19-12-2012, 05:44 PM
STIRLING ENGINE
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Introduction
The Stirling Engine was invented by Robert Stirling. This device was born as a
competence to the vapor machine, since a Stirling Engine works with smaller pressures than
the device created by Watt and it did not require a qualified train engineer. At the end of
s.XIX with the development of the internal combustion engine and the appearance of electric
engines, the machine of this study was forgotten.
Nowadays the technology that involves the invention of Robert Stirling is in
completely development because of the fact that now very useful applications are available.
This document travels in the history of this curious device looking for reasons of this
incredible development in this called high technology with its different applications and doing
an analysis from the point of view of the economy. This project explains the principle
function of the engine with a deep investigation. And we show how the Sterling Engine in
combination with renewable energy sources can be part of a sustainable energy supply.
History
The Stirling Engine is one of the hot air engines. It was invented by Robert
Stirling (1790-1878) and his brother James. His father was interesting in engine and
he inherited it. He became a minister of the church at Scotland in 1816. At this period,
he found the steam engines are dangerous for the workers. He decided to improve the
design of an existing air engine. He hope it wound be safer alternative. After one year,
he invented a regenerator. He called the “Economiser” and the engine improves the
efficiency. This is the earliest Stirling Engine. It is put out 100 W to 4 kW. But the
internal combustion engine substituted for it quickly. The Ericsson invented the solar
energy in 1864 and did some improvements for after several years. Robert’s brother,
James Stirling, also played an important role in the development of Stirling engines.
Engine configurations
Mechanical configurations of Stirling engines are classified into three
important distinct types: Alpha, Beta and Gamma arrangements.
These engines also feature a regenerator (invented by Robert Stirling). The
regenerator is constructed by a material that conducts readily heat and has a high
surface area (a mesh of closely spaced thin metal plates for example).
When hot gas is transferred to the cool cylinder, it is first driven through the
regenerator, where a portion of the heat is deposited. When the cool gas is transferred
back, this heat is reclaimed. Thus the regenerator “pre heats” and “pre cools” the
working gas, and so improve the efficiency.
But many engines have no apparent regenerator like beta and gamma engines
configurations with a “loose fitting” displacer, the surfaces of the displacer and its
cylinder will cyclically exchange heat with the working fluid providing some
regenerative effect
Beta Stirling
The Beta configuration is the classic Stirling engine configuration and has
enjoyed popularity from its inception until today. Stirling's original engine from his
patent drawing of 1816 shows a Beta arrangement.
Both Beta and Gamma engines use displacer
engine has both the displacer and the piston in an in
engine uses separate cylinders.