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# ME250 Study Guide - Thermodynamic Cycle, Joule, Thermal Efficiency

Department
Mechanical Engineering
Course Code
ME250
Professor
Dongqing Li

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Thermodynamics I Fall 2010
HW#3 1
st
law involving ideal gases:
5
th
edition 6
th
edition 7
th
edition
4-66 4-80 see bellow
4-67 see bellow 4-77
4-138 (1
st
law involving ideal gases and composite systems) see bellow 4-144
4
-
80
. An isolated piston-cylinder device initially contains 0.3m^3 of the carbon
dioxide at 200KPa and 27C. An electric switch is turned on, and a 110-V source
supplies current to a resistance heater inside the cylinder for a period of 10min.
the pressure is held constant during the process, while the volume is doubled.
Determined the current that passes through the resistance heater.
4
-
77.
A piston-cylinder device contains 1.5Kg of nitrogen initially at 100KPa
and 17C. The nitrogen is now compressed slowly in polytrophic process during
which P V
1.3
= constant until the volume is reduced by one-half. Determine the
work done and the heat transfer for this process.
4
-
77.
consider a well-isolated horizontal rigid cylinder that is divided into two
compartments by a piston that is free to move but does not allow ether gas to
leak into the other side. Initially, one side of the piston contains 1 m
3
of N
2
gas
at 500 KPa and 120C while the other side contains 1 m
3
of He gas at 500KPa
and 40C. Now thermal equilibrium is established in the cylinder as a result of
heat transfer through the piston. Using constant specific heats at room
temperature, determine the final equilibrium temperature in the cylinder. What
would your answer be if the piston were not free to move?
N
2
1m
3
500KPa
120C
He
1m
3
500KPa
0C
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