Quote Originally Posted by Brian_UK View Post
Yes, simply.

Refrigeration cycle, in simple terms...Pressures and temperatures for indication only.

Compressor sucks in low pressure vapour, 1bar 5°C, compresses vapour and discharges it (act of compression generates heats, think bicycle pump) now 10bar at 60°C.
High pressure/temperature vapour enters condenser at 10bar 60°C, air blown over condenser to cool hot vapour. Vapour now cools and condenses back to a liquid, temperatures has dropped to 30°C but pressure still at 10bar.

10bar liquid now passes through expansion device which lowers it pressure from 10bar to 1bar to enter the evaporator. Act of dropping pressure reduces temperature and you have a mix of liquid/vapour at the start of the evaporator. Pressure of 1 bar remains and temperature now down to 5°C as the vapour leaves the evaporator and gets sucked in again by the compressor.

A very rough description, yes it is late, but hope it helps a bit.

Brian, the one point in your description that stands out for me is the fact that upon entering the condenser, you can go from 60C/10bar to 30C/10bar (the pressure does not reduce). It would seem to me that in order to NOT have a pressure reduction, the volume in the system, condenser and subsequent pipework would have to be much smaller than that which moves the vapour and this is why the pressure does not change much.

The act of condensing the vapour to liquid should, at first glance, reduce the pressure as well as the temp (regardless of area volume). The non changing pressure side of this can be confusing to people.