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Active control requires actuators that require energy and may operate in a time-dependent manner. [1] Active flow control includes steady or unsteady suction or blowing, [2] the use of synthetic jets, valves and plasma actuators. Actuation may be pre-determined (open-loop control) or be dependent on monitoring sensors (closed-loop control).
All mass flow controllers have an inlet port, an outlet port, a mass flow sensor and a proportional control valve. The MFC is fitted with a closed loop control system which is given an input signal by the operator (or an external circuit/computer) that it compares to the value from the mass flow sensor and adjusts the proportional valve ...
For example, a symbol of a pump can show the operator that the pump is running, and a flow meter symbol can show how much fluid it is pumping through the pipe. The operator can switch the pump off from the mimic by a mouse click or screen touch. The HMI will show the flow rate of the fluid in the pipe decrease in real time.
Droplet formation using a flow focusing device. [17] Diagram of flow focusing droplet formation device commonly used in microfluidic devices. Liquid flowing in from the left is pinched off into droplets by an oil flowing in from the top and bottom. [10] Two stream reagent addition using a flow focusing approach with a planar chip format. [18]
Example of level control system of a continuous stirred-tank reactor. The flow control into the tank would be cascaded off the level control. A further example is shown. If a control valve were used to hold level in a tank, the level controller would compare the equivalent reading of a level sensor to the level setpoint and determine whether ...
Continuous flow reactors allow good control over reaction conditions including heat transfer, time, and mixing. The residence time of the reagents in the reactor (i.e. the amount of time that the reaction is heated or cooled) is calculated from the volume of the reactor and the flow rate through it:
The control action is the switching on/off of the boiler, but the controlled variable should be the building temperature, but is not because this is open-loop control of the boiler, which does not give closed-loop control of the temperature. In closed loop control, the control action from the controller is dependent on the process output.
A control loop is the fundamental building block of control systems in general and industrial control systems in particular. It consists of the process sensor, the controller function, and the final control element (FCE) which controls the process necessary to automatically adjust the value of a measured process variable (PV) to equal the value of a desired set-point (SP).