SpudFiles

OMG
fins would help a lot but in most cases they are not needed as fridge compressors work only for a limited amount of time.
what is more, compression heating isn't a big deal normally as it is a closed circuit

if you convert AC or fridge compressor you get more heat:
1. from the motor
2. from compression heating

If you're using the compressor to fill your launcher directly, I would say that beyond the (literally ) cool factor it isn't worth the bother, but for filling larger chambers it would be worth fitting a fan, if nothing else to promote the longevity of the compressor.

An opinion not validated by experiment.

Incidentally, the air input to my a/c compressor is heated and not cooled!


I am feeding it hot compressed air at about 25 psi from a wobble pump.

The a/c compressor load is reduced by the input pressure and it runs cooler than trying to pump 600 psi from atmosphere.

(It never got beyond 550 psi without pressurized input)

Perhaps that is the secret to its success.

boyntonstu wrote:Did you ever see a fan installed in a refrigerator or a/c unit directed at the body of the compressor?

I believe this satisfies the above criteria, technically

jackssmirkingrevenge wrote:

boyntonstu wrote:Did you ever see a fan installed in a refrigerator or a/c unit directed at the body of the compressor?

I believe this satisfies the above criteria, technically

See the blades?

See the condenser radiator?

Which way is the fan blowing?

The compressor creates hot gas.

The condenser is cooled by the fan to condense the gas into a liquid.

The liquid expands in the evaporator coil (not shown) to cool the fridge or the air in the room.

Lesson 101 on how the refrigeration cycle works.

Did you ever see a fan installed in a refrigerator or a/c unit directed at the body of the compressor?

yer but my fridge compressor it desingd to run at 300psi for 10 min then shut off for 25min or so. but i have to turn it on and off or leave it on for 20min to fill my bulk tank

i don't know why your saying it don't work because i can feel it with my hands that it cools it down might not be the most eficant way but it was free and only took 2 min to set up

in a fridge thats set up legit it has been tested and built to run on that fridge not to fill up a air gun. + a fridge is a closed system where my set up is open

-_- wrote:yer but my fridge compressor it desingd to run at 300psi for 10 min then shut off for 25min or so. but i have to turn it on and off or leave it on for 20min to fill my bulk tank

i don't know why your saying it don't work because i can feel it with my hands that it cools it down might not be the most eficant way but it was free and only took 2 min to set up

in a fridge thats set up legit it has been tested and built to run on that fridge not to fill up a air gun. + a fridge is a closed system where my set up is open

"yer but my fridge compressor it desingd to run at 300psi for 10 min then shut off for 25min or so."

When you buy a new refrigerator it usually runs for 24 hours straight until it cools everything down.

The piston is where the compression and friction heat is occurring.

Cooling the skin at the surface does squat to the piston temperature.

Does it bother you that you cannot touch your car engine without burning your hand?

boyntonstu wrote:See the blades?

See the condenser radiator?

Which way is the fan blowing?

The compressor creates hot gas.

The condenser is cooled by the fan to condense the gas into a liquid.

The liquid expands in the evaporator coil (not shown) to cool the fridge or the air in the room.

Lesson 101 on how the refrigeration cycle works.

Did you ever see a fan installed in a refrigerator or a/c unit directed at the body of the compressor?

I know that, hence the "technically" - it's a fan, installed in a refridgerator unit, and it's directed at the body of the compressor

Have a look at this

Have a look at [url=http://www.modmyrv.com/2008/07/18/rv-re ... ooling-fan]

"An RV refrigerator is not like a residential unit. It uses a heat absorption system rather than an electric compressor, condenser, and evaporator, as a residential refrigerator does. Heat absorption requires removing the heat from the absorption unit via chemicals and air circulation. This is accomplished by convection or draft. A narrow space behind the refrigerator allows cooler air to be drawn in to the space at the bottom of the unit. The air rises and passes over the heat absorption unit fins, and out of the vent on the roof above the unit.

NO COMPRESSOR.

Your point is what?

Darn, that'll teach me to post while trying to size BBs

jackssmirkingrevenge wrote:Darn, that'll teach me to post while trying to size BBs

The secret to a cool compressor is to lower its load.

At home, spray water on the condenser coils and you will save 10%-15% on electricity.

For pneumatic compressors, pressurize the input.

Quite simple, actually.

Grasshoppers, you are welcome.

boyntonstu wrote:The secret to a cool compressor is to lower its load.

The point is though that the outer casing gets hot in use, because it is heated by the internal workings, and by blowing air over the casing and cooling it, by definition you are also cooling the internals. The compressor might work perfectly well without this cooling in performing its design function within the confines of a fridge, however once it's taken out of that environment and used as a compressor it might be under a higher load and used for longer periods than intended, therefore not able to cope in terms of heating, so every little bit of additional cooling will help it function well and last longer.

jackssmirkingrevenge wrote:

boyntonstu wrote:The secret to a cool compressor is to lower its load.

The point is though that the outer casing gets hot in use, because it is heated by the internal workings, and by blowing air over the casing and cooling it, by definition you are also cooling the internals. The compressor might work perfectly well without this cooling in performing its design function within the confines of a fridge, however once it's taken out of that environment and used as a compressor it might be under a higher load and used for longer periods than intended, therefore not able to cope in terms of heating, so every little bit of additional cooling will help it function well and last longer.

Let's get quantitative.

How much is a "little bit"?

Cooling is a term that means removing BTU's.

A 1 ton air conditioner removes 12,000 BTU/hr. (same as a ton of ice melting)

How much cooling will a little fan take away from a compressor?

H=mS delta T

Heat in BTU's = mass x specific heat x difference in temperature.

A 1,000 Watts of electrical heating will produce 3,414 BTU/hr.

A tiny 10 Watt fan can make your 87*F skin feel about 2*F cooler.

Measure the a/c compressor skin with and without a fan.

Anything else is an opinion.

damn I wish I had one of these... just drill another hole in the casing and you've got oil cooling... I wonder if it would work without a pump... ?

@boytonstu
I think that 'ohh it's too hot to touch' when there is no fan....

and

'ohh it's cold' with that bigass fan on

is qualitative enough

POLAND_SPUD wrote:I think that 'ohh it's too hot to touch' when there is no fan....

and

'ohh it's cold' with that bigass fan on

is qualitative enough

Maybe since you have a wind turbine on your fridge compressor, you could do a quick thermometer test running the compressor for 5 minutes with and without the fan, starting at ambient temperature for each test? Would be good to have some actual data

yeah why not... I'll try ot test it tommorow but I am affraid that 5 minutes won't be enough to measure any difference... 0.5 hour should be enough