Give an example of ‘hybrid system’?
Answers
As a typical example of hybrid systems, consider the evaporator vessel in that is part of the secondary cooling system in a fast breeder nuclear reactor . In this system, a sodium pump maintains a sufficient flow of coolant in the loop. To keep the level of fluid in the evaporator vessel from going over a prespecified maximum, an overflow mechanism is activated to drain excessive fluid once this level is reached. The flow of liquid through the overflow pipe builds up momentum, and the evaporator behavior can be described by the level of fluid in the evaporator, L, and the fluid momentum, p. A detailed continuous phase space diagram is shown on the left in for a given inflow. It exhaustively depicts how relevant system variables relate to each other. The system tends to a steady state, and highly nonlinear but continuous behavior may occur near the overflow level because of adhesive forces in the fluid, the intake area of the overflow, and the fluid surface area. If the detailed effects are abstracted away, the overflow mechanism can be modeled to create a model configuration change between two distinct modes where the fluid level is below the overflow level, and the fluid level is above the overflow level. Phase space behavior is piecewise linear, shown on the right in , and switching occurs which is called the switching surface. We refer to this form of model abstraction as a parameter abstraction