Stirling Engine

Operation Principles,

Performance and Applications

Prepared by :

Ehab Foda

Mohamed Hamdy

Stirling Engine In Lines

• Closed- cycle regenerative heat engine

• External heat engine

• The core component of the domestic combined heat and power plant (CHP).

Stirling engine is:

a closed-cycle regenerative heat engine with a gaseous working fluid.

Operation Principle

• "Closed-cycle" means that the working fluid is

permanently contained within the engine (there

is no inlet or exit valve).

• "Regenerative" refers to the use of an internal

heat exchanger called a regenerator which

increases the engine's thermal efficiency.

Stirling engine needs only to be connected to a

heat source and a heat sink

Operation Principle

Operation Principle

• Alpha type

• Beta type

• Gamma type

The Alpha type engine relies on interconnecting

the power pistons of multiple cylinders to move

the working gas, with the cylinders held at

different temperatures.

1 and 3 Isothermal

2 and 4 constant volume

The Alpha type engine

relies on interconnecting

the power pistons of

multiple cylinders to

move the working gas,

with the cylinders held at

different temperatures.

Gamma Type Stirling Engines

Operation Principle

The Beta and Gamma type Stirling engines use a

displacer piston to move the working gas back

and forth between hot and cold heat exchangers

in the same cylinder.

Beta Type Stirling Engines

Beta type engines have a displacer and power

piston

Gamma Type Stirling Engines

Gamma type engines have a displacer and power piston,

This type allows a convenient complete separation

between the heat exchangers associated with the

displacer cylinder and the compression and expansion

work space associated with the piston.

Performance

Stirling Engine efficiency

• Theoretical

Stirling engine efficiency = carnot efficiency

(But because of non ideal properties of the working

gas it is less than carnot efficiency)

• Actually it depends on

Temperature Ratio (proportionally)

Pressure Ratio (inversely proportional)

Specific heat ratio (inversely proportional)

Stirling Engine Specific Power

• Specific power = power output / engine (Kg)

• Actually it depends on

Temperature Ratio (proportionally)

Pressure Ratio (proportionally)

Stirling Engine Limitations

• Non ideal properties of the working gas

• Engine Material Properties

1. Friction (Lubricating oil….series explosion hazard)

2. Thermal conductivity (engine size)

3. Creep

4. Tensile strength (high Pr provides high Power)

5. Rupture strength (high Pr provides high Power)

6. Melting Point (high Tr provides high efficiency)

Applications

• Water pump stations

• combined heat and power plant

• Solar power generation

• Stirling cryocoolers

• Heat pump

• Marine engines

• Nuclear power

• Aircraft engines• MicroCHP

Applications

• Water pump station

• A Stirling engine used for pumping water can be configured so that the water cools the compression space. This is most effective when pumping cold water.

Applications

• combined heat and power plant

– Stirling engine is the core component of the domestic

combined heat and power plant (CHP). Where it can run directly on any available heat source.

• Solar power generation

– Stirling engine can convert solar energy to electricity

with an efficiency better than non-concentrated

photovoltaic cells, and comparable to Concentrated Photo Voltaics.

Applications

• Stirling cryocoolers

– Any Stirling engine will also work in reverse as a heat

pump: i.e. when a motion is applied to the shaft, a temperature difference appears between the

reservoirs.

• Heat pump

– A Stirling heat pump is very similar to a Stirling cryocooler, the main difference being that it usually

operates at room-temperature and its principal application to date is to pump heat from the outside of

a building to the inside, thus cheaply heating it.

Applications

• Marine engines

– They can be built to run quietly and without an air

supply, for air-independent propulsion use in submarines.

• Nuclear power

– Replacing the steam turbines of nuclear power plants with Stirling engines might simplify the plant, yield

greater efficiency, and reduce the radioactive by-products.

Applications

• Aircraft engines

– They are quieter, less polluting, gain efficiency with

altitude due to lower ambient temperatures, are more

reliable due to fewer parts and the absence of an ignition system, produce much less vibration

(airframes last longer) and safer, less explosive fuels may be used.

– However, the Stirling engine often has low power

density compared to the commonly used Otto engine

and Brayton cycle gas turbine.

Applications

• MicroCHP

– Stirling engines would supply the client with hot water, space heating and a surplus electric power that could be fed back into the electric grid.

– Stirling engined microgeneration is the most cost effective of various microgeneration technologies in terms of reducing CO2

Conclusions

• Unique Technology

• Large market experiencing rapid growth

• Political awareness of green heat and power production

• Fuel independency

• Many different possible applications

• Many different geographical markets

• Many different customer types

Kiitos!