Low-temperature multiple-effect desalination/organic Rankine cycle system with a novel integration for fresh water and electrical energy production

Abstract

This paper presents a novel energetic integration of a Multiple Effect Thermal Desalination System (MED) and an Organic Rankine Cycle (ORC) for simultaneous production of potable water and electrical energy, using low-temperature energetic sources. The thermal energy required for the system's operation is supplied by the MED's evaporator, while the ORC is activated using a fraction of the latent heat of condensation of the water vapor produced in the first effect of the MED. By doing this, the production of water in the first stage of the desalination system increases and, thus, the final production of distillate also increases. A simulation and validation of the proposal was conducted. The MED/ORC system has a 3.95% increase on the average Performance Ratio when the electrical energy production increases in 10 kW, presenting only a 1.57% increase on the total heat transfer area. MED/ORC system with an electrical energy production of 50 kW is 22% more efficient in water desalination than a MED system without integration, while requiring only 6.9% more heat transfer area. The results show that the MED/ORC energetic integration studied benefits both the final production of desalinized water, and the MED's efficiency without considerably increasing the required heat transfer area.