N°1 – Heat pump operating principles training (VTC to A level)

Heat pumps are refrigerating machines (see E-Books « Presentation of Refrigerating Machines » and the dossier “Air Conditioners – Part 1”).

Refrigerating machines permit the transfer of heat from a space to be cooled down (“heat source”, e.g.: an air conditioned room) to a space of evacuation (e.g.: outside air).
This transfer is obviously difficult when the space of evacuation can be at a higher temperature than that source of heat.

This abnormal displacement of heat from a cold space (“inside”) to a warmer one (“outside) requires some amount of external power subject to the size of temperature difference between the two.
The energy transfer is carried out by successive evaporation/condensation of a fluid.

The energy transfer is carried out by successive evaporation/condensation of a fluid

 
 
In winter, it is no longer the goal to take heat out of rooms but to put in. This is what heat pumps permit.
To understand the operation of heat pumps, we must first of all convince ourselves that even in cold weather, outside air contains lots of heat…It is in fact only at – 273 [°C] (459.4 °F) that there is no longer any (see applied physics E-book “Temperature and expansion in HVAC”).

We can use a refrigerating device to “cool outside air” which is the same as drawing out heat, and release this recovered heat in the space to be warmed.