BeginnerTopic 36 of 105Thermodynamics & Fluids
Vapour compression refrigeration
Compressor, condenser, expansion valve and evaporator cycle.
In depth
Cycle: compressor raises refrigerant pressure; condenser rejects heat; expansion valve drops pressure; evaporator absorbs heat. COP=q_L/w_comp. Superheating and subcooling ensure good operation. Components sized by refrigeration capacity in kW or tons.
Key points
- P-h diagram
- Evaporating and condensing temperatures
- Compressor types
ExampleA domestic refrigerator cycles R-600a through these four stages.
Vapour compression refrigeration is the most common cooling method, so understanding its four components helps with fridges, air conditioners and heat pumps.
What is Vapour compression refrigeration?
Compressor, condenser, expansion valve and evaporator cycle.
Why is it important to understand vapour compression refrigeration?
Vapour compression refrigeration is the most common cooling method, so understanding its four components helps with fridges, air conditioners and heat pumps.
What are the four components?
A compressor, a condenser, an expansion valve and an evaporator, which together move heat from the cold space to the warm surroundings.
What makes the refrigerant cool in the evaporator?
The refrigerant boils at low pressure and low temperature, absorbing heat from the cold space as latent heat.
How is Vapour compression refrigeration used in practice?
Typical applications include sizing a compressor for a supermarket refrigeration rack, diagnosing a fridge that does not cool because the evaporator is starved and choosing an expansion valve for a split air conditioner.
What should I learn before Vapour compression refrigeration?
Study "Combined cycle plants" first (topic 35 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
What are the key points of Vapour compression refrigeration?
P-h diagram. Evaporating and condensing temperatures. Compressor types.
Can you give an example of Vapour compression refrigeration?
A domestic refrigerator cycles R-600a through these four stages.
What comes after Vapour compression refrigeration?
The next topic is "Refrigerants", which builds directly on this one.
How difficult is Vapour compression refrigeration?
It is classed as Beginner in Thermodynamics & Fluids (topic 36 of 105). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.