Evaporator refrigerant migration

[Dave the Fridge]

Hi All,

I have been working on a Mcquay water chiller which has got a 4 system, screw compressor system. This evaporator end plate has had refrigerant migration between systems i.e the refrigerant is migrating through the end plate into different systems. Have any one else had this experience before? And has anyone done a repair to this before by removing the end plate and getting it repaired and re shaped??

Regards

Dave

[Dave the Fridge]

Hi,

We have pressurised the low side of the circuit 3+1 with OFN to 8 bar to check for leaks on the low side of these systems and found none. This chiller has 4 circuits total, and 1 year ago McQuay have repaired the evaporators end plate as it was found that the refrigerant was migrating between circuits. We have also got another chiller next to this one which is having this problem with migration. We left circuit 4 with no refrigerant in so that we can get a new evap, and now there is 6 bar standing pressure in it.

I have with circuit 3 and 1 on the first chiller pulled a vaccum to 10 torr to see if i can prove that migration is occuring with this chiller also!!but nothing....i have now left both circuits with nothing in them and will be returning on monday to check it out.

I would like to prove that it is migrating, but how??

Dave.