Introduction to Vapor and Gas Power Cycles

Now that we understand the 1st and

2nd Laws

of Thermodynamics we can consider some important applications and the equipment used to generate mechanical power from heat. In this chapter, we will consider

power cycles

and in the next chapter we will discuss

refrigeration cycles


heat pumps

In this chapter, we will study both



gas power cycles

in greater detail and consider how their performance can be improved.
During the cycle the working fluid exists as a vapor for part of the cycle and a liquid for the other part. Key components include a condenser and a boiler.

Vapor Cycles

During the entire cycle the working fluid remains in the gas phase. No phase changes occur.

Gas Cycles

After each pass through the cycle, the working fluid remains within the system.

Closed Cycles

In an open cycle, one heat exchanger is missing. After the working fluid passes through three processes, it is discarded and replaced by fresh working fluid.

Open Cycles



Diagram of a heat engine.
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Ch 9, Lesson A, Page 1 - Introduction to Vapor and Gas Power Cycles