Page 10 - BASIC CONCEPTUAL OF THERMOFLUID

CHAPTER 1: CONCEPTUAL PRINCIPLE IN THERMOFLUIDS

working fluid in refrigerators, for example. Without the cyclical process, a car would not be able to
continuously move when fuel is added, or a refrigerator would not be able to stay cold.

Visually, any thermodynamic cycle will appear as a closed loop on a pressure volume diagram.
The following are examples of thermodynamic cycles:

1.5.1 Brayton Cycle

This a thermodynamic cycle used in some heat engines. Notably, it is used for gas turbine engines and
some jet engines. The cycle consists of compressing ambient air, mixing the air with fuel, then igniting the
mixture, which expands, doing work [1]. In many Brayton cycle engines, the hot air can then be recycled,
heating the fresh air coming through. See Fig.5 as below:

Fig. 5: A Brayton cycle with reheating and regeneration. Although it's not on a pressure volume diagram,
this exemplifies the concept of the continuous loop, where the final and initial states are the same [1].

1.5.2 Rankine Cycle

This process is widely used by power plants such as coal-fired power plants or nuclear reactors. In this
mechanism, a fuel is used to produce heat within a boiler, converting water into steam which then
expands through a turbine producing useful work. The schematic diagram Fig.6 below shows there is no
'break' between the steps in a Rankine cycle, and exemplifies the process is a continuous loop.

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