Ultrasonic2's TEC liquid chilled pc

[Ultrasonic2]

no, i meant electronically - not stacked (i know that has a set of problems all by itself). if you connect TECs in series (electrically) will you still get the desired dT increase? or do they have to be stacked to get that effect? ie: if they were side-by-side would you have a greater dT with half the voltage each vs a single at full voltage? what effect on QMax does this have? (still working exactly what QMax does for a TEC)

so far i understand UMax (max voltage), IMax (max current), QMax (max heat transfer), dT (temp differential between hot and cold sides at IMax), and COP (heat transference curve relative to current (amperage) at specific hotside temp) and how they all interrelate (mostly). i understand why more TECs is better than a single with similar total UMax/IMax. i assume the massive QMax you guys recommend is due to the undervolting of the TECs, whereas the actual power draw from those undervolted TECs is considerably less than total UMax/IMax for all the TECs combined?? still trying to figure out the relationship between UMax/Imax and QMax - i thought QMax was simply the product of volts and amps, but then i saw high QMax TEC's that were well under what i thought they would be. (35V/20A@403QMax) note: CoP will always be highest as dT approaches zero. but, since our chiller loops depend on a greater dT, how do we compensate for the lack of efficiency (ie: higher power requirement/current draw) of an ever increasing dT - at what point are we simply wasting power for diminishing returns?........anyway - still reading/learning/trying to figure this all out. thanks for all the input and help - and thanks for putting up with my MANY questions!!

idea: i was thinking about a barely sub-ambient (no condensation) water loop. since TEC's are most efficient at dT=0 then (ideally) you would want your hot side close to your low side. now, since it's impossible to get your hotside below ambient.......why not put a radiator in teh cold loop? (hear me out)...by doing so you would increase the cold side of the TEC to ambient - and if you can keep your hotside to within a few degrees of ambient you would then have a super efficient cooling method that would ensure ambient even under high load. you would have more cooling **potential** than you would at higher a dT and would (should) be able to remove more heat from your cold side loop (note: and with your radiator taking out some of the heat - as well as the TEC keeping the temps at room temp) you would then have a C/W of ZERO!! right? granted, you would not have a negative C/W but the cooling potential would be the same or greater than a subambient loop.

if you connect TECs in series (electrically) will you still get the desired dT increase?

no as you decrease the input voltage the delta will also decrease


interestingly applying 50% of Imax while applying Umax like a pwm controller at 50% is not the same thing as applying 50% of umax

or do they have to be stacked to get that effect?
stacking is the only way to increase their delta

if they were side-by-side would you have a greater dT with half the voltage each vs a single at full voltage?
assuming no load is applied then the one at full voltage would have the greatest delta


what effect on QMax does this have? (still working exactly what QMax does for a TEC)
placing TEC next to each other increases the Qmax while stacking decreases it. (relative to a single TEC)

i assume the massive QMax you guys recommend is due to the undervolting of the TECs, whereas the actual power draw from those undervolted TECs is considerably less than total UMax/IMax for all the TECs combined??
YES

i thought QMax was simply the product of volts and amps, but then i saw high QMax TEC's that were well under what i thought they would be. (35V/20A@403QMax)
PMax is 35V*20A Pmax is the power required to achieve dtmax (no load applied )

CoP will always be highest as dT approaches zero
YES

since our chiller loops depend on a greater dT, how do we compensate for the lack of efficiency (ie: higher power requirement/current draw) of an ever increasing dT
Add more radiators

at what point are we simply wasting power for diminishing returns
That depends on a lot of things

thanks for all the input and help - and thanks for putting up with my MANY questions!!
All good i enjoy it

.by doing so you would increase the cold side of the TEC to ambient - and if you can keep your hotside to within a few degrees of ambient you would then have a super efficient cooling method
Adding a rad to the cold side would then add heat to the cold side that the TEC's would then have to move back . On paper the TEC's would be operating at a very high COP. but you wouldn't actually see any benefits from it. not having the cold side rad and simply deceasing the input voltage further would be a better way to increase COP


but that was the whole point - to warm the cold side (to get closer to dT=0). i know - i have seen it said here many times not to do this because it defeats the purpose. and if you are trying to go subambient than yes, it certainly does, but if you only want to maintain ambient (better than normal LC, and without the increase in temps under load) then why wouldnt this make an efficient heat pump. it is still doing what it is intended for - it is removing heat generated by your heat sources.

you've just created a loop . tec's move heat to the hot side which gets put into the air via the rads. then on the cold side this air and heat is then put back into the cold side via the rads. The TEc's then move it back to the hot side. it's a ever worsening situation that never ends.