The space heating of a facility is accomplished by natural gas heaters that are 85 percent efficient. The compressed-air needs of the facility are met by a large liquid-cooled compressor. The coolant of the compressor is cooled by air in a liquid-to-air heat exchanger whose airflow section is 1.0 m high and 1.0 m wide. During typical operation, the air is heated from 20 to 52°C as it flows through the heat exchanger. The average velocity of air on the inlet side is measured at 3 m/s. The compressor operates 20 hours a day and 5 days a week throughout the year. Taking the heating season to be 6 months (26 weeks) and the cost of the natural gas to be $1.25/therm (1 therm = 100,000 Btu = 105,500 kJ), determine how much money will be saved by diverting the compressor waste heat into the facility during the heating season.
The space heating of a facility is accomplished by natural gas heaters that are 85 percent efficient. The compressed-air needs of the facility are met by a large liquid-cooled compressor. The coolant of the compressor is cooled by air in a liquid-to-air heat exchanger whose airflow section is 1.0 m high and 1.0 m wide. During typical operation, the air is heated from 20 to 52°C as it flows through the heat exchanger. The average velocity of air on the inlet side is measured at 3 m/s. The compressor operates 20 hours a day and 5 days a week throughout the year. Taking the heating season to be 6 months (26 weeks) and the cost of the natural gas to be $1.25/therm (1 therm = 100,000 Btu = 105,500 kJ), determine how much money will be saved by diverting the compressor waste heat into the facility during the heating season.
Solution Summary: The author analyzes the amount of money saved by diverting the compressor waste heat into the facility during the heating season.
The space heating of a facility is accomplished by natural gas heaters that are 85 percent efficient. The compressed-air needs of the facility are met by a large liquid-cooled compressor. The coolant of the compressor is cooled by air in a liquid-to-air heat exchanger whose airflow section is 1.0 m high and 1.0 m wide. During typical operation, the air is heated from 20 to 52°C as it flows through the heat exchanger. The average velocity of air on the inlet side is measured at 3 m/s. The compressor operates 20 hours a day and 5 days a week throughout the year. Taking the heating season to be 6 months (26 weeks) and the cost of the natural gas to be $1.25/therm (1 therm = 100,000 Btu = 105,500 kJ), determine how much money will be saved by diverting the compressor waste heat into the facility during the heating season.
B
150 mm
120 mm
PROBLEM 15.193
The L-shaped arm BCD rotates about the z axis with a constant
angular velocity @₁ of 5 rad/s. Knowing that the 150-mm-
radius disk rotates about BC with a constant angular velocity
@2 of 4 rad/s, determine (a) the velocity of Point A, (b) the
acceleration of Point A.
Answers:
V₁ =-(0.600 m/s)i + (0.750 m/s)j - (0.600 m/s)k
a=-(6.15 m/s²)i- (3.00 m/s²)j
3
Answer:
002
PROBLEM 15.188
The rotor of an electric motor rotates at the constant rate
@₁ = 1800 rpm. Determine the angular acceleration of the rotor as the
motor is rotated about the y axis with a constant angular velocity 2
x of 6 rpm counterclockwise when viewed from the positive y axis.
α = (118.4 rad/s²)i
12 in..
10 in.
PROBLEM 15.187
At the instant considered the radar antenna shown rotates about
the origin of coordinates with an angular velocity
@ = ai + @j+wk Knowing that (VA) = 15 in./s,
(VB), 9 in./s, and (VB), = 18 in./s, determine (a) the angular
velocity of the antenna, (b) the velocity of point A.
B
10 in.
Answers:
=
(0.600 rad/s)i - (2.00 rad/s) j + (0.750 rad/s)k
V₁ = (20.0 in./s)i + (15.00 in./s) j + (24.0 in./s)k
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