10 W Class Low Temperature Difference Stirling Engine

Object of development

Stirling engine can be driven theoreticaiiy, even though it is a very small temperature difference of an only 1 deg C. And the engine use many energies are thrown away up to now (natural energy (hotly terrestrial heat, Onsen , etc) and exhaust heat that fuel results as burning ). 10 W class low temperature difference Stirling engine is desined and produced for using a comparative low temperature.

Sequence of events of research development

10 W class low temperature difference Stirling engine is used development about a fundamental characteristic of a low temperature difference Stirling engine. In the following it shows that the main result of research.

1. Influence of temperature ratio.
Shaft power is so high that temperature retio is small.
2. Influence of heat exchanger ( heater, regenerator, and cooler ).
Heater : plate Finn type , shell and tube type , Finn tube type is used.
Regenerator : material and a mesh number is changed.
Cooler : shell and tube type , Finn tube type is used.
3. Influence of buffer pressure.
Shaft power is so high that buffer pressure is small.
4. Influence of average pressure.
There is oputimum on engine inside average pressure.
5. Influence of phase difference.
There is oputimum on phase difference.
6. Influence of ratio compression.
There is oputimum on compression ratio.(because a large specification change of an engine does this experiment mainly.)

Structure of the engine

10 W class low temperature difference Stirling engine is gamma type Stirling engine to have a power piston and a displacer piston. The gamma type Stirling engine is suitable for it, in case that it uses low temperature heat-source as greatly being able to take a heating area with respect to the structure.
A displacer piston becomes a rectangle with respect to structure. With a plate fin type (heater), shell and tube type, fin tube type, a heat exchanger changed it accompanied with research and development. About a heater in a plate fin type by means of an electric heat line, and in a shell and tube type and fin tube type by means of an heating fluid for ethylene glycole business. And a cooler uses water works.
In order to investigate a variation of compression ratio, power piston diameter is changed from 100 mm to 200 mm. And in order to change a compression ratio, variable crank is used to change a stroke.

Specifications of the engine

Engine type	Gamma type
Power piston	Bore	200(mm)
	Stroke	20乣70(mm)
	Stroke Volume	628.32乣2199.11(cc)
Displacer piston	Length*Width	296(mm)*276(mm)
	Stroke	40(mm)
	Stroke Volume	3267.84(cc)
Heater and Cooler	Type	Shell and Tube(fin type)
	Pipe diamater	10(mm)
	Pipe length	276(mm)
	Pipe number	16*2
Regenerator	Type	Wire net(Brass)
	Length*Width	10(mm)*276(mm)
	Sheet number	30*2

Engine performance

A figure is the object to show relation of a compression ratio and a shaft power at 10 W class low temperature time difference Stirling engine. An experimental data at a figure is an object to show a maximum shaft power at every condition. A maximum shaft power 12.6 W was obtained in the case that a temperature of constant-temperature water bath (heated fluid) is set up on 400 K at compression ratio 1.224. And it is confirmed that the most suitable compression ratio to make a shaft power to be one largest characteristic performance exists at Stirling engine. The most suitable compression ratio can confirm what it changes on parabola formed accompanied with a variation of a temperature ratio. Therefore it becomes an importance to optimize a compression ratio and a temperature ratio, when We design a low temperature difference Stirling engine.

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