Refrigeration

Refrigeration
Refrigeration is perhaps the largest single consumer
of electrical power

in the US.

There is a very large central chilling plant below the
Science Center that is electrical driven.

We will visit the plant but we first need some material
on how the refrigeration cycle works.

Basics
The refrigerant is the fluid that carries heat through
the refrigeration

cycle
Most refrigerants are liquefiable vapors as the working
fluid.
Freon was such a substance - it had the property of
boiling in the evaporator at a temperature below the
temperature of the room or material to be cooled and then
after the vapor is compressed it is cooled to a liquid again in
the evaporator by rejecting heat to an external fluid at a
higher temperature. At one time freon was a “wonder” fluid.
Now we know better.

Refrigeration can be though of as pumping or lifting
heat from a low temperature and then rejecting it at
a higher temperature.

Refrigeration Cycle
Mechanical refrigeration is a process that which changes
the state

of a volatile liquid in these four processes

to vapor in the cooling stage - the Evaporator

then raises the vapors to higher pressure and temperature
in the Compressor

to the heat rejection stage in which the vapors are condensed
in the Condenser

The liquid is then returned to low pressure and temperature
through the expansion

And the cycle continues