Idustrial cooler question R22/134

[wulff]

Hi guys, I am new on here and had a question.
We have a water cooling system for supplying cold water to semiconductor equipment in a clean room. Unlike most cooling towers this unit is a little strange.
It has a 1 hp Copleland compressor and the 'evaporator' is a large coils of copper tubing in a 105 gallons of cooling water. It uses r134 as the refrigerant and it's designed to create a large block of ice on the tubing at night during low power once the ice is 2" thick it hits a small canister that freezes expanding and shuts off a refrigerant valve near the expansion valve, this causes the pressure in the compressor to rise,shutting off the compressor! It uses 14 lbs of r134!
I had to replace the expansion valve and switched over to R-22 which worked better but now the compressor is dying I have a Tecumseh 1.5 hp compressor (was off of cooler using R22).
But here are my questions: The ice water is just too darn cold and all the pipes leading to the equipment is sweating and running down into the electronics on he tools (they are designed for cooling water, not ice water!).
I wanted to replace to trashed compressor and remove the valve that shuts off the refrigerant and add a watlow controller to shut off compressor to maintain about 40 degree F water. I also wanted to use less R-22 as 14 lbs seems like a lot!
I know 134r uses PAG oil so should I flush out all the original parts, add mineral oil and install a new dryer?
Did I kill the old compressor by using the original 134r oil when I changed to R22?
Has anyone ever seen such a set up?
What are you experts advice on the changes I want to make?
Sorry for all the questions, I do all our smaller Neslab coolers but they all use R22 and will get cold but not freeze.. LOL!!
Best regards,
Phil
Mesa, AZ USA

[monkey spanners]

Hi guys, I am new on here and had a question.
We have a water cooling system for supplying cold water to semiconductor equipment in a clean room. Unlike most cooling towers this unit is a little strange.
It has a 1 hp Copleland compressor and the 'evaporator' is a large coils of copper tubing in a 105 gallons of cooling water. It uses r134 as the refrigerant and it's designed to create a large block of ice on the tubing at night during low power once the ice is 2" thick it hits a small canister that freezes expanding and shuts off a refrigerant valve near the expansion valve, this causes the pressure in the compressor to rise,shutting off the compressor! It uses 14 lbs of r134!
I had to replace the expansion valve and switched over to R-22 which worked better but now the compressor is dying I have a Tecumseh 1.5 hp compressor (was off of cooler using R22).
But here are my questions: The ice water is just too darn cold and all the pipes leading to the equipment is sweating and running down into the electronics on he tools (they are designed for cooling water, not ice water!).
I wanted to replace to trashed compressor and remove the valve that shuts off the refrigerant and add a watlow controller to shut off compressor to maintain about 40 degree F water. I also wanted to use less R-22 as 14 lbs seems like a lot!
I know 134r uses PAG oil so should I flush out all the original parts, add mineral oil and install a new dryer?
Did I kill the old compressor by using the original 134r oil when I changed to R22?
Has anyone ever seen such a set up?
What are you experts advice on the changes I want to make?
Sorry for all the questions, I do all our smaller Neslab coolers but they all use R22 and will get cold but not freeze.. LOL!!
Best regards,
Phil
Mesa, AZ USA

Hi Phil,

This is very similar to the ice bank milk coolers i work on.
I'm curious as to why you changed to R22, surely thats a backward step with regard to long term system viability, new R22 has already been withdrawn from sale here and only recycled is available, i'm sure a world leader such as the USA can't be far behind in banning R22 too.
The 1hp copeland would have had Polyolester(POE) oil in from the factory, PAG oil is for automotive use.
R22 is compatible with POE, so no problems there, but i expect the condenser would now be undersized and possible the compressor would be out of its designed range in this system, if it was even designed to run with R22.
Compressor manufacturers will mix and match different hp motors to different sized pistons/displacements to suit the evaporating temp and the refrigerant in question, its doubtful your R134a comp is designed to work with R22 in this type of system even if it would be happy at other evaporating temperatures.
The 'new' Tecumseh unit will likely be oversized for the ice builder, you will need to compare the duty the original copeland did with the duty the tecumseh does at the same evaporating temp to see.

For the problem of the chilled water supply being too cold to the tooling, you need to find out the temperature the tools need to be and install a mixer valve (or buffer tank) to mix the return water with just enough ice water to maintain your desired temperature. Have seen a similar set up on dairy refrigeration when using glycol at -5C to prevent the freezing of milk in the heat exchangers.

A few points, if the original fault was just a bad txv, why not just fit an R134a one?
If this is a important system (as i assume it is being in a semiconductor clean room) don't mess around with second hand compressors, fit a new one. Businesses like this don't need 'cheap' (even though they think they do) they need 'working'
Your system should cut out on low pressure when the solenoid valve shuts near the txv, if it is shutting off on high pressure then the system is either over charged or the reciever capacity is too small, don't assume that the factory supplied reciever is sufficient for the system.

Jon

[wulff]

Thanks for the reply Jon, the company I work for is very small so every dollar counts therefore I have to try to use what I have on hand. We only use the cooling system during testing therefore it might be a week or more between use.
I realize r22 is getting harder to find but I have plenty so I was going in that direction.
I have other compressors that are 3/4 hp, do you think this might be better than using a larger compressor? I thought if I used a larger unit and kept the pressures lower it might work better.
I don't like the size of the condenser but I have to use what I have.
Oh, I'm sorry you were right I meant the compressor shuts off when the suction line drops.
So the bottom line is I have to replace the oil in the replacement compressor to use 134r or flush the system and use mineral oil.
I know R22 pressures will be higher than 134r but in my experience 134 just doesn't make a good refrigerant for stationary cooling equipment!
one other thing, doesn't 13-14 lbs seem like a lot? There is a lot of coils in the water and this return runs into a container that probably holds about 2 liters from there it goes through the air-cooled condenser, then to the compressor, and into another 2 liter tank and from there it goes to the balanced expansion valve.
Do you think all there tanks are to hold the extra refrigerant during the off cycle?
Any help you can give me would really be appreciated!
Best regards,
Phil

[monkey spanners]

Sometimes people say compressor when in fact they mean condensing unit (compressor/condenser/fan assembly/ receiver (a tank to store excess liquid))

So im not sure in your case which you are refering too.
If is just the compressor that you plan to fit to the existing condensing unit, i would go with the smaller one which will in effect mean the condenser is now oversized, this is less of a problem as you can slow the fan down with a speed controller or if you are on a very tight budget and can keep an eye on it you can restrict the airflow through the condenser.
If you go with the bigger compressor and the heat load is high, it will get too hot and not work.
Check the pressure rating of your existing condensing unit and reciever, it may not be rated for the higher pressures R22 runs at and could burst.

No need to flush the POE oil to use with R22, its a better combination that R22 and mineral oil. POE and mineral oil mix fine too. I have many R22 systems that have had the old mineral comp replace with an POE replacement.

You can't control anything by adjusting the pressures (presumably by adjusting the system charge quantity) the low and high side pressures are determined by the water or ice temp in the tank and the air temperature over the condenser. Get your self a pressure temperature chart (google r22 pt chart) and see how the pressure rises with the temperature.

13-14Lbs dosen't sound too excessive, they do hold a lot more than a dx system.
The tank in the low side (big pipe) is an accumilator (slop tank) to prevent any liquid refrigerant that hasn't boiled in the evaporator for any reason reaching the compressor and snapping a rod.
The tank in the high side (little pipe, after the condenser) is to hold excess refrigerant as the system load changes or its pumped down.

Jon

[NoNickName]

Ice banks were relatively common in the 80s and 90s, but recently, thanks to the availability of better regulation loops and devices like inverters, they have become less common.
In your case, removing the suction solenoid would cause liquid slugging, because the evaporator is very cold for a long time and would cause the refrigerant to condensate in it.
I would not recommend to remove it, unless a liquid solenoid valve is installed instead.
As for the dripping of water onto the tools, just insulate the piping better, with a vapour barrier insulation.

[wulff]

Thanks guys, I will go with the smaller compressor based on this information. I thought POE and mineral oil would cause "black Death" if mixed (to coin a phrase when auto part companies sold the r12 to 134r it came with a can of synthetic oil and 134r, the ac guys told me the mineral oil would mix with the synthetic oil and quickly ruin the compressor.
So you are saying if I used the r22 compressor (the smaller 3/4 hp one I could leave the mineral oil in it?)
Would you use 134r or go with r22?
Oh, we can insulate the tubing but the chambers are big blocks of aluminum and about 2' X8" and buried in the tool making insulating impossible. Also the vacuum pumps warn against using water that is too cold so I have to avoid the ice bank if I cam unless I build a 'tempering unit'.
Thanks again guys,
I'll be looking forward to your answers.
-Phil

[NoNickName]

The advantage of an ice bank is that it stores 87 kcal/kg°C of ice, while water has just got a thermal storage of 1 kcal/Kg°C. Basicly icing and deicing is 87 more thermally advantageous than chilling water.
In your case, you need to keep the delivery water temperature above the dew point of the room where the tool chambers.
Either you decrease the dew point, with a powerful dehumidifier in the chamber, or increase the water temperature with a three way valve, as somebody already suggested.

SI system used this side of the pond, sorry for that.

[wulff]

Thanks again, I forgot to mention the chiller company uses the same compressor for both 234 and r22.

[wulff]

Thanks again, I forgot to mention the chiller company uses the same compressor for both 234 and r22.

Thanks for all your input on this project guys. I did have a question that has me wondering. I am going to use the 3/4 hp Tecumseh (which was in an r12 system) here's the question. It had Alkylbenzene oil in it which I drained and saved. Now if I use this compressor in the original r134a ice bank will I have to remove any trace of this oil or will POE mix with Alkybenezene? I am replacing the dryer but other than removing the 'overflow' tanks on the suction and pressure side to remove the old POE oil? This will be a chore as they are all soldered in without removable fittings. I was going to flush it but I'm sure the tubing in the tanks don't go all the way to the bottom of the tanks so there will still be POE oil mixed with water, right? (the system was open for about a month before I took over so I'm sure there is water in the POE oil).
Let's put it this way, I respect your decisions as you have a lot of experience in this area!
Please don't give me a hard time just because I am an American LOL!!!
Thanks guys,
Phil

[Fire Fly]

this is a very helpful and interestingly informative forum