Retrofit of R 22 Chillers

Like you, I don't know how to do it. But, I certainly wouldn't ask a bunch of total strangers how to do it, either.

And, to top it all off, I certainly wouldn't yell at them when asking them to do my job for me.

You can start here:

Elementary mechanical refrigeration; a simple and non-technical ..

Good Luck. Maybe there's a consultant wherever you are that you can retain.

If you are close to this guy, maybe you can use the same consultant: sizing compressor for refrigeration system,

R-134a is a pretty good "drop-in" retrofit for former R-12 applications, though the old oil may need to be flushed and replaced.

If you can redesign the system for higher pressures, R-410C seems to be the choice for former R-22 systems, but it is not a simple "drop-in" replacement.

I am not at all sure about using R-134a as a substitute for R-22. Putting in a different ratio gear drive for a centrifugal compressor looks like a "big deal." Maybe it could work, but I would urge caution.

R 134a is a gud replacement for flooded centrifugal chillers of higher capacity such as 3000 TR and above with R 22. The problem is oil return system should be with liquid bleed off from higher liquid level of chiller thro a heat exchanger to separate the liquid refrigerant as the oil always floats on top of liquid in flooded chillers. TRANE is developing R 134a chillers only to be marketed in place of R 22. Mqway has successfully tested this refrigerant. The problem is not the know how but the cost involved in R&D type of experiment in a system of this capacity involving high cost and time.

Yep. Contact the manufacturer of the chillers for detailed assesment and advice. Do turn off Caps Lock before making the call.....

U think the manufacturer will divulge the details of engineering to a competitor? The compressor is already running at 5600 RPM and a marginal increase in RPM only possible with increased gear ratio. The derating of appx. 35% when R 22 is retrofitted with R 134a have to be attended to by not only increasing the RPM of compressor to the safe operational speed but also have to increase the dia of impellers of all the stages. This will not be posible as the existing compressors are with micron's tollerences and there will be no scope for machining and fixing a higer dia impellers and such you have to replace the compressor. In nutshell, the ecnomicality of retrofit with reference to the new replacement is to be studied.

It sounds either as though either the issue is constrained beyond the point where a solution is possible, or that the issue is attempting commercial competition with the original equipment manufacturer.

If the second, the widely-known acronym WIIFM is applicable.

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"U think the manufacturer will divulge the details of engineering to a competitor". I want to ask U why not. they have to do business. They will charge U for their effort. What is the original make? I have few observations on this issue:

1. Phase out year of R22 is 2040. So why you want to retrofit immediately. Do you have some problems with existing chillers?

2. How old they are? If more than 20 years old, then do not try to retrofit, change them with new R134 chillers. It will be economical in long run.

3. Specific volume of R22 is much lower compared to R134a. due to this reason R22 is more used in small reciprocating chillers. Because of this reason it is to be de-rated. Increasing the compressor speed by changing gear is not a good solution to get rated capacity. System may not be reliable. Your existing compressor may not be designed for that. If marginally increase the speed, you may encounter critical speed. Increasing impeller dia means replacing whole compressor which is the costliest item after gear box.

4. To attain rated capacity any way U want to go for bigger evaporator and condenser (air cooled condenser may be huge in size, why not water cooled). Replacing gear box is not technically feasible, so U will replace compressor which is the costliest item. So out of 4 major items U have to replace 3, just to get rated capacity. It may cost U just little less than new units, if U use old drive.

5. In view of the above I suggest two optional solutions:

(a) Run your existing R22 chillers as long as possible, to get return from investment and then replace with new R134a chillers.

(b) De-rate Existing chillers by 35% by adopting R134a (lube oil, seals & some valves and controls may also need to be changed). Install new 2x2400 TR R134a centrifugal chillers to make up deficit. Change the rest with R134a later.

The Multi stage chiller is of YORK make installed in 1983 of 3,600 TR. I agree with u that it is not economically advisable to retrofit. It is better use it along as R 22 is phased out and go for a new 134a chiller.

Thanks Padmanabhan for accepting my suggestion.

On further investigations, it is learnt that if u retrofit this chiller with 134a after recovering R 22 and changing oil as it is, the capacity will be derated by 35%. That means u have to reduce the water flow to eveporator and condenser correspondingly. The drive motor will be over sized or 35% under loaded. There are 2 way of solving this problem. (i) increase the condenser and eveporator surface areas by adding 35% more as additional component in pareller to the existing one. Replace the compressor with 35% more COP capacity to get the original tonnage. This will cost SR 6 millions only. A new chiller of this capacity will cost anything around SR 13 millions. US $ 1 = SR. 3.77

(2) Alternately, use this chiller with R 22 as it is till it is phased out and arrange for a new R 134a chiller as replacement.

"That means u have to reduce the water flow to evaporator and condenser correspondingly." Is your 'condenser' water cooled? In your original post it is mentioned as air cooled. Earlier also I had doubt on this issue, because large capacity condensers of this size must be water cooled. Please clarify.

"(2) Alternately, use this chiller with R 22 as it is till it is phased out and arrange for a new R 134a chiller as replacement." This I have suggested as 1st alternative at post-7. This you have accepted at post-8. Why again rethinking and invite problems for you.

Retrofitting R-22 with R-134a is not so easy. Condensing temp and pressures of both are different, and so for evaporating. Liquid density may not have much difference, but vapour specific volume is increasing considerably. But if you are so keen on retrofitting, contact a proper service company to study and implement. You can contact Siad Services or Advent Enterprises in Mumbai besides OEM, York.

The condenser is water cooled. Error is regretted.

The cost of a new chiller of this capacity is more than 100% of retrifiting charges. And I have seen in Saudi itself YORK chillers of this type working over 50 years without practically any maintenance or break down except regular changing of oil and filters. The performance is so smooth that retrofit will last for another 50 or so years more with original capacity. It require complete critical design to replace inter coolers, balancing of water flow thru different capacity eveporators and condensers for best performances. After all we engineers are suppose to handle this. Retrofit is to be done with the OEMs consultancy only. As there are large numbers of chillers of this capacities to b phased out, retrofit will b a very attractive propositions.

Have you received any retrofit proposal from OEM? What they suggested? Cost of new chiller appear more because it will come with new instrumentation and control system including automation. Here, you have to re-rate compressor, evaporator and condenser (inlet pressure & temp, outlet pressure & temp and flow rate), including piping in between. The only item may not require change is expansion valve, because density of both R-22 & R-134a liquids are nearly the same.

Retrofitting R-12 with R-134a is much easier because their characteristics are nearly matching. I still have lot of apprehension in retrofitting R-22 with R-134a. Wish you good luck.