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rbartlett
14-04-2005, 07:16 PM
hi guy's

this was thrown to me today..i have some thoughts but...

temperature controlled switch room approx 3mx3mx3m.. 21 deg'c

'outdoor' conditions range + 60 deg 'c to -20 deg'c

whatcha fink??

cheers

richard

chemi-cool
14-04-2005, 07:23 PM
Where on earth you get 80c temp difference?

You Can not survive such heat, So how can one service ac unit?

48c was my maximum, it was hard to breath.

Chemi :)

frank
14-04-2005, 07:24 PM
Indoor conditions - no problems.

Outdoor conditions - well if the ambient temperature is above the condensing temperature of the refrigerant you won't get condensation taking place and bang goes your refrigeration circuit.

Unless you or Marc know of high temp refrigerants :)

rbartlett
14-04-2005, 07:34 PM
Indoor conditions - no problems.

Outdoor conditions - well if the ambient temperature is above the condensing temperature of the refrigerant you won't get condensation taking place and bang goes your refrigeration circuit.

Unless you or Marc know of high temp refrigerants :)


well my mind drifts on to various options like a water cooled condenser water spray during the extreme..a cascade type -a mis matched system 10kw outdoor +7kw indoor etc

I know that the japanese splits are rated to near 50 deg'c and I know the middle east gets chilly at night sometimes

anyway keep expanding your thoughts..

cheers

richard

Brian_UK
14-04-2005, 10:48 PM
My first thought is this is not a UK spec is it ?

Is the condenser mounted under glass somewhere or are we back to the a/c in space question?

What are the chances of having additional cooling to the +60C area to reduce that temperature ?

No. the more I think about it....where are you getting +60C from ???

TXiceman
15-04-2005, 01:57 AM
To handle the high ambient condition you will pretty well be stuck with R-134a as a refrigerant. I presume you you will have a heat load and have to operate the cooling system at the -20 dC ambient. The easiest way to handle this is to use condenser flooding and a heated and insulated receiver.

The unit controls will need to located in the cool space as the 60 dC ambient will cook an outdoor control panel.

Water is probably not an option, as most places that have such a high ambient, do not have the water to waste on an evaporative cooler.

You might consider a glycol cooling loop with a free cooler (air to glycol exchanger) for when the ambient drop low enough to shut down the compressor.

Ken