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Topic: Air popper technical esoterica, value unknown. LONG! (5 msgs / 253 lines)
1) From: Douglas Strait
I thought I would throw out some data for those who might be 
interested. It's value in unknown.
My popper of choice for converting into roasters is the 1400W Wear 
Ever. Like the West Bend Original Poppery it has a cast aluminum roast 
chamber with 16 slots that discharge into the roast chamber. These 
slots each measure about 0.1" X 0.4". I was curious about the 
uniformity of the discharge air temperature among the slots. I built a 
little fixture that permitted me to position a thermocouple in roughly 
the same relative position in each slot. I was surprised to find that 
there is large variation among the slots. Checking several different 
poppers of the same model I found that they all exhibit the same 
variation from slot to slot. Data to follow below.
Viewing the popper from above, I assigned #1 to the slot which is 
centered on the butter tray indentation. I counted slots clockwise 
from this number 1 position. Here is what the slot exit air 
temperatures measured with the popper heated to near steady state:
Slot#  Temp F
1           432
2           549
3           483
4           458
5           537
6           574
7           380
8           293
9           355
10         415
11         538
12         471
13         516
14         623
15         641
16         563
After checking several other poppers and finding the same pattern, I 
disassembled one to see why. It became apparent that the geometry of 
the air flow path from the fan though the ceramic assembly housing the 
heater coil as well as the gap in the heater coil accounts for the 
pattern of temperatures measured. Below is a link to a disassembled 
1400W Wear Ever which shows what is involved. These are links to 
photos on Felix Dial's Popper page [I hope Felix doesn't mind, I 
didn't ask first]http://members.cox.net/felixdial/WEP1.fan-heat.jpghttp://members.cox.net/felixdial/WEP1.heatcoil.jpg
In the first photo you can see that the air is passed through four 
elongated slots of the plate at lower right in the photo. The solid 
area between these four slots produces four regions of reduced airflow 
over the coil which is manifested as the temperature maxima measured 
at slots 2,6,11, and 15. Other perturbations in the airflow are 
associated with the five ceramic nubs better seen in the second photo. 
BTW, the slot adjacent to the ceramic nub at the 5:30 position is my 
#1 slot and they would count counterclockwise since you are viewing 
from the bottom in this photo. In my data, you can clearly the dip in 
temperature in the slots downstream of the gap in the heating element 
at the top of the photo. This shows up in the data for slots 7-10. 
Note that there is a clockwise, circular, component to the air 
movement as seen in this photo.
Whether these data have any significance to roast results, I do not 
know. It would seem that if the roast chamber where loaded to the 
extent of no circulation, something we already know is bad, the beans 
adjacent to the hotter slots would burn quicker. If the bean mass were 
just barely circulating, a bean passing each slot in sucession would 
be subjected to rapid surface temperature fluctuations. I do know that 
early in my air popper learning curve I would sometimes load up the 
popper until there was no bean movement and I would pick up the whole 
popper and shake it to move the beans at the beginning of roast. 
Occasionally I would see an obviously burnt bean rise to the top. I 
now would surmise that it had been stationary at one of the hotter 
slots.
As an experiment to see if it might be possible to even out the 
temperatures among the slots, I tried widening the slots that measured 
the hottest on the theory that this would induce more airflow over the 
hotter portions of the heating element thus cooling them. To this end, 
I widened slots 2,5,6,11,14,15 by about 50%. This does seem to have 
had some affect. Whether it is of value is unknown. I did find, 
contrary to popular belief, that in the case of this particular model 
of popper widening these slots did not increase that amount of beans 
that could be moved. Post slot widening data below:
Slot#   Temp F
1          434
2          539
3          518
4          455
5          587
6          377
7          298
8          244
9          286
10        396
11        440
12        458
13        450
14        500
15        510
16        468
I would caution against attaching significance to the absolute values 
of these temperatures relative to those in the first data set because 
the modified popper is a different one than that used in the first 
data set. Of more significance is the relative variations from slot to 
slot.
Having seen a picture of the internals of a West Bend Original 
Poppery, I theorized that it would have a different distribution of 
slot temperatures because the air flow path around the heater coils is 
relatively unobstructed and also the heater coil overlaps itself for 
the span of about 3 slots rather than having a gap as the Wear Ever 
does. Here is a photo of the Poppery heating element, link from Mr 
Shaw's popper mod site:http://members.shaw.ca/espressomio/popper4.jpgTo this end I procured an original Poppery and checked it out. Here 
are the corresponding slot temperature data. For this one I assigned 
#1 to the slot directly under the fin in the roast chamber and counted 
clockwise, viewed from above. The overlapped portion of the heater 
coil is adjacent to slots 15,16, and 1.
Slot#  Temp F
1         405
2         401
3         422
4         415
5         438
6         439
7         446
8         474
9         492
10       566
11       590
12       613
13       641
14       626
15       614
16       557
As you can see, the influence of the overlapped heating coil is 
shifted a few slots downstream due to the circular component of the 
airflow motion over the heating coil. The circular motion is in the 
direction of descending slot numbers.
Data supplied for those inquiring minds that wish to know. They rest 
of you should go have a good cup of coffee.
Doug

2) From: Gary Townsend
 Douglas Strait wrote:
<Snip>
  Doug,
 I'm curious as to why you like using the 1400W Popcorn Pumper. I've though=
t
that there was potential to improve the air flow. I have 5 of them, and I'm
not having much luck with increasing the load. My goal is to improve the
machines performance as much as possible, without adding any additional
electronics.
 I also have collected 1/2 dozen P1's, and use them pretty much stock. Well=
,
4 of them I took my dremel to the bakelite housings and ported them out,
along with the raised ridge inside of the roasting chambers. And I tweaked
the thermostat to run a little hotter. One of them is split-wired, andthe
other 1, I just picked up for $1.98, like new and decided to leave it
alone...for the time being, that is...
 OTOH, I have 4ea 1250watt Popcorn Pumpers that I tweaked by widening the
vents with a 1/8" screwdriver, and removed the bimetallic metal piece from
the thermostat. I was careful not to destroy the contacts, and other than
using a glass hurricane chimney, that's the only mods that are needed to
push 6 5/8 oz of greens (with a little help from a wooden spoon). However, =
I
found that 5 oz of greens are 'just right', and plugging directly into the
wall socket, using a 20 degree tilt, I get easily repeatable results
averaging 5:50 - 6:45 min to 1st crack and 12:30 - 14:45 min to 2nd crack. =
I
do not pre-heat the poppers at all, and rotate 4 of them to net a little
over a full pound of roast. Not bad results using 4 $2. poppers.
 I plan on boosting a set of P1's, when I get more time this winter...but
those 5ea 1400 watt Pumpers sitting on the shelf are begging me to convert
them, as well !
 Thanks for the data, logging all those temps was probably a PITA!
 Gary

3) From: miKe mcKoffee
100 CSA techno-geek points;-)
 
<Snip>
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snip snip snip snip snip snip...
<Snip>

4) From: Douglas Strait
This is a multi-part message in MIME format.
Gary Townsend wrote:

5) From: Michael Dhabolt
Ahaa - The truth comes out!!
 >>From a purely aesthetic standpoint, I prefer the styling of the pumper
housing.<<
 An artistic temperment.
 Mike (just plain)


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