Musings on cooling down coffee...

Soldato
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So while I'm sat here sipping my slightly-too-hot coffee before work, I started pondering the factors that might affect the rate at which it cools.

Mainly, the timing of the adding of milk.

My thoughts are as such:

You have a cup of coffee which is too hot and you are going to leave it to stand for 10 minutes to cool.

At what point should you add the milk to achieve the optimum cooling performance?

My scientific mind suggests that the most efficient method is to leave the coffee black until the last possible moment. In doing this, the temperature differential between the coffee and surroundings is higher, meaning the energy is lost quicker, and then when you add the milk it obviously drops further.

E.g. it loses 4c through the atmosphere and a further 4 when the milk is added.

I'm also however thinking that it makes no difference, as when adding the milk at the beginning of the waiting period, there is a higher differential, so the coffee loses 5c to the milk, however then goes on to only lose 3c to the environment as the differential is then far lower.

There are also of course the arguments that coffee should be taken black (I agree unless it's instant), or that one should drink tea (these people would have course be wrong).

So, over to you, oh great minds of OcUK, please unite and solve this query for me :)
 
Soldato
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I think you probably have too much time on your hand.

Fridge/Freezer it for a few minutes or put cooler water in - surely it's pretty obvious?

Oh and tea ftw!


M.
 
Associate
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Adding the milk will absorb the same amount of heat energy no matter when you add it. Infact I would say it's better to add it sooner rather than later as it'll increase the surface area contact with the side of the mug.

You could also speed it up by putting it ontop of something thermally conductive, like an upside down frying pan, a heat sink for your coffee mug.

Airflow will also make a big difference, maybe you could rig yourself up a pc fan to blow at your cup.
 
Soldato
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There are also of course the arguments that coffee should be taken black (I agree unless it's instant)
So, over to you, oh great minds of OcUK, please unite and solve this query for me :)

Get one of These and take freshly ground coffee in (the base holds enough for two decent mugs of coffee)

Was the best solution I could find to not having access to decent coffee at work :)
 
Caporegime
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Blow on the coffee. Your breath is filled with cold negative ions which will quickly lower the temperature of coffee. Be careful! If you over deflate the coffee (the scientific term for artificially lowering the temperature of hot drinks) then you have to make a sucking in motion to drag the negative ions back out of the coffee and into your mouth.

This does not work for tea for reasons I was never clear on.
 
Associate
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Get a set of Coffee Joulies, they cool down the coffee and then keep them at that temp for longer. I personally think they are a ridiculous idea but someone buys them (someone on here has a set from the original lot on Kickstarter).
 
Soldato
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[FnG]magnolia;23123386 said:
Blow on the coffee. Your breath is filled with cold negative ions which will quickly lower the temperature of coffee. Be careful! If you over deflate the coffee (the scientific term for artificially lowering the temperature of hot drinks) then you have to make a sucking in motion to drag the negative ions back out of the coffee and into your mouth.

This does not work for tea for reasons I was never clear on.

Excellent :p

That almost sounds scientific enough for someone to fall for :D
 
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Without actually interfering with the composition of your coffee (ie something like adding ice), and assuming you are holding it in your hands, the rate at which coffee cools is mostly controlled by

1. how much heat energy it loses to the air particles directly above it. So you basically want to blow new air over it continuously, and the colder that air is the better. (So a fan would beat your own air because your body warms up the air you breathe)

2. the heat energy it loses to the container it is in. So a highly conductive metal container would itself heat up, taking this heat from the coffee, while a plastic foam container is a good insulator and helps keep the coffee hot for longer, while keeping your hands safe from that heat, which is precisely the aim of plastic foam cups.
 
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Soldato
OP
Joined
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Location
Birmingham
Get a set of Coffee Joulies, they cool down the coffee and then keep them at that temp for longer. I personally think they are a ridiculous idea but someone buys them (someone on here has a set from the original lot on Kickstarter).

Those look simultaneously awesome and utterly pointless :D

Without actually interfering with the composition of your coffee (ie something like adding ice), and assuming you are holding it in your hands, the rate at which coffee cools is controlled by how much heat energy it can transfer to the air particles directly above it. So you basically want to blow new air over it continuously, and the colder that air is the better.

So you reckon strapping one of these to my mug would do it?

http://www.overclockers.co.uk/showproduct.php?prodid=BU-024-TL&groupid=701&catid=2330&subcat=
 
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