Adiabatic Processes

Monday, 7 May 2018

4:26 PM

An adiabatic process is one which no energy enters nor leaves a system as heat.

 

Recall the first law of thermodynamics

If , then

 

 

In order to change the internal energy of an adiabatic system, work must therefore be done.

 

// (Q+W)=W

 

 

Minimising heat transfer

• Insulate the container
• Perform the process very quickly
• So that the gas reaches a new equilibrium state before there is time for heat to enter the system

 

 

 

 

 

 

 

Adiabatic Processes in a P-V Relation

 

 

In an adiabatic process, the pressure, volume and temperature all change, and are given the relation

 

Where

 - pressure

 - volume

 - ratio thingy!?!?!??!

 - constant - constant during the process

 

 

 

Temperature Volume relation

 

 

 

Isothermal

• constant temperature
• 
• 
• Any energy that enters the system by heat but leave the system by work

 

Isobaric

• constant pressure
• Work is generally non-zero as the volume changes
• 
• Heat is generally non-zero as the temperature changes as work is done
• 

Isovolumetric

• Constant volume
• No work is done as volume does not change
• 
• 
• 
• 

 

Adiabatic (Q=0)