Stirling engine invented by Robert Stirling in 1816. It is a heat engine which works on the principle of cyclic compression and expansion of working fluid at different temperatures, in such a way that there is a net conversion of heat energy
into mechanical work.There are many
types of Stirling engine like alpha type, beta
type, gamma type and many more. But we are using alpha type Stirling engine in our project due to its simplicity. The Stirling engine is well-known for high efficiency as compared to steam engines, quiet operation, and its ability to use almost any heat source.
Main Problem During Power Generation through Stirling Engine
Energy is the most essential necessity for economic growth and social transformation for all the countries in the world. It is a vital input in the field of production. We required additional energy to produce more. One can say that economic growth and prosperity of a nation largely depends upon the availability of energy. The Stirling engine is well-known for high efficiency as compared to steam engines, quiet operation, and its ability to use almost any heat source. The heat energy source is combusted external to the Stirling engine rather than by internal combustion as with diesel cycle engines. Because the Stirling engine is well-matched with alternative and renewable energy sources it could become increasingly important as the price of conventional fuels rises.
Constant Volume Heat Addition
The gas passes back through the regeneratorn where it recovers much of the heat that isdelivered in cycle 2, heating up in theexpansion space. These cycles are graphically shown in figure.
The process lines in the figure above shows the properties of an ideal gas. The major processes are cooling, compression, heating and expansion. A Stirling engine works through the use of an external heat source and an external heat sink having a suitably large temperature difference between them. Compared to the ideal cycle, the efficiency of a real engine is reduced by irreversibility, roughness, and the loss of short-circuit conducted heat, so that the overall efficiency is frequently only about half of the ideal (Carnot) efficiency.
The gasses used inside a Sterling engine never leave the engine. There are no exhaust valves that vent high-pressure gasses, as in a gasoline or diesel engine, and there are no explosions take place. Another useful feature of the Stirling engine is that if supplied with mechanical power, it can works as a heat pump (reversibility of the Sterling cycle).
Alpha Stirling Engine And its Working.
The alpha type Stirling engine consists of two power pistons, one in a hot cylinder and other in a cold cylinder separately, and the gas is driven between the two cylinders by the pistons. The hot cylinder is placed inside the high temperature heat exchanger and the cold cylinder is placed inside the low temperature heat exchanger.
This type of engine has a high
power-to-volume ratio but has technical
problems due to the generally high
temperature of the hot piston and the
durability of its seals.
A beta Stirling engine consist of a single power piston within the same cylinder on the same shaft as a displacer piston. The displacer piston is a loose fit and does not take out any power from the expanding gas but only assists to transfer the working gas between the hot and cold heat exchangers. When the working gas is pushed to the hot cylinder it expands and pushes the power piston. When it is pushed to the cold end of the cylinder it contracts and the momentum of the machine, usually increased by a flywheel, pushes the power piston, the other way to compress the gas. Unlike the alpha type, the beta type engine avoids the technical problems of hot moving seals