Applications and Working Principles of the Four Types of Stirling Engines

  

 

The Introduction of Stirling Engines 

  

The invention of the Stirling engine came about in the year 1816 by means of the Rev. Robert Stirling, who desired to create a more secure opportunity for steam engines because of the common explosions in their boilers with the impact of excessive steam stress and, additionally, the constraints of a few primitive substances that were to be had at that time.  

  

 The Stirling engine works in exactly the same manner as the alternative warmth engines, which can be used to transform warmth electricity into mechanical electricity. Whereas the critical capabilities of a Stirling engine are that it's a closed-cycle and an external-combustion engine, this means that the engine makes use of a hard and fast quantity of operating fluid, normally air and some exclusive gases, which can be enclosed in a sealed container, and the warm temperature this is used up through the manner of the engine is provided externally. This function lets the engine run on any heat supply, which could encompass fossil fuels, warm air, solar electricity, chemicals, nuclear electricity, etc. 

  

 It is likewise right to understand that those engines can operate with very low temperature differentials as well, which may be as little as 7 °C between the warmth supply and the warmth sink, so it may be powered with the resource of the warm temperature of the body and the steam.

 

 

Stirling Engine Working Principles

 

The main working principle of the Stirling Engine relies on the property of gases, which says that they expand when heated and contract when cooled, or it can be explained. 

 

In the event that the gas is filled in any volume container which is variable or is made from a piston in a cylinder which is movable and closed at one end, it will be noticed that the pressure will increase and decrease and will cause the piston to move in and out. The heating and cooling processes will develop a reciprocating movement of the piston, which will be converted into a rotary motion by the use of a conventional connecting rod and a crankshaft accompanied by a flywheel. 

 

The rate at which the temperature of the gas varies due to heating and cooling is kept limited to the large thermal capacity of the working pistons and cylinders. However, this constraint can be overcome by the movement of gas from one end of the cylinder to the other by maintaining a constant high temperature at one end and a constant cold temperature at the other end of the cylinder. The condition is attained with the help of a loose-fitting piston, which is known as a displacer. As the displacer is kept moving, the gas starts leaking around the gap that is present between the displacer and the cylinder wall. The displacer does not produce power itself; it only uses enough energy to circulate the amount of gas within the cylinder.

 

 

 

Application of Stirling Engines

 

Stirling engines are found to have various applications and have been used in a variety of forms since the 1930s with a motive of power in the range of vehicles and engines of 75kW or more. Even if the early engine developments were for automotive use due to their low specific power, the Stirling engine was still better suited for stationary applications. So, here are some of the most commonly known applications of Stirling engines:

 

Combined Heat and Power: The Stirling engine is an ideal engine for its use in small combined heat and power installations to capture the wastage of heat. These engine generators are used to develop the electrical power output between 1 kW and 10 kW and are most commonly available for domestic applications with the utmost aim of using the waste heat from the central heating boiler. This system's overall thermal efficiency can reach up to 80%.

 

Solar Power: The depositors of Stirling engine generators are used to generate electricity from the thermal energy that is captured by very large solar thermal arrays.

 

 

Stirling engine types

 

1.   Alpha Configuration Types: Stirling Engine

2.   Beta Configuration Types: Stirling Engine

3.   Gamma Configuration Types: Stirling Engine

4.   Stirling Engines with Dual Acting Mechanisms (Swash Plate)

 

 

Alpha Configuration Types: Stirling Engine

 

There are two cylinders which are enclosed with a fixed amount of air and other fluids, one being hot and the other being cold.  This is done as the hot air expands, which is present in the hot cylinder, and contracts when it interacts with the cooled air, which is present in the cold cylinder. This is the source of energy that is used to perform mechanical work in the process.

 

 

 

Beta Configuration Types: Stirling Engine

 

You would be amazed to know that the thermodynamics of the Stirling beta engine are very similar to those of the alpha engine, but the fact is that their physical configurations are quite different from each other.

 

This engine consists of only one cylinder, which is highly heated from one end and kept cool from the other. For this, a single power piston is arranged coaxially accompanied by a displacer which moves within the cylinder. The displacer piston does not take any sort of power from the gases which are expanding but only serves to transfer the working gas back and forth between the two ends.

 

 

 

Gamma Configuration Types: Stirling Engine

 

This engine with the gamma configuration is the same as that of a Stirling beta engine, which does not have the power piston mounted coaxially with respect to the displacer piston.

 

 

 

Stirling Engines with Dual Acting Mechanisms (Swash Plate)

 

The gas, which works consistently, is moved back and forth with the help of regenerators in between the adjacent cylinders that are heated from the top and cooled from the bottom. The arrangement is found to have no displacers as the pistons in the nearby cylinder perform this function well. It is important to keep the cylinders closed from both ends, and the connecting rods should pass through the seals into the adjoining cylinder caps on the lower side in order to protect the gas from escaping the cylinder.