**6. Conclusions**

104 Frontiers of Model Predictive Control

(a) (b)

 (c) (d) Fig. 10. Behavior of the temperature in the evaporator to a change of a step in the temperature

The following figures show the response of GPC controller, when conducted disturbances on the manipulated variables, ie giving an overview of the steam temperature and feed flow, one step at time 5 hours on the steam temperature and an increase to 10 hours in the feed stream**.** 

Fig. 11. Behavior of the final product concentration at the outlet of the fourth effect

of the input solution (increase of 5% - decrease of 5%).

**5.2 Close loop** 

In analyzing the results obtained by performing perturbations in each of the four variables that enter the equipment, is considered appropriate the choice of manipulated variables chosen as the income flow of the solution to concentrate (grape juice) and the steam temperature and as measurable disturbances to the feed concentration and temperature that enters the solution concentration, this conclusion after observing emanates figures 3 to 10. We can also observe that the process of concentration has a complex dynamic, with long delays, high nonlinearity, coupling between variables, added to the reactions of deterioration of the organoleptic properties of the solution to concentrate

From the results shown in Figures 11 and 12 on the behavior of the controlled system verifies that the design of GPC has performed well since the variations in the controlled variable are smoother. As well as you can see the robustness of the proposed controller.
