3.7
3.7.1
Processes
Introduction
The concept of a state diagram and properties has already been introduced. This section now considers moving from point to another on a state diagram, a so-called process.
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Terms
Be able toBy the end of this section you should be familiar with terms such as:
Process, path, cyclic process
Process diagram
Quasi-equilibrium
Adiabatic, isothermal, isobaric, isochoric
Evaluate the change in properties during a simple process
3.7.2
Processes
James Watt and the Steam Engine
The Steam Engine
Images of steam engines evoke nostalgia and passion, but they are based on some fundamental thermodynamic principles.
Watch the video and consider what is actually happening to the steam within the cylinders, especially how the temperature and pressure is changing.
3.7.3
Processes
Pause for thought
Illustration of a steam engine
Water
Heat
Vapour
Cross section illustration of a steam engine
In the video we learnt about the development of the steam engine – a power cycle whereby steam is used to generate reciprocating motion in a continuous cycle.
The vision of a steam engine locomotive and the moving pistons driving the wheels is easy to image.
What is actually happening to the steam within the pistons?
How is the temperature and pressure changing?
What sort of diagram might we use to illustrate this?
3.7.4
Processes
Screencast
Outline
The concept of a state diagram and properties has previously been introduced. In this unit we will now consider moving from one point to another on a state diagram, a so called process.
We will introduce a process and define a process path. We will define the criteria to describe a process completely and introduce a very important definition, that of a quasi-equilibrium process.
3.7.5
Processes
Review Questions
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Referring to the material presented in this section, can you answer the following questions -
What is a process?
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Referring to the material presented in this section, can you answer the following questions -
What is a process path?
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Referring to the material presented in this section, can you answer the following questions -
What do we need to describe a process completely?
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Referring to the material presented in this section, can you answer the following questions -
What is a quasi-equilibrium process?
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Referring to the material presented in this section, can you answer the following questions -
Do thermodynamic properties depend upon the process or the path taken?
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Referring to the material presented in this section, can you answer the following questions -
What do the terms, isobaric, isochoric, isothermal, adiabatic, refer to?
