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Discussion Starter · #1 ·
I'm a tree farmer/ nursery owner.

Each year I bring in bare root seedlings for my own use and for resale to customers. Keep in the shade, and packed in damp compost or sawdust the trees have a shelf life of 2-3 weeks before they wake up enough to start growing and tangle their roots.

This makes scheduling deliveries a pain.

If I had an industrial refrigerator, I could stack them in the reefer and keep them at 33 degrees for weeks.

But I don't need a reefer year round, and they are expensive to own, and draw a lot of power.


Here's my idea:

I can get a used insulated sea container for about 4K used. Put it in place somewhere in the shade.

I have a bunch of plastic 50 gallon drums. Fill them 3/4 with water (to leave room for expansion) and stack in the back half of the container. (Yes yes, stack first, *then* fill. Lifting 400 lbs of wet drum is not for the faint of heart)

Build an insulated partition wall with door and a pair of fan ports.

In January open the main door.

A differential thermostat turns the bottom fan on when the outside temperature is colder than the barrel room. Cold air enters the barrel room, slightly warmer air exits the top.

By the end of february I've got several tons of ice at -40.

Come April: Reprogram the thermostat, or use a second thermostat to run when the front room gets above 34 F, and to turn off when it is at 33 F. In addition mount a ceiling fan, possibly two, to mix the air constantly to keep the temperature uniform.

Basic numbers: Insulation is about R20. A barrel is just over 2 feet, so using closest packing in 20 feet of space I can get length wise rows of 9 and 8 barrels. I can fudge the partiion and 10 and 9. So 38 barrels per layer. Two layers high is 76 barrels. We will leave a spot without barrels by the door for working room. So 72 barrels.

Each barrel has a volume of 55 US gallons, but to leave room for expansion, we ill only put 40 US gallons each. At 8 lbs per gallon thats 320 lbs. So 72 barrels is 23,000 lbs of water. 144 BTU per pound of ice is 3.3 million BTU. In addition if the ice is cooled to -28 F, I have to warm the ice up 60 degrees. This gives about another 700,000 btu. Total now of about 4 million btu of cold.

The outside area of a 40 foot seacan is 2*( 9*40+8*40 +9*8) or 1500 square feet. If it's R20 everywhere it takes 75 BTU/degreeF/hour to cool it or 1800 per day.

Average temps for April, May and June are 38, 44, and 48. So April would take 5 * 30 * 1800, May 11* 31 * 1800 and June 17 * 30 * 1800 btu = 1.8 million btu.

That gives me a factor of 2 to deal with cracks, leaks, bad insulation, and climate change.

Gotchas:

There's a bloody great hole at the front where the cooler unit was mounted. Plywood, 4" of polyurethane foam.

There is going to be condensation. Everytime the outside door is open humid air flows out, warm air with some water flows in. Humidity is good for the plants, but it will condense. All stuff has to be suited for a condensing environment.

So sloping the container with the front door a few inches below the back might be a good idea.

Will ceiling fans work in this environment, or will they corrode to junk. (I like them becuase they move large amounts of air with little power, and they are quiet.)

Water and electricity in a metal box have issues. First thing the power line does is go to a GFI receptacle in a weather proof box on the outside of the container.

Low power fans (300 cfm should be lots) that are tolerant of continuous high humidity, and that will operate at -40. Suppliers? Somehow I don't think that a bathroom fart fan lubricated with rancid yak butter will cut it for this application.

Differential thermostat to run the fan in winter mode when the outside is colder than the inside. Where do I find these?

Ok, guys, shoot me down -- will this work?
 

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Try Acklands/grainger and johnstone and fantech.

Chances are they may last a yr or 2 and need replacing but if they are not expensive then that is just the cost of doing biz. Not a bad idea. The earliest refrigeration systems used ice and the railway cars did it like your idea.

E-mail fantech and maybe they have a Engineer on staff who can give you advice.


http://www.grainger.com/


http://fantech.com/

https://www.johnstonesupply.com/storefront/index.ep

https://www.acklandsgrainger.com/?cm_mmc=PPC:+Bing%20Main-_-Brand%3EMain%3EEXM-_-Grainger%3EOfficial%20Site%3EExact-_-Grainger%20com&ef_id=dwpPBvmrdzkAAA9c:20150430140823:s
 

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A 9x40 container would have 1144 sq ft of surface area exposed to the air(I didn't include the floor area exposed to the ground). If its 5 degrees warmer outside. With R20 insulation, it would have a heat gain of 286 BTUs an hour sensible. So 6864 BTUs a day, or 205,920 sensible BTUs a month that it is only 5 degrees F warmer outside. That doesn't include solar gain, or any gain from natural infiltration, or the opening and closing of the door. Nor any heat allowance or the fans or lights.

At a 5 degree difference for April, each barrel of 40 gallons at a starting temp of -28F would have 67,972 BTUs of cooling capacity stored.
 
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Neat concept that might well work but are you sure you can't pick up a used commercial walk in cooler for the same $5500?
 

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Discussion Starter · #6 ·
So far the one's I've found run about 10,000 and have no floor, and only an insultated panel for a roof. So it's 10,000 + a building to put it in with an insulated floor. Insulated floors get tricky, in wet environments. Not just bats under an OSB layer between floor joists.

Worse walk in coolers have big compressors. I'm in a rural location, and the breaker at the pole is only 35A. So I've got a 7500W service. The transformer is rated at 10Kw so I could upgrade to a 50A breaker -- for $40 per month.

I used to work at a school with a walk in cooler and freezer. EVERY summer we had to have it serviced. Usually ended up with a $500 bill for doing that. We are an hour drive from the nearest industrial cooler service company.
 

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I would look for a refrigerated conex trailer. I saw one listed at $7500. I stopped there.


And if the cooler where you worked had to be serviced every year either they were
Just plain worn out and the repairman was doing a lot of band aid fixes or you needed a new repairman.
 

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I think your idea could work BUT the great unknown is the solar load and air infiltration. Would not want to run out of ice.

Do you have access to dry ice? If there is some within driving distance and you run out of ice you are saved or it is good to have as a reserve.

Walk in coolers have compressors/expensive to run and could get damaged by low voltage or power surges which are more common in rural areas than cities.

I would try your system and pour a concrete pad with rebar if weight is an issue.

Curious where do you live?

I thought maybe Abbotsford BC but then they don't get Winter or cold enough to make ice. I have relatives there.:laughing:
 

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Discussion Starter · #9 ·
Nap: I've yet to find a working reefer trailer for under 20 grand. I'm a tree farmer, not a diesel mechanic. I can rent one of these units for $1500/month plus $60/day for generator + $1/hour per generator run time + fuel.

Yuri: I'm in Canada, near Edmonton. Winter's are bitter, spring is short.

Dry ice here is about a buck a pound. And a 2 hour round trip to get. I'd hate to try buying enough to keep a reefer cool that way. And the gas is an asphyxiant. Ever put your head in a dry ice chest and inhaled? Unpleasant. Two guys broke into my uncle's controlled atmosphere apple warehouse. CA means 34 degrees and all the O2 replaced with CO2. They died. 20 feet inside the door.

Voltage surges: I go out of my way to get stuff that tolerates over/under voltage. We had a surge one day that took out 6 fluorescent bulbs -- the kind that are 'guaranteed' 10,000 hours. All our computers are on UPS's. The UPS have paid for themselves in replaced power supplies.


Standard 115v is usually 122. I've seen 135. And 95. We average about 20 power outages a year, some only a few seconds. About 6 a year require that we shut down the comptuers becuse the UPS only has 20 minutes of power.

I'm *really* trying to avoid a concrete pad. That's another 3K no matter what else I do.

Rural place: An hour from *anywhere* bigger than a village. 20 minutes to a village hardware/lumber store. So you pay for 2 hours time to get 1 cubic yard of concrete. You pay for 2 hours time to get a bobcat to do anything. Or it costs me 4 hours time to drive in and rent a bobcat and a trailer. And the extra hours because I'm not a trade bobcat operator.

If I have to go to town to get something, I get 3. I know I will break one. I know I will forget to add it to the errand list. And I damn well better have a spare when the working one breaks next time.

I never buy a bolt. I buy a box. I buy screws and nails by the 25 lb box if they are a size I've ever used more than once. The nearest hardware store is 30 km away. That's a 60 km round trip, or about 25-30 bucks to take the truck in and out.
 

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I think your plan might work out well---how many weeks/months do yeu need the cold box to work?

A roof for sun shade would cut the solar gain----need not be fancy or even water proof--
 

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Yon certainly made your case for doing it your way and with a slew of valid reasons.

Insulation values and weight are the 2 biggest issues I see. We had an unused ice house on the farm when I was a boy. It was pretty much nothing but a rock lined deep hole in the ground with an insulated cover inside a shed. Just to prod your thinking:

Would 2 two connected containers offer the potential for better weight distribution?
While the harsh winter is required for the freeze cycle is there some potential to Earth shelter for the greater efficiency of thaw cycle?
Might it be more efficient to circulate an antifree solution through the frozen part and then use the chilled solution and evaporator area?

I'm convinced all the equipment mentioned in your first post exists. It may be hard to locate and expensive. And more 'get you thinkng' http://www.motherearthnews.com/diy/buildings/root-cellar-plans-zm0z14amzreb.aspx
 

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Too bad about the thieves dying but hey they were doing the wrong thing.

I know ALL about rural areas. Lived near Dauphin MB for awhile and almost ended up working at the base in Cold Lake. Not much in the way of hardware stores in rural areas and you pay thru the nose for everything. Raccoons shorting out power transformers and animals damaging them is a rural issue and it sounds like you have seen it all.

Did not know about the fumes from dry ice. Lots of cooling potential in it.

Dig a big pit and make a underground ice bunker so you have more storage. Cannot afford to run out and lose your product. Did some work in a BIG greenhouse. Had a dozen 250,000 BTU furnaces running with the chimneys off. They wanted CO2 and heat for the plants so yeah it makes sense.
 

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Do they have to be kept at 33 deg?

You could use well water and a fan coil but well water may be around 40F.
 

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Colbyt;2012258]
Insulation values and weight are the 2 biggest issues I see. We had an unused ice house on the farm when I was a boy. It was pretty much nothing but a rock lined deep hole in the ground with an insulated cover inside a shed.
that's a heck of an idea. I don't know what the OP's ground temp is but around me once you get below about 5 feet it is around 50º F year round. A good ol' fashion root cellar. That'd a good start to the target temp.


gee, I feel dumb for not thinking of a ROOT cellar already since the OP does in fact want a chilled root cellar.

wouldn't have to worry about the floors being strong enough to hold the weight of the ice
 

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Did not know about the fumes from dry ice. Lots of cooling potential in it.
well, it is solidified/frozen carbon dioxide.

and since it does not melt into a liquid but rather through sublimation changes directly to a gas so you have all of that lack of oxygen thing going on and all. .
 

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Too bad about the thieves dying but hey they were doing the wrong thing.

I know ALL about rural areas. Lived near Dauphin MB for awhile and almost ended up working at the base in Cold Lake. Not much in the way of hardware stores in rural areas and you pay thru the nose for everything. Raccoons shorting out power transformers and animals damaging them is a rural issue and it sounds like you have seen it all.

Did not know about the fumes from dry ice. Lots of cooling potential in it.

Dig a big pit and make a underground ice bunker so you have more storage. Cannot afford to run out and lose your product. Did some work in a BIG greenhouse. Had a dozen 250,000 BTU furnaces running with the chimneys off. They wanted CO2 and heat for the plants so yeah it makes sense.

Only about 270 BTUs per pound in the OPs use for it. So in a month where his outdoor temps only require 6,000 BTUs per day. He would need over 660 pounds for the month. Which would cost around 500 bucks.
 

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Discussion Starter · #17 ·
Well water temperature here is about 50F = 10 C. Well temps if you are not in a geothermal area are close to the average of the climate.

Ground temps are similar. 8 feet down,the ground temp averages about 50 F. So burying it still requires insulation.

If I was going to do 2 containers, I'd do them side by side, so that they had one surface in common, and only half would have an open door at a time. (Might make an internal door between them. Positioning 8 tons with that precision is tricky, and it has to have a solid foundation. No longer can be done by setting the thing on 3 PT beams.

I plan to put in in the shade of a spruce grove, so it gets year round shading.

Dry ice is good for keeping things frozen, but it has less coolth per pound than water ice, and costs a bunch more.

Temp: Needs to be as close to freezing as possilble, without getting below. Roots wake up at 5-6C Mold is much more common at 5 C. The keeping time at 0.5 C is about 3 times as long as at 6 C.
 
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