Evoprator super heat,

[sensek75]

HI,

pl guide me to calculate super heat of the R404 A gas chilled brine system ( MEG),

my system suction pressure is 50 - 60 psi,
discharge pressure is 230 PSI ,

The temperature not dropping beyond minus 12 deg c,

what is the reason.

pl any can suggest ??


Regards

Sekar.S

[Glenn Moore]

Check your brine solution strength . We also need the temperature of the suction pipe where the Tev bulb is fitted

[martinw58]

check the brine

[keapog]

what is your target temperature ?
is the compressor running all the time ?

the amount of superheat is the temperature of gas above the corresponding evaporating temperature (pressure related) . for r404a 50 psig pressure correspond to -9,5 c . aadding at least 5 c superheat the temperature of gas (pipe) at the outlet of evaporator =-4,5 c .

[Magoo]

what type of evaporator do you have, a shell and tube, a plate HX or a an ice bank type system.?
What is the entering and exiting brine brine temperature.?
To add to keapog post: check entering brine temperature and deduct SST at evaporator, that is your evaporator system TD, multiply that figure by 0.65 and add that result to SST in evaporator and that should be your suction vapour temp exiting evaporator. This method works everytime in either pull down or at design conditions. That is if everything is in balance, things that can screw up are too high brine flow rate, system short of refrigerant, TXV faulty or not set up correctly and a multitude of other things.


More system information please.