Avoid Condensation During Cool Down

Hi Ron it Jamie @ Victoor Seed Farm Inc. We had talked last fall about grain drying. I had a question for you. We are having a wet fall so far in AB. Relative Humidity Very High but if air temp around 8’C at night and grain @ 24’C will I put much moisture into Bin as I want to Just Cool Grain Down. We only have Temp Cables in Bin not moisture & Temp Cables. Grain from 13% Moisture with 2000 Bus of a 10,000 Bus Bin Testing 16%

On Sep 7, 2016, at 2:18 PM, Ron Palmer <Ron.Palmer@uregina.ca> wrote:
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> Jamie, this is exactly what my grain drying calculator was made for.  You can find it at planetcalc.com/4959/  you just punch in the moisture content, 16, and the grain temp, 24, and the outside air temp of 8 and it comes back and tells you the outside relative humidity, below which, drying will occur.  If you scroll down to hard spring wheat it will give you 214.4%.  This means that as long as you have an outside relative humidity of less than 214 you will be drying your grain.  So, let’s say the RH is 85% outside;  85 is much less than 214, so yes you will be drying, and because there is such a huge difference, you will be drying a lot.  However you have another problem–a big problem.  The moisture coming off your grain will condense when it hits the cold roof walls and roof, and the moisture that you just got out of your grain is going to be raining back down onto your wheat.  You should have cooled and dried your grain as soon as you put it in the bin, before it got so cold.  But what to do now?  Turn your fan on when it is warmer so that condensation will not occur.       I used the calculator and plugged in 20 for an outside temp, and it came back with a threshold RH of 97.4   In fact any number below 100 and you won’t get condensation on the inside of your bin.  So, let’s say you turn your fan on when it is 20 and RH is 70.  Will you be drying? Yes quite a bit.  Will you get condensation? No   The temp of the grain will come down fairly quickly, in just a few hours of running your fan the grain temp will maybe go to 22, and then we can use a lower outside temp. and still be below the 100.   And sure enough these numbers give a calculated threshold RH of 97.5
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> So, here is what you do.  Wait for a slightly warmer day of 19 to 20 degrees.  Turn your fan on and as the temperature of the day goes down, the temp of the grain will also go down.  I am thinking that you should be able to chase the grain temp down fast enough so that you won’t be getting condensation.  But you can use the calculator to make sure you are not in a situation where the threshold RH is larger than 100.    I have loaded the grain drying calculator onto my Iphone and use it like an app.
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> Another thing,  we found that cooling your grain down by 15 C will typically remove 1% moisture.  You cooling the grain from 24 to say 9 C should get your moisture close to 15%

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