heat exchanger between subcooling and superheat line

[david2008]

Does anyone use heat exchanger between subcooling line and superheat line? It works or not? I remember there is a discussion post about this in forum. But I couldnt find it now. Thanks.

David

[SteinarN]

Here is a link to one thread.

http://www.refrigeration-engineer.co...ad.php?t=11946

[GXMPLX]

Here is a link to one thread.

http://www.refrigeration-engineer.co...ad.php?t=11946

TKS SteinarN, great post!

You should add to it a discussion on useful and not useful superheat, because of the possitive effect a SG/LL HE would have to reduce energy loss in a suction line that can't improve insulation like the ones in trenches in old supermarkets.

[NoNickName]

It works, but as most people due, irresponsibly increase superheat to increase subcooling as much as they can. This is the best way to have a high efficiency, quickly dying, compressor. It will suck rarefied, superheated vapour at high temperature, and the motor will soon burn.

[SteinarN]

It works, but as most people due, irresponsibly increase superheat to increase subcooling as much as they can. This is the best way to have a high efficiency, quickly dying, compressor. It will suck rarefied, superheated vapour at high temperature, and the motor will soon burn.

I think this is way oversimplified. I agree it is not the best idea to install a SG/LL HE on a system running at -40C evaporating and 50C condensing. However there is many systems running at operating conditions where a SG/LL HE can be aplied with great success. If very high condensing is experienced only a short time every year, then a SG/LL HE can be combined with a demand cooling system for lowering the suction gas temperature those days ambient is very high.

The efficiency of the compressor is also an important factor under these circumstances. An ineficcient compressor leads to even higher discharge temperatures than a more efficient compressor does.

[NoNickName]

I think this is way oversimplified. I agree it is not the best idea to install a SG/LL HE on a system running at -40C evaporating and 50C condensing. However there is many systems running at operating conditions where a SG/LL HE can be aplied with great success. If very high condensing is experienced only a short time every year, then a SG/LL HE can be combined with a demand cooling system for lowering the suction gas temperature those days ambient is very high.

The efficiency of the compressor is also an important factor under these circumstances. An ineficcient compressor leads to even higher discharge temperatures than a more efficient compressor does.

Agreed, but these days I've seen too many pirates, who simply downsize the compressor and gets the extraquid with a SG/LL HE, causing 25K subcooling and 40K superheating, with a discharge temperature in excess of 130-140°C.
For example icecream makers of an important italian brand.

[US Iceman]

Agreed, but these days I've seen too many pirates,...

Unfortunately, this is what the refrigeration business is becoming. A situation where owners (or accountants) are making business decisions on the lowest initial cost without any regard for equipment life.

The lowest common denominator everyone sees is cost, because they don't understand the long term effects and usually don't want to listen to someone.

[GXMPLX]

Unfortunately, this is what the refrigeration business is becoming. A situation where owners (or accountants) are making business decisions on the lowest initial cost without any regard for equipment life.

The lowest common denominator everyone sees is cost, because they don't understand the long term effects and usually don't want to listen to someone.

I thought this happened only here! Good to know we are not alone!

[david2008]

Thank you everyone. Great discussion. Let me digest them before I can make new comments. Thanks.

Happy holiday!

David

[Peter_1]

Holiday you said??? What's a holiday??

[david2008]

Peter, I think this long weekend is holiday. July 4.