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Karlosbubi t1_iu9kx5w wrote

So what does this tell me about when to add ??

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also_roses t1_iu9lawn wrote

Seems to indicate that it doesn't matter when you add

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Prunestand OP t1_iu9me3t wrote

> Seems to indicate that it doesn't matter when you add

In this simulation: the temperature after 10 minutes was 55.4 °C if milk was added at the end, compared to 56.5 °C if milk was added in the beginning. So adding the milk at the end made it about 1 °C cooler.

So I would say it probably will not make a huge difference, at maximum some degree give or take.

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a_user_to_ask t1_iua8mvr wrote

The style of graph is nice for informal report (copy of xkcd), but if the difference of the experiments at the end are 1º C, it is the worst style to use because you can't know if the difference at the end is because the data or the drawing style of lines.

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Prunestand OP t1_iuacv7x wrote

I mean, it is a simulation after all. Not a study or an experiment.

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iamchairs t1_iu9r3vn wrote

Simulation? You didn't do it irl?

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Prunestand OP t1_iu9rn8t wrote

> Simulation? You didn't do it irl?

This is a simulation based off Newton's Law of cooling, yes.

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iamchairs t1_iu9rsul wrote

Interesting idea. But it's somehow less interesting this way

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Relevant-Brain-733 t1_iu9lio6 wrote

Don't put it too late if you still want to drink something hot enough, that's what I can conclude 😀

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WorldlinessWitty2177 t1_iu9qxea wrote

That there is zero difference in temperature whenever you add the milk. So this is BS

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Vince_Vice t1_iua4exf wrote

No, there is a technical difference. At higher temperature difference (to the surroundings) the general temperature loss is faster than at lower temperature differences.

If I have boiling water in a surrounding at room temperature than it will lose, say 5 degrees Celsius in the first minute.

If I have water at 5 degrees C above its surroundings it will only lose 1 degree C in the same minute.

So when I add the milk instantly to the freshly brewed coffee I never let the coffee have the highest temperature difference at which the heat loss would've been the highest.

While adding it just before drinking it the coffee experieced a higher heat loss rate before I cooled it with the milk.

Instantly adding the milk leads to a warmer coffe, adding the milk later leads to a cooler coffee

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N8Lux t1_iubsk25 wrote

Vince_vice is correct. Heat transfer is proportional to the temperature delta. In other words, the coffee cools fastest when the coffee is hottest. The rate of cooling slows as the coffee and outside approach the same temperature. So yes, it makes a difference when you add the cream.

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Equivalent-Bench5950 t1_iuadkac wrote

Mostly wrong. If you choose either the temperature or the time at which you want to drink, it only matters that you add the milk "in time" - all other parameters are meaningless.

There is neither a theoretical nor a practical difference. I think it is the first law of thermodynamics.

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Vince_Vice t1_iub1rt9 wrote

> Mostly wrong.

Not treading ligthly I see. But you're wrong

> I think it is the first law of thermodynamics.

The first law of thermodynamics is conservation of energy in a closed system.

My thought experiment does not violate it. The closed system is the room in which the hot coffee resides.

There is no difference in the amount of energy but in the process in which thermodynamic equilibrium is reached.

At some point the coffee and the room will reach an equilibrium temperature that is very close to room temperature (bc its heat capacity is much higher than that of the coffee)

The coffee is drunk before equilibrium is reached (who wants cold coffee) so this is not about the energy content of a closed system, but about at which point of the state transition it is drunk.

First lets make a slightly different but simpler argument that proves that you are wrong: Lets assume the milk comes from a fridge, it therefore is colder than room temperature, while the coffee is hotter.

It should be obvious that allowing the hot coffee to give its heat to the room, then pouring the milk will be colder than pouring the colder milk into the still hot coffee resulting in the coffee heating the milk instead of the room, right?

I chose this example with cold milk because it makes it easier to comprehend that the milk has a heat capacity that it adds to the mix. With room tempered milk that is still true, its just not as ELI5.

Therefore both methods will eventually reach equilibrium temperature, but pouring the milk earlier will leave you with a warmer beverage at consumption

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Prunestand OP t1_iu9ln61 wrote

Depends if you want the cup of coffee a couple of degrees hotter or cooler. If you like it hot, add the milk asap. If you like it to be a couple of degrees cooler, then wait.

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Fivethenoname t1_iu9mj6v wrote

Uh what? To reach any given temp you're going to have to add or wait or wait then add. Or add differing amounts or change the the starting temp... I don't see any argument for any specific timing given that you can reach whatever temp you want by changing your method.

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Vince_Vice t1_iublcg1 wrote

The milk adds heat capacity to the beverage.

Think about it this way: say the milk is out of the fridge, its cooler than room temp, the coffee is hotter than room temp.

If you add the milk to the hot coffee immediately much of the coffees heat warms the milk. If you add the milk later instead it dissipates into the room and when you add the milk your beverage is cooler.

The same is still true for room tempered milk, just not as obviously. It still adds heat capacity. But adding it after much of the heat is gone is like adding SSDs to your server after your company already lost 80% of the customer data, its just not gonna fly.

So yeah, adding milk early gives you a warmer beverage. Adding milk later produces a cooler one.

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tarkovLoadedwCheatrs t1_iub5cbm wrote

The data indicates the longer you wait to add the milk, the colder the coffee will be. You should add the milk first and pour the coffee over the top.

This data sucks though because it's unclear what the temperature of the milk is initially.

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