How to decrease head pressure for an existing system?

[david2008]

Assume constant ambient temp, constant evap load. What we can do to decrease heat pressure. (put larger condenser? Or smaller compressor?):)

[GXMPLX]

In order of (my) preference:


Correct maintenance of condensers like cleaning, checking for incondensables, rust, fin spacing, fouling, etc.
Modify control philosophy if controls are the ones that are keeping head pressure up.
Improve cooling media flow like checking for hot air recirculation or water flow.
Check correct design at refrigerant exit so they are not being flooded.
Modify condenser characteristics like changing fans in air cooled or sprays in water cooled.
Look for other aids like water, for example read this: http://www.refrigeration-engineer.com/forums/showthread.php?t=13978
Change condensers is obvious solution a little extreme.
Changing compressor is even more extreme and I thing this should be done after a thorough system revision including demand estimation, energy use, etc.

[afak]

Hi
Large condenser will decrease head pressure to a point limited by ambient temperature but would need another regulation in colder weather when we may forced to find away to rise head pressure to prevent a serious decline in system capacity.Changing the compressor leads to out_design system.

[david2008]

Thank you both!

[Peter_1]

Add a water heat reclaim

[NoNickName]

Reduce subcooling

[GXMPLX]

I always forget to make a distinction between head pressure and condensing pressure.

With this in mind you can reduce head pressure by decreasing any pressure drop from the compressor to the condenser without (necessarily) affecting condensing pressure.

[Peter_1]

Reduce subcooling

This need some clarification A...o.

[powell]

David,

Check out the "Add-A-Cool" section at this web site.
I've never applied to but it makes sense.

http://www.boisdarccoils.com

[NoNickName]

This need some clarification A...o.

Subcooling increases the heat rejection and normally it is obtained through a overcharging the condensing coil, so that at least one tube is filled with liquid.
Reducing subcooling will clear the codnensing coil of the extra liquid (increasing the exchange surface) and decrease the compressor performance and the resulting heat rejection. :D

[Peter_1]

If the condenser has an in-build SC coil (last bends going upwards making a liquid seal like Guntner or Goedhart is doing it or even an additional SC coil mounted after the condenser, then no condensing surface was taken at all.

You're right with a standard condenser with no receiver.

[monkey spanners]

Fit a crankcase pressure regulating valve.

[NoNickName]

If the condenser has an in-build SC coil (last bends going upwards making a liquid seal like Guntner or Goedhart is doing it or even an additional SC coil mounted after the condenser, then no condensing surface was taken at all.

You're right with a standard condenser with no receiver.

Any tube filled with liquid is less surface for the condenser, whatever the geometry of the last bend, with or without receiver. :cool: