how to cool copper pipe

I guess this might be a good newsgroup for this question.

I want to make a cooling-unit more efficient by cooling the copper suction pipe, ie: the pipe
that returns to the compressor and contains high pressure freon or something similar (not ammonia).

I was thinking that winding copper wire around the pipe might act like a heatsink and
draw some heat away from the pipe, which would help lower the pressure inside the pipe and
lessen the work for the compressor. That's the theory!

But copper wire doesn't contact the pipe very well. I was wondering if there is a better way
to actively or passively cool this pipe.

jim wrote:
suction pipe, ie: the pipe
something similar (not ammonia).
like a heatsink and
pressure inside the pipe and
if there is a better way

If the pipe is hotter than the environment it passes through, add more
length or a coil to it; if it's cooler let it be. My two cents.

Don

jim wrote:
suction pipe, ie: the pipe
something similar (not ammonia).

The cooling accomplished by such a system is done thermodynamically.
When the working fluid is allowed to expand the thermodynamic work done
draws from the internal heat, reducing the pressure.

The working fluid in the pipe on its way to the compressor is at low
pressure and low temperature. The compressor puts energy into the
fluid in the compression step, and the energy is removed from the fluid
in the expansion step.

The efficiency of the whole cycle is constrained by thermodynamic
variables of pressure and volume - related by the gas laws to
temperature and compressibility.

like a heatsink and
pressure inside the pipe and

Heat sinks are limited, like tanks for heat. They fill up
(equilibrate) quickly, and once they are full they cannot do anything
else. It will not affect the overall efficiency of the cooling system.

if there is a better way

The fastest, most efficient form of cooling involves passing a cooler
liquid with a high specific heat over the object to be cooled. Running
water is relatively inexpensive and widely available. You can defrost
a large turkey most quickly by placing it in a basin and letting cold
water run slowly over and around it.

Your best *passive* cooling is the radiator portion of your cooling
system. You can find it located where the fluid pressure and
temperature are stll high - downstream of the compressor and before the
expansion valve. On my kitchen refrigerator it is the coil of tubing
with metal fins mounted on the back of the unit.

Tom Davidson
Richmond, VA

> But copper wire doesn't contact the pipe very well. I was wondering if

fins and fans

Dear jim:

cross-posting to sci.engr.mech

"jim" <[Only registered users see links. ]> wrote in message
news:ekPZd.17$[Only registered users see links. ].net...

Be very careful. Compressors can be damaged by encountering a
snootfull of liquid refrigerant on the intake. Increasing the
cooling here would be counterproductive.


I think you need to review your basic cycles. On a refrigeration
cycle:
1) gaseous refrigerant is drawn in and compressed,
2) the hot refrigerant gas is cooled across a condensor,
3) the warm refrigerant liquid has its pressure dropped across an
orifice ("expansion valve"),
4) the cold refrigerant gas absorbs heat through the evaporator.

Increasing the effective size of the condensor will make your
unit more efficient. But only to a point. Only so much liquid
can go through the expansion valve, and a 2 deg difference in
this liquid means very little additional cooling.

Keeping the correct pressures for the ambient-to-cold-space
temperature difference will make it more efficient also.

I'd look at more efficient insulation, and leave the
refrigeration cycle alone. You never know the damage you can do,
or the quality of the person you will call in to service it.

David A. Smith

jim wrote:


Google "Subcooler"

Are you just bored, or can't afford the electric bill? In either case,
*you* probably don't need to be screwing with what you have not one
clue about.

Richard Perry


Richard Perry