SOLUTION MANUAL
All Chapters Included
Process Dynamics and Control
(Second Edition)
1-1
,Solution Manual: Process Dynamics and Control (Second Edition)
Dale E. Seborg, Thomas F. Edgar, Duncan A. Mellichamp
2004, John Wiley and Sons Inc.
Chapter 1
1.1
a) True
b) True
c) True
d) False
e) True
1.2
QL Q T TC
ON/OFF SWITCH
Controlled variable- T (house interior temperature)
Manipulated variable- Q (heat from the furnace)
1-2
, Disturbance variable- QL (heat lost to surroundings); other possible
sources of disturbances are the loss of gas pressure and the outside door
opening.
Specific disturbances include change in outside temperature, change in
outside wind velocity (external heat transfer coefficient), the opening of
doors or windows into the house, the number of people inside (each one
generating and transmitting energy into the surrounding air), and what
other electric lights and appliances of any nature are being used.
1.3
The ordinary kitchen oven (either electric or gas), the water heater, and the
furnace (Ex. 1.2) all work similarly, generally using a feedback control
mechanism and an electronic on-off controller. For example, the oven uses
a thermal element similar to a thermocouple to sense temperature; the
sensor's output is compared to the desired cooking temperature (input via
dial or electronic set-point/display unit); and the gas or electric current is
then turned on or off depending on whether the temperature is below or
above the desired value. Disturbances include the introduction or removal
of food from the oven, etc. A non-electronic household appliance that
utilizes built-in feedback control is the water tank in a toilet. Here, a float
(ball) on a lever arm closes or opens a valve as the water level rises and
falls above the desired maximum level. The float height represents the
sensor; the lever arm acting on the valve stem provides actuation; and the
on-off controller and its set point are built into the mechanical assembly.
1.4
No, a microwave oven typically uses only a timer to operate the oven for a
set (desired) period of time and a power level setting that turns the power
on at its maximum level for a fixed fraction of the so-called duty cycle,
generally several seconds.
Thus setting the Power Level at 6 (60% of full power) and the Cook Time
to 1:30 would result in the oven running for a total of one and one-half
minutes with the power proportioned at 60% (i.e., turned on 100% for 6
seconds and off for 4 seconds, if the fixed duty cycle is 10 seconds long).
This type of control is sometimes referred to as programmed control, as it
1-3
, utilizes only time as the reference variable .
1-4
All Chapters Included
Process Dynamics and Control
(Second Edition)
1-1
,Solution Manual: Process Dynamics and Control (Second Edition)
Dale E. Seborg, Thomas F. Edgar, Duncan A. Mellichamp
2004, John Wiley and Sons Inc.
Chapter 1
1.1
a) True
b) True
c) True
d) False
e) True
1.2
QL Q T TC
ON/OFF SWITCH
Controlled variable- T (house interior temperature)
Manipulated variable- Q (heat from the furnace)
1-2
, Disturbance variable- QL (heat lost to surroundings); other possible
sources of disturbances are the loss of gas pressure and the outside door
opening.
Specific disturbances include change in outside temperature, change in
outside wind velocity (external heat transfer coefficient), the opening of
doors or windows into the house, the number of people inside (each one
generating and transmitting energy into the surrounding air), and what
other electric lights and appliances of any nature are being used.
1.3
The ordinary kitchen oven (either electric or gas), the water heater, and the
furnace (Ex. 1.2) all work similarly, generally using a feedback control
mechanism and an electronic on-off controller. For example, the oven uses
a thermal element similar to a thermocouple to sense temperature; the
sensor's output is compared to the desired cooking temperature (input via
dial or electronic set-point/display unit); and the gas or electric current is
then turned on or off depending on whether the temperature is below or
above the desired value. Disturbances include the introduction or removal
of food from the oven, etc. A non-electronic household appliance that
utilizes built-in feedback control is the water tank in a toilet. Here, a float
(ball) on a lever arm closes or opens a valve as the water level rises and
falls above the desired maximum level. The float height represents the
sensor; the lever arm acting on the valve stem provides actuation; and the
on-off controller and its set point are built into the mechanical assembly.
1.4
No, a microwave oven typically uses only a timer to operate the oven for a
set (desired) period of time and a power level setting that turns the power
on at its maximum level for a fixed fraction of the so-called duty cycle,
generally several seconds.
Thus setting the Power Level at 6 (60% of full power) and the Cook Time
to 1:30 would result in the oven running for a total of one and one-half
minutes with the power proportioned at 60% (i.e., turned on 100% for 6
seconds and off for 4 seconds, if the fixed duty cycle is 10 seconds long).
This type of control is sometimes referred to as programmed control, as it
1-3
, utilizes only time as the reference variable .
1-4
