carrier chiller desuperheater fot hot water

[Lc_shi]

HI sir
There's one 30HRZ-280 carrier recip chiilers need to add desuperheaters to recover heat for hot water.
I consider to apply stainless PHE for this application. I've not done this job before and not sure if there's any risk for the existing chiller. The process should be : let off the refrigerants --cut off the discharge line--connect the PHE to it --leakage check --reevacumm the system ---charge --confirm the operation is OK.
The chiller capacity is 930kW and will recover the 2/4 circuits. It's a rather big system. I'm not sure how long time to take to do the vacumm.

Anybody can give me some clues?thx!

regards
LC

[Lowrider]

Vacuming should be done until it's, on a analog vacuum gauge, between 0 and 5 mbar, depending on the surrounding temperature and left standing for at least 2 hours. If there's more then 30 kg of refrigirant in it, you'll have to vacuum until 10 mbar and then broken with ofn to 0,05 bar and then vacumed until 0-5 mbar. Then again standing test of at least two hours.

Do keep in mind, you'll have to keep the crankcase heaters on while vacuming, otherwise you won't get all the refrigirant out off the oil.

Use ofn while brazing, that way you will keep everything clean and also flush out some resudial refrigirant from the oil.

Vacuming the system takes as long as is needed until the system is between 0 and 5 mbar. It can be 2 hours or two days, depending on how large the system is.

Good Luck!

[Brian_UK]

..... The process should be : let off the refrigerants --cut off the discharge line--connect the PHE to it --leakage check --reevacumm the system ---charge --confirm the operation is OK.....

I do hope that you mean to recover the refrigerant and not let it go to the atmosphere.

[AmmoniaMan]

Well, what happens with hot water when cooling load goes down?

[PaulZ]

If you are using a stainless steel PHE make sure you use the right grade of stainless and you will also need to check the hot water for Chlorites, should not be more then 200ppm from memory as they will eat into the stainless and cause leaks.

[absrbrtek]

I have seen this setup designed and built at the factory on both Carrier and Trane recip chillers. They rarely performed as designed. Just shooting from the hip and adding a PFHX IMO is asking for problems.

They tended to go thru compressors. The compressor failures happened if it was the factory servicing the chillers or independents. By the time you added up all the additional expenses, I don't see how they ever recieved any type of a payback. JMHO

[Lc_shi]

Hi sirs
Thanks for your kind suggestions and serious doubt about it.
I'll recover the refrigerant by using a split ac outside unit(I've no any recovery machine at hand). The selected PHE has 0.3bar pressure loss which has little affect to the chiller.
It's no problem if the retrofit process is well controlled.
Recover heat to hot water is better than to disperse the heat to the atmosphere.
The system contains 68kg R22. Is there any good way to recover it? welcome your input.

thx and regards
LC

[Josip]

Hi, Lc_shi

Recover heat to hot water is better than to disperse the heat to the atmosphere.

I am always to utilize recuperation of heat from process ....better then to throw it to mother nature....

....if not for us payback will be for our children...

Best regards, Josip

[TXiceman]

If the hot water is potable, you will need a special vented wall design exchanger to meet the required codes of prevent cross contamination of the water with refrigerant.

Also, in this type application, you will still require a full sized condenser to reject the heat if you are not removing any with the heat recovery condenser.

Ken