Javiera Valdivia, Jesfis Lopez-Villada, Joan Carles Bruno*, Alberto Coronas

Universitat Rovira i Virgili, CREVER — Group of Applied Thermal Engineering, Mechanical Engineering
Department, Avda. Paisos Catalans, 26, 43007-Tarragona, Spain

Corresponding Author, iuancarlos. bruno@urv. cat

Abstract

The use of power cycles driven by solar energy to provide the required mechanical energy to drive the high-pressure pump of Reverse Osmosis systems for desalination is an interesting alternative to the conventional electric systems. In this paper it is presented a model developed in Trnsys/Trnopt for the optimisation of the operating temperature in these systems to maximise the desalted water production. Two systems are studied and compared to provide the mechanical energy required for the Reverse Osmosis system: a steam Rankine and an organic Rankine cycle using n-pentane. The solar field consist of solar trough collectors. The complete solar field/organic Rankine cycle is modelled using Trnsys in the case of steam and an EES model linked with Trnsys in the case of the organic fluids. the results in terms of energy efficiency and production of desalted water are very similar operating the system at an optimal hourly temperature at the collector’s outlet or at an optimal daily temperature. However, significant differences where found between the optimal temperatures in winter and summer days. In the future the developed model will be extended to study also other types of solar collectors and working fluids.

Keywords: Reverse osmosis desalination, solar thermal energy, organic Rankine cycle