Friction Effects

For the sake of clarity the line 'F~F' is transposed to a new diagram. Fig. 9.4.

Mechanical friction

There arc two important friction effects to consider in Stirling engines. The first is the mechanical-friction effect arising from the action of piston rings, rubbing seals, bearings, oil pumping, and the like. With the engine idling and producing no useful output power there will still be considerable mechanical friction. This will increase as the engine speed and pressure increase. Inclusion of mechanical friction reduces engine output and efficiency as represented by the line lG-G' in Fig. 9.4.

Aerodynamic friction

Aerodynamic friction is another important friction effect. This is manifest in the fluid pressure drop which occurs across the heater, regenerator and cooler. The difference in pressure between the compression and expansion spaces results in a reduction of the amplitude of the pressure variation in the expansion space. As a consequence the area of the work diagram for the expansion space is reduced and so the net cycle work is reduced. The pressure drop is a function of the density and the square of velocity of the fluid flow. It may be represented by the line 'H-H" in Fig. 9.4.


Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

Get My Free Ebook

Post a comment