energy efficiency
• Exergy efficiency