Rims Input Needed

[rwmingis]

Hi everybody,

Wow, I really got side tracked, it's been over a year since my last post and working on this thing. I moved away for a year, then moved back and bought a home, so not much has been happening on the brewing front. Getting 'round to it though.

So yes, my RIMS is built now, and it works great. I wrote the PID routine last night and tested it out today; I seem to have gotten it right the first go - beginners luck. Attached is the graph of the data below:

The red line is the heating chamber discharge temperature, the brown the mash tun temperature, black the set point temperature, purple the power to the element in % (2400W element) and blue is the pump flow in L/min measured on the right axis (4-5 L/min typically) It goes right to the set point and stays there which is what I want.

These numbers reflect a maximum heating element power of 100% but I imagine I need to limit this to some value. At full power it's 72 W/m which doesn't sound bad, but I don't know what sounds good either. I've done a google search and only found one fellow that limits his to 30 W/m which sounds low. For mine this would mean limiting my power to the heating element to 42% max. Given that at mashing temperatures i'm loosing 25% of the total power out of the uninsulated heating chamber, I don't have much left over to go that low.

Does anyone know a reasonable watt density to start with from experience?

Cheers!

BB

 

[squirt in the turns]

Bob, that graph, like this whole set up, is a thing of beauty. Nice one! I just went with an off-the-shelf Sestos PID for my recent HERMS control panel. Looking at all the amazing work that's being done with the Brauduino and other embedded systems, I'm already thinking about the next version...

 

[rwmingis]

Hi Squirt,

Thanks for the kind words.

The embedded controllers are great fun they can do nearly anything all in one package. I know little of the Arduino ones, I just happend to start on PIC by chance so I'm using the SBC44UC http://www.modtronix.com/product_info.php?products_id=286 which does a lot of of stuff, in this case:

- Read multiple DS18B20 temperature sensors
- Reads a flow sensor
- Controls the heating element using burst fire control
- Opens and closes HLT solenoid
- Controls the pump
- Reads several level sensors in the mash tun
- Reads and control the HLT temperature.
- Talks to the PC

It's a busy little thing, and done mostly using interrupts. You program it in C too which is pretty good. It has the built in USB's too and routines to chat straight to the PC using a serial port style routine which makes it much easier.