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Originally Posted by Joe Camel
ok, here is the theory in logic steps, tell me where it goes wrong...
after trying to explain this theory of mine to a few people at work, ive come up with this:
lets make the 4 following assumpions:
1) my cold loop will have 2x the flow of my hot loop.
2) a (big) pump adds +1C (50W) to the water.
3) a WB adds +2C (100W) to the water.
4) when 2 equal amounts of water @ different temps are mixed together, the resulting temps is the average between the two.
ie 1 cup 20C + 1 cup 40C = 2 cups @ 30C.
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lets follow 10 (cm3) of water thru my setup:
--start at the water coming out of the rads, lets say its [30C]...5(cm3) goes to a pump [31C] then to WB [33C] then back to res where it mixes with the other 5 (cm3) which is still 30C [30+33=63 /2= 31.5C] then it goes to the second pump [32.5C] then into the rads.
so the rads have 32.5C water going into them.
now lets follow 10 (cm3) thru a normal loop:
--same starting point, out of rad [30C] pump [31C], WB [33C] ....rads.
so the rads have 33C water going into them....
if the 4 assumptions are true, how is the theory false? ( i know the +1C / 50W is NOT true, but it makes the math a lot easier)
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there should be lots of holes in this if the theory is wrong...right? :shrug:
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a) the water in the 2 setups wouldn't be at the same temp. it is the product of the rad(s) ability to shed the constant heat input (from block+pumps) - we know that (assuming the series was delivering a reasonable flow rate in the first place) the (better) flow in the rads in the 2 pump system will have virtually no effect on the rad's C/W (from billA's tests) - for the purposes of the excercise lets take it as nil. therefore the 2-pump system's water temperature will be higher by whatever temperature is required to allow the rad to shed the 2-pump systems higher heat load (block + 2 pumps not block + pump.) in your example the 1 pump system has 150W input and the 2 pump 200w input - therefore the temperature (above the air flowing through the rad) of the water would be 1/3 as much again as teh 1 pump. using your figures the 1 pump system has +3C, and the 2 pump system +4C - the only way your cpu temps could be more favourable in the 2 pump system is if the increased flow in the
block loop reduced the block's C/W by enough to be worth more than 1C over water temperature