Heatercore series or parallell

[BGP Spook]

I would like to draw from well of knowledge.

If I ran multiple 2-302 heatercores in series about how much resistance/flow vs. cooling would I be looking at compared to the same # and type of heatercores in parallel?

Please, no one .

When I say parallel I do not mean a bunch of "Y" fittings.

Take a fair sized copper tube, with one 'in' near one end and the other end pluged, that has four 'outs' perpendicular to the length of the copper tube. The four 'outs' each go to one heatercore.(copper tube to heatercore tubing would be short, maybe 4" or 5" each) Each heatercore's out feeds into the mirror image of the first copper tube('out's previous are now 'in's and vice versa), with the one out down to the reservoir->pump(s?)->rest of loop->back to first copper tube.

The thought that lead me to this was, is it possible to run a multiple of heatercores off the same fans if they are stacked carefully.(and well sealed between the heatercores)
However, I was concerned about the large multiplication of water flow resistance, especially with the rest of my perceived loop.(I can over come the air resistance more easily, at least I think I can)

My reasoning is based on the hydraulic properties of a liquid.(I know water is about the worst possible example but such as it is...) The difference in pressure(from the feeding tube to the returning tube) might be all that is needed to a maintain relatively consitent flow among the heatercores.(assuming flow resistance is ~= )

OK, I am ready for my .

[bigben2k]

(took care of the duplicate thread).

I'm not sure, but I believe that someone (probably Bill) posted pressure drops figures for a number of cores, possibly including 2-302.

Best to run a search here.

[BGP Spook]

Thanks for the duplicate thread delete. Big on that one.

Thanks for the heads up, I will do a search for those numbers now.

[Long Haired Git]

I need a picture to understand.
Are you talking about buying say four heater cores, and then removing both end tanks from two of them and one end tank from two of them, and then joining up the tubes in order to make a single radiator? This radiator would be one radiator tall, one radiator wide, but four radiators deep so that air flow goes through all four radiators, right?
First, I wouldn't worry too much about the liquid pressure drop.

For example, imagine having four MCR120QP radiators and make them joined up using 10cm of 3/8" tubing. This will be worse for flow rate, right?

MCP350, Storm waterblock, single MCR120QP, 1m of 3/8" tubing = approx 3.4LPM
Using MCP655 @ 5 instead: approx 5.6 LPM

Now add in another three MCR120QP radiators each with 10cm of 3/8 tubing,
MCP350: 2.5LPM
MCP655: 4.3LPM

So, around 25% reduction in flow rate.

Adding them the way you describe will, IMHO, result in even less degregation of flow rate. Example is having two MCR120QPs vs single MCR220QP. I was going to use my Approximator to show you what I meant, but the MCR120QP has 3/8" barbs and the MCR220QP has 1/2" barbs and my approximator can't yet handle swapping barbs over and thus the figures are not accurate and hence a MCR220QP has BETTER flow rate than a MCR120QP!

Now, two things of import:

1. Super long radiators may suffer from performance reduction due to a lack of turbulence in the tubes as the uniform shape results in laminar flow. Hence, the coolant touching the tubes gets cooled, but as water is a crap conductor, it insulates the rest of the coolant in the tube. This is one reason why dual pass radiators which mix their coolant in the bottom end tank do so well.

2. Single pass radiators such as what you might be describing cause lower overal tube velocity than double pass radiators and this again reduces turbulence and thus performance.

3. Whilst water has awesome specific heat propertes, and hence doesn't increase in temp much whilst dumping energy into it, air does not have this quality. The air temp coming out of the first radiator will be significantly hotter than the air going in. The entire system works on the delta-to-air-temp, and as you're heating the air I would suspect that air-flow-series radiators to be completely awful for their performance.

4. Our fans are weedy, pathetic creatures. One radiator is bad for air flow, but four stacked would be like a brick wall. You'd seriously reduce the overall air flow, further reducing performance.

Overall, best avoided.

[Long Haired Git]

Oh, and my numbers are based on the results posted on the Swiftech web site for their MCR120QP and MCR220QP radiators, on the pump PQ figures available here in the forums in a spreadsheet, and from Robotech's PQ testing of the Storm waterblock. Tubing figures are from a PQ tool: would love some real world numbers if anyone can find them?

[BGP Spook]

The way you envisioned of my proposed setup was not entierly correct; it was very informative, though.

I expected the waterflow resistance to increase empirically while decreasing on a per unit bases much as you said.

The idea I was originally describing would have avoided changing or modifying the heatercores except to shorten the copper tubes comming out of them. I would have mounted them on a rack parallel to the earth and run the two copper tubes verticularrly on the left and right sides of the rack, with short runs between the in and out of each heatercore and respective copper tubes.

|_|
|_|
|_|
|_|
Something like the above with the two rows of " | " being the two copper tubes perpendicular to the heatercores.( the " _ " would have been the heatercores)

However, as you pointed out I would basically have to run the air comming out of one into another if I did that. (Effectively running the air in series.) There are ways around doing that and maintaing the same basic structure of my idea, which I will be exploring, along with a total redesign.(more to the 'picture' than what I asked about)

[Long Haired Git]

If the heatercores are each in parallel to each other, then you get a reduction in the resistance compared to a single heater core, and hence an increase in flow rate.
The reason is that the PQ is typically some function of the velocity of the water, which is some linear function to the flow rate. Example is the MCR120QP, which I calculate the head (in meters of water) as being:
0.021*Flow*Flow + 0.015*Flow
where Flow is the flow rate in litres per minute.

Now, place two radiators in parallel, and you halve the flow rate through each. Take that MCR120QP and put 4 LPM through it and I get 0.4m of head. Put only 2 LPM through two rads in parallel, and both present only 0.11m of head. Put four in parallel and you get 1 LPM through each and only 0.04m of head.

However, you get increased restriction from both the tubing linking them up, and also the intersections (maninfolds, Y's, T's whatever). Even so, the overall flow rate is typically superior in a parallel setup.
Tragically, performance is typically NOT superior. Each radiator is getting a flow rate far lower than the overall flow rate. This reduces turbulence and mixing, and reduces the effectiveness of the radiator. Sure, its not much of an effect (see yellow line on Graph 11 here: http://thermal-management-testing.com/ThermoChill.htm) but its present.

In the end, radiators are all about getting maximum air to metal contact to cool the coolant. More air and cooler air equals better performance. Sharing one fan between four radiators will be rather detrimental to performance. You're getting close to a passive setup and should expect similar temps (and, to your benefit, similar noise).

[BGP Spook]

After more thought I would like to bounce more ideas off of you guys.

I have two ideas about how to possibly setup multiple heatercores.

One I know would work but I feel it is....awkward do to the surface area it would take up. (one hole per heatercore in a plane)

The second idea is a little different.

For the purpose of my a mental picture, think of a square (24"x24") piece of plywood, then cut two rectangles in it. This is where it gets tricky. Put a, say 4" tall, piece of narrow wood down middle, length wise of the rectangles cut out of the piece of plywood. Now lean one side of a heatercore on the edge of the piece of wood running down the middle of the cut outs, and the other side of said heater core on the edge of the cut out.
So it's profile looks something like this.
|\
(the " | " is the piece of wood, the " \ " is the heatercore.)
Repeat with a second heatercore on the other side of the center piece of wood, like this:
/|\
Then seal the open gaps on the sides and place a fan underneath to draw from bother heatercores.

The idea is to getaway with less fans and to reduce the "foot print" of having four heatercores.

Would the fans be operating at a higher efficency with respect to effective CFM as per RPMs?
Am I right to think net resistance to airflow(after accounting for directional change do to angle of entry vs angle of exit) would be reduced for fans having more than one heatercore to pull from?

I believe I understand the implications, basically threw heatercore air velocity would be reduced per heatercore, based on number of heatercores.

[Long Haired Git]

Its a rad box with four rads making a W shape.
Providing you had appropriate distance between the rads and the fans, it would work.
Lower fans:rad SA means lower air-flow-rate per SA and hence worse performance.
If you are aiming for low noise, its certainly an approach. Check out the air-flow vs CW charts at thermal-management-testing and ensure you get enough air flow to get the performance you want: there is a definate "elbow" in the chart.

[BGP Spook]

The primary purpose is to reduce the foot print of having four heatercores in the same relative plane.
When they measure 12"x6" and you want to fit more components than just four heatercores in a 24"x24" plane it gets very difficult.

Thank you, Long Haired Git, for you help, advice, and numerous usefull links.

And yes I understand it is all about airflow. The reason for all this fuss is I am trying to get a design for a personally made case sorted out in my head and on paper before I go shopping for components.

In short, I have a self-imposed dimension limit, and I need to get the basic structure designed and 'ideal' componets fitted.

There is no rush, however, since I don't plan on buying or building anything until the May at least, likely later.

[-=Mr_B=-]

Dont know exacly how great the impact is, but connecting a bunch of radiators the way i think you mean, on different distane from the plugged end of the "distributor tube" gives the radiator connected closest to the plugged end most water, and the one closest to the inlet least.

Forgive me, i feal my linguistics fail me, so some crude ansi, if i may...

===|#1#2#3#4#| (imagine this to be a pipe, connected to the hose, on the left side(work with me here, please))

The numbers are the 4 outlet connectors, 1 gets least, 4 gets most water flow, simply due to the water trying to continue straight forward. For an even flow, 3 Y's and a bunch of "exacly as long tubes" on both in, and outlet, would performe better. However, i dont know if it would be more resistive and hence kill performance through lower over all flowrate.

B!