Question about ice cube tray freezing first in the front

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Ranger Mike
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why is it, the ice cube tray freezes first, at the front of the tray closest to the door.
This should be the warmest place of the refrigerator. The back does not have enough time to send the colder air out to atmosphere.
I think i know the answer but lets us explore this..
 

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I would GUESS better circulation.
 
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Ranger Mike said:
why is it, the ice cube tray freezes first, at the front of the tray closest to the door.
How big is the refrigerator? The snowline is lower towards the pole. If you turn the unit 180°, so the door is towards the equator, you may find the opposite.

I jest. We all know it is due to the Mpemba effect.
https://en.wikipedia.org/wiki/Mpemba_effect
 
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Partially - Mpemba effect with modification. We are not adding hot water to the ice cube tray, we are observing the effect however. Note -the front of the ice cube tray freeze before the rear of the tray!
I maintain that the refrigerator has a steady state until the door is opened. Then the hot air moves in seeking a lower energy state so the front of the refrigerator area is warmer. This area has the greatest temperature difference. The rear of the refrigerator is more or less stable due to the frozen food present there. The front only has the inside of the door which is a very poor heat conductor due to insulation. The same is true with top and bottom and sides. Poor conductors of heat. So instead of having water with warmer temperatures the front area of the refrigerator has the fastest freezing conditions due to warm air intrusion. Temperature is "heat density." Warm air contains more heat than cold air. When you open the door and air gets mixed up, you increase the heat density in the FRONT of refrigerator. Since the volume of the refrigerator is sealed ( has no entrance and exit portals) you do not have a mass of hot air rushing into the refrigerator. So the ice cube tray freezes in front before it freezes towards the rear.
Or did I miss sumthing???
 
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Ranger Mike said:
I maintain that the refrigerator has a steady state until the door is opened. Then the hot air moves in seeking a lower energy state so the front of the refrigerator area is warmer. This area has the greatest temperature difference. The rear of the refrigerator is more or less stable due to the frozen food present there. The front only has the inside of the door which is a very poor heat conductor due to insulation. The same is true with top and bottom and sides. Poor conductors of heat. So instead of having water with warmer temperatures the front area of the refrigerator has the fastest freezing conditions due to warm air intrusion. Temperature is "heat density." Warm air contains more heat than cold air. When you open the door and air gets mixed up, you increase the heat density in the FRONT of refrigerator. Since the volume of the refrigerator is sealed ( has no entrance and exit portals) you do not have a mass of hot air rushing into the refrigerator. So the ice cube tray freezes in front before it freezes towards the rear.
I do not understand your argument. Why does “increase the heat density in the FRONT of refrigerator” imply “so the ice cube tray freezes in front before it freezes towards the rear”?
 
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Ranger Mike said:
so the front of the refrigerator area is warmer.
Maybe this is true for an old fashioned model but the two freezers I have owned recently (frost free) have forced air circulation and the specific layout of food in the drawers will have a large effect on the temperature distribution. Both front and back and top and bottom temperatures seem to vary very little. I notice, for example that ice cream in the bottom drawer is much more usable in my later freezer than it is in the earlier one so plain old convection is a secondary effect, perhaps.
 
Baluncore said:
I jest. We all know it is due to the Mpemba effect.
Whilst there has been some good experimentation to 'prove' the existence of Mpemba, the effect was spread amongst fridge owners years before the 60's. In many cases. My non-scientific Mum used to swear it was true (but people didn't actually swear ins the mid fifties).

I am convinced that the reason is often that warm water kicks the compressor into action earlier than a tray of cold water might. End product would be freezing earlier when the cooling cycle is designed to be long.

I suggest that the front/back effect could also depend on the placing of the thermostat. You'd need to do the experiment with small quantities of water, to be sure,
 
The freezing process includes five distinct stages as shown by Fig. 1: (1) liquid cooling (super cooling), (2) nucleation (water molecules start to form ice crystals) (3) recalescence, (a sudden spontaneous increase in the temperature of cooling resulting from an exothermic change in crystal structure occurring at a particular temperature.) (4) freezing and forming a solid piece of Ice (volume expands) , and (5) solid cooling.

Temperature gradient enhances the free energy barrier for heterogeneous nucleation to reduce the nucleation rate, and the modified function is in linear correlation with the temperature gradient under our experimental conditions.

Where there's a large temperature gradient, that means the temperature is changing by a lot over a relatively small distance. Big Temperature change over a small distance reduces nucleation rate.

I SHOULD HAVE SAID TIME NOT RATE.


Nucleation is simply defined as the first random formation of a distinct thermodynamic new phase (daughter phase or nucleus (an ensemble of atoms)) that have the ability to irreversibly grow into larger sized nucleus within the body of a metastable parent phase.

So when you open the door of the freezer portion of your refrigerator, you let in hotter air and this causes a large temperature gradient. The warmer air hits the wall of denser cold air and becomes static but it is still hotter than the rest of the freezer volume.

This action reduces the nucleation rate at the front of the ice cube tray. So it freezes before the rear of the freezer volume.
 
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Ranger Mike said:
This action reduces the nucleation rate at the front of the ice cube tray. So it freezes before the rear of the freezer volume.
A reduced nucleation rate should delay freezing.
 
I have a bottom freezer (two-door) refrigerator and the air is actively drawn from the front of the freezer into the refrigerator just above the ice cube trays so the airflow depends upon a host of factors, most importantly how the freezer is packed. I will wager this "anomaly" has more to do with your reserves of ice cream and frozen corn than any physical process.
 
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Baluncore said:
I jest. We all know it is due to the Mpemba effect.
The Mpemba effect may be incompletely explained, but it specifically relates to hot water freezing faster than cold water.

In this case, there was no hot water versus cold water. The rate of freezing of the ice cubes cannot be due to the Mpemba effect. The only variable here was the position, in the freezer, of the individual cubes.
 
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Bal, I respectfully disagree. There has to be a reason. You are on track regarding the position. Time to clear out the freezer shelf. Put two cube trays in ..same water, same temp. one tray up front, one tray in the rear.
should i put aluminum foil on complete freezer shelf? It is wire shelf. also ice cube maker is off as from the start of this goat screw! ideas?
 
Ranger Mike said:
Bal, I respectfully disagree. There has to be a reason. You are on track regarding the position. Time to clear out the freezer shelf. Put two cube trays in ..same water, same temp. one tray up front, one tray in the rear.
should i put aluminum foil on complete freezer shelf? It is wire shelf. also ice cube maker is off as from the start of this goat screw! ideas?
Why don’t you like air circulation in the freezer?
 
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because the two inches of the front of the tray are freezing faster than the rest of the tray. All circulation occurs at the rear of the refrigerator. You think GE is going to plumb an air exchanger at the front? Both intake and exit ports are in the rear of the refrigerator. i stand by my posit of temperature gradient until some one can prove different...and I am not an expert. Ifin the cold air is coming in from the rear..why does the tray not freeze in the rear first?
 

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ok guys, I know about race cars and how to make um win but you folks on here are the absolute best and should know the answer. or has this dumb country boy from Ohio just have things fouled up?
so far, Mpemba effect is on hold. could it in fact be that energy seeks the lowest level, When a better avenue to get there presents it self, the heat released from freezing ice takes the path of least resistance and energy exits on this path.
 
Ranger Mike said:
because the two inches of the front of the tray are freezing faster than the rest of the tray. All circulation occurs at the rear of the refrigerator. You think GE is going to plumb an air exchanger at the front? Both intake and exit ports are in the rear of the refrigerator. i stand by my posit of temperature gradient until some one can prove different...and I am not an expert. Ifin the cold air is coming in from the rear..why does the tray not freeze in the rear first?
If it is a
Single Evaporation SystemThe air is circulated through vents from the freezer section to the fresh food section and back to the freezer section.
https://products.geappliances.com/appliance/gea-support-search-content?contentId=18270
I am not so sure. Even it‘s not, I am not so sure unless it is directly under the blower.
 
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i would like to take this time to thank you for the advice and use this as a teaching moment for students. I know this is a frivolous question about the tray freezing, but let us use this to demonstrate to the students, the thought process in solving a real world situation. As you can see i have a rather old refrigerator. can defrost it. I also have a medical freezer used to freeze race car fuel before we qualified. I do not know if you know this but residential refrigerators and freezers only freeze to 20 degrees F. Medical freezers go 20 degree F
but i want some guidance on the scientific method of problem solving with this...why not?? not costing anyone anything...Greg Bernhardt you home?
 

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This is a very hard problem to solve using your 30yr old refrigerator as the lab. There are so many factors that could come into play beyond what a student could possibly consider.

it was mentioned that airflow may be different, that other items retaining the coldness, the insulation surrounding the ice box, the fluctuating coldness, the fact that you are using the fridge for everyday use, the resident vibrations from the cooling machinery…

As an example, Samsung refrigerators have an ice maker in the refrigerator section that periodically must be defrosted because everyday use of the refrigerator allows warm air to enter the unit. The issue appears to be the lack of good insulation around the unit allowing ice buildup that stops the ice maker. There is a class action lawsuit against them for a fix.

https://www.classaction.org/samsung-refrigerator-ice-maker-lawsuit

This is why scientists do detailed experiments under controlled conditions in a lab with a specially built freezing unit where they can minimize extraneous sources of energy and truly isolate the system.
 
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Ranger Mike said:
ok guys, I know about race cars and how to make um win but you folks on here are the absolute best and should know the answer. or has this dumb country boy from Ohio just have things fouled up?
so far, Mpemba effect is on hold. could it in fact be that energy seeks the lowest level, When a better avenue to get there presents it self, the heat released from freezing ice takes the path of least resistance and energy exits on this path.
No sure what all that means ie' path of least resistance.'
Mpemba probably doesn't have anything to do with it, and if it does( if one would care to take that route) one would need a more controlled situation that what is currently in your freezer compartment.

But the circulation pattern of the air within the compartment has a determination of water freezing at one location before the next. No way for anyone to know what is going on in there without adding in some sensors to record air movement and temperature. Otherwise a guess.

A guess:
Rear exit and entries provide an air movement within the compartment.
The cold air exit would blow towards the front, circulate around, and exit.

if the tray is in the centre of the compartment ie equal left and right distances:
the front of the tray would experience forced convection.
It could be that the air in the centre at the rear is rather stagnant, and here cooling would be not as robust as with force convection.

Try putting the tray completely to the left, or right and see what happens.
Put the tray the same height as the exit and see what happens.
 
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Ranger Mike said:
i would like to take this time to thank you for the advice and use this as a teaching moment for students. I know this is a frivolous question about the tray freezing, but let us use this to demonstrate to the students, the thought process in solving a real world situation....

but i want some guidance on the scientific method of problem solving with this...why not?? not costing anyone anything...

jedishrfu said:
This is why scientists do detailed experiments under controlled conditions in a lab with a specially built freezing unit where they can minimize extraneous sources of energy and truly isolate the system.
A better quality experiment is really the only way to go here, if you won't accept the answer given in Post #2. When I did my Mpemba experiment 15 years ago(!) I used coffee cups with a measured amount of water, and a 4-channel data logger. If you start with warm water you will certainly be able to observe and quantify the significant difference in heat transfer for different positions in the freezer.
 
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