How does stirling engine

Here are the key points. Every Stirling engine has a sealed cylinder with one part hot and the other cold. The working gas inside the engine which is often air, helium, or hydrogen is moved by a mechanism from the hot side to the cold side. When the gas is on the hot side it expands and pushes up on a piston. The cycle is as follows: [2]. The Stirling cycle can give more power by having a hotter source of heat in step 1, or by having a cooler cold sink in step 2. Click here to learn about the different types of Stirling engines.

Stirling engines have many applications: [5]. The U. Fossil Fuels. Nuclear Fuels. Acid Rain. Climate Change. In the cold cylinder the gas cools and its pressure drops. As the hot piston reaches the top of its stroke almost all the gas has now transferred to the cold cylinder where cooling continues and the gas contracts reducing the pressure even more.

The reduced pressure allows the cold piston to rise. The power of the flywheel momentum, compresses the gas and forces it back towards the hot cylinder. The gas reaches its minimum volume and forced into the hot cylinder where it starts to push the hot piston downwards.

The gas is heated once more in the hot cylinder where its pressure increases and it expands pushing the hot piston downwards in its power stroke and the cycle starts again. The regenerator located in the air passage between the two pistons is not strictly necessary but serves to improve the efficiency of the engine.

It is typically a metal or ceramic matrix with a large surface area capable of absorbing or giving up heat. As the gas cycles from the hot cylinder to the cold cylinder, some of its heat is transferred to the regenerator thus helping to cool the gas.

As the cold gas returns to the hot cylinder it picks up heat from the regenerator on the way back. This reduces both the amount of heat which must be put into the gas by the heat source and also the amount of waste heat which must be removed from the gas by the cooling system. It thus reduces the fuel consumption and improves the overall working cycle efficiency.

The gas transfer passage between the two cylinders is essentially dead space and in most designs this kept as short as possible. The working fluid may simply be air but other gases such as Hydrogen, Helium and Nitrogen may be used to increase the specific power.

The thermodynamics of the Stirling beta engine are similar to those of the alpha engine but the physical configuration is quite different. The beta engine has only one cylinder which is heated at one end and cooled at the other. A single power piston is arranged coaxially with a displacer piston and both pistons move within this cylinder.

The displacer piston does not extract any power from the expanding gas but only serves to shuttle the working gas back and forth between the hot and cold ends. As in the alpha engine, the cyclic motions of the pistons are 90 degrees apart with the motion of the displacer piston leading the power piston by a quarter revolution of the crankshaft.

The mechanism for linking the motions of the two pistons is quite complex. The connecting rod for the displacer is made up from two parts. The upper link is rigidly attached to the displacer and passes through the centre of the power piston and must maintain an airtight seal with the piston so that the working gas does not escape.

The second part of the displacer linkage is a normal connecting rod connecting the upper link to the crankshaft. Since the displacer mechanism occupies the space normally occupied by the power piston connecting rod, the linkage for the power piston must also be split into two parts, one on either side of the displacer linkage to maintain balanced forces on the power piston. As the gas heats up in the hot end of the cylinder it expands and is forced through the regenerator into the cold end of the cylinder.

As the displacer reaches the top of its stroke, all the gas is transferred to the cold end where is cooled and contracts. At the same time the piston follows the displacer upwards. As the displacer begins to move down the piston continues to move up and the cold gas is transferred to the hot end of the cylinder and the cycle starts again.

The engine may also incorporate a regenerator to improve efficiency. For clarity this has been shown as being separate from the cylinder. In practice it is more likely to be incorporated into the cylinder wall. In some designs, the displacer piston itself acts as the regenerator.