Abstract
This chapter deals with single-component fluids, i.e. pure fluids not being mixed with other fluids. In Part I idealised single-component fluids have already been introduced: Ideal gases, that follow the well-known thermal and caloric equations of state, and incompressible liquids, whose specific volume remains constant. For incompressible liquids the caloric equations of state can be adapted easily. The behaviour of real fluids, however, deviates from the idealised models. In particular, real fluids can change their state of aggregation.
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Notes
- 1.
Particle is a synonym for molecules respectively atoms!
- 2.
Hence, at small specific volumes!
- 3.
That does not contain any water.
- 4.
Which will be explained later in this chapter. However, for carbon dioxide the temperature at the triple point is at \({-56.5}\,^{\circ }\mathrm{C}\).
- 5.
Thus, ice!
- 6.
This is named latent heat, as the supplied heat does not cause a measurable caloric effect, i.e. rise of temperature, but a phase change that can not be detected by a thermocouple for instance. In contrast, supplied heat that causes a temperature rise, is called sensible heat.
- 7.
Unfortunately, x in Part II has multiple meaning!
- 8.
For states (1) and (5) it does not make sense to define a vapour ratio x!
- 9.
I.e. the vapour pressure curve.
- 10.
As mentioned before, outer energies shall be ignored!
- 11.
The liquid is boiling!
- 12.
Johannes Diderik van der Waals (\(\star \)23 November 1837 in Leiden, \(\dagger \)8 March 1923 in Amsterdam).
- 13.
James Clerk Maxwell (\(\star \)13 June 1831 in Edinburgh, \(\dagger \)5 November 1879 in Cambridge).
- 14.
The acentric factor is a measure of the non-sphericity (centricity) of molecules.
- 15.
The listed tables follow the International Association for the Properties of Water and Steam (IAPWS). Several digital tables are available that utilise the IAPWS guideline, e.g. citeXSteam. When applying state values from different sources, it needs to be checked if the reference points for caloric state values are identical. If not, they need to be corrected!
- 16.
For other fluids the reference point has to be carefully checked!
- 17.
Thus, the change of state is supposed to run very slowly, see Example 7.24.
- 18.
For a quasi-static change of state the balance of forces results in \(p=p_{\text {env}}\).
- 19.
Representing internal friction!
- 20.
The system now includes the cylinder wall!
- 21.
Mind, that the temperature inside the system, where the heat passes, is relevant. According to the boundary given in Fig. 18.16b it is \(T_{\text {env}}\)!
- 22.
The change of potential energy of the fluid is neglected!
- 23.
As described before the change of state is isobaric, so that no dissipation occurs.
- 24.
The specific volume increases largely during vaporisation!
- 25.
Note, that the change of kinetic as well as of potential energy is ignored! This is applied in the following two cases.
- 26.
Changes of kinetic and potential energy shall be ignored.
- 27.
Note, that the change of kinetic as well as of potential energy is ignored!
- 28.
No dissipation due to isobaric, see Sect. 18.4.1!
- 29.
No work can be exchanged under these conditions, since the piston does not move.
- 30.
There is no fluid motion or dissipated electrical energy, so there is no dissipation, see Problem 11.4.
- 31.
The influence of the mechanical energies has been investigated in Problem 12.10.
- 32.
The subscript h indicates, that the specific enthalpy is constant!
- 33.
It needs to run along an isenthalp, since the first law of thermodynamics has shown, that \(\text {d}h=\text {const.}\)! However, Fig. 18.30 shows several isenthalps—depending on the inlet state of the fluid.
- 34.
Changes of kinetic and potential energy are ignored!
- 35.
- 36.
In fact, applying the correlation for ideal gases is the second approximation!
- 37.
It is assumed, that \(C_{p}=\text {const.}\)
- 38.
In order to solve this problem, the knowledge of the isothermals in a p, v-diagram is required!
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Schmidt, A. (2019). Single-Component Fluids . In: Technical Thermodynamics for Engineers. Springer, Cham. https://doi.org/10.1007/978-3-030-20397-9_18
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DOI: https://doi.org/10.1007/978-3-030-20397-9_18
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