Why does C3H6 gas when compressed (in a reciprocating compressor) comes out with a pressure of 11 bar and 60 degrees celsius and when it is a mixture of C3H6 liquid/gas stored inside of a vessel reaches also the 11 bar but at a lower temperature of around 25 degrees celsius?
Compressing the gas will raise its temperature, whether it compresses it enough to turn to liquid or not. If you leave it stored in a compressed state, it will cool to the temperature of its surroundings.
If you then release the gas from the pressurized container, it's temperature will be lower than ambient.
Putting many compressed cylinders in a row enabled air to be "liquified" by chemists such as Dewar over 100 years ago, hence the vacuum "Dewar flask" was invented to help prevent them from boiling away. Vacuum creates an insulating layer that lessens heat transfer.