Monday, 11 April 2011

How Does a Stirling Engine Work and Its Use in Solar Thermal Technology

A stirling engine is extremely simple heat exchange engine and works by low temperature difference between two metal surfaces. One surface is heated at one end of the engine while other is cooled down on the other end, causing the air to expand near the hot surface (high temperature) and compress near the cold surface (low temperature). This expansion and compression of air within the engine cylinder enables the movement of displacer or piston in upward and downward motion between the two surfaces into a cycle or loop. This efficient heat engine was invented by Robert Stirling in 1816 as an alternative to steam engines at that time and a great contribution in heat engine technology.

Stirling Engine Basics Explained

An ideal model for understanding the basics of a Stirling engine consists of a closed cylinder containing two metal surfaces (aluminium) at top and bottom of the cylinder. A displacer is placed between the two plates which is connected to a flywheel through a wire to transfer mechanical energy during upward motion. When one plate is heated for example; bottom plate, the air near that plate expands and causing the displacer to move upward. On the other hand flywheel is connected to a small piston which takes the mechanical energy from flywheel and push the displacer to aid in downward motion. When displacer reaches top position the small piston moves downward enabling the compress air to fill in the cylinder and push the displacer downward. Making a loop of upward and downward motion of both displacer and piston, resulting in the circular motion of flywheel.

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