Developing and validating linear dynamic models for direct contact membrane distillation during start-up over wide operating conditions

This work concerns analyzing, modeling and validation of the dynamic behavior of a Direct Contact Membrane Distillation (DCMD) pilot-plant. The reaction curve method is used to analyze the dynamic characteristics of the outlet permeate and brine temperatures. The time constant for these two process outputs were extracted from the experimental data and analyzed. A low order and high-order linear models in the form of state-space and transfer functions were developed and used to approximate the dynamic of the permeate and brine temperatures, respectively. It is found that these linear dynamic models cannot fully describe the physical process behavior over wide operating conditions. The global deviation between the measured and simulated transient response of the brine temperature and permeate temperature over the entire operating conditions is found to be 15% and 24%, respectively. Hence, there is a potential to improve the dynamic model effectiveness by incorporating the nonlinearity aspects of the real process. (C) 2019 Elsevier Ltd. All rights reserved.