RIMS heater in MT ?

[rudylyon57]

Rather than placing a RIMS heater in a tube, is there a downside to installing it directly in a MT? In my case my 10g MT has a 2" space under the false bottom which should provide plenty of room for circulation?

Other than having the element and its wiring "fixed" to the MT, which may make cleanup a little cumbersome, I can't think of other issues.

Cheers

 

[jimyson]

It will scorch the wort. You need MORE circulation on it to stop that.

 

[rudylyon57]

That makes sense. Funny though as I actually did a few CFD studies when designing a tube and saw that there are some really hot spots on a 4.5kw heater with 20 L/min flow in a 1-1/2" tube. It would be much worse with much slower moving wort in the MT.

Wonder if using 220v to heat water quickly to mash-in temp and then back off to 110v during RIMS process would still scorch?

 

[rudylyon57]

jimyson piqued my curiosity so I ran a CFD model of the system I asked about:
16" MT, 2" space between MT bottom and false bottom, 7 gpm flow through grain bed, 1 kw heater, 155F water, 1/2" exit port. See attached image. All looks okay at 1 kw with respect to not scorching wort. jimyson was spot on correct.

 

[jimyson]

Whoa. I'm not sure what to think about all that math. Haha.

 

[rudylyon57]

I'm at the point where I need to decide to place my RIMS heater in a RIMS tube or directly in the MT. I am leaning toward placing heater directly in MT for simplicity sake but would like to hear of any pro's and con's from you e-brewers. I know what I am planning is somewhat unconventional.

My plan is this: Control the MT heater with PID running 4500W heater on 220V to rapidly heat strike water. Once I have mashed-in and circulating, I'll switch the heater to 110V to cut peak power by 4, still with PID temp control. Two DPDT relays (full power using L1/L2 and 1/4 power using L1/N) will take care of the switching. This will address concerns associated with scorching in light of the low flow rates in the MT (vs RIMS tube).

The heater will be connected with tri-clover fittings so removal for cleaning will be easy.

Thoughts?