Airflow in solar wooddrying kiln

[Menuisier]

Hello,

I am designing a solar kiln for wooddrying. My design is based on the well known virginia-tech kiln. How ever I want to make some modifications.

The one i am really not shure of is the airflow generated by the fan. (see joined drawing).

The original design works with 3 fans along the whole length of the baffle.
This should garantie a good air spread over the solar collector , absorber.

I friend wants to give me a big approx. 39 inch fan, wich will generate enough airflow on it's own.

The problem how ever will be the spread of the air flow. I think i can solve part of this problem with a few deflectors (drawing).

But i fear this won't be enough to fetch the hot air that might stagnate in the upper corners of the solar collector.

I have been thinking of :

- little fans in those corners, wich means initial costs and energy costs ;

- Little holes in those corners so the fan will suck some air directly from here to re-blow it in front. This seems also energy inefficient, and will this work ?

- Maybe there will be enough turbulence to salvage this hot air and i am seeing trouble where there is not.

Does anyone have some idee about this ?

Thank you very much,

Frans

 

[Compositepro]

I wouldn't worry about it. Hot air will rise and collect at the top. With the fan at the top and blowing strongly enough to circulate it to the bottom of your oven, it will collect, mix and circulate all the heat collected. Temperature uniformity of the wood is important not the temperature of the collector surfaces.

 

[Menuisier]

Thank you for your response.

You are right about importance of the hot air beeing distributed equaly through the wood stack. Thats why the fan(s) are positioned this way. The air can spread out before reaching the stack.

I just want to take total advantage of the absorber's surface in order to obtain maximum heat exchange.. That's why i thought it would be important to have air movement all over the collector surface. And as you say, hot air rises and that is why i feared a fair amount of heat staying blocked in those upper corners.

Thanks for your hopefull vision !

Frans

 

[MiketheEngineer]

Just try it. It may work better than you ever thought!! You can always modify it latter and at a greater cost..