Freezing An Ice Battery Technique

You are wasting time and energy.

The thermal conductivity of ice is greater than water.

Thermodynamic Anomalies of Water

The energy used to freeze the water will negate any savings you may get from this "battery".

If I am interpreting the above link data correctly at T11 the thermal conductivity of water below freezing continues to drop sharply as shown by the gray line.

Thermal Conductivity

From the referenced site: "As the temperature of water is lowered, the rate at which energy is transferred is reduced to an ever-increasing extent. Instead of the energy being transferred between molecules, it is stored in the hydrogen bonding fluctuations within the increasingly large clusters that occur at lower temperatures."

Ice fishermen won't help your air conditioning woes because few of them even have AC in their homes.

I agree with Lyn

To improve the ice block making. Add as many {already made} cubes of ice to the tank as possible along with the water. The warmer the source water, the more ice necessary.

Are there a few ice fisherman available for comment? Does a layer of ice on a lake tend to insulate the lake water from further freezing?

Please try here.

I don't ice fish but given open air exposure and enough time our lakes regularly freeze to 3 - 4+ feet thick in open areas in the winter.

So given a common home deep freeze unit running at -10F or lower internal temperature yet one of those will freeze its internal volume filled with water to a solid block of ice if given enough time. Not over night and maybe not in a week or two but given a month or more yes it will.

Lakes freeze to any thickness given enough time and cold. They always freeze from top to bottom. So the answer is no the ice does not isolate!

They freeze from top to bottom, as you put it, purely because ice floats, being less dense than water. Water is densest at 4degC (about 36degF). It's one of the wonderfully weird things about water that allows life on Earth to exist.

But don't go thinking there's any designer at work....

Hey, I designed that, and here you are raining on my parade.

ξ

Designed what, ice, water, or life?

I ice fish and would have to say no it doesn't insulate the water but I have seen the ice much thinner under snow.

Yes snow has insulating capabilities or more the entrained air has.

But this should not be the question in a freezer.

Never eat the yellow snow!

A bit like that, but one that utilizes a "residential freezer". which is why .. (unless he's chilling a bread box).. that it will not work.

Is it possible to freeze 40-50 pounds of ice into a block in a freezer on a hot summer night? Not mine... But if I started with 35-45 pounds of ice cubes.. no problemo..

OP don't wanna hear it.

That is the issue as how to effectively cool with a residential freezer. It may require 2 days to refreeze. The freezer(s) would be located in a basement next to the furnace including the AC A coil and is normally an over cooled space.

Yes a bit like the link.

Quote "The key factor here is how much thermal energy do you need to transfer and in what time frame."

Enough to offload the compressor and condenser fan for several hours during peak and could refreeze over 2 or 3 days if need be. Mass produced home freezers are fairly economical and could be used as is with the addition of a water tank and a glycol circulation loop to harvest. A fairly low tech energy storage system. Lack of a good energy storage system is the major issue in regard to the massive grid load required for peak use as well as effective use of intermittent sources such as wind solar etc.

And your numbers say what?

All the heat you pump out of the water in the freezer over that 2 - 3 days is still being pumped a second time by the central air system to get it out of the house.

As for the grid load do you own, operate and pay for that system? If not then it's not your problem to deal with and what you yourself do to lessen the load is so insanely microscopic your actions are of no value.

Especially considering that the typical home freezers heat pump system is nowhere near the efficiency of a decent central air unit and even worse once you factor in that any heat that the freezer takes out of the ice has to be re pumped a second time by the central air system to actually get it out of the house.

If you are out to lessen your own energy usage and costs simply turning your system off at peak times will get you way further ahead than any homemade ice block thermal sink battery ever will. Especially compared to one made from a home freezer unit and a tank of antifreeze.

Without any numbers on what your central air system is rated at and what size of freezer and its relative rating is along with the realistic run times you want for each and how often no one here can give you any definitive numbers on things other than the basic ones that will show that over all what you are proposing will be a waste of your time money and effort and will gain you or the grid nothing in the end.

Quote "All the heat you pump out of the water in the freezer over that 2 - 3 days is still being pumped a second time by the central air system to get it out of the house."

The freezer(s) would be in a somewhat cool basement next to the furnace which is usually overcooled by the AC ductwork so it's an opportunity to recover some of the unused coolness.

That said some good points to be looked into such as freezer efficiency and capacity. Also need to look into off peak electric discounts if available.

Not going to even try to refute, "Mass produced home freezers are fairly economical" but if you take tcmtech's 12,000 BTU figure and figure 1 BTU of energy is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit you may be able to put this in perspective.

Good luck.

QUOTE: "I have pondered this type of question from time-to-time but instead of using a residential freezer, use the residence's central air conditioner to freeze a volume of water using a heat transfer liquid or 'embedding' the evaporator coil in the volume of water."

Interesting idea as the residential freezer could then be primarily used for storage. Perhaps a bypass normally used for setting static air pressure could go full bypass at night and cool a coil to chill the storage tank in the freezer?

Can an evaporator coil operate at a below freezing temperature without slugging the compressor? I am more familiar with R22 I guess.

Wow, are you ever using a lot of word salad without knowing what any of the words mean.

Can an evaporator coil operate at a below freezing temperature without slugging the compressor?

It depends on the heat transfer fluid's properties and freezing point. If you try and mix your own and (for example) the water separates out of the mix then you likely will.

This all sounds like an interesting project but I don't think you will see enough savings to pay for the equipment necessary to make it work properly. Then again I am not an HVAC expert.

You might end up with slugging, but you would need to get the refrigeration tables for the specific compressor and refrigerant and the expected temperatures and run the numbers. I have no way of being able to answer that question here with the information I have. A low pressure cut-out switch is employed in automotive refrigeration systems to prevent just that.

That's a perfect example of something that a knowledgeable and experienced heat pump technician or avid experimenter would have no major problems dealing with, or even cheating a non ideal compressor/condenser/evaporator combination to do,but if a person isn't of such already established background it's way harder to do than it sounds on paper.

It is at the bottom end of what most heat pumps can handle, so perhaps better to use the ammonia cycle (in Vcc mode) to achieve maximum attainable freeze efficiency for storage of the cold temperature.

It seems to be what many ice plants use.

Bottom end in what way?

I have personally worked with many old refrigerator, freezer and even modified small window AC units that ran common R-22 refrigerants that easily handled operating with as low as -30 F evaporator temperatures without issue either as part of their design or during excessive long run hard freeze up conditions due to stuck thermostats or damaged frost detect interlock malfunctions.

The coldest continuous run R-22 based heat pump operation I have ever seen first hand was a old deep freeze my mom had that had a broken thermostat so the compressor never shut off and she had it running that way for several years before I found out about it and put a new thermostat in it for her.

The old mechanical thermometer inside it was pegged at -40F and the digital one that hung on the wall behind it that read via a pigtail sensor showed between -45 and -53F depending on the season. The only reason she had me fix it was because didn't like having to microwave her ice cream to get it soft enough to scoop out of the containers.

As for central air units the one I made up of surplus parts for my old house runs an air duct temperature around 35 - 40 F with a return line temperature of - 5 to +5 F in normal operations with light suction line frosting all the way back to the main outdoor unit most days.

As calculated EER is 12 - 14+ depending on the inside and outside temperatures and humidity which isn't bad for a 40+ year old outside AC unit and compressor roughly matched to a modern A coil.

Cheers on that. It was only a recommendation I read somewhere. Probably a college boy.

Hey, that works for me, the old stuff is hard to come by these days, if it is still working, keep it!

I still say that most ice manufacturers use ammonia cycle.

Best part was she picked it up at an auction for $5 or so.

I've only been in one bagged ice plant before and that was some 12 - 15 years ago and the guy who ran it openly admitted he built much of the cooling systems himself. I cant recall the exact tonnage capacity he could top out at but I do know that his main ice maker system was custom built around 3 - 4 large central air units and was standard R-22 based.

Filtered municipal water went in and a steady stream of ice cubes augered out the other end into a automatic bagger system. ~7 - 8 cents a bag to make and sold to the local markets for 50 - 70 cents a bag.

He was the one who got me into DIY refrigeration by telling me the dirty little secrets behind the HVAC industry laws and regulations regarding legally buying 'licence only' refrigerants and working on various heat pump systems that have them. Lots of grey areas and loopholes in that industry being its largely ran by greedy crooks.

~15 years later and if anything the regulations have gotten looser rather than tighter. Refrigerants that were banned or special application only back, like R-290 (propane), then are part of the standard operating list now.

Apparently buying a 30# tank of R-22 for $100 and selling the contents to customers for $1000 wasn't good enough so now we have commercial R-290 refrigeration grade propane that sells for $50 a tank and they can rip the customers off for $2000 a tank because it's 'more environmentally friendly'.

Interesting commercial application of an ice battery:

"The brine, which is a combination of propylene glycol and water, begins to freeze at -6°C. Brine-ice is then generated and accumulated overnight.
During the day, the brine fluid exits the thermal storage tank and is circulated throughout Yamato’s simulated indoor retail environment at -6° C."

See Yamato ice battery

To get back on topic, assume that you install several or even many small heat pipes sticking up out of the vat to be used to contain the ice in this freezer.

These will conduct heat out of the water below the iced over surface, and facilitate the freezing. Now imagine that instead of using heat pipes, there are small heat walls made just in the same way as a heat pipe.

Does that help you with your design?

Your key aim is to get maximum surface area for heat transfer into and out of the battery. If I were repurposing to make up an ice battery, I would use flat aluminum tanks just large enough to accept the core of a car radiator and place several of these with air gaps between them inside the freezer. You then put in a small circulating blower to move the air around the surface area of the flat tanks. Increasing the surface area increases the freezing rate and decreases the differential temperature across the water/ice. You then plumb the radiator cores in parallel and circulate the ethylene glycol to your outside heat load.

All things considered the reality of this project is that a reasonable cost analysis study has to be done to show the actual range of likely costs Vs payback times Vs perceived other gains involved before much of anything is worth pursuing.

Right now if no off peak electrical power is being used for the thermal battery charge cycle there is already zero cost savings justification behind the concept which put the rational viability behind the project to be one of purely learning and hands on fabrication experience.

Of which, if a person doesn't already have practical applied working knowledge and the tools in hand to chop up their central heating and cooling systems and put them back together it's a totally irrational concept to pursue to which effect as I see the OP right now obviously he doesn't have such technical capacity to undertake such a project.

I looked up ice battery and found it was originally intended for storage of solar power for use in air conditioning after the sun goes down. If that's the purpose in this case, it seems perfectly reasonable to me.

I've always thought about using well water at 56 deg put through auto radiator cores as spot coolers for the cooling season, but if I were using solar, the ice battery makes sense.

I recall some canned stuff with a 60 degree liquid/solid phase change that was intended for putting into tromb walls for passive air cooling/heating from back in the 80's. Had a friend who used it and it worked.

Even those solar application of ice battery face an uphill cost justification and practical utility battle.

If you build it yourself from repurposed idle material, it's a no-brainer. The conditions would need to be a little specific. Surplus solar capacity. expensive or off-the-grid electricity, a need for overnight air conditioning and a supply of "stuff" to rob for parts of the system.

There are a couple of companies that are entering the market for off-grid, solar powered refrigerated storage based on some licensed NASA patents. For that use, the ice battery makes a lot of sense unless you could find an alternate "electrolyte" that has a greater heat storage capacity during phase change.

Thought out of the blue: Use fermented juice as the electrolyte and tap the freeze distilled ethanol off of the bottom of the tank as a saleable side product or as an anesthetic while you watch the ice freeze.

Might not be necessary in Canada, Alaska or the North Pole.

You left off Tasmania, Patagonia, and the South Pole. Be thorough.

Thanks, buddy.

...remind me that I'm going to have an AC question in a few months.

it's a bit of a tomb raid as years ago somebody drywalled over the indoor blower portion. (except the filter slot) how thoughtful