| List three common devices that make use of thermodynamic
cycles and explain how you know they operate using a thermodynamic
cycle. |
| |
|
| Read: |
Not much to say here. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Given: |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Find: |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Assumptions: |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Equations
/ Data / Solve: |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Answers: |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| 1- |
Refrigerator |
|
|
|
|
|
|
|
|
Work and heat
cross the system boundary, but mass
does not. The refrigerant undergoes a cyclic process involving changes in both T & P,
but the refrigerant
always returns to the same initial state to begin the cycle again. |
|
|
|
|
|
|
|
|
|
|
| 2- |
Air conditioner |
|
|
|
|
|
|
|
|
Work and heat
cross the system boundary, but mass
does not. The refrigerant undergoes a cyclic process involving changes in both T & P,
but the refrigerant
always returns to the same initial state to begin the cycle again. |
|
|
|
|
|
|
|
|
|
|
| 3- |
Automobile |
|
|
|
|
|
|
|
|
This one is a bit
trickier. Work and heat cross the system boundary. Heat enters the working fluid (air) from the heat source (burning gasoline) and
work leaves the system
in the form of a rotating drive shaft or gear train. It is not as clear that
the air undergoes a cyclic process. It may help to
consider all the air
in the world as the working fluid for the cycle. The engine draws in air at ambient temperature. It undergoes changes in T & P inside the engine and is exhausted back into the environment
at a higher temperature. Eventually, the exhausted air cools back down and returns to its initial state to complete
the cycle. |
|
|
|
|
|
|
|
|
|
|
