Why do steam engines need a condenser?
Strictly speaking a steam engine doesn’t need a condenser, it can blow the waste steam from its cylinders out into the air. Railroad engines did this. However they had to stop and take on more water to replace the lost steam. If you run an engine on something like Freon which you don’t want to lose then you have to condense it back to a liquid and recycle it to the boiler. The condenser removes heat from the Freon gas and converts it back to Freon liquid. This means that the gas must be hotter than the air which is cooling the condenser. It also means that the gas must be under high pressure since otherwise it won’t condense.
