Temp question reguarding design

it doesn't...
what is going on is there is LESS AMPS per square inch than in the bath types in almost every case you look at...
typically speeking more electrolite makes ANY cell run cooler... even a FLOODED Tero-cell runs much cooler with more electrolite at its disposal ...
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So its not a funtion of Electrolite per square inch of plate area, but Amps per square inch of plate area. Yes its true that what you pointed out seams to be the RULE... container types usually run hotter because they have LESS Plate area than the Dry cells typically do...
a single Randy cell has approx. 50 to 55sqr Inches of plate area... feed it 20 amps and you'll get 170~180 degrees a tero cell has close to 350 to 500sqr inches of plate area feed it 20 amps and it won't even break a sweat... but the output will almost be identical...
this is because its the AMPRAGE that does the work 20 amps will give you 1 to 1.5LPM even 2LPM at the best case Randys MKII cell brakes this rule ! getting 2LPM at only 10 amps !
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So you can see that even with a small amount of plate area the same Output can be obtained as a cell with a large amount of plate area... the diference is the heat output... one is working its butt off getting that output out and the other one is hardly working at all because of the larger plate area
... more plate area makes it EASIER for the cell to produce gas, but it is not a pre-requisit!
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I am glad you asked that question because I don't think many understand why the heat is such an ishue
untill they have a cell running and it starts to melt things.
...Steam or water vapor is part of the ishue but only part, the other part is how hard the cell is working in the first place...
when You have a cell like the Randy cell (MKI) in its one container and a gallon of electrolite
and feed it 40 amps its going to get very hot ! even with the 1 gal capasity
if you have a 500SQR,INCH. Dry cell 40 amps is barely makeing it work in comparison
take 50sqr in of the Randy cell and feed it 20 amps you have 20/50=.4 amps per sqr inch
and at that ratio its working very well indeed...
now take the 500sqr inch Dry cell and feed it 20 amps 20/500=.04 amps per sqr.in. which is barely starting to work at all !
... according to what I've read a cell needs .5 to 1.5 amps per sqr. inch to operate well
and as you can see nether one of these cells have enough amps to "Work at their best"

it takes the Randy cell 25 amps to make it to .5 amps per sqr inch
and the 500in dry cell 250amps to get to .5 amps per sqr inch !
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so if a fair compairison were done you'ed need 2 cells of the same wetted surface area
fed the same amprage, one a dry cell type and the other a wet cell/container type
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the outcome of that test would be identical in LPM with only a slight veriation in the heat output... because the SAME work is being done in each case...
work done = heat...
you can't have high output without heat... you can disipate the heat however, but the heat is ever present.
Manta will be the first to point out P=I.E where Power in watts is equil to Amprage times the voltage.... so the 25amps x 14vdc of the randy cell produces 350watts
where the 250amps of the dry cell at 14vdc produces 3500watts
but that is at the same Amprage per square inch... and sense one is bigger , obviously its heat output will be bigger as well
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but we don't use the cells like that... we typically power a dry cell with below 50 amps
and a wet cell with 20 to 30 amps... sense the DRY cells almost ALWAYSE are much bigger in plate area they run cooler
so you can have a Wet cell run just as cool as a Dry cell by simply having enough plate area in the cell... notice I didn't say NUMBER OF PLATES, I said plate AREA....
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if you take a DRY cell and take it appart and make a wet cell out of it it will inevitably run cooler because of the more Electrolite available to cool it.
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thats my 2 coppers on it !
...fwiw...
Bob......