Presentation is loading. Please wait.

Presentation is loading. Please wait.

Gas Cycles 2 nd Law of Thermodynamics. Work done by a cycle When a gas undergoes a complete cycle, it starts and ends in the same state. The gas is identical.

Similar presentations


Presentation on theme: "Gas Cycles 2 nd Law of Thermodynamics. Work done by a cycle When a gas undergoes a complete cycle, it starts and ends in the same state. The gas is identical."— Presentation transcript:

1 Gas Cycles 2 nd Law of Thermodynamics

2 Work done by a cycle When a gas undergoes a complete cycle, it starts and ends in the same state. The gas is identical before and after the cycle, so there is no identifiable change in the gas.  U = 0 for a complete cycle. The environment, however, has been changed.

3 Work done by cycle P V P2P2 V1V1 A V2V2 B P1P1 C D Work done by the gas is equal to the area circumscribed by the cycle. W ABCD Work done by gas is positive for clockwise cycles, negative for counterclockwise cycles. Work done by environment is negative of work done by gas.

4 Sample Problem Consider the cycle ABCDA, where – State A: 200 kPa, 1.0 m 3 – State B: 200 kPa, 1.5 m 3 – State C: 100 kPa, 1.5 m 3 – State D: 100 kPa, 1.0 m 3 A) Sketch the cycle. B) Graphically estimate the work done by the gas in one cycle. C) Estimate the work done by the environment in one cycle.

5 A: 200 kPa, 1.0 m 3 B: 200 kPa, 1.5 m 3 C: 100 kPa, 1.5 m 3 D: 100 kPa, 1.0 m 3

6 Problem Calculate the heat necessary to change the temperature of one mole of an ideal gas from 300K to 500K A) at constant volume. B) at constant pressure (assume 1 atmosphere).

7 Second Law of Thermodynamics No process is possible whose sole result is the complete conversion of heat from a hot reservoir into mechanical work. (Kelvin-Planck statement.) No process is possible whose sole result is the transfer of heat from a cooler to a hotter body. (Clausius statement.)


Download ppt "Gas Cycles 2 nd Law of Thermodynamics. Work done by a cycle When a gas undergoes a complete cycle, it starts and ends in the same state. The gas is identical."

Similar presentations


Ads by Google