CO2 (R744) Evaporator

[Cewek ITS]

Dear All,

Do anybody have experiences about designing CO2 Evaporator ?
Is it different max. operating pressure pump evaporator and DX evaporator ? Because I've ever known for DX evap max operating pressure design is 32 bar and Pumped evap design is 50 bar, but they use same material tube from stainles steel 304. Why is it different ?


If I have pumped evap CO2 and only use test pressure (1.1 x 32 bar) 35 bar. It is OK ?

BR
CITS

[NoNickName]

No it is not. You have to consider the standstill pressure, not the working pressure or the phase of refrigerant. If for any reason your evaporator will have two-phase CO2 at standstill, then the design pressure is much, much higher. It all depends on how you are sizing the safety valve on the low side.