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comment by kleinbl00
kleinbl00  ·  1786 days ago  ·  link  ·    ·  parent  ·  post: Spherical Ice Fallacy

    The amount of energy it takes to raise or lower a gram of water by 1C doesn't change depending on how you do it.

No. But the SPEED does. The EFFICIENCY does. And your entire line of questioning is about "how long."

    Find a credible source that says otherwise and show me.

Take your pick.




q-  ·  1786 days ago  ·  link  ·  

    No.

Ah, so you agree that the energy transfer doesn't differ. Good. You said earlier that it did, which had me confused.

So, yeah, at point in time t, when the fluid being cooled has experienced delta T, the amount of energy pulled from it is the same, regardless of how long it took to get to delta T. Good, that's what I was saying. The heat energy went into the ice, either warming it, melting it, or warming the melted water. We know it didn't go into the glass or atmosphere, that would violate one of the LAWS of thermodynamics.

So, knowing that all of that heat energy went into the ice, all we have to do is decide how it was distributed. If any of the solid ice remain un-heated (from -10 to 0C), then the balance of the energy must have been removed by phase change or heating the water.

So, does one large sphere warm more evenly than 4 small cubes? I don't need a precise answer, just >, <, or =. Or is it sometimes yes, sometimes no, depending???

kleinbl00  ·  1786 days ago  ·  link  ·  

    You said earlier that is did, which had me confused.

Show me where.

    So, yeah, at point in time t, when the fluid being cooled has experienced delta T, the amount of energy pulled from it is the same, regardless of how long it took to get to delta T

But point in time t is variable and indeterminate, delta T is variable and indeterminate. THAT'S WHAT YOU'RE SOLVING FOR.

    We know it didn't go into the glass or atmosphere, that would violate one of the LAWS of thermodynamics.

It would do no such thing. You're presuming the glass and atmosphere are perfect insulators, which would violate the laws of thermodynamics.

    So, knowing that all of that heat energy went into the ice,

You know no such thing.

    all we have to do is decide how it was distributed.

…and how it got there.

…and how long it took.

…and what the efficiency was.

…all of which are variable based on the geometry of your ice and the convection caused by it, which is - again - a variable you're attempting to solve for.

    If any of the solid ice remain un-heated (from -10 to 0C), then the balance of the energy must have been removed by phase change or heating the water.

wat

    So, does one large sphere warm more evenly than 4 small cubes?

Remember when I said I wouldn't model this with a ten foot pole? That statement has not changed veracity lo these many weeks.

q-  ·  1786 days ago  ·  link  ·  

    You keep holding on to this as if wishing would make it true:

        It doesn’t matter how you cool it, the answer is always the same.
    
    It does. It really does. All the stuff you're discounting is the difference between "real world performance" and "ideal performance" and even "ideal performance" doesn't get anywhere without conduction and convection at a bare minimum.

Right there. You said it really does matter how you cool it. "The answer" being Q in the equation right before the quote of mine you used. "Q" stands for heat energy removed, which you said can be different depending on how you cool the 100g of whiskey from 21C to 15C.

    It would do no such thing.

That's exactly what I said.

    You're presuming the glass and atmosphere are perfect insulators

No, I simply know that heat flux doesn't go from cool bodies to warmer ones. Heat goes from warm to cool (glass to liquid.) That's one of the laws (2nd, I believe.)

    So, knowing that all of that heat energy went into the ice,

    You know no such thing.

Yes, I do. If the ice didn't make the whiskey colder, what did? The warm glass, the warm air, or the warm hand holding the glass? 2nd law, bro.

It's clear to me that you're not going to wrap your head around this problem or how it's solved. I was hoping to get the light bulb to come on for you. You still want to calculate how long the cooling will take. (You and I seem to be in agreement that the spherical ice will cool the whiskey more slowly, so I'm confounded that you think you need to calculate exactly how much slower it is. For me, "well, it's ain't gonna cool faster, that's for damn sure!" is good enough.) I'm calculating how much ice will melt once the whiskey has reached the desired temperature. And as I've said before, the longer it takes, the more energy will have to be removed from the whiskey by the ice due to the heat transfer from the surrounding environment. Again, I don't even care for the precise answer, only "it sure as hell ain't gonna melt less" will do.

kleinbl00  ·  1786 days ago  ·  link  ·  

    Right there. You said it really does matter how you cool it.

What I said:

    It does. It really does. All the stuff you're discounting is the difference between "real world performance" and "ideal performance" and even "ideal performance" doesn't get anywhere without conduction and convection at a bare minimum.

What you said:

    The amount of energy it takes to raise or lower a gram of water by 1C doesn't change depending on how you do it.

What I said:

    No. But the SPEED does. The EFFICIENCY does. And your entire line of questioning is about "how long."

So what you're saying is that I agreed with you when I quoted you to say you were incorrect.

Just so we're clear:

Your standpoint is that the amount of energy is the same, therefore nothing else needs to be calculated.

My standpoint is that the speed of energy transfer is what we're focused on, therefore we have to calculate a whole bunch of ugly shit.

Worse, you're no longer arguing fact, you're attempting to depose me - you're trying to argue my statements hold no value because you think you've tricked me into contradicting myself. This isn't court, this is physics, and no matter how much you wish to dance around the issue, I have a lot more training in it than you do - which means, I suspect, that you can't even follow my arguments closely enough to understand them. Further, it doesn't matter how much smarter you think you are or how incorrect you presume me to be, the fact remains: I spent several thousands of dollars being tested on this stuff in an ABET-certified 4-year institution (one of the top ten in the country at the time, in fact) and I feel like I'm beating a dead horse: This isn't a Physics 101 problem. Which only makes the following that much more insulting:

    It's clear to me that you're not going to wrap your head around this problem or how it's solved. I was hoping to get the light bulb to come on for you.

So. You and your high school physics can be as self-assured as you wish about this particular problem. I said before and I'll say again: it's a lot more complex than you think. I'll add this, though: I no longer have any interest in helping to illuminate the problem to you. I've been purposefully ignoring your condescending tone in the face of an exceptional amount of patience, but I can't do it any more.

Good luck with this and your future endeavors.

q-  ·  1786 days ago  ·  link  ·  

So, what is that, the fourth time you've removed yourself from this conversation?

    My standpoint is that the speed of energy transfer is what we're focused on

No, it's what you're focused on.

    ignoring your condescending tone

Wow. Go back and read your own posts in this thread. You have been extremely condescending towards me.

    Right. it's a cute equation. Positively adorable.

Would you speak to your work peers or boss the way you have to me?

Here's a rundown of your total contribution here:

1. This problem is too difficult for me; I have a masters degree in engineering. (Where'd you get it, Ohio State?)

2. Ambient conditions matter. Like, on a humid day, spherical ice melts less, but on a dry day, square cubes will melt less. Or is it the other way around? You never enlightened us on that, you only said that it mattered...

3. Spherical ice cools faster because it's bigger. (Highlighting to me that you don't understand the difference between shape and size.)

4. The laws of thermodynamics are over-simplifications of the real world and do not apply to something as complex as melting ice. (Even though those laws were conceived and proven by observations from the real world.)

Thanks for all your thoughtful contributions!