TABLE OF CONTENTS Thermodynamics is the discipline of the conversion of heat to other forms of energy and provides the theoretical background to calculate the transformation of heat to mechanical work in idealised processes. Thermodynamic laws will be used to describe the compression and expansion of air in pneumatic components, the resulting changes in pressure and temperature and the required mechanical work. A thorough derivation of the underlying theory is beyond the scope of this book and the reader is referred to introductory text books on thermodynamics, e.g. (Rogers and Mayhew 1992; engel 1997).
An easy way to compress air is the use of a piston that moves free from frictional forces in a cylinder and reduces the space available to the air. A thorough theoretical modelling of this process is much more complicated than expected. However, there are four simple models that describe ideal processes. They will be used to introduce some basic principles and definitions from thermodynamics. These processes can later be used to verify the implementation of simulation models.
The simplest way to increase the pressure of air is to use a rigid, airtight container and heat it up with a torch from a temperature T 1 to a temperature T 2 where suffix 1 denotes initial conditions and suffix 2 final conditions. Assuming a uniform air temperature in that container and an ideal gas, the pressure can be calculated as a function of temperature:
| (3.1) |  |
The required energy, i.e. the supplied...
