2.Review the processes sketched in below Figure in which the controlled variable is to be maintained at its desired value. (a) From your chemical engineering background, suggest the physical principle used by the sensor. (b) Explain the causal relationship between the manipulated and controlled variables. (c) Explain whether the control valve should be opened or closed to increase the value of the controlled variable. (d) Identify possible disturbances that could influence the controlled variable. Also, describe how the process equipment would have to be sized to account for the disturbances. Feed Product AC) Heating medium (a)