Ahome heating system can be controlled by a thermostat. identify two other feedback control systems that can be found in most residences. describing briefly how each control system works, identify the sensor, controller, and actuator (the means by which the manipulated variable is controlled). identify the controlled variable and manipulated variable in each case, as well as a potential disturbance (remember: disturbance variables are factors that are accounted for in overall mass or energy balances, not bizarre fantasy impacts).

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

Which of the following components of a pid controlled accumulates the error over time and responds to system error after the error has been accumulated? a)- proportional b)- derivative c)- integral d)- on/off.