"Ice Box" the apparently not-quite-as-efficient-as-it-should-be ice maker cooling method.

[WanderingKid]

12 hours ago, mathmanican said:

I played with this for hours last night.

• Water (outside the icemaker) turns to ice at 269.5K (checked with debug to 4 decimals).
• Ice jumps to 271K (estimate) instantly on phase change.

Note that there is NO change in temp when ice swaps back to water. This means that the ice maker's changing of water to ice (at 272.5K) does NOT create an SHC abuse. 

If you'd be so kind as to clarify a few things:

Does the 269.5K Water jump to 271K ice when naturally cooled to ice?  I attempted to test this via the heat gun and it acts very strangely.

I assume this is why you say you 'generate' the heat.  You're getting the 1.5K increase simply because you froze the water from 269.5K and it swapped to 271K.

You say heating the ice back to water requires 1/4 of the heat that you took out of it.  Making sure I understand why, it's because you need to put in 4.179 DTU/g/K into the water for 3K & SHC of cooling, but you only need to put the energy back for ice, which is 2.050 DTU/g/K and then only 1.5K * SHC worth of it.

This would definitely Net thermal energy if accurate.

All of that, however, actually confuses me further in understanding why this system is self cooling as well as netting cooling.  I'm really trying to understand Kitten's point above, but it's eluding me.

Let's do hard math.  Maybe that'll help.  Let's ignore the ice maker for a moment.

1kg of ice melts at 272.5K.  Up to that point it has 272.4 * 1000 * 2.050.  Total Energy in the ice at that point: 558,420 DTU of thermal energy.

Immediately upon transfer to 272.5K, that same mass is now 272.5 * 1000 * 4.179: 1,138,777.5 DTU of thermal energy.

It will cost you, thermally, 12,537 DTU to move that water back to ice at 269.5K.  Once it's ice, reversing this process (I'll just assume you're right, you usually are) it's actually at 271K, so you only need 3,075 DTU of thermal energy to return to water.

So, that's the heat #'s you're seeing in the heat generation.  Where I don't understand is how the ice maker is helping anything with the phase change.  Even if the water immediately cycles between ice and water at 272.5K and 272.4K, my understanding is that it's got a thermal constant with itself in the local environment.  I can certainly understand the 20% heat deletion if you were to, say, put in 370K water through it, but that's just the simple math and how the machine works.

However, if you put 2K DTU worth of heat into the water as it's helping the cooling, it's got to give it back to the ice machine as it chills it back down from 274.5K back into ice at 272.5K.... right?

[mathmanican]

4 hours ago, WanderingKid said:

Does the 269.5K Water jump to 271K ice when naturally cooled to ice? 

Yep. I built a small heat exchanger that cooled from above and heated from below. The heat was added only when a hydro sensor detected no liquid. My build generated thermal energy over time. Quite odd.

4 hours ago, WanderingKid said:

Where I don't understand is how the ice maker is helping anything with the phase change.

I'm with you. I still dont understand either. All I get is a 20 percent heat reduction. Maybe the effectiveness has to do with the conveyor bug... 

4 hours ago, WanderingKid said:

I'll just assume you're right, you usually are

Not always. My thermdynamics understanding is more book learned from @Yothiel and @wachunga and so I sometimes miss quote and propagate my poor understanding. The stuff I posted above I tested several times.

Fluid dynamics is where I spend most of my testing time. This build is a thermodynamics build.