PVT phase model of an ideal gas

Stirling Engine

CD Demos :

Stirling Engine

Relevant Resource questions :

Concepts demonstrated :

• conversion of mechanical work
• use to demonstrate the Stirling cycle

Equipment needed :

• pvt apparatus
• data taker
• Macintosh computer

A computer program has been written for the Macintosh computer which takes the data input from the compression apparatus and allows the operator to display either P, V and T against time or display P versus V. This program may be obtained from the people in charge of lecture demonstration.

Accessories (ie posters etc) :

None

Physics involved :

PV = nRT

How to use the Demonstration

Experiment 1

• This experiment may be used to demonstrate adiabatic and isothermal expansion or compression of a gas.
• Observe P, V and T versus time.
• Demonstrate isotherms versus time.
• Demonstrate adiabats versus time.
• Demonstrate both of the above on a PV graph.

• Demonstrate the stirling cycle or the Carnot cycle.
  NB Most students are unable to draw either of these cycles even when they know what an isotherm, an adiabat and a constant volume process are. Therefore do this as a POE and then perform the experiment. Ask them to explain their discrepencies. Then get them to repeat the problem for the other cycle. more on this and break into separate items

Things to do or add :

• Link the demonstration to an animation that shows what happens mechanically to the particles in a gas.
  i.e. conservation of Kinetic Energy (KE) and momentum (p) when particles collide with a gas(??? glass) wall.