Will you change??

[rbrunel]

Anytime we put tough/damp grain in the bin, no
matter the temp of relative humidity we leave fans
running. I have dried down 19-20%mc wheat
down with this method. It might take a couple
months. Theory goes keep moisture font moving.
Sf3 s right though. Grain dryer is quickest and
most reliable to know how dry grain is.

[Burbert]

Interesting, very interesting. This is
probably the Comedian Wheatie Bored,
trying ta du a number on Comedian framers.
Why couldn't they have released these
findings on April 1st? Then it wooda been
way more confusing.......

[craig]

No one has talked about grain kernel
temperature. I was always told the grain
needed to warm up to give off moisture. In
our area( central alberta) aeration is
usually only good for cooling unless your
in August, early September.

[cottonpicken]

From my brother


If you cool air, then you increase the Relative
Humidity (the RH is the ratio of the total amount of
moisture that is in the air (moisture content)
compared to how much it can hold total before some
must condense-out (dew point moisture content)
...cooler air can hold less moisture before some must
condense-out than hot air....think: it takes a bunch of
kinetic energy at the molecular level to keep water
from coalescing ... the more energy (higher temp) the
faster the particles in the air are moving and colliding
to keep the moisture in suspension).

So as the warmer air enters the bin it may have a
lower RH, however it has a significant amount of total
moisture in it (the total amount of moisture that air
can carry vs temperature is a non-linear
relationship....
http://upload.wikimediaorg/wikipedia/commons/4/4
1/Relative_Humidity.png ). The grain acts as a huge
heat-sink and cools the air thereby raising it's RH (not
it's total moisture content) so there is a tendency for
water to condense-out and be deposited in the bin.

Not sure why pre-heating the air is counterproductive
... perhaps you aren't really removing moisture from
the air, just reducing the RH? This would reduce the
tendency for water to condense-out as it gets worked
by the fan (before entering the bin). It has been a
while, but I think I remember moisture pouring off
the fans when they run at night? It could be that the
act of running the air through the fans (increasing the
velocity of the air) increases the tendency of the
moisture to drop out of suspension...? It is important
to note that there is a difference between increasing
the velocity of the air (with a fan) and increasing the
kinetic energy at a molecular level (heating) the air. A
fan will inevitably heat the air, however an efficient
fan heats the air less than inefficient fan.

Air temperature and RH are related to the kinetic
energy at a molecular level and I believe it is not
related to the velocity of the body of air.

Running at night when the air is cooler gives air with
a lower total moisture content and higher RH. If the
grain is warmer than the air (due to daytime heating),
then it should transfer heat and moisture to the air.

It would be interesting to see what would happen if
you first cooled the air, then ran it the through a
dessicant (i.e. an enthalpy wheel
http://cipco.apogee.net/ces/library/tdew.asp ), then
heated the air before sending it into the bin...the trick
would be: what do you exchange the moisture from
the enthalpy wheel with?

[TOM4CWB]

"It would be interesting to see what would happen if you first cooled the air, then ran it the through a
dessicant"

In the 'cooling process' this is EXACTLY what happens.

The bottom of the full grain bin has NEVER gotten too wet... has almost always been 'dry' grain by CGC standards.

This is a system of averages... and exactly why the fan should run night and day... except perhaps on peas/beans when warm high RH air (25-35C 80RH) can rewet the pea/bean (and reck bin bottoms) as peas/beans ability to reabsorb moisture is much greater than the other small grains.

The absorbtion rate of the grain is important on RH controls for natural air drying.