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Stirling-Cycle MachineStirling-Cycle MachineBrief Review of Basics Brief Review of Basics

Dr. Sergey Riabzev

RICOR Cryogenic &Vacuum Systems

25.06.02


A bit History

Physical Phenomenon utilized

Working Fluid employed

Basic Schematics

Four Stages of Operation

Carnot Efficiency

PV Diagram

In simple words, what is the Stirling Cooling Machine ?

Classification of Cryocoolers

Typical Designs of Tactical Stirling Cryocooler

Components of Overall COP

Some examples of Stirling Cryocoolers

SCOPE


In 1816, a Scottish reverend, Dr. Robert Stirling (1790-1878) won a patent on a hot air engine that converts heat to work (or vice versa) through repeated compression and expansion of the working fluid at different temperature levels.

The concept was not used as a refrigeration cycle until 1834, when John Hershel used a closed cycle Stirling engine for making ice.

A bit history


For almost 200 years, the basic concept of the Stirling engine remains unchanged, although the advances in regenerator materials, clearance seal technology, flexure bearing designs etc., have made the Stirling engine a very reliable and robust machine.

A bit history

The Scottish vicars first engine was a large affair with a cylinder 3.05 meters (10 ft) high and with a bore of 0.6 meters (2 ft).


Q1Q2

The principle of the Stirling cycle is based on the next physical phenomenon:

Emission of heat energy from a compressed gas into environment

or

Absorption of heat energy into an expanded gas from environment

Physical phenomenon utilized


Pure Helium (99.999%) is the most usable working fluid in a Stirling Cooler, due to extremely low liquefaction temperature (4.2°K) and other appropriate characteristics.

Working fluid employed


CompressioCompression Volumen Volume

(warm area)(warm area)

PistoPistonnExpanderExpander

RegeneratoRegeneratorr

Expansion Volume Expansion Volume (cold area)(cold area)

Basic Schematics


QC

QE

Isothermal Isothermal CompressioCompressionn

Isochoric Isochoric CoolingCooling

Isothermal Isothermal ExpansionExpansion

Isochoric Isochoric HeatingHeating

Four Stages of Operation


During Isothermal Compression, an amount of heat equals to Qc is being rejected from the compressor, which also equals to the work input Wc.

Qc = mRTc ln(Vmax/Vmin) = Wc

During Isothermal Expansion, an amount of heat equals to Qe is being absorbed into the expander.

Qe = mRTe ln(Vmax/Vmin) = We

Carnot Efficiency


Consequently, the Carnot Efficiency of Stirling cycle is:

h = Qe / W = Qe / (Wc - We)

or

h = Te / (Tc - Te)

Carnot Efficiency


P

V

1

2

3

4

Q1

Q2

dW PdV

Pressure-Volume Diagram is one of the fundamental diagrams in the Stirling Cycle Theory

PV-diagram’s area indicates a cooling work W done through the cycle

PV Diagram


Q

Q

Thermal Pump

In simple words, what is the Stirling Cooling Machine ?


Classification of Cryocoolers CRYOCOOLER

HEAT EXCHANGER

REGENERATIVE RECUPERATIVE

VALVES CLAUDE LINDE-HAMPSON JOULE-BRAYTON

YES NO

ERICSSON STIRLING

SOLVAY GIFFORD-MCMAHON

POSTLE

COMPRESSION

MECHANICAL THERMAL

VILLEUMIER DOUBLE-ACTING

SINGLE-ACTING

SIEMENS FRANCHOT

TWO-PISTON PISTON-DISPLACER

INTEGRAL STIRLING

SPLIT-STIRLING


Rotary Compressor + mechanically driven Expander

Rotary Compressor + pneumatically driven Expander

Linear Compressor + pneumatically driven Expander

Typical Designs of Tactical Stirling Cryocooler

PistonPiston

ExpanderExpander--regeneratorregenerator

CrankshaftCrankshaft

Expansion Expansion spacespace

Compression Compression SpaceSpace

Dynamic Dynamic sealsseals

PistonPiston






PistonPiston






PistonPiston






PistonPiston





Linear motorLinear motor

PistonPiston





Linear motorLinear motor


Components of COP

The overall COP (Coefficient of Performance) of a Stirling machine is a product of partial efficiencies of subsystems:

COP of CONTROLLER (~0.9)

COP of PRIME MOVER (~0.7)

COP of STIRLING CYCLE (~0.1)

XXCOP =

Due to significant thermo-gaso-dynamic losses that drastically diminish Carnot efficiency, an overall COP of a miniature Stirling machine does not exceed typically several percents (3-6% @80K).


Split Rotary Cooler

Some Examples of Stirling Cryocoolers

Integral Rotary Cooler


Integral Linear Cooler

Split Linear Cooler

Some Examples of Stirling Cryocoolers

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Documents

stirling cooling

carnot efficiency

stirling cycle

heat energy

expansion

qe

isothermal

bit history