A transient model for forward and parallel feed MED

Abstract

The aim of this paper is to investigate the performance of a multiple effect distillation (MED) unit potentially coupled to a concentrated solar power plant and validate the results with the predictions of a dynamic model that was developed for this purpose. A small-scale (10 kWthermal) four effect distillation system was designed and built to demonstrate proof of principle of the concentrating solar power–desalinating sea water system integration. In order to fully characterize this small-scale MED unit, an understanding of the performance for steady state and transient conditions is required. Initially experiments were performed in a steady state situation, various parameters were examined and the experimental findings have already been published. After the initial experimental findings of the steady state operation, the performance of this unit was also investigated for transient conditions. The experimental procedure followed was identical as in the steady state conditions, with the main difference being the variation in the heat input supply to the system as a function of time. For the present study, the heat input supplied to the unit varied between 5 and 10 kWthermal. At the same time, a dynamic model was also developed in order to predict the performance of this unit in consecutive time steps of operation. The performance was calculated in terms of performance ratio (the ratio of the distillate product flow rate to the feeding steam flow rate) and the model results were validated against the experimental findings. The results showed that there is a really good match between the experimental data and the predicted ones from the model.