Stumped with Plate Chiller

[siwelwerd]

*Joule (after whom the unit of energy is named) was the son of a wealthy brewer and did much of his seminal work in a laboratory attached to his father's brewery).

They just don't teach this kind of stuff in physics classes anymore.

[Cliff]

In a counterflow chiller the amount of heat transfer depends on many things,

Yes it does. I spoke to one of them.

There is no phase change in a properly operated wort chiller.

Did I say there was a phase change? Or did I mention it because it was relevant?
There is a difference you know.
When you are trying to use some one else as your foil you might at the very least read and understand the material you claim to be responding to or offering a critique of, before you go off on it.

Did you miss the part where I discusses the way water takes up thermal energy differently at different temperatures? The fact of it being a phase change material is of no small moment there.

No it doesn't (at least not appreciably - the specific heat of water changes by less than 1 % over the entire range from freezing to boiling).

Do my experiment and you’ll be singing a different tune.

That's not because of a change in specific heat but rather because the rate of heat transfer between two systems depends on the temperature difference between them.

Did you deliberately misread my post just so you could quarrel with things you hoped that I’d said?

I get it that you enjoy displaying knowledge, but you might first read and understand the material you are using as the foil for your display. Either that or just state your stuff without trying to use any one else as your sounding board.

[Kbar]

Hang in there Cliff. I think AJ means good. All is better with homebrew!

[brewranger]

No it doesn't (at least not appreciably - the specific heat of water changes by less than 1 % over the entire range from freezing to boiling).

Do my experiment and you’ll be singing a different tune.

That's not because of a change in specific heat but rather because the rate of heat transfer between two systems depends on the temperature difference between them.

Did you deliberately misread my post just so you could quarrel with things you hoped that I’d said?

I get it that you enjoy displaying knowledge, but you might first read and understand the material you are using as the foil for your display. Either that or just state your stuff without trying to use any one else as your sounding board.

[/quote]

not to pile on cliff, but im with AJ on this one. The main driving force in heat transfer is temperature difference. As the temperature difference decreases the heat transferred will decreases as well. The heat capacity may as well be constant.


To answer the OP question. I think most of what has already been said should solve the problem. make sure it is countercurrent. Also, as AJ touched on, flow regime will have a huge effect on the overall heat transfer coefficient. Since you are only gravity feeding, if you can get the kettle higher or the exchanger lower that will help get your wort side velocity up. Cooling water side should be wide open. Other than saving water you are doing nothing to help cool your wort by throttling cooling water (unless you have a nozzle at the exchanger inlet to force turbulent flow).

[anday6]

Throttling your cooling water will actually help greatly once the temperature difference drops below a certain point. At that point, your heat transfer rate is such that you need greater 'contact' time between the wort and cooling water to remove a given amount of heat.

I typically run full flow until I reach 140, throw ice in the prechiller, and then throttle the chilling water once I get under 100. I usually go by the cooling water exit temperature by feel.

[MachineShopBrewing]

I think it is funny when people go after AJ. He's probably the smartest dude on this whole forum.

[Henning1966]

I think it is funny when people go after AJ. He's probably the smartest dude on this whole forum.

That depends on subject matter cause code Is a smart guy too. But I agree when aj posts it is allways spot on correct.

[brewranger]

throttling the cooling water will reduce the LMTD as well as the overall heat transfer coefficient due to the increase in film temperature. therefore reducing the efficiency of the exchanger. letting the cooling water outlet warm up isn't "taking more heat out" its just more noticeable. like putting one cup of water on the stove for 1 minute will be warmer than 2 cups of water.