Hybrid Parallel Feed Multi-Effect Evaporation Desalination System With Adsorption Cycle

Abstract

Because thermal based desalination systems are still contributing a substantial share in the desalination industry in the GCC and MENA countries, there is a need to optimize their energy consumption in order to minimize oil consumption. The solution used in this paper is connecting the Multi Effect Desalination (MED) system to an Adsorption cooling (AD) system to improve the performance of existing MED plants. A transient mathematical model is developed to predict the performance of multi-effect parallel feed (MED-PF) evaporation desalination system integrated into an adsorption cooling system to achieve both cooling and potable water production. The study aims at examining the impact of operating conditions on the system performance and comparing the performance of different adsorbent materials (HKUST-1 and silica gel RD-2060) at similar operating conditions. It is found that the integrated system allows lowering the MED last effect temperature below the ambient temperature due to water vapor uptake by AD adsorbent bed. As a result, operational gap increases. Thus, the multi effect desalination system can have more effects within the extended flashing range, resulting in more distillate water production and better recovery of heat input. It is worth mentioning that the number of effects is the most influential parameter in increasing the production of multiple effect desalination systems. Parallel feed layout is selected as a preferred layout of MED systems. The average distillate water production increases by two to three times compared to the conventional MED cycle. Using the HKUST-1 instead of the silica gel reduces the last effect temperature by 9 °C. This leads to the use of more effects in the MED system compared with using silica gel in the adsorption sub-system.