Need all your help/opinions... 2nd Rev. CAD models...

[jaydee]

Originally posted by Cathar


My biggest concern is ensuring an even spread of water flow out from the middle. The water is going to naturally want to head straight for the outlet sides, and not move up and down to the edges unless you create specialised pressure drop regions that forces the water into those locations.

I was thinking about this very issue. I thought about making the outlets on the sides of the block instead of ontop of it. That way the water will go all the way down and then left and right into the outlets and then up instead of water hitting water already in the block and pushing out the nearest outlet wich is right next the to inlet. Did that make any since?

[Albigger]

Originally posted by Cathar
Your block as it stands doesn't seem to need the middle plate.

I'm not quite sure what you mean about not having the water spread out, 'cos that's what it's going to want to do. As long as you have the inlet barb directly over the place where you want the water to go it'll push the water down fairly "firmly" against where it's pointed. It's not going to go spreading sideways up near where it just leaves the barb by very much at all.

My biggest concern is ensuring an even spread of water flow out from the middle. The water is going to naturally want to head straight for the outlet sides, and not move up and down to the edges unless you create specialised pressure drop regions that forces the water into those locations.

There's still a lot of work for you to do. I'm also concerned about base flex too with nothing really bracing the tops of the pins, but this is dependent on how thin you make your base. It you stay at or above 2mm thickness you should be fine.

There's a few other things crossing my mind concerning the way the pins will affect fluid flow. I tend to agree with the above statement about having the pins rotated by 45 degrees.

1st - thanks for all the input.

okay, the tabs in the bottom of the middle plate are supposed to somewhat block flow from going directly from the center barb to the outside ones. The tab does NOT go all the way to the bottom of the water channel, but it is deeper than the short row of pillars, forcing some water to go the opposite direction of the barbs first, then flow around the tabs (they don't go all the way to the sides either). I'm not sure how much this would
#1 work?
and
#2 hurt flow rate?

you have a good point about the water input coming straight down. I also wanted the square inlet in the middle block to increase water velocity, however. do you think it is important from this standpoint? As your block incoporates a similar design here.

another idea about spreading the water out more evenly is to leave some of the pillars "connected" effectively creating a wall in between the inlet and outlet barbs, forcing the water to go around. Not a whole row, but maybe the middle 3 or 5 pillars leave connected? this means less milling too

About the base flex - the tops of the shortest pillars are directly contacting the middle plate, I could even leave them a couple thousands higher than the o-ring surface, if it would help. However the middle most and tallest pillars have no top brace. Do you think base flex is still a concern when the shorter pillars are braced on top but the taller ones aren't? I was planning a base thickness of .090in = 2.25mm but it would get down to .060in = 1.5mm where the dimples bottom most point is. but the nominal base thickness i would think would be closer to the 2mm mark.

Thanks again for your help/comments.

*EDIT* I forgot to address the comments on pin orientation. I'm not exactly sure why this is an issue? Assuming fluid flows equally in all directions - pin orientation would have ABSOLUTELY no effect, correct?
Now, that assumption is probably bogus, as most of the water will tend to flow from inlet straight to outlet, so I can maybe see here why orienting them at a 45 would help - increase fluid flow with less hard restrictions - the water would hit the 'point' of the pillar first. Also more velocity-contact area? it would hit two sides of the piller hardest and the two backsides hardly at all, as opposed to hitting on side head-on-hard, brushing by two sides, and one side having minimal fluid pressure against it.

More reasons i am missing? (i'm sure there are)

here's mad paint skills:


this is showing the majority of the flow, is the picture basically correct?? Again this is all assuming that block doesn't do a good job of making the water spread in all directions evenly. And assuming higher fluid pressure against walls is good (more ability to absorb heat from the block, the higher the pressure, correct?).

[Albigger]

Originally posted by jaydee116
I was thinking about this very issue. I thought about making the outlets on the sides of the block instead of ontop of it. That way the water will go all the way down and then left and right into the outlets and then up instead of water hitting water already in the block and pushing out the nearest outlet wich is right next the to inlet. Did that make any since?

the tabs sticking out the bottom of the middle plate were supposed to be for the purpose of making the water travel 1st in the direction opposite the barbs, then around the sides and under the tab, then into the outlets...

i'm not sure if it will work though or if it would hurt flow rate too much


EDIT: * and I kind of understand your idea about having side outlets, but i'm not exactly sure where you are talking about putting them. plus that might be bad for motherboard clearance, though the block size could get decreased...

[jaydee]

Originally posted by Albigger
the tabs sticking out the bottom of the middle plate were supposed to be for the purpose of making the water travel 1st in the direction opposite the barbs, then around the sides and under the tab, then into the outlets...

i'm not sure if it will work though or if it would hurt flow rate too much


EDIT: * and I kind of understand your idea about having side outlets, but i'm not exactly sure where you are talking about putting them. plus that might be bad for motherboard clearance, though the block size could get decreased...

I would drill the outlets into the block itself on the left and right sides. drill a hole strait down and then cross drill it from the outside and cap the hole. Also make the inside top to bottom clearance the same as the hole cross drilled or maybe a little narrower so the water is forced to the left and right out the side outlets. I will try to make a drawing sometime. Way to tired to mess with acad right now.

[Albigger]

Ok, here's what I'm thinking - got rid of some bolt holes, allowing the outlets to be moved farther apart. No more problems with cramping, now just problems with
#1) too much volume of water sitting in the block
#2) flow control

Here's what I plan:





Notice the extened water cavity and o-ring. Also notice the pillars on the outer row are connected, and the hole in the middle of them is offset (i.e. its right in front of another pillar instead of an opening) Will this be enough to deter enough flow to the outside and around to the outlet - hopefully. The gap in that wall is only 1/16" wide, and I don't even have to mill it all the way down if I don't want.

Also to help with flow control (only if needed) would be the implementation of a middle plate, but for now I would just build it like this and see how it goes.

Also, here's a revision I'm considering for the middle pillars, what do you think?


Having 4 smaller ball mill plunges instead of the one large one?

just some ideas to kick around.... maybe ordering the copper soon....


P.S. I know there would be fillets in the water cavity walls as it would be cut with an endmill, but i forgot and i'm not putting them in now...


EDIT: as of now, the bottom tier of pillars is .175in = 4.4mm tall and the upper tier is .350 in = 8.9mm tall. I'm thinking of shortening these even more, especially if I go the way in the last picture. Thoughts on height of these???

[bigben2k]

This is getting dangerously close to Cathar's "White Water" block.

What's your target flow rate? Pressure drop?

[Albigger]

Originally posted by bigben2k
This is getting dangerously close to Cathar's "White Water" block.

I hope you didn't mean that in a bad way...

I've had my aluminum prototype designed/milled before I saw Cathar's block, I just realized that a lot of people here know A LOT about this stuff and I wanted to get some input on tweaking it.

There always were a lot of similarities - Center inlet - dual side outlets...

But I'm not going to sit here and point out the diffs/similarities, you can see those quite easily. If Cathar want's to say something to me I'm open to it and I of course respect his design and all the work put into it. I'm just trying to do my homework in order to acheive a very decent performing waterblock.

That being said, I hope it didn't sound mean and no one takes it the wrong way.

Originally posted by bigben2k

What's your target flow rate? Pressure drop?

Target flow rate - as high as possible. I'd like to maintain or increase the 6.5 gpm (~ 24.5 lpm) flowrate i had through the aluminum prototype with barbs on (i.e. I tested with just pump, some tube to block, inlet barb, and outlet barbs). I didn't test the whole system, but from what I say guessing still > 4gpm through all components. I'd like to maintian this.

I'm not exactly sure what is meant by pressure drop, or how to find it, or what it means to me here. I've seen the term pop up, mostly in talking about radiators and such, but i'm still not sure about this....so if anyone wants to give a link/quick overview i'd appreciate it

[bigben2k]

4 gpm, OK.

Now you must know that you can achieve 4 gpm through a 1/4 inch pipe, the same way that you can achieve it in a 24 inch pipe...

The difference is the pressure. It's proportional to the speed of the coolant.

In my design, I'm headed towards a 3/16 center nozzle, and if I keep it short, then I might achieve 4 to 6 gpm. The pressure drop would be the equivalent of 8 to 11 feet of head or (3.5 to 4.8 psi) or (2.4 to 3.4 meters of water). My pump can handle this, and can do it at its top efficiency (Little Giant 2-MDQ-SC).

I'm sorry I brought up Cathar's block. I'm surprised no one did the same to my design! Although I've had the original idea for quite some time, Cathar's results inspired me to finish what I started.

I'd be happy to take a shot at calculating the pressure drop on your block. Shoot me some more numbers!

[utabintarbo]

Originally posted by Albigger

Notice the extened water cavity and o-ring. Also notice the pillars on the outer row are connected, and the hole in the middle of them is offset (i.e. its right in front of another pillar instead of an opening) Will this be enough to deter enough flow to the outside and around to the outlet - hopefully. The gap in that wall is only 1/16" wide, and I don't even have to mill it all the way down if I don't want.

It seems that a modification like this will make machining more difficult (not a lot, but some). You might want to reconsider milling the pillars at 45 degrees.

I would also take the sharp angles out of the outer corners.

Bob

[Albigger]

Originally posted by utabintarbo
It seems that a modification like this will make machining more difficult (not a lot, but some). You might want to reconsider milling the pillars at 45 degrees.

I would also take the sharp angles out of the outer corners.

Bob

yeah, this means i will HAVE to go cnc, with the new shape of the 0-ring and the water cavity, but I probably wouldn't want to do it on a hand crank mill anyhow, as more rpms are better for this small of cutting bits...

There shouldn't be any sharp angles in the corners, and probably not even in the bottom-to-sidewalls, i may mill it with a ball mill.

is has been brought up to mill the pillars at a 45 degree orientation, but i have not heard much to back up this consideration (see my pics earlier in the thread)...

Originally posted by bigben2k

I'm sorry I brought up Cathar's block. I'm surprised no one did the same to my design! Although I've had the original idea for quite some time, Cathar's results inspired me to finish what I started.

dont' be sorry, its perfectly respectable. I just didn't want people getting the wrong idea, i certainly wouldn't plagiarize another's idea. besides, its fun to come up with new stuff, even if it doesn't end up performing as well (but I can try).

Originally posted by bigben2k
4 gpm, OK.

Now you must know that you can achieve 4 gpm through a 1/4 inch pipe, the same way that you can achieve it in a 24 inch pipe...

The difference is the pressure. It's proportional to the speed of the coolant.

In my design, I'm headed towards a 3/16 center nozzle, and if I keep it short, then I might achieve 4 to 6 gpm. The pressure drop would be the equivalent of 8 to 11 feet of head or (3.5 to 4.8 psi) or (2.4 to 3.4 meters of water). My pump can handle this, and can do it at its top efficiency (Little Giant 2-MDQ-SC).

I'd be happy to take a shot at calculating the pressure drop on your block. Shoot me some more numbers!

ok, still getting used to this pressure drop thing. so there's a pressure drop going from the inlet into the block, or from into the block to out of it? And this is equivalent to some load placed on your pump, in terms of feet of head? I hope the drop of my block isnt too great then, as my pump is only spec'd at 120 gph at 10 feet.

anyhow, i'll try to read up on it some more, and thanks for your offer to calculate it. Does it have something to do with an equation of the form:
[Sum of external Forces] = [mass flow rate][change in velocity] ?? or is that completely different?

anyway (again) - what numbers do you need? the internals of the water chamber mostly?

[bigben2k]

Getting there...

If you take a look at the "pump roundup" thread, you'll find lots of graphs. Those graphs indicate what kind of flow you can expect, using different pumps.

All pumps deliver their maximum flow rate when there is no restriction, aka 0 head, aka no pressure drop.

When you put the pump in a cooling loop, there are restrictions, and there is pressure.

The pump will deliver the flowrate that matches the pressure drop on those graphs.

Pressure is measured between two points. For a waterblock, once you've established the flow rate, it's only a matter of calculating the restrictions, in order to come up with a figure, for the expected pressure drop. This pressure drop is between the inlet, and the outlet.

Note that the graphs that come with pumps will give you the pressure drop between the pump inlet and outlet. The total restriction in your rig will be composed of the waterblock, and the rad (tubing is usually not a factor).

So yes, if you give me the inner dimensions of the block, I'll take a shot at calculating the flow restriction. The equation you posted doesn't really have anything to do with it. and I mean that it's not complete.

[utabintarbo]

Originally posted by bigben2k

...

So yes, if you give me the inner dimensions of the block, I'll take a shot at calculating the flow restriction. The equation you posted doesn't really have anything to do with it. and I mean that it's not complete.

And when you do so, you will share your work with the rest of the class, right?

Bob

[bigben2k]

Of course

What's the point of doing it, if no one can learn from it!

[nicozeg]

What are the internal diameters of the barbs you want to use?

It seems that the outlets are going to be a bottleneck.

[Albigger]

Originally posted by nicozeg
What are the internal diameters of the barbs you want to use?

It seems that the outlets are going to be a bottleneck.

why does everyone think this??? I've gotten this question on 3 different forums so far. Here's what I worked out:

(cut and pasted)
----------------------------------------------------------------
5/8 ID tube inlet and 2 x 3/8 ID tube outlet work out good - I think: consider:
--The barbs I have, 5/8 barb measures actual ID of ~ 7/16 = .4375in
cross sect. area works out to (.4375/2)^2 * PI = .1503 square in.
--The 3/8 barbs I have measure actual ID of ~ 1/4, I think I can drill out to 5/16 or at least 9/32, giving cross sect. Area: (.28125/2)^2 * PI * 2 (for 2 outlet barbs) = .1243 square in.

This is slightly less than input Area, but that means velocity will be higher as the water is exiting the block (assuming no change in density - which there wouldn't really be). I was aiming for the water to leave the block faster than entry, however, this only tells that the water at the instant it is leaving the exit barbs has higher velocity than the water coming in the inlet barb, it says nothing about what it is doing in the block itself....

-------------------------------------------

I should note those measurements were taken at the most restricive part of the barb.

I should also note this:

on the aluminum prototype I made, I tested it with my danner model 7 700gph pump, ~ 3 foot of 5/8 ID tubing, and the inlet barb, with NO outlet barbs.

Resultant flow rate: 7 gpm

I then tested the same thing only WITH putting on the two outlet barbs (but no tubing)

Resultant flow rate: 6.5 gpm

And this was BEFORE I drilled out the outlet barbs like I planned on. So I do not think it hurts flow rate all that much.

Originally posted by bigben2k
Getting there...

If you take a look at the "pump roundup" thread, you'll find lots of graphs. Those graphs indicate what kind of flow you can expect, using different pumps.

All pumps deliver their maximum flow rate when there is no restriction, aka 0 head, aka no pressure drop.

When you put the pump in a cooling loop, there are restrictions, and there is pressure.

The pump will deliver the flowrate that matches the pressure drop on those graphs.

Pressure is measured between two points. For a waterblock, once you've established the flow rate, it's only a matter of calculating the restrictions, in order to come up with a figure, for the expected pressure drop. This pressure drop is between the inlet, and the outlet.

Note that the graphs that come with pumps will give you the pressure drop between the pump inlet and outlet. The total restriction in your rig will be composed of the waterblock, and the rad (tubing is usually not a factor).

So yes, if you give me the inner dimensions of the block, I'll take a shot at calculating the flow restriction. The equation you posted doesn't really have anything to do with it. and I mean that it's not complete.

Found all the graphs, they look great, i see what you mean. But i was just thinking the term "pressure drop" corresponds to a lower pressure, which would be fine for the pump. The pump just pumps less when there is higher pressure on the pump, correct? So can the term "pressure drop" apply to higher or lower pressures? Or am I still not quite understanding the term.

I also couldn't find these graphs for my specific pump:
Pondmaster Danner Mag Drive model 7.

Not that's its that big of a deal, i do have a chart for every one foot increments for what it flows though, so that should give a rough estimate
Linkage
(have to scroll down to Supreme Mag Drive Model #7)


Now that that's out of the way, i'm going back to a 3 layer design, I just won't get the water velocity over the center that I think I want to have. I posted pics later on down.

Attention BigBen2k - Here you Go (others may skip unless HIGHLY interested):

Middle Plate:
Inlet - 15 Degree hole with .500" diameter on the top surface, minus 15 degrees taper through the block (to focus water and increase velocity)

Outlets are tapered the opposite way, with the biggest opening towards the water channel. They are 10 degree tapers, with a diameter of .350" on the top of the middle plate.

The middle plate rests on the bottom plate and makes contact with the tops of the lower pillars, and the outside of the bottom block (around the o-ring)

the water cavity is .075" deep (from the ledge where the o-ring groove is), and the red protrusions on the bottom of the middle plate stick down .040" (this is both to increase water velocity in the block and to defer some of the flow to the outside and around to the outlet instead of straight from inlet to outlet).

The upper tier of pillars rises .100" above the lower tier, for a total height of .175" All the pillars (except the longer connected ones on the outside) are .0625" x .0625" The 146 dimples in the base are half spheres made by plunging a ball mill of radius .03125" down a depth exactly equal to its radius, into the base.

The fillets in the corners are all .046875" radii.
The pillar arrangement is 9 columns by 7 rows, with slight variations on the outer columns.

See the pic for the dimensions of the water cavity.

...(take a big breath)... And that's about it, I think.


these dim. are to the walls of the water cavity, from the center of the block:


Here's the revised stuff:








Thanks for bearing with me, all that have made it this far. I'm sure you're all sick of seeing this by now, but I want to get the best design down and working (who doesn't?)

Another quick question: since the barbs will just be screwed into the topmost plate (and not stick out the bottom, so they don't quite hit the middle plate when assembled) would it be ok to use aluminum for the top plate and copper for the rest of the system? Since the water wouldn't really be hitting the aluminum top plate (much) it would just be hitting the inside of the barbs. Thoughts?

Thanks again to everyone who comments. Thanks to bigben to trying to work this out for me. Please post something about it when you get around to.

[Albigger]

I should also note that Solidworks does something nice like this for me:




I looked up the density of copper alloy 110 (is this acceptable to make waterblocks out of) here:
Metal Mart

which said to be .322 lbs/cubic inch at 20 degrees Celcius.

I input that into solidworks so it give me mass, etc...


but I was just thinking (if you don't want to do a mess of calculations bigben) that i could calculate the volume of a solid rectangle for the base, and subtract out the volume for the holes and o-ring groove, and the difference between what I got and the true volume (said by solidworks) would the the water cavity volume.

This might be a little easier to get a rough estimate?? not sure.

by the way the specs i posted are for the base plate only. I could do the same for the other plates/parts.

[Nick C]

If you insist on using a middle and top plate, may I recomment making it out of brass? I know brass is much heavier, but It is a ton easier to mill, and may possibly be cheaper (not sure...)

-,e

[Albigger]

Would I get the same kind of (galvanic?) corrosion with the brass and copper that happens between components when using aluminum and copper? If not then I will look into this. If it still will corrode maybe I can still get away with aluminum or brass for the top plate, as I dont' think it will really be in contact with the water that much. However the middle plate will, so....

EDIT: and although brass (as you say, i've never milled it before) and i know even aluminum would be easier to mill, most of the operations that need done to the middle and top block consist of drilling straight or tapered holes.

Only real milling to be done is on the middle plate :
o-ring, and take .040" off the underside except where the islands are.

none the less, easier is easier, so i will def. look into it. thanks for suggesting it.

[utabintarbo]

Originally posted by Albigger
Would I get the same kind of (galvanic?) corrosion with the brass and copper that happens between components when using aluminum and copper? If not then I will look into this. If it still will corrode maybe I can still get away with aluminum or brass for the top plate, as I dont' think it will really be in contact with the water that much. However the middle plate will, so....

EDIT: and although brass (as you say, i've never milled it before) and i know even aluminum would be easier to mill, most of the operations that need done to the middle and top block consist of drilling straight or tapered holes.

Only real milling to be done is on the middle plate :
o-ring, and take .040" off the underside except where the islands are.

none the less, easier is easier, so i will def. look into it. thanks for suggesting it.

As I understand it, you will have essentially no corrosion problems with brass/copper. Most heatercores are brass/copper mixed.

Bob

BTW, SolidWorks also works in metric, you know....

[Albigger]

Originally posted by utabintarbo
As I understand it, you will have essentially no corrosion problems with brass/copper. Most heatercores are brass/copper mixed.

Bob

BTW, SolidWorks also works in metric, you know....

... yeah i know. but i work in U.S. standards..... ...good ol' inches



ok good, thanks for pointing that out about the brass/copper. now to look at cost/availibility of that....

too many variables...too little time....

[bigben2k]

Brass is an alloy that includes copper. There will be galvanic corrosion, but these metals are so close to each other on the galvanic scale, that it's barely worth mentioning. Thermal properties are a different story.

Albiger: go ahead and see what you come up with, and we'll compare notes.

Mag Drive #7
Flow (gph)
700 @ 0 feet
550 @ 2 feet
480 @ 4 feet
400 @ 6 feet
300 @ 8 feet
120 @ 10 feet
max 13'

Here's the data, graphed. Notice the bump in the 300 to 500 gph range: that's your pumps most efficient range. You should target 5 to 8 gpm, which would give you a total headloss of 8 feet and 4 feet, respectively.


About the 3/8 barbs: Ideally, you want to keep the speed of the coolant under 5 fps (feet per second), otherwise the pressure created restricts flow (I'll have to revisit that sometime).

My calculations indicate that a 3/8 opening with a 5 fps (4.9 actually) flow speed will result in a pressure drop of 1 inch of head, for each inch of length of that 3/8 opening, resulting in a flow rate of 1.7 gpm.

Using two of these as outlets, that would give you ideal flow at 3.4 gpm, or ~200 gph.

At that flow rate (3.4 gpm), the 5/8 inlet flow speed is 3.6 fps, with a pressure drop of 1/3 inch, for each inch of length.


If you target 5 to 8 gpm:

5 gpm:
the 5/8 inlet will have a flow speed of 5.2 fps, with a pressure drop of 2/3 inch per inch of length.

the 3/8 outlets will each have a flow speed of 7.3 fps, with a pressure drop of 2 inches per inch of length.


8 gpm:
the 5/8 inlet will have a flow speed of 8.4 fps, with a pressure drop of 1.4 inch per inch of length.

the 3/8 outlets will each have a flow speed of 11.6 fps, with a pressure drop of 4.8 inches per inch of length.


Now of course you want most of the restriction to be in the block, not in the surrounding tubing.


You said that a free flow test got you 6.5 gpm, with both barbs on. That's about 400 gph, which means that you're getting a pressure drop of about 6 feet, according to the pump chart.

At 6.5 gpm:
the 5/8 inlet has a flow speed of 6.8 fps, with a pressure drop of 1.0 inch per inch of length.

the 3/8 outlets each have a flow speed of 9.4 fps, with a pressure drop of 3.3 inches per inch of length.


All this doesn't take into account the rad that you'll be using, if any.

[Albigger]

Wow........ all i can say is....you guys really know your stuff!

First, I want to say I can get the numbers you get for water velocity, but not for the pressure drop??

I don't know how to calculate this by hand, so i'm using this:

Press. Drop Calculator

which I'm not even sure if its the right thing to use in this situation. anyhow, here is what I plugged in, for example:

mass flow = 1478.1 kg/h (6.5gpm)
density = 1000g/l
viscosity = .81cP or .00095131 kg/(ms) (looked up value)
Length = 1 in.
Diameter, inside equiv = .625 in
condition: new, clean

it gives me:
pressure drop = 0.4 in H2O
head loss = .033 ft
Rey. number = 40654 turb. flow (don't know what this means)
velocity = 6.8 ft/s

the velocity agrees with your numbers, as it does when i plug in your other numbers for diameter and mass flow, but i never get a pressure drop that matches yours? what am i doing wrong?

also - most of the things i come across seem to have calculators for doing this stuff. is there a site where it explains the equations/theory/whatever so i could read up more on this that you might happen to have a link handy to?? if not i'll keep lookin'


i can't wait to take fluid dynamics courses. I'm considering a B.S. in fluid and thermal engineering - this stuff really interests me. But I'm not there yet - stuck in all my pre-req courses for now
/end personal info

my radiator is 6" x 7 3/4" x 2" heater core, 5/8" inlet and outlet. Could I just hookup the pump to a tube, measure flow rate, then hook up rad, measure flow rate, and the difference would correspond to some head loss?

and at 6.5 gpm, which i think would be good to target, like you said, between 5 an 8, and i don't know how realistic the upper portion of that spectrum is - would you suggest going with 3/8" NPT and 1/2" ID outlet barbs, as opposed to the 1/4" NPT and 3/8" ID barbs i have now, to reduce the feet per second of the outbound water (9.4 fps at 6.5 gpm) less than or closer to 5 fps, as you suggest?

when you say target, do you mean target for the block? or for the whole system? Because 6.5 gpm would be a lot for the whole system.


EDIT: so - if you in theory calculate the head loss from everything in your system you just add them up to get a total then read your flow rate off the graph? or does it not work this way?

alright, i guess i'll be trying to learn and read more on this....

back later.......

[bigben2k]

Oops...

I'm using the Hazen-Williams formulae, and I just noticed that I used a factor of 80 for those calculations.

80: old steel pipe (rusty?)
100: new steel pipe
140: smooth copper
150: PVC (tested to 155 OK)

so again, with a factor of 150...

6.5 gpm
the 5/8 inlet has a flow speed of 6.8 fps, with a pressure drop of 0.3 inch H2O, per inch of length.

the 3/8 outlets each have a flow speed of 9.4 fps, with a pressure drop of 1.0 inch H2O, per inch of length.

That's closer to your numbers. Given brass barbs, you probably want to use 140.


I still don't know what kind of rad you have in mind, but if you have 6.5 gpm with the block alone, you'll have to try to keep it all near 5 gpm (unless you switch barbs).

The pressure drop is proportional to the fluid speed. You can add all the pressure drops of each individual component, if they're all at the same flow rate. If not, you have to recalculate/measure everything.

I can't advise you on replacing the barbs, until you have a narrower target flow rate range, but you're on the right track. In my block, I've had to go with 3/4 ID tubing which, at 4 gpm, drops 0.1 inch of head for every inch of tube. Flow speed is 2.9 fps (0.9 m/s). My original idea had 1/2 inch ID tubing, which drops 0.4 inch head per inch of length, for a flow speed of 6.5 fps (2.0 m/s) (factor = 150).

[Albigger]

yeah those numbers seem to mesh pretty well

the heatercore I'm using is FEDCO # 2-150 and can be seen here:

heatercore4u

I want total flow throughout my system to be 5 gallons per minute, 300gph, at which my danner model 7 pump will push at roughly 8 feet of head loss (according to the chart)

I'm adding a big restriction in the block though (in the middle block) - the tapered hole underneath the inlet will taper from ~.400" down to ~ .290" diameter, with a 15 degree taper.

So basically - now that i have a specific flow rate in mind, I should measure (if I can) the pressure drop or head loss, then attempt to calculate this for my waterblock? How would I go about doing that?

Then once I know those I can figure out what tubing size lengths to use so as to not get too far from the head loss target?

How do I go about computing pressure drop for the block? And how to convert this to head loss?


EDIT: just thought about this, i actually want the highest flowrate i can get (within the efficiency of my pump) so I will target 8 gpm, but i want AT LEAST 5, if possible, through the system.

[bigben2k]

Seeing that you're already down to 6.5 gpm with your Alu prototype, 5 gpm would be a target. A definite minimum.

I found an absolutely amazing link:
http://www.lmnoeng.com/index.shtml

I'll be using it to help calculate the resulting flow restriction through your block (and mine!).

As for the flow restriction through the rad, there's no way to tell, because there are no graphs available to give us such info. However...

We might find a chart for a similar core over here .

Looking at big momma, I'd extrapolate a pressure drop of 5 psi@5 gpm. Dang, that's 11.5 feet of head!