Post by meddo on Jul 17, 2019 16:34:22 GMT 10
- I would prefer to use a set flow-rate (as high as the grain bed will allow) for a constant recirculation throughout the mash and adjust the temperature using the medium inside the HERMS, is this reasonable?
- If so, what's the best way to take advantage of say 3600-4800W? Long coil with the HERMS medium set to the target temperature? Shorter coil with the HERMS temp higher than the target? My suspicion is the former since maintaining a temperature delta would get harder at higher temps as the medium approaches boiling point, and presumably the control logic would be more complex.
- My preliminary idea is to use a 4" tri clamp cooling coil in a length of 4" TC spool. I've already got a cooling coil for my unitank sitting idle so will potentially use it initially, although the straight section will be fairly inefficient - fully coiled units seem to be available from China for a later upgrade. Any general concerns with this approach?
1. Parallel. You'll get less resistance and better heat transfer (the greater the temp difference between two bodies the more rapid the exchange). In any home brew case with a HERMS higher flow = better heat transfer.
2. No reason why you can't, but I don't know why you would. You will reduce the effectiveness of the control, so you are better to use the wort outlet temp as your process setpoint.
3. Safest - long coil, medium at target temp. Overshooting the target temp in the medium is ideal but if you're not using the mash liquor as your control value then I don't know what sort of control system you can use. The complexity of the logic won't change (P / PI / PID) but the system will, and the more complex the system the more challenges you'll run into.
4. SPEAK SI UNITS BOY! I know you did uni in Australia and don't pretend I don't. Ideally:
minimise the heating medium/fluid
- maximise the flow
- maximise the conductive surface area relative to the conductive fluid (this means a smaller pipe is better BUT don't compensate for flow)
BTW, what happened to Nev's coils? Looks like they're not available from anywhere any more.
Ha, while I completely agree with the sentiment I've never seen tri clamp flange sizes specified in anything other than 'Murican 😝