In Bin Cooling
This page pictorially shows the capability of moisture removal utilizing the right amount of air used in the cooling process.
It is often assumed and frequently promoted that one should use high airflow in order to cool the grain dumped from a dryer as quickly as possible. This is not necessarily so. It is advantageous to use a lower airflow in order to utilize the heat of the grain. Heat in the grain together with airflow decreases the relative humidity of the air moving through grain, maximizing moisture removal from the grain during the cooling process. The key is the right amount of air.
Bin cooling of grain from a dryer is an established method of fuel savings, keeping grain quality high and increasing the dryer capacity. A Rule of Thumb says, “You should be able to remove 1% of moisture for every 25 degrees F that you drop the temperature of the grain”. This, however, depends on the proper fan size. The maximum airflow should be approximately .3 CFM per bushel when cooling in a bin. If your fan has too high an airflow you will not get the anticipated moisture removal during the cooling process. Heat will be removed rapidly and there will not be warmth to decrease relative humidity of the air needed to remove moisture. The fan "must be small enough to do the job" rather than too big.
The same principle may apply to grain harvested slightly "tough". On a hot day grain may be coming from the field at 90 or 95 degrees Fahrenheit. When cooling this tough warm grain using a low airflow one can remove a small amount of moisture to bring the grain to dry without starting a drying front and over drying the grain. Over dried grain incurs income losses that you may get with a high airflow fan.
The pictures below show the moisture removal capabilities of a very basic "right sized system" utilizing low airflow.
- Temporary storage bins were constructed of plywood.
- Size - 40' diameter with 8' side walls.
- Capacity - approximately 15,000 bushels.
- Fans used - Farm Fans 1/2 HP and 1 HP.
- Air distribution - 12" perforated ducts spaced for optimum air flow.
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View black & white close-up of water vapour removed. Enlarged Picture |
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View color close-up of water vapour being removed. Enlarged Picture |
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View of bins and water vapour being removed. Enlarged Picture |
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View of the bins with air ducts cut through the walls. Enlarged Picture |
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View of the air duct placement in the bins. Enlarged Picture |
