cooling process rollers

[multisync]

Customer of ours orered a 11kw chiller from us to cool their new plasic sheet maker.

The spec was done by themselves and we just delivered it etc. Commissioned on Monday all good to go. Got a call on wednesday "Chiller isn't working water temp now at 54 deg's c"

Went to site on Friday and chiller was working but with a return temp at 45 and rising! A bit under sized..poor little chiller .

They plumbed through the 3x 300mm dia rollers in series with 15mm id areoquip type hoses by Pirtek to which we said they would have to go as they are too small. (500 quid down the drain)
We will re-pipe with larger 25mm id but in parallel which we feel would lower the return temperature in any case.

So a 11kw is too small but how would we go about sizing it as we were thinking of a 26 or 37kw in a that's gotta be enough type scientific way

[mad fridgie]

One sure fire way of calculating plastic cooling, is to use the original energy input from the start of he process. (normally a bit oversized)

[mad fridgie]

had a closer look ar the pics, look like you need a high flow of water going through the rollers (very low TD) this to keep the cooling process constant.
what temp water do they require?

[mad fridgie]

as well as changing the pipes you will need to increase your pump size. (4 to 5L/ sec) Take a side stream off for your chiller.

[multisync]

They don't need any set temperature per se, rather they need to keep the roller below a certain temp or the plastic starts to stick. This starts about 50 dec c return water temp.

The chiller comes with a pump set and buffer tank complete so the new whiller will have the uprated pump attached.

[US Iceman]

Parallel water flow through the rollers would be the first thing to do. This would help to establish a consistent roller temperature for each. Series flow is not what you want IMO.

For applications like these you also need high flow rates to keep the water temperature rise to a minimum. This helps with the above comment also. In addition, the higher water flow through the rollers slightly increases the heat transfer of the roller itself.

Larger piping and fittings will reduce the pump head requirements. If the head required to overcome resistance in the pipe and fittings is too high a centrifugal pump will flow less volume, which will hurt your results.

They may have spec'ed the chiller and process but that does not mean your chiller is at fault either. It might only mean their process does not work like they thought it should (or would).