Design pressure ammonia refrigeration India

[virk]

I was asked about pressure design conditions for an ammonia refrigeration system in India for rough budgetary costs. Who of you can guide me to an appropriate site or can give some information about pressure design conditions there. (I know min. design pressure in Germany is 16 barg high pressure, 12 barg low pressure)

Kind regards

virk

 

[TXiceman]

For US standards, check out

http://www.IIAR.org

and also the ANSI/ASHRAE standard 15-2004

I do not know hwo you would check in India.

Ken

TXiceman

http://www.rae-corp.com

 

[mtaffish]

Hi virk

in order to estimate operating pressure limits for refrigeration cycles you must ensure that:
1.Make sure the low pressure is higher than the atmospheric pressure so air will not leak into the system but at the same time make sure the low pressure is not too high as to leak an excessive amount of ammonia into the atmosphere.<<<<atmospheric pressure=14.696psi>>>>

2.High pressure (superheated state) has a temperature higher than the maximum outside temperature so that heat can be rejected through the condensor.A greater pressure will give a higher pressure leading to more heat rejection but you need a larger compressor.

3ALso the the temperature(athigh pressure) leaving the condensor should be well above the outside temperature.If it is less than the outside temperature than the heat lost from the condensor is regained which is undesirable.


hope this helps

 

[sterl]

No reason not to run an Ammonia installation at a vacuum suction condition...Lots of systems run 18" Hg all day long.
The consequence of air infiltration is, the purger has to operate harder or longer...

The normal large scale system practise is to employ Evaporative Condensers and a free draining High Side arrangement. The Condensing Temperature is thereby established as a temp higher than Design Wet Bulb, and the Dry Bulb is for most purposes, not a determinant.

ASHRAE 15 and IIAR-2 both establish Design Pressures for Pressure vessels, and by implication, test pressure for field piping, the factory setting requirements for Safety Relief valves, the Field Setting for compressor disengagement (high pressure cutout) and so on. Be careful with 150 Psig DWP for Low Side Vessels, it corresponds with a pretty low standby temperature so if the duty cycle is such that the operation will not be continual, the Low Side DWP should probably be 200.