Consider the chattering behavior in Fig. 10 for the evaporator shown in Fig. 1. If the sliding mode algorithm is applied, simulation yields the results in Fig. 20. The temporal, dynamic behavior of the system has not changed, but the error has decreased dramatically. This is even more obvious in the phase space plots in Fig. 21. Note that the mode switch where the overflow mechanism becomes active is detected with a large error from 0.8 because of the fixed simulation step. In fact, this error is of the same order of magnitude as the chattering behavior. However, a variable step cannot be used if no sliding mode algorithm is available.
Figure 20: Simulation of the evaporater using the sliding mode algorithm.
Figure 21: Fixed step Euler (left) vs.
variable step Euler with sliding mode simulation (right).