Cold rooms. Refrigeration.

Kiwi Phil

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Jun 23, 2003
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Anybody any experience with these things?

I don't want to do it, but I may have to consider a coldroom for a min of 3 pallets, possibly 4.

Product will be in carboard boxes, and when they go in sealed (they do have 6 slot-holes in them) the outside packing area will be anywhere from 25C-40C with high humidity.

They will only be there for 2-5hrs....until the truck arrives.

Not sure if I need to take the temp down to 4C, but I would like the contents in the carton to be maybe 18C-22C, dry (no hunmidity).

I have no knowledge or understanding of different types of refrigeration or the movement of cold air thru a pallet of boxes.

I do know I don't want the one that causes carboard boxes to absorb moisture and collapse.

Anyone know anything about them?

Cheers
Phillip

PS life is hell here at the moment.....36-40C with humidity I don't even want to know about....and we are out there working in it!!!
 

pduquette

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Jun 22, 2007
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Re: Cold rooms. Refrigeration.

Hi Kiwi Phil !
I worked in a company that manufactured walk in cooler/freezers for about 10 years . I'll try to help with your questions as best I can . I was in the manufacturing / construction/ installation end of the business, not the designer /engeneering end .....:redface: I've put together small floral coolers to deep freeze wharehouses . If I remember right you run a floral farm / greenhouse ?
 

Kiwi Phil

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Jun 23, 2003
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2,182
Re: Cold rooms. Refrigeration.

I grow herbs, hydroponically, but in a small pots with potting mix.
They are in reality a pot plant, but water'd and fed by hydroponics.

They are classified as a green leaf product, similar category to lettuce.

If they get too cold, the basil burns....just like it would if grown in the ground and hit by a frost.

The boxes i use are black, so absorb the heat very quickly, and hold it.

Last week when the trucking company put a temp probe in the boxes while on the pallet, it measured 27C.

The herbs are in a cellophane sleeve, with about .75" of water in the bottom.
High temp causes the plant to draw up that water and expel it out its leaves, and of course it then dries out and wilts = un-sale-able.

I think that loss of water deminishes drastically when the temp in the box is under 20C.

I have a new packing area, (steel roof and no walls) and the radiant temp of the roof is fierce.

Yesterday I left the boxes open and used domestic fans to move the air about.....certainly seemed to reduce the temp inside the boxes. I sealed the boxes when the truck arrived.

Will the circulating air draw the water out of the plant?

What effect does high humidity have? eg 27C with low humidity.
I ask because when we turn the air conditioner on in the house, we set it at 25C and it is very comfortable....is that because it is dry air?

I can post photos if you want.

Cheers
Phillip
 

pduquette

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Re: Cold rooms. Refrigeration.

Hi Phil , I think what you are doing is is going in the right direction . Too much humidity will cause them to over perspire and encourages mold fungi etc. Using the fans should stimulate the plants (make 'em stronger )and cut down on wilt problems . I'd suggest adding foam board insulation to the underside of your over-hang to re-direct the heat and/or lighten it's colour. Building a shelter to regulate humidity will prolong your storage time but will cost;) I think most herbs will tolerate a wider range of humidity ,yes you can steam them to death with too much temp+humid just as they can be dried out by de-humidifing ..... I'm Leafing through my references to narrow a set of perameters -most of my green thumb comes from growing Chiltepins + Habeneros:D:D
 

Kiwi Phil

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Re: Cold rooms. Refrigeration.

OK....now that makes a lot of sense!

The area is 9mx6m (30'x20'?) at 2.4m (8') high.....covered in corrigated iron on steel rafters/purlins...open on 3 sides.

For an area like that....if I used fans....would I be better with 4 ceiling fans blowing down, or 2 big wall mounted fans blowing across?

I can see big value in sealing off the roof (putting in a insulated ceiling) to stop the radiant heat that comes thru the tin roof....I reckon it could be well over 50C just under it....it is fierce.

I am also faced with the problem....

I pick and pack into the sleeves in the paddock (outside).
I then pack into cardboard boxes under the lean-too.
So the heat is already trapped in the cellophane sleeve but as i do it early it seldom gets over 25C.
I can't see a coldroom being capable of reducing the temp of the herbs inside a closed carton, stacked 6 levels high on pallets.

So maybe I pack the cartons, leave them open until the truck arrives, with fans circulating air and keeping herbs at the ambient temp (in the shade), then when truck comes, seal cartons, load pallet and into refrigerated truck.

Now going to have to think about my insulated ceiling options......styro in coldroom sandwhich material seems expensive.
Needs to be sealed at ends, and waterproof material.

Cheers
Phillip
 

pduquette

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Re: Cold rooms. Refrigeration.

Phil I think you will have an easier time controlling the temperature in an open air enviroment than it would be to controll the humidity ( it's ok to say thats a no-brainer ):redface:
Even if you were to ad a layer of foil insulation under the roof and have a tube fan between the tin and foil ,drawing the air away from the loading area it should reduce the temp to a satisfactorary level .
Even if you do decide to make a room it's going to require quite a bit of energy to keep cool . you'll be continually feeding the beast!:eek::eek:
 

Kiwi Phil

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2,182
Re: Cold rooms. Refrigeration.

OK....got that.
I will go look at ceiling materials this week, plus fans (ceiling or wall), as I now think I have two objectives to overcome:
1. reduce radiant heat from tin
2. get air circulating

Will keep you posted.
If you have other suggestions please let me know.

Thanks for your time and effort.
Very much appreciated.

I suffer from tunnel vision.

Cheers
Phillip
 

jonesg

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Feb 22, 2008
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Re: Cold rooms. Refrigeration.

The principle of cooling is evaporation, as water evaporates it takes energy with it, heat is the energy that is drawn out...

Homemade cooler...

a chicken wire enclosure covered and draped with sack material, straw and covered with tarp, drenched and allow the water to evaporate will chill the interior, it doesn't help that your packages are cardboard, they'd need covering with a plastic tarp.
Keep the whole thing wet and the temp will definately drop.

Up in pre-electricity New Hampshire they used to save hand cut lake ice in the basement, covered with straw and a tarp, it would last into July.

Refrigerators work on the same principle, they have evaporators and a compressor to recycle the freon back through the evaporator.

Another thing that would help is to dig a deep room size hole. Insulate the top with styrofoam and a roof, I doubt it would need anything else.
 

pduquette

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Re: Cold rooms. Refrigeration.

Hi Jonesg , I like your ideas ,and think they could work well . I've got a couple of berm houses in my area and they are supose to be very temp / humid neutral . Esentialy turn the loading area into a big cold frame , with shade . the "swamp cooler" is another good addition to the setup . Phillip , is it possible to change the color of the boxes or move to a light color paper wrapper ?


P.S. Phillip-It's about 4*c and 3" of snow just fell last night :) I can just about smell the Basil through the cpu !:D
 
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