Feasibility of using induction heater circuit for my coffee sample roaster.

shortbus

Joined Sep 30, 2009
7,945
Why not use a band/nozzle heater around the drum? https://www.watlow.com/products/heaters/cable-nozzle-heaters.cfm The heater , using a thin band of silicone rubber between the drum and band for a bearing surface, would be the 'bearing' for the drum.

If you really want to do the induction thing, one of these would be where I would start. http://www.theinductor.com/ Or http://www.mrinduction.com/ There are other brands out there too.Thiswill give you the induction circuit already made without the hassle, all you need then is to make your coil. Doubt very much if you can do a DIY circuit as cheap as this ready made proven device.
 

Thread Starter

Viridian

Joined Oct 7, 2014
12
The big advantage with the HF heating method would be that the rotating drum does not have to have contact with the stationary coil, as it probably would with the resistive method to be efficient, where power would have to be transferred to the drum if the heater was attached, otherwise it would rely on radiated heat for a fixed htr.
Max.
This is exactly what I was thinking but probably did not articulate very well.
 

Thread Starter

Viridian

Joined Oct 7, 2014
12
If you really want to do the induction thing, one of these would be where I would start. http://www.theinductor.com/ Or http://www.mrinduction.com/ There are other brands out there too.Thiswill give you the induction circuit already made without the hassle, all you need then is to make your coil. Doubt very much if you can do a DIY circuit as cheap as this ready made proven device.
Good links, thanks!
 

shortbus

Joined Sep 30, 2009
7,945
You also are going to have a problem you probably haven't thought of in this - temp measurement for heat control.:) You will need to do this with a infrared thermometer. A regular thermocouple style won't work for measuring in an induction heater, the thermocouple is metal. The induction will heat it, not give the 'bean' temp.

Some thing else to look at, similar but not quite the same is, induction rice cookers. They are at a slightly lower temp than you need but may give some ideas to you.
 

Thread Starter

Viridian

Joined Oct 7, 2014
12
You also are going to have a problem you probably haven't thought of in this - temp measurement for heat control.:) You will need to do this with a infrared thermometer. A regular thermocouple style won't work for measuring in an induction heater, the thermocouple is metal. The induction will heat it, not give the 'bean' temp.
Actually, I used a non-contact IR thermometer for years with the first roaster I made and had actually come to the same conclusion as you. Thanks.
 

wayneh

Joined Sep 9, 2010
16,399
Just curious - in your fluidized bed, did you recycle the air to retain heat? Of course you'd have to bleed off some to remove the humidity, but it would be inefficient to not recycle. I think industrially you recycle so that the exit bleed is nearly saturated in humidity.
 

Thread Starter

Viridian

Joined Oct 7, 2014
12
Just curious - in your fluidized bed, did you recycle the air to retain heat? Of course you'd have to bleed off some to remove the humidity, but it would be inefficient to not recycle. I think industrially you recycle so that the exit bleed is nearly saturated in humidity.
Yes, I did. It was limited though. I tried to keep input air temp below 170F just because of the blower's exposed wiring, etc. An arbitrary number perhaps, but I did not want to overheat things. I also restricted the exhaust from the roast chamber to create some pressure. This actually seemed to affect oil migration in the bean during the roast in a positive way. Beans stayed fresh longer and flavor was more intense.
 
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