chiller sizing help 1

[RobWard]

Could someone please answer a simple question for me?
We have a 15.75kW vapour degreaser and would like to use a chiller to cut down on the coolant water consumption (currently goes straight down the drain).

How would I calculate the size of chiller I need?

(We would probably buy second-hand, so we can't really go to the manufacturers for advice).

(I did a keyword search, but couldn't find the info I need. I may not know the correct terminology, so apologies if this is one of those all-too-frequently asked questions)


"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[Cooky]

Rob,

Probably the best way to determine the cooling load, is to measure heat gain of the water running through the cooling coil.

To do this, you must measure the flow rate of the water running to drain (measure liters/second). Then measure the temperature rise of the water as it passes through the degreaser (outlet - inlet deg.C).

Cooling load of chiller (kW) = flowrate x temp rise x 4.2

I would estimate your required cooling duty at about 10kW

As for the terminology, the machine you need is called a Packaged Air Cooled Liquid Chiller.

Try this link....

http://eto.carrier.com/litterature/psd/13066.pdf

 

[ChrisConley]

In order to size a chiller, one would need to know exactly how much heat you are looking to move around.

One way to size the actual waste heat would be to determine the coolant water flow (in gallons per minute) and the temperature rise (deg F) it experiences through the unit. The cooling the unit requires would be:

Q = 500 * GPM * deltaT

The next step would be to determine how much you want to decrease the coolant flow. The 'Q' above would remain the same, you select the GPM and then solve for deltaT. Once you have the required deltaT you could size for a chiller to take you incoming water down to the required temp.

Once you have the flows, and the required temperatures I would contact a chiller manufacturer. Even if you aren't going to buy most of them will offer advice and sizing tips, and some of them offer used equipment.

Hope that helps.

 

[RobWard]

Ahhhhhh....
Yes, that all makes sense. It's a bit like an old A-level lesson coming back to me.
We have an old chiller unit from a MUCH smaller degreaser that my boss asked me to plumb in.
I'd been about to explain that we have 15.75kW of heat and the small chiller runs off a 13A plug so could only chill a maximum of about 3kW when I fortunately stopped my mouth and engaged my brain and realised that that was wholly incorrect.
So I sat down to think about what we really needed.
Then I got stuck, and came to you guys....

Thanks for your help.

I'm off to get a thermometer, stopwatch, and a 5 gallon bucket.....


"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[kico]

Have you considered using an evaportative closed circuit cooler? Depending what the weather is in your area, you might be able to get 75F supply water to the degreaser.

 

[ClydeMule]

Remember to check the rating point of the chiller. For HVAC chillers and some process chillers the rating of the chiller is based on 44F chilled water @ 95F ambient air.

A lot small process chillers designed for lasers and the like are rated @ 68F chilled water. If you only need 68-70F water than go for one of those. THey will be cheaper/ton.

Watch out on Nesalab chillers though, they are good but rated for 68F water in something like a 75F ambient. I only mention this beacause there are a lot of those floating around on ebay. Nice chillers if you run them in an air conditioned room.

Good Luck,

Clyde

 

[Rustyowls]

I would contact a manufacturer, probably York...they are still the chiller guys!

 

[robinj1000]

Write me back at robinj1000@direcway.com. We have several types of small chillers available