Increasing Discharge pressure

[mukunthavs]

Hi Guys, I run a cold storage which is an NH3 vapour compression refrgn system. We have 2 compressors 40HP,60 HP...operating suction pressure of 30-35 . It has a shell and tube condenser with forced air cooling tower. We have no problems with scaling in the tubes but the discharge pressure is on the high end of 210 rather than 170-180. Wat could the problem be? Is the condenser capacity insufficient? Can the existing be made more efficient with some less expenditure?

[smpsmp45]

Does this problem is a recent happening or is it from Day 1. If it is from Day1, then it has to do with the Condenser capacity itself.

But if it is happening after some time of running, then there are lots of possibilities. You have to check the log books on Condenser pr. details & after what point of time, this has changed?
There is a typical situation in India, The oil in the system It may be getting accumulated in the Condenser & hence effective area is getting less. Are you required to charge the Oil?

Since you claim that cooling tower is Correct & scaling has been taken care of, that issue need not be checked. But I think the Log books can throw more light on this. As if the condesner was repaired etc?

[US Iceman]

This could be caused by a number of factors:


non-condensable vapors
higher than normal air humidty
low water flow from the tower
suction pressure higher than normal (or what the system was originally designed for)
moist air recirculation on the cooling tower
My first impression is this relates to the tower performance or non-condensables.