suction preesure

[Ianh]

how do you work out the suction pressure and head pressure for a system. I am looking for air off of about 10c for a cellar cooling application

[eggs]

forgive me, for i am not a technical man.
if you want air off at 10c, why not use an a/c system? insted of cellar cooling.

cheers

eggs

[chillin out]

Considering most celler rooms wants to be at 10 - 12deg C why would you only want air off at 10 deg C?

[Brian_UK]

how do you work out the suction pressure and head pressure for a system. I am looking for air off of about 10c for a cellar cooling application

If you know that air off is going to be 10°C then you can work out the suction pressure from the refrigerant being used. The head pressure depends on all sorts of things, fan control, refrigerant type, etc.

The question is ambiguous, what are you trying to achieve ?

[paddy]

Anyone remember 12? Cellar cooling was always 20-24 psi back pressure and about 95 psi head, get yourself a comparator and you can work out for yourself the temperature relationship. Transpose this to any of the 'new' refrigerants and ther's your problem solved !! O.K

[botrous]

Hi Ianh and Paddy , good evening , good morning . good day , how are you ??????

[lana]

For 10°C air out of the evaporator you must have an evaporating temperature of 5°C or below (but not 0°C because of frost build up). The best choice is te=2°C like it is in any water chillers. The evaporator must be sized with this evaporating temperature.
Then when te=2°C and the refrigerant say is R22 then with temperature-Pressure chart you can find the corresponding pressure (Pe). If the condenser is air cooled then measure the ambient air and add approx.12°C to it which will be your condensing temp.( if the condenser is sized correctly).
From the temperature-pressure chart find the pressure(Pc).
Suction and discharge pressures depend on the refrigerant used and also to the operating conditions (te,tc).