Multi-effect Distillation with Heat Pump Integrated

Abstract

This article presents a study and simulation of the desalination system consisting of a heat pump HP and a multi-effect distillation MED unit. Electric energy using in HP is provided by photovoltaic panels and wind turbines ,for a possible installation of the system on an isolated sites.The proposed desalination system uses an additional source of thermal energy in order to make HP and MED integration optimal and to reduce HP Electrical energy consumption per cubic meter of distilled water (kwh/m3).The main idea is to use geothermal-solar thermal energy and heat from HP as two thermal inputs in the multi-effect distillation unit MED. Thermal rejection from MED is recovered to be used as heat input in HP that based on mechanical compression of working fluid. The HP can use the working fluids (R22, ammonia) for a number of reasons, including that the two previous fluids are very dense at the saturated vapor state compared to water. A thermodynamic analysis of the desalination system was performed at steady state, using the thermodynamic properties of the Coolprop database. The simulation results showed a minimum value of electrical energy consumption, without consideration the contribution of auxiliary thermal energy :(10.487 kwh/m3 | effect numbre:5).The simulation results showed a minimum value of volumetric flow rate of the working fluid ,before compression : (17.685 m3 of working fluid per m3 of distilled water | effect numbre:12 | contribution ratio of auxiliary thermal energy:46.6 %).