TC-4 My First Thoughts

[CooledByWater]

Having been using a Gemini High Volume water block, I wanted to make a change as I had felt that the Gemini block was restricting the flow. With its small water channels and small inlet/outlet I thought the Ehiem 1250 was developing backpressure and added heat to the system. So I ordered a D-Tek TC-4 REV 2 block. To my surprise the TC-4 is running 2c delta hotter. The only thing I changed in the entire system was the W/B. I even used the same mounting spring I used on the Gemini. Because the Gemini is thinner. I removed some nylon washers so the pressure applied to the chip was the same on the TC-4.

When I get back from vacation I am going to lap the TC-4 to a mirror finish as I had done to the Gemini. The TC-4 has some small machine marks that everyone claims holds the AS-II in place. My thoughts on this is B/S. The more contact you can place the W/B to the chip the better.

[SiGmA_X]

How did you attach it to your mb? I mean, what is the reccomeneded way? Spyder got mine on, but not the right way...

[The Spyder]

It fit, and we had no instructions, therefore i got it on the best i could :-P
SPyder

[CooledByWater]

I used 6/32 standoff's with nylon washers and nuts. The standoff's mount through the board. Next was to place the block in place. I used 1-3/4" 6/32 machine screws with nylon washers and steel springs. I did not like the system that D-tek supplied. Reason: using the above method, once the screws bottom out into the standoff and with everything of equal size or length, you can be 100 percent you have equal pressure on all for corners. In D-tek's method it's up to the user to tighten the thumb nuts to equal pressure. Although using this method you can add or subtract pressure on the chip easier.

[Random Nonsense]

bigger wider channels = less surface area, and also lower velocity, so the water is getting warmer in the block. E.G. one waterblock will always maintaing a core temp of 10c over the coolant temp. now, if the coolant is in the block for longer (lower velocity) then its going to get warmer. so core temp will be higher, surface area and velocity are pretty important! yes, a narrower channel will mean lower flow rate, but if you have more surface area because of it, and more fluid velocity it will perform better.

[CooledByWater]

I had been using the Gemini High Volume water block. With this block I had changed the barbs to 1/2" fittings, but the inlet on the blocks were still 1/8" fittings. This was causing back pressure on the 1250 pump and creating heat.

Now with the D-Tek TC4 the water is flowing through the block without nearly the restrcitions. I had wrote last week that the temps were below the Gemini, but I need to retract that statement because the ASII had not had time to set. My current temps are 2c below what the Gemini was giving me, but I do believe had I had a Eheim 1048 pump that has an output of 10 watts the Gemini would hold its ground.

The TC is going to stay in my system because it matches up with my Eheim 1250 pump.

[webmedic]

what are you going to do with your gemini?

[Claudius]

Originally posted by Random Nonsense
bigger wider channels = less surface area, and also lower velocity, so the water is getting warmer in the block. E.G. one waterblock will always maintaing a core temp of 10c over the coolant temp. now, if the coolant is in the block for longer (lower velocity) then its going to get warmer. so core temp will be higher, surface area and velocity are pretty important! yes, a narrower channel will mean lower flow rate, but if you have more surface area because of it, and more fluid velocity it will perform better.

I would think that the water in the block with the smaller channels would get warmer. Since there is more resistance, fewer gph is going to pass through the small-channeled block than the large-channeled one. Also, since more water is in contact with the small-channeled block, the water will heat up faster.
If water is be pumped too slowly through smaller channels it will reach its heat capacity and won't remove heat from the end of the channel, lowering the efficiency of the system. In this case you would want larger channels so that there is more water to heat up.
You don't want water moving too fast through large channels though because the water in the center of the channel will not heat up and will prove useless.
Depending on how your pump moves water through the block, there must be an ideal channel size/surface area which proves to be most efficient.
Just going with a block with smaller channels and more surface area may not be a good idea if your pump can't force water through it fast enough.

[Kaitain]

Originally posted by Claudius and Random Nonsense
[b]

I think actually both you and Random are focusing on single effects rather than the system-wide effects of both. In fact both of you are correct in many ways...

bigger wider channels = less surface area, and also lower velocity

so actually the rate of heat transfer into the water is slower. Although the residence time of the water is greater, if it has slowed down sufficiently for the flow pattern to be laminar, then you'll get orders of magnitude less heat into the water than with the narrow-bore channels.

I would think that the water in the block with the smaller channels would get warmer.

I disagree. Heat moves into the water faster. The water leaves the block sooner. The result is negligible increase in water temperature (remember it takes a lot of Joules to heat a gramme of water). The difference between the exit temperatures of blocks is unlikely to be measurable within reasonable accuracy.

Since there is more resistance, fewer gph is going to pass through the small-channeled block than the large-channeled one.

Very much depends on the pump. Centrifugal pumps are very forgiving of back-pressures, producing maximum flow-rate up to almost their full design spec. Provided you don't exceed that, developing a back pressure is NOT going to reduce the number of gph through the system.

Also, since more water is in contact with the small-channeled block, the water will heat up faster.

Which is actually what you want!

If water is be pumped too slowly through smaller channels it will reach its heat capacity and won't remove heat from the end of the channel, lowering the efficiency of the system. In this case you would want larger channels so that there is more water to heat up.

The "heat capacity" of a system like this is only reached when it boils. You really don't want that, now. If the water is pumped too slowly through a channel such that it's flow pattern ceases to be turbulent, you'll get crap heat transfer. Doesn't matter whether the channels are large or small.

You don't want water moving too fast through large channels though because the water in the center of the channel will not heat up and will prove useless.

That's actually totally wrong. You can NEVER flow the water too fast. You can reach a point of diminishing returns, but there's no threshold where the increase in speed disimproves the system.

Depending on how your pump moves water through the block, there must be an ideal channel size/surface area which proves to be most efficient.

YES!!!!

Just going with a block with smaller channels and more surface area may not be a good idea if your pump can't force water through it fast enough.

NO!!!! It's easier to force water "fast enough" through small channels. All you're after is turbulent flow, pref with Re > 10,000.

I have written a simple way of calculating pressure drops in tubes in this very topic (do a site search for "kplonk" and "bends" and you should have it). You'll find that, yeah, the largest pressure drops are due to the inlet and outlet points in the system. If you follow through this and the relevant calculations on heat transfer rate (here's another guide: http://www.wlv.com/products/databook/ch2_4.pdf ) you'll be able to determine the trade-off between the flow velocity (that's in ft/s, gal/h is a flow rate) and pressure drop that will give you the most efficient cooling, at a rate your pump can handle.