ukdan
New Member
Posts: 13 
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Post by ukdan on Sept 3, 2013 11:59:11 GMT -8
Thanks peter. I have read that complete thread and was certain there was nothing about port height positioning but I will be going back over the thread again before I start casting and shaping. All my reading on here is done just before bed so there is a good chance my tired eyes missed something!  |
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Post by misterkel on Jan 25, 2014 6:33:34 GMT -8
What is a Peterberg Batch Box?
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Post by peterberg on Jan 25, 2014 7:55:51 GMT -8
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Post by 4seasons on Feb 23, 2014 10:42:06 GMT -8
I have a question about the riser height. For example on a 5 in system the riser height is 36 inches. Is this 36 inches from the bottom of the firebox or from the top of the core?
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Post by peterberg on Feb 23, 2014 10:57:23 GMT -8
That's an easy one, the riser height is measured from the firebox floor.
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Post by mintcake on Mar 12, 2014 11:05:18 GMT -8
Continuing on this line of calculations, here are some more numbers for this "standard batch-box": Where "inch" is the system size in inches: const(inch)=inch*0.7236*2.54 # Constant turned into cm... woodvol(inch)=const(inch)**3*(2*3*.75-.75**2)*4*.6 # 0.6 packing constant, 3/4 high, minus the slopes.. (volume in cm3) energy(inch)=woodvol(inch)*10600000*544/1e6 # Joules (wood density and usable energy in wood with flue gas at 100 deg C, from elsewhere on this board) avgpower(inch)=energy(inch)/(60*40) # I think Peterberg said the normal burn time was 40 mins archbps1.campus.tue.nl/bpswiki/images/5/53/H8.pdf gives the heat lost (Watts) per meter of pipe for an insulated pipe as: phi(x,d)=(Tgas-Touter)/(r(x,d)+r(air)), where r(x,d)=ln((d/2+x)/(d/2))/(2*3.14159*lambda), x is insulation thickness and d is riser diameter. Lambda for perlite at 1000F is roughly 0.1 or so according to engineering toolbox. This of course assumes there's not temperature drop in the riser. OOPS.. Edit:Putting this all together (using 1000C in the riser) ... I get that 10cm (2in) of perlite means that once everything is heated through, a 7inch batchbox is losing about 1.8% of its heat through the riser, a 6incher is losing more like 2.2% that way, and a 5incher should be losing a whopping 2.9% of its heat through the riser. With less insulation the numbers are more significant. With 1cm perlite equivalent, then it's 8%, 11% and 14% respectively, and I expect it doesn't work very well. |
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morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Mar 14, 2014 8:19:49 GMT -8
I get that 10cm (2in) of perlite 10cm = 4 inches |
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Post by mintcake on Mar 14, 2014 12:16:57 GMT -8
I get that 10cm (2in) of perlite 10cm = 4 inches It is isn't it? Sorry. Calculations were for 10cm, or 4 inches of perlite. Is the recommendation at least two or at least four for the heat riser? I've finally found a local supplier of perlite... I can get 3 litres for about 3USD. Ouch... |
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Post by tftxyz on Sept 26, 2014 12:26:41 GMT -8
I'm joining in the conversation, Peter. I will be able to catch up after the workshop. I cannot wait to be advantaged more by you and others "beautiful" work. I notice there are many things I am unaware of. Thank you again for your great innovations and all the fun we had. You are a great man; what an experience! Say hello to your family, send my love, many blessings. - Taylor
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Post by craigmiller on Oct 20, 2014 19:49:12 GMT -8
Does the bottom of the p-channel match the top of the port? Also am l correct that the p-channel comes down in the batch box side, not the heat riser side? I'm building a 6 in square style heat riser with fire brick splits. Is primary air intake still calculated based on a circular 6 in csa?
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Post by pinhead on Oct 21, 2014 9:34:57 GMT -8
Does the bottom of the p-channel match the top of the port? Also am l correct that the p-channel comes down in the batch box side, not the heat riser side? I'm building a 6 in square style heat riser with fire brick splits. Is primary air intake still calculated based on a circular 6 in csa? See the attachment in the second post of this thread.  For our purposes, a 6x6 riser is equivalent to a 6" round riser. |
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Post by photoman290 on Oct 21, 2014 10:41:29 GMT -8
hi pinhead, could you add the primary air equation to the spreadsheet please. i know i can calculate it easily enough but as you don't need the calculator for all the other dimensions it would be handy to have that one on there as well. then all you need is the list and a tape measure.
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Post by craigmiller on Oct 22, 2014 5:00:47 GMT -8
Thanks for the response, pinhead. Does the bottom of the heat riser contain any slope?
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Post by pinhead on Oct 22, 2014 5:03:55 GMT -8
Thanks for the response, pinhead. Does the bottom of the heat riser contain any slope? According to Peterberg's design, the back half of the floor of the heat riser is at a 45 degree angle. |
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Post by craigmiller on Oct 22, 2014 7:29:20 GMT -8
That's very helpful, pinhead. Primary air intake is at the bottom front of the batchbox, correct? In other words, an opening through the door or a hole in the batchbox floor right behind the door. I really appreciate your response, since I'm laying firebrick today.
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