BINcast critique

When should the fan be turned out?  There is another calculator — other than mine that tells you when the fan should be operated.  But it is based on assumptions that are not realizable — judge for yourself.

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Hi Ron
Have you seen the BinCast calculator (http://www.weatherwest.ca/bincast.cfm).
Does it work on the same principles as your methods?
Sarah

 

On Thu, Sep 22, 2016 at 3:34 PM, Ron Palmer <Ron.Palmer@uregina.ca> wrote:

Sarah:
I have not seen BINcast as a webpage, but have followed the theory of operation.  It does not work; because they do not take into consideration the grain temperature. Here is the reasoning behind it, and at first glance, it appears to be a rational theory:
If one takes the outside air temp and relative humidity, and inserts these into an EMC equation for — let’s say barley — you will get an Equilibrium Moisture Content. Let’s assume this is 16%.  If I blow this air at my barley, it will eventually reach a moisture level of 16%.  And that is true, if this air is blown at the grain long enough, eventually the barley and air would reach equilibrium.  Reaching equilibrium means that the barley must be the same temperature as the air.  One can not assume that the barley is the same temp as the outside air, in fact it never is.  It takes hours and hours of blowing air (probably a thousand air exchanges) to change the barley’s temperature.  But the outside air is not a constant it is changing hour by hour, and the barley is always playing catch-up.  The outside air and the barley are NEVER in equilibrium.  Sorry but this is not a good calculator.  I can come up with example after example, where this calculator will give the wrong answer.
I use EMC equations, but for temperature I use the temperature of the grain, (because the air becomes the temp of the grain) and I use the EMC equations differently.  You will notice I ask for the moisture content of the grain; using the moisture content and the temperature of the grain, I get the equilibrium relative humidity. That is where the grain wants to put the air’s RH.
If you are really interested, I can give you concrete examples of how the BinCast is totally different than my calculator, and it makes the huge false assumption that the air and the grain are at the same temperature.
Ron Palmer

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