Easy question on suprheat and sub-cooling, just I cannot do it...

[johnmorrison]

Hey,

So I was wondering why is it necessary to corret the performance for different degrees of superheat and sub-cooling, and how can these corrections be carried out?

Thanks

johnmorrison

[Toosh]

Hey,

So I was wondering why is it necessary to corret the performance for different degrees of superheat and sub-cooling, and how can these corrections be carried out?

Thanks

johnmorrison

Hi Search the forum there are plenty of threads discussing superheat and subcooling

toosh

[cool runings]

Hey,

So I was wondering why is it necessary to corret the performance for different degrees of superheat and sub-cooling, and how can these corrections be carried out?

Thanks

johnmorrison


Superheat and subcooling is important to maintain the working of the system.

Superheat from the evap garentees no liquid floods back to the comp, thus protecting it. Too little and it can risk liquid floodback - too much superheat and you lose the effieciency of the evaporator plus the correct superheat returning maintains the correct temperatur of the compressor.

Subcooling garentees pure liquid to the expansion valve.

cool running

.

[Gary]

Start here:

http://www.refrigeration-engineer.com/forums/showthread.php?t=19701

[VGV]

Hey John,

Simply put:
Rerigerant sub-cooling reduces the quantity of refrigerant that must be circulated to produce a given refrigeration effect. This in turn reduces the compressor displacement required for that effect... So... if a given compressor produces 10 tons refrigeration without sub-cooling, it could produce 12 tons (or more) with proper sub-cooling.

Superheat works in the opposite direction in that the greater the superheat, the greater the specific volume of the gas...So, a fixed displacement compressor would handle less pounds per unit time, resulting in less capacity. The other disadvantage of increasing compressor suction superheat is that it increases the discharge temperature to the point where it exceeds manufacture's limits.

If you understand refrigerant tables, specific volume, and enthalpy, we could go through the simple math involved for a typical case should you so desire..

My best.

VGV

[Gary]

Hey John,

Simply put:
Rerigerant sub-cooling reduces the quantity of refrigerant that must be circulated to produce a given refrigeration effect. This in turn reduces the compressor displacement required for that effect... So... if a given compressor produces 10 tons refrigeration without sub-cooling, it could produce 12 tons (or more) with proper sub-cooling.


Well... not necessarily.

If subcooling is increased by lowering liquid temp, then efficiency increases. If subcooling is increased by raising saturated condensing temp, then efficiency decreases.