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DIY Chest Freezer for Off-Peak make-shift air-con - Hardtuned.net

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DIY Chest Freezer for Off-Peak make-shift air-con 

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#1 buoy

  • Joined:15-June 03
  • Location:Australia NSW
  • Car:RAV4

Posted 01 November 2013 - 07:23 PM

Hi all,

-INTRODUCTION- (only read if interested... otherwise proceed to topic question below)
We had at our new place a reasonably sized air conditioning unit installed. The unit is great, it cools, it's reverse cycle so it heats in the winter etc. We have our 1 year old son so during the recent winter months we were quite liberal with using the air-con as a heater, heating the lounge room so he could play etc.

Then came the electric bill..... and boy oh boy. Just a shade under $2000...... and the usage was off the chart, especially during the peak times. I really thought we could bring the bill down so I made several adjustments to the house - and for this summer coming up I did a bit of stuff to the house: energy saver blubs, external shades on the windows getting lots of sun..... am selling our huge plasma for a much cheaper LED TV very soon.

Then I started to tackle the air-conditioner problem. Looking at my energy bill, our provider gives us Peak, Off-Peak and Shoulder. So as to keep everything streamlined for discussion let's just concentrate on peak and off-peak:
Peak usage costs around 50c per kwh. This is from 2pm - 10pm.
Off-Peak usage costs around 11c per kwh. This is from 10pm - 7am.
(Shoulder is around 20c and occurs at other times and even some times in-between but lets keep it simple for arguments sake).



-TOPIC QUESTION-
When you use the air-con, it uses a lot of electricity from the moment you turn it on. I want to "shift" the cooling work to the off-peak portion of the day (between 10pm and 7am) since there is a significant difference in price - peak is roughly 5 times more expensive than off-peak. So... whatever inefficiencies due to reduced operating efficiency, containment or anything else... it must not exceed 5 times the consumption of our air-con... otherwise it's not worth doing. But anything less than 5x would see some benefit.

In other words, if it takes X amount of energy to use our air-con..... as long as the "shifted cooling" solution takes less than 5X, even though we are using more electricity, we are saving money due to the way the electricity bill is calculated.



SCHEME: Chest freezer to freeze a liquid eg water + anti-freeze... then run some sort of piping to an air/water heat transfer radiator - since chest freezers have hose outlets at the bottom for drainage ---- and exchange the heat with a few fans, thus cooling the house. Run the freezer only during off-peak hours (10pm - 7am). Rely on the freezers insulation to preserve the work done to cool the liquid during the day until it is needed by us - most likely between the hours of 3pm until around 10pm - after which time we would either be asleep or the actual air-con could be used at off-peak rates, negating the need to use this system entirely.

CAVEATS:
The freezer is not as efficient as an air-conditioner: This is true... but the big question is: How MUCH less efficient. Even if the air-con is in the range of 50% more efficient at generating cool air, we have a 500% ceiling with which to play around with due to peak vs off-peak.

The freezer will heat up the room it is in. This is correct... but we will have the freezer in the laundry and with the windows open... so it will be exchanging heat with the ambient air very slowly.

The freezer will not have enough cooling to last the whole night. Perhaps not even until 10pm. While true, it still means that it is cutting into the cost of running an air-conditioning unit during peak - thus it is still reducing our electricity bill.



INTERNET RESEARCH:
I've seen a few videos on youtube which exploit this system - some quite DIY like this one:


and then there is this thread on another forum:
http://cr4.globalspe...Air-Conditioner

One thing that constantly appears in those threads is that the commenters hammer the point home that an air-con is much more efficient than a freezer and they talk about putting it outside, that you are wasting money, that your bill would be more. Ok. Apparently those thread posters have a point, and it still holds to this day and it is this: The freezer solution is ONLY applicable to people who have an energy Peak and Off-Peak zone in their billing system. If you do not have a peak and off peak rate then just use your air-con because there are no savings with this method. You'd actually use more power and pay more money.


Has anyone done this before? Do you know of any off-the-shelf off-peak air conditioner units for residential households you could buy? I notice that there are none on e-bay and there seem to only be a few systems like this in the world for some strange reason :o one of which is called the "Ice Bear" and I'm not about to spend a massive amount of money. I'm looking to hopefully drop my powerbill by some moderate percentage. If I achieve say a moderate 30% reduction then... my bill would go from $2000 to $1400 so the cost must justify the means.

#2 just_learning_import

  • Joined:03-February 06
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Posted 01 November 2013 - 08:53 PM

This is by no means a good way to cool a large room , but mate of mine filled an old intercooler with water and froze it in his deep freeze while he was at work , then when he was home he hung 6 x 3 inch computer fans on the back of it with a speed controller placed it in a home made ply box that was fiberglassed lined and turned it on in his room ...very clever and cheap solution to a warm room , it would cool the room a fair bit for around 6 hours . ..................................On another note I hear a lot of people who are having solar panels fitted just to off set there split cycle with doesn't cost them any thing to run 24/7 due to the solar panels

#3 Wrexy

  • Joined:06-June 04
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Posted 02 November 2013 - 08:48 AM

theres an easier way

Posted Image

#4 Rhysee

  • Joined:23-November 08
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Posted 02 November 2013 - 05:52 PM

Just buy one of those hats with a fan attached to the brim.

#5 just_learning_import

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Posted 02 November 2013 - 06:47 PM

what about using the chest freezer option with anti freeze solution in radiators have that transfer to an outer unit like an old intercooler . have the radiators packed with bags of ice or even dry ice , then you could simply use a fan to have a flow of air from the intercooler to the room ...............also I know if you add salt to water when freezing it , it will make it around 7 deg colder again

Edited by just_learning_import, 02 November 2013 - 06:48 PM.


#6 richo79

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Posted 02 November 2013 - 06:47 PM

Changeover switch?

#7 buoy

  • Joined:15-June 03
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Posted 02 November 2013 - 11:30 PM

I think we are getting there. J.L.I your idea is spot on.

Chest Freezer connected to wall outlet with a timer that only activates during off-peak loading.
I am sourcing a 2nd hand CPU Radiator + fan and I just purchased a USB water pump from eBay for $5. To test this I'm first just going to put a bucket in the fridge and make sure there is decent cooling coming from the CPU radiator.

BTU HEATING / COOLING CAPACITY OF PROTOTYPE:
From a few Google searches a typical high-end computer puts out around 1400 BTUs an hour.... and by comparison an air-conditioner puts out anywhere from around 12000 BTUs for a smallish one all the way up to 20000+ BTUs for a medium sized home A/C. The CPU heat exchanger is technically only a fraction of the PCs total output - but on full load the CPU (apart from the GPU) can dominate the power draw - hence the huge cooler on it on the big PC builds. Thus a 1400 BTU heat exchanger isn't going to do the job of one air-con by itself....................... so maybe I'll have to either buy several used CPU-coolers (very very cheap on ebay and I have a few friends who have "old" CPU water cooling kits that, for their use cooling a CPU - is already surpassed in usefulness so instead of throwing it I ask for the radiator and fan bits). Or I go for a used oil cooler for a car and whack on some fans. The car fans tend to be quite loud and anything "brand new" is ridiculous in price.... but 2nd hand is dirt cheap. Probably a goal would be several thousand BTUs and we will "see how it goes". Will cool sufficiently until 10pm? Will we need more cooling than that? Is it only good for mildly warm days? For super-hot days is it worth running + the air-con to off-set the air-con's job so it doesn't run too hard?

We'll the prototype is going to cost me less than $20 to build anyway. Just a USB pump from china ($5), an old CPU water cooling kit (free), some hoses from an aquarium place and a bucket of cold water to "test".

If the design seems promising maybe I might decide on getting a larger freezer with a larger compressor...... that way it can draw more power during off-peak and store a larger amount of cold water.

I also am probably going to try "chilled water" at 3 degrees celsius instead of going for the anti-freeze. If I go sub-zero, I may have to purchase sturdier hosing, pumps and radiators that have been built to withstand that amount of temperature day-in-day-out. There is also the issue of not just condensation on the radiator housing and hosing but ice crystals forming. Not sure if it will be problematic but we'll see if 3 degrees is sufficient. If not, according to the Carnot efficiency scale we will gain more efficient operation by driving the temperature down even further. If I use antifreeze we can dive down to easily -20 degrees celsius no problems. That effectively doubles the cooling capacity of the whole system and makes it twice as efficient according to the Carnot efficiency law (2nd law? whatever... something like that) the point is, the bigger the difference between the hottest and coldest parts of your system, the better.

Just like your car, it follows the same efficiency law. The hotter the temp in the combustion chamber after the burn with the coldest air... you produce more horsepower OMG WOW! Really? :P So you build stuff that pushes these 2 points farther and farther apart. Colder intake air. Intercoolers after the turbo etc.... and of course the highest compression you can muster without predetonation.

Anyway, back to our cooling reservoir / radiator: I'll get it done over the next few weeks and chime back in here with photos and perhaps a video.

#8 buoy

  • Joined:15-June 03
  • Location:Australia NSW
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Posted 02 November 2013 - 11:52 PM

Just found this video on YT which shows a similar idea implemented.


Basic points: It works....... but as I had guessed earlier, a small radiator and small pump is going to get you a thousand or so BTUs of cooling (compared to the aircons that regularly push out 10,000 - 20,000 BTUs) so we are at 1/10th the cooling capacity of an air-con with 1 small radiator and 1 pump and with an esky full of ice, say 40L capacity we are pushing 2 hours of cooling.

He also gets crazy condensation on the radiator itself due to moisture in the air reaching due level... so perhaps that extra water can make its way back into the tank in our design somehow... or out the window.

BUILD TO SCALE - 200L and -20 DEGREES IS THE GOAL:
Thus to make this system work for many hours and cool significantly more, you'd need to run anti-freeze and put the coolant down to -20 or so. You'd need a much larger cold-sink reservoir - not 40L but say 200L capacity. At 200L an entry level chest freezer usually starts at around 150L - 200L capacity for a "small" unit. So that being said, a decent sized cooling unit with freezer and heat exchanger would have a cooling output many times greater than this youtube unit and could last several hours longer... so we should be looking at 6-8 degrees cooling for 5 hours as a reasonable expectation of such a system. This video is obviously only attempting a proof-of-concept - and at that it is very successful.

#9 GHOSTY

  • Joined:14-September 05
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Posted 03 November 2013 - 12:41 AM

More people need to buy solar, like on a massive scale, so solar becomes so cheap due to high volume and high competition, take it a step further, solar companies need to offer off the grid battery packs so for the most part, people don't need to rely on the grid, this will inturn real in the electricity prices, hopefully. On a side note, I still can't believe in this day and age that every single surface area of roof and skyscraper wall is not covered in solar panels....

#10 buoy

  • Joined:15-June 03
  • Location:Australia NSW
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Posted 03 November 2013 - 04:16 AM

Hi Ghosty - that is a good goal - kinda like (in my opinion) the race to get a PC in every home back in the 90s... or a TV in each house in the 70s... or a Radio in each household back in the 30s and 40s... or a Fridge/Freezer in a household back at the turn of the century. These were all lofty goals at those times but if we look at the most recent "PC in each home" goal - Not only was that goal met but we superseded it several times over.

The issues we have today are that battery power is expensive. I actually looked into getting a large UPS or DIY-car-battery-hack instead of the whole chest freezer project..... so I could run the air-con via the UPS and charge the thing during off-peak, effectively shifting the air-con electricity usage to off-peak rates only --- but the UPS solutions cost upwards of $5,000 for an off-the-shelf solution and the DIY gang via marine power components and chargers will still set you back a few thousand. Doing it complete DIY getting car batteries and some inverters / battery chargers creates hydrogen gas and leaking issues since these battery packs don't have the sophisticated recharge curves the marine chargers have - and - you really need to get deep cycle AGM batteries otherwise the car batteries just won't last that long under these conditions. AGM batteries are expensive per unit - like $400 per battery.

The second issue with battery power is the conversion loss. You get hit hard. For every 10 joules of energy you put in to the battery you would be lucky to get back 3 or 4 joules. Thus, using electricity as a storage medium.... and THEN running a freezer which already carries an efficiency penalty, then there is the heat/cold sink temperature dissipation leakage you factor in and you end up almost wasting your time for very little gain. If your off-peak rate was 1/10th your peak rate it may still be worth it but with a 1/5th rate I couldn't waste too much on conversion after conversion of energy. You just lose too much each time you convert.

The third and final blow to the UPS idea was unfortunately that UPS systems weren't designed for running air-cons (but marine power systems were... so there was still hope with that method). It was at about this point I decided battery power wasn't the solution I'd go for in this situation at this point in time.


=====================

More information on the cooling potential of a 200L freezer:

A standard "TR" (Can't find what it stands for) is the energy required to freeze 1 short ton of water from "room temperature" (whatever that is... perhaps they are talking about T in textbook "STP") down to zero degrees Celsius. This works out to be 12000 BTUs/hr. That is the cooling level of an entry level air-conditioning unit that has a power draw of 3.5kW.

In other words, if you ran a 12000 BTU Air-Con at full power for 24 hours, you would freeze 1 ton of water into ice.

So now we have a solid metric to make some guesstimates as to what we could expect with a 200L (read: 1/5th of 1 ton) freezer.

200L - being 1/5th would mean if it were in fact frozen at 0 celsius, we'd be able to "extract" approximately 12000 BTUs of cooling from this cold-reservoir for 1/5th of 24hours.... in other words, we'd be able to run it for a shade under 5 hours straight. Firstly, the water isn't at zero, it's at around 3 degrees celsius... so we'd have to shave off say 10 or 20 minutes from the top end of that right off the bat. Also, unfortunately due to Carnots thermodynamics 2nd law, as the temperature of the water in the freezer compartment gets closer to the temperature of the room, the efficiency of the cooling cycle drops. So lets say you'd get a "strong" 12000 BTU cooling for 2.5 hours and then you'd see less and less BTUs for the remaining few hours.

That may seem quite miserable but this is in comparison to a 12000 BTU air-con AT FULL BLAST. If you've run an air-con at full blast you know how incredibly cold it could make a room very quickly and thus many air-cons have inverters or at least thermostats fitted to switch the power on/off or at partial power to prevent the room from diving right down. So--- ok, it can't do 12000 BTUs for very long, granted.... but reality says you wouldn't want it to anyway. Realistically you may use 12000 BTUs for the first 20 or 30 minutes then after the room is nice and cool you'd run it at a partial load of that... perhaps 3000-6000BTUs to maintain the lower temperature. If that is a realistic assumption then we've just pulled another 2-3 hours of "strong" cooling out of our asses.

Another note is that this is just 200L at 3 degrees celsius. If you want to increase the longevity and power of the system, you could opt to dive under 0 degrees for your cooling reservoir... by several methods:

1. You could run a mineral oil like sunflower oil which has a freezing temperature of -17 degrees celsius and hover at around -14. This would give you a lower cold-sink starting temperature so your heat exchanger would run more efficiently for the first few hours. You'd have extended the useful range of everything- the cooling capacity, the cooling rate and all without changing the number of liters of the system.

2. You could run a 1:1 mixture of water and anti-freeze. Anti-freeze freezes at around -37 degrees Celsius. Thus you've increased your cold-sink reservoir's efficiency yet again over oil... you'd get even more hours of useful cooling out of it. But obviously to do this day-in-day-out you may have to reconsider your heat exchanger components, especially the pump, which may not be able to operate at those extremely low temperatures. You may have to purchase equipment designed for extreme temperatures. They are definitely out there... but I haven't done any internet research on them yet.

3. You could simply buy a larger freezer.

So there you go. On paper at least, given these assumptions, you could conceivably build a hypothetical 200L-driven system with anti-freeze that would run "strong" cooling for 8-10 hours straight. Or you could get a 300 or 400L freezer and have an entire full days worth of "strong" cooling on tap. By only allowing the freezer to run during off-peak times you limit your power bill yet receive the benefits of cooling at any time of the day or night.



======

This guy has done a great mod for $20 that is literally what I'm trying to do... but his goals were much more modest than what I'm planning. Still, the method looks quite sound. PS: 1 "gallon" = 4 Litres.


#11 TheApothecary

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Posted 03 November 2013 - 09:05 AM

View PostGHOSTY, on 03 November 2013 - 12:41 AM, said:

I still can't believe in this day and age that every single surface area of roof and skyscraper wall is not covered in solar panels....

+1111111111111111111111111111111111111111111111111111111111111111111111111111111

What I don't get, is in Adelaide, it seems as if almost every roof has solar and yet the price of electricity keeps going up - how does that work?

#12 antonio

  • Joined:26-September 05
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Posted 04 November 2013 - 12:33 PM

View PostTheApothecary, on 03 November 2013 - 09:05 AM, said:

View PostGHOSTY, on 03 November 2013 - 12:41 AM, said:

I still can't believe in this day and age that every single surface area of roof and skyscraper wall is not covered in solar panels....

+1111111111111111111111111111111111111111111111111111111111111111111111111111111

What I don't get, is in Adelaide, it seems as if almost every roof has solar and yet the price of electricity keeps going up - how does that work?

It really is a huge scam from power companys, i guess they do know there time is on the way out as Solar Energy becomes better and better, and really i presume the generation will come where Energy Companys will moreso do more Business instead of providing you energy cause we will be giving it all to them anyway.

Ive heard of some people feeding energy back to the grid and getting a discount off there bill aswell.

#13 Fire_Child22

  • Joined:12-May 07
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Posted 04 November 2013 - 01:10 PM

View Postantonio, on 04 November 2013 - 12:33 PM, said:

View PostTheApothecary, on 03 November 2013 - 09:05 AM, said:

View PostGHOSTY, on 03 November 2013 - 12:41 AM, said:

I still can't believe in this day and age that every single surface area of roof and skyscraper wall is not covered in solar panels....

+1111111111111111111111111111111111111111111111111111111111111111111111111111111

What I don't get, is in Adelaide, it seems as if almost every roof has solar and yet the price of electricity keeps going up - how does that work?

It really is a huge scam from power companys, i guess they do know there time is on the way out as Solar Energy becomes better and better, and really i presume the generation will come where Energy Companys will moreso do more Business instead of providing you energy cause we will be giving it all to them anyway.

Ive heard of some people feeding energy back to the grid and getting a discount off there bill aswell.

feeding energy back to the grid is what home solar energy does.

It offsets your bill by the usage and times generated.

Even if the whole city was under solar, we would still need energy companies to 1, store the energy when it's in abundance (off peak) and 2, provide continuous power when conditions change (cloud cover causing a sudden surge on power demand and sudden power demand during colder and warmer months) and 3. peak nighttime use.

Until batteries are efficient enough to store energy and return it to us to reduce the fluctuations caused by changing weather conditions, it won't be where you guys want it for another 10 years.

Edited by Fire_Child22, 04 November 2013 - 01:12 PM.


#14 antonio

  • Joined:26-September 05
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Posted 04 November 2013 - 01:17 PM

Hrmm you do raise a good point, i guess the storage of power is the biggest problem.. I also see a problem being funding aswell.. Like which companys would want to fund these projects that cost into the Millions? The government gets attacked heavily if they spend money all willy nilly..
No power company would want to invest unless its going to make them more money or they want to control the development process to get Patents out of it too.

10years might still not even be possible on the large scale, i know in Victoria all new houses need to add upto some 5star energy rating which i think means a Water Tank and Solar Panels..

We don't even have Hover Boards yet, so that Documentary was completely false aswell.

#15 Fire_Child22

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Posted 04 November 2013 - 02:37 PM

When Julia was leading, she launched an initiative for tenders on renewable energy concepts that could sustain some percentage of the demand.

The company that won the tener got upto a 20 million dollar grant for a proof of concept model.

I don't know if the recent election has changed that or not though.

#16 Wrexy

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Posted 04 November 2013 - 03:52 PM



#17 TheApothecary

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Posted 04 November 2013 - 04:40 PM

Apparently you could go off grid completely for $80,000. But you still get charged a service fee as the powerlines run past your house or some nonsense (despite it being on council land as you don't own the footpath).

#18 sr180

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Posted 05 November 2013 - 07:53 AM

50c a kilowatt hour. Farrk... I thought 30 was bad... Jeezus we get screwed.

#19 Jarryd F

  • Joined:04-November 06
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Posted 05 November 2013 - 03:50 PM

View Postsr180, on 05 November 2013 - 07:53 AM, said:

50c a kilowatt hour. Farrk... I thought 30 was bad... Jeezus we get screwed.

Yeah $0.50 is crazy per kW/h

Maybe you should change companies or plans. In Melbourne just on a standard rate I pay $0.27 per kW/h (Energy Australia). no off peak/shoulder business.

Why are you using your A/C in reverse cycle for heating? Isn't natural gas readily available in NSW? It's much cheaper and much more cost effective.

As for cooling, its probably cheaper, easier and a lot safer to suck it up deal with a portable evaporative cooler than some dodgy hacked up A/C system.

#20 sus023

  • Joined:21-September 10
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Posted 06 November 2013 - 11:18 AM

Get split systems. You can put them on timers to cool the house in off peak. Then spend more money on insulation.

Split systems work more efficient as the air doesn't need to run through a hot roof to get to the room.

My brother is a Fridgy and this was his advise to me to other day. As I'm having the same issue

#21 buoy

  • Joined:15-June 03
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Posted 07 November 2013 - 10:04 AM

I have just received the cooler with piping. I've put a 50c coin in there for reference so you can gauge the size of it. It's one of the "bigger" CPU coolers out there. Should be good for a few thousand BTUs of cooling. Now I have to either wait for the pump to arrive via snail mail or pop over to the local aquarium shop and buy a bilge pump.

Attached Thumbnails

  • Attached Image: cooler.jpg


#22 buoy

  • Joined:15-June 03
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Posted 08 November 2013 - 03:23 AM

UPDATE: I ran my first tests with the unit tonight. They were promising. I also did a lot of googling and I discovered something amazing (for me at least).

When water converts to Ice, it takes a lot of energy to extract all the heat ( http://en.wikipedia....halpy_of_fusion ) whlist the hydrogen bonds are formed to create the ice crystals. In fact, to heat 1L of water from 10 degrees to 30 degrees takes 84 kilojoules of energy........... but to thaw 1L of ice from 0 degrees to 20 degrees (same temperature difference but from the freezing point of water) it takes 415 kilojoules... or about 4 times as much. Another way of looking at it is, if you can cope with the expansion of water into ICE in at least some portion of the your coolant storage then you can have 4 times the effective cooling or have the same amount of cooling in a quarter of the space.

Using ICE would in fact result in more cooling than water + antifreeze since antifreeze is effective until around -35 degrees celsius.... yet if you wanted to compete with the thermal efficiency of ICE you'd have to keep going way way way down to almost -90 degrees as a liquid. O_o geebus. Don't misunderstand this point. Anti-freeze at -35 will give you frost-bite, but the total amount of cooling is less than ice. The ice will take longer to melt over the entire duration going back to room temperature than the anti-freeze.

I was thinking then that I could run a double-container design. The interior "bin" with an open lid contains water that gets frozen. The bin itself is not rigid... it's bendy like plastic or thin metal to cope with the deformation pressures exerted when ice forms - and the lid open of course and not filled to the top. The outer bin is slightly larger, contains water + some anti-freeze. Even though plastic is not a good conductor of heat, the transfer process need not be very fast as the cold storage is just going to be siphoned slowly over many hours. For the freezing temperature, I'm hoping that I can get everything maintained at -2 degrees which freezes the internal chamber but leaves the external chamber as a liquid, which then goes through the radiator.

I'm now looking at a 100L tiny chest freezer to do the whole thing. Also..... I found this interesting entry in Wikipedia on Ice Thermal Storage:

Quote

Ice-based technology[edit]

Main article: Ice storage air conditioning
Air conditioning can be provided more efficiently by using cheaper electricity at night to freeze water into ice, then using the cool of the ice in the afternoon to reduce the electricity needed to handle air conditioning demands. Thermal energy storage using ice makes use of the large heat of fusion of water. One metric ton of water, one cubic meter, can store 334 million joules (MJ) or 317,000 BTUs (93kWh or 26.4 ton-hours). In fact, ice was originally transported from mountains to cities for use as a coolant, and the original definition of a "ton" of cooling capacity (heat flow) was the heat to melt one ton of ice every 24 hours. This is the heat flow one would expect in a 3,000-square-foot (280 m2) house in Boston in the summer. This definition has since been replaced by less archaic units: one ton HVAC capacity = 12,000 BTU/hour (~3.5 kW). Either way, an agreeably small storage facility can hold enough ice to cool a large building for a day or a week, whether that ice is produced byanhydrous ammonia chillers or hauled in by horse-drawn carts.
As such there are developing and developed applications where ice is produced during off peak periods and used for cooling at later time.

taken from http://en.wikipedia....ased_technology

#23 pmod

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Posted 08 November 2013 - 09:19 AM

Personally, I'd just make a huge swamp cooler using an industrial-style pedestal fan. Use some jersey material stitched into a loop, two aluminium tubes (the upper one attached to a single roller bearing and a small high-torque DC motor, with the lower roller running over a plastic tube), a freestanding aluminium frame mounting one roller inside a long plastic storage container filled with water.

Portable evaporative coolers can be had cheaply, but for one that pushes any meaningful air volume, it costs a lot more than it's worth. A DIY swamp cooler like this would push an immense amount of air, and with a modified fan controller, with minimal noise. In stock form it will be quite loud, so the current to the motor would have to be reduced prior to hitting the potentiometer.

#24 buoy

  • Joined:15-June 03
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Posted 08 November 2013 - 10:29 PM

I am not too fond of the swamp cooler. I had an evap cooler a long time ago and it hardly worked and rusted my PC and chair. hinges. Here in the inner west of Sydney the humidity sometimes doesn't leave much room for evaps to work very well.

I've pushed on with the freezer and since tonight was (well "is" still outisde) especially hot, I'm in the room with a cool breeze blowing around and have been since 10pm, the thing still going strong. All I did was buy 2 bags of 5kg Ice from the 7/11 at $4 a bag (so $8 total... of course it's just for testing. I'd have to provision for making ice at home) and a 25L Esky we had lying around.

I had to put around another 5L of tap water to create a liquid base so I could submerge the water pump... then I just set it up on my desk and turned it on with the room fan behind it.

Results were nothing short of spectacular. It cooled parts of the bed so well that it was cold cold COLD to touch. Condensation became an issue so I got a pan from the kitchen to stand the cpu cooler in.

From these preliminary tests, even 10kg of ICE aka frozen water at 0 degrees celsius... which has approximately the equivalent cooling potential as 45L of liquid water at 0 degrees celsius, has cooled down a pretty hot room for at least 2 hours as of typing this message - it's now a little past midnight and it's still going strong - perhaps another hour or so. Of course, the cpu cooler is a "bottleneck" in that its only allowing the ice to cool the room at a lowish rate - nothing like full blast of an air-con. Localised cooling (as I mentioned with parts of the bed) is great. It did take a while to cool down the entire "ambient" feel of the room. It became noticeable when I left the room a few times and came back. That door opening and that whoosh of cold air, that kinda "signature" air-con blast was definitely there.

I now realise that getting a 200L chest freezer would in fact be more than ample to cool down the room all night and even all day - but the main issue is that ice expands and if I pursue it I'm going to have to work out a way to freeze the water without busting the freezer itself. Perhaps a huge plastic stretchy container... but I'm more impressed with the esky conversion now.

What I'll probably do is create a little lid for the esky and put the cpu cooler in there along with a fan. I'll also put an internal lid slightly lower than the lid with the cpu cooler and fan which will have some styrofoam insulation (perhaps... not sure) to keep the ice compartment separated. There will be 2 holes in this interior lid for the 2 hoses and the power chord for the water pump. That way I can just carry the esky into a room, plug in 2 power sockets and away it goes. Any condensation on the cpu cooler will just simply drip down onto the interior lid and perhaps if I put 1 or 2 small holes it will just drip back down into the ice / water reservoir.

Since the pump is submerged its whisper quiet. The only thing to hear is the fan. It's as quiet as, well, an aquarium.

Every now and then the ice shifts around as it slowly continues to melt... and as long as both hoses are submerged there is no sound of water at all.

All in all I am really impressed with the results. I may perform this on a larger Esky. This one is pretty small as I could only fit 2 bags of ice (5kg ea) in there. I'd probably go for an Esky 1.5 or 2x bigger so I could fit at least 15kg of ICE in there. That should extend the useful cooling time to somewhere around the 3-5 hour mark (guesstimate since I don't even know how far the current 10kg test esky is going to go).

I've taken a pic.

PS: Also, since this is simply a heat exchanger setup, in winter time I'm guessing that it could be used in a similar way with hot water... although I don't think the water pump is rated for very hot liquids (probably maxes out at 65 degrees or so)... the cpu cooler and piping was designed for this sort of heat exchange anyway so I'm sure those parts are up to the task. But in any case, for summer I'll be using this.

Attached Thumbnails

  • Attached Image: cooler-2-adj.jpg


#25 just_learning_import

  • Joined:03-February 06
  • Location:Australia QLD
  • Car:Nil

Posted 09 November 2013 - 11:32 PM

what about having a container say a 50 litre esky or similar submerge a radiator in the water with two hoses coming up above the water level , 1 to feed the cold air and the other is to pull cold air from the contained unit , so in turn your getting two lots of cold air . freeze the water while the radiator is submerged so the cold air it would create while being captured in ice , plus the cold air that it pulls from th contained area , so the next thing is to use some thing that can pull the cold air out the the hose ( this would need to be of radiator hose diameter to eliminate heat build up due to drag of air being pulled through a smaller diameter hose ) so the air would remain cool ..................another trick used to be when we went fishing was an old bar fridge , we packed it with 10 bags of ice taped up around the seal and it was still keeping every thing frozen for up to a week . so there is a thought with your chest freezer as well , eliminate any chance of air getting in that doesn't need to be there

Attached Thumbnails

  • Attached Image: cooler idea.jpg

Edited by just_learning_import, 09 November 2013 - 11:38 PM.


#26 buoy

  • Joined:15-June 03
  • Location:Australia NSW
  • Car:RAV4

Posted 10 November 2013 - 07:27 AM

That looks brilliant but there is 1 thing which we'd have to somehow "get around" and that is that submerged cooler will get condensation inside itself and start to fill up with water.

As for the cold air over the ice-cold water bit - I've got a feeling that this will introduce more moisture into the air... so everything around will start to feel damp after a while. Using just the submerged cooler actually extracts water out of the air (a dehimidifier if you will) which is why we get condensation in the first place. Perhaps you could have a third pipe out of the submerged cooler that extracts the moisture every now and then... wouldn't have to be very large... maybe once every 10 minutes it turns on for a few seconds and siphons the water out and into the esky.

#27 sr180

  • Joined:05-January 03
  • Location:Australia ACT
  • Car:Nissan 1996 180sx.

Posted 13 November 2013 - 10:39 AM

View Postjust_learning_import, on 09 November 2013 - 11:32 PM, said:

what about having a container say a 50 litre esky or similar submerge a radiator in the water with two hoses coming up above the water level , 1 to feed the cold air and the other is to pull cold air from the contained unit , so in turn your getting two lots of cold air . freeze the water while the radiator is submerged so the cold air it would create while being captured in ice , plus the cold air that it pulls from th contained area , so the next thing is to use some thing that can pull the cold air out the the hose ( this would need to be of radiator hose diameter to eliminate heat build up due to drag of air being pulled through a smaller diameter hose ) so the air would remain cool ..................another trick used to be when we went fishing was an old bar fridge , we packed it with 10 bags of ice taped up around the seal and it was still keeping every thing frozen for up to a week . so there is a thought with your chest freezer as well , eliminate any chance of air getting in that doesn't need to be there

Have the air intake through the bottom of the ice container. That way water will self drain as it condenses.

#28 Judas

  • Joined:20-April 06
  • Location:Australia VIC
  • Car:S1 - S14

Posted 26 November 2013 - 09:12 AM

What pump did you end up using buoy? just the USB one? I been meaning to set one of these up near my network for ages

#29 GHOSTY

  • Joined:14-September 05
  • Location:Australia QLD
  • Car:'02 S15

Posted 26 November 2013 - 06:34 PM

Updates?

#30 Judas

  • Joined:20-April 06
  • Location:Australia VIC
  • Car:S1 - S14

Posted 27 November 2013 - 08:47 AM

I say I say I say buoy you better answer me ya hear

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