Radiators and Fans

[BillA]

heater core connectors are sized and oriented simply to fit up with the rest of the heating system;
the engine water pump has more than enough head to push whatever,
and normally the heater control valve is not fully open

we are the ones with pissant pumps

[Since87]

Originally posted by unregistered
heater core connectors are sized and oriented simply to fit up with the rest of the heating system;

It seems to me, like it would be easier on the manufacturers to use consistent tubing sizes, but what do I know? Maybe where the tubing has to be routed is the major factor?

Originally posted by unregistered

and normally the heater control valve is not fully open

You clearly live well south of me.

[Les]

Originally posted by unregistered

and the heat dissipation ?
unfortunatly we have only one datum
just convert to "dissipated W/in²/CFM" (or metric) ?

Metric but ugh.
Still a bit fuzzy what this quantity "dissipated W/in²/CFM" is called.
Current favoured flavour for Air Flow is "m^3/min"
This would m^3/min per radiator(?)


Area cm^2 and probably referring to frontal area i guess

Am only slow learning the ways of radiators.Using this series of pdfs by Wolverine
http://www.wlv.com/products/databook/ . Finding some interesting snippets (e.g suggested Erosion Velocity Velocity limit 6ft/s for Water impinging Cu) in addition apparantly sound theory.

[BillA]

seriously good link Les

the metric units I'm using are:
Pa for air pressure, m³/min for air volume
mH2O for pump related (liquid) pressures, lpm for flow rate

for the dissipation 'constant',
how about: W/cm²/m³
but note that this will be a very small # (the air unit is 'too' big)

think you need to get into 3D graphs
air flow and backpressure,
coolant flow and head loss;
for a given rad type - will then yield the dissipation
-> at the 'design' air/coolant temp differential of course

there is nothing that cannot be made more complex

[Since87]

Here is a 'user' spreadsheet for calculating PQ curves for heatercores. No guarantees as to the accuracy of the results.

[BillA]

very professional, a worthwhile addition
I'm impressed

somewhere a note needs to be made that this applies to 1 15/16" thick heater cores

[Since87]

Originally posted by unregistered

somewhere a note needs to be made that this applies to 1 15/16" thick heater cores

True. Probably other notes that should be attached as well.

I'll leave this one up for a bit and collect suggestions then put a revised one up.

[Les]

Neat
Big Momma* no problem
Works with Alien Fudge Factor(0.0159722222222222222222222222222222)
Use Bill's http://forums.overclockers.com.au/sh...threadid=58005 to correct for 3/8" barb to 0.488"ID(Works with my sums).
Experimental Big Momma* ~ 1.1mH2O at 7.5LPM


Tried a Wider HC( re Bills comment)
Radiator E* 30 Tubes(9/8"wide) 2 pass (0.4" ID entry) , (2 Pass ?)
Dunno but perhaps not so clever
Used an Alien Fudge(0.008151) and Quadrupled(4x) "per tube resistance coeffs"
Experimental* ~ 1.75mH2O at 7.5LPM



* {url]http://thermal-management-testing.com/radiator%20testing%201.htm[/url]

EDIT Corrected some stupidity.

[Since87]

Originally posted by Les
Neat
Big Momma* no problem
Works with Alien Fudge Factor(0.0159722222222222222222222222222222)
Use Bill's http://forums.overclockers.com.au/sh...threadid=58005 to correct for 3/8" barb to 0.488"ID(Works with my sums).
Experimental Big Momma* ~ 1.1mH2O at 7.5LPM

Hmm. I need to add something explaining 'one pass' vs 'two pass'. It looks like you setup the spreadsheet for Big Momma with only one pass. Because the water flows down one set of seven parallel tubes and up another set of six parallel tubes, the pressure drops for the two sets of tubes will be in series rather than parallel.

I think the flow resistance of the 3/8" barbs, swamps the resistance of the heatercore itself so much, that whether the heatercore were one pass or two would make a few percent difference in the total pressure drop of the two systems. (No time for a more in depth look right now.)

It does look like it would be reasonable to add a factor to the spreadsheet accounting for the ID's of barbs that have been added to the heatercore.

Originally posted by Les

Tried a Wider HC( re Bills comment)
Radiator E* 30 Tubes(9/8"wide) 2 pass (0.4" ID entry) , (2 Pass ?)

Radiator E is a single pass, but regardless, I would expect a substantially different set of fudge factors to be required to approximate the PQ behavior of Rad E. Too big a difference in the flat tubes. I think it would take data from a group of three rads, with flat tubes identical to Rad E's tubes, but different overall lengths and/or configurations. That gives you three equations using the three unknowns. (The fudge factors.)

[Les]

Originally posted by Since87
. It looks like you setup the spreadsheet for Big Momma with only one pass.

Yes
For the Big Mamma all is well
The only reputable report* marks no mention of 2-Pass for the Big Mamma.


"Rad F - OCWC PN: Big Momma
Tube: 13 full thickness corrugated brass “plates” "

. I am onlly suggesting it is very difficult.

* http://thermal-management-testing.co...esting%201.htm

[Les]

[i]

Radiator E is a single pass, but regardless, I would expect a substantially different set of fudge factors to be required to approximate the PQ behavior of Rad E. Too big a difference in the flat tubes. I think it would take data from a group of three rads, with flat tubes identical to Rad E's tubes, but different overall lengths and/or configurations. That gives you three equations using the three unknowns. (The fudge factors.) [/b]

Single pass worsens the agreement.
Fudge factors were changed in favour of a correlation.

Think it is difficult

[Since87]

Originally posted by Les
Single pass worsens the agreement.
Fudge factors were changed in favour of a correlation.

Think it is difficult

I'm not sure if you mean 'Coming up with a set of fudge factors to get a curve match is difficult.', or 'Coming up with a plausible set of fudge factors is difficult.'

I wouldn't even attempt the latter with only data from a single HC from a given 'family'. I'm grossly unqualified to even offer a guess.

The former is simple algebra though. There is an infinite set of bogus combinations of fudge factors, that will give a curve that appears to be a reasonable match to Bill's data for RAD E. (See attached image.) All output curves are of the equation:

y = k * x^2

User inputs and fudge factors only affect k.

I hope I'm not stating the obvious. Wondering if you're giving me too much credit.

[Les]

Originally posted by Since87
I'm not sure if you mean 'Coming up with a set of fudge factors to get a curve match is difficult.', or 'Coming up with a plausible set of fudge factors is difficult.'

I wouldn't even attempt the latter with only data from a single HC from a given 'family'. I'm grossly unqualified to even offer a guess.

By "It is difficult"
I was meaning "It is difficult to assess pressure drop fom a set of dimensions".
Which I think is akin to the "latter".

[Les]

Would have helped if I had looked at the photos of the radiators.
Yes the Big Momma cannot be 1 Pass, and Rad E cannot be 2 Pass(could be 3,5,7 etc)
. For the record the difference between 1Pass and 2Pass on Big Momma .:-


Apologies for confusing the issue.
To quote Bill "there is nothing that cannot be made more complex"
I am certainly capable of that.

[Blackeagle]

It would seem that in the case of the Big Momma rad that those highly restrictive 1/4" ID barbs are acting as a leveler when comparing single vs dual pass.

Be interesting to see the differance if somebody moded the inlet/oulets to 1/2" ID.

BE

[Since87]

Originally posted by Les
Would have helped if I had looked at the photos of the radiators.
Yes the Big Momma cannot be 1 Pass, and Rad E cannot be 2 Pass(could be 3,5,7 etc)
. For the record the difference between 1Pass and 2Pass on Big Momma .:-

LOL, was wondering.

Good point on Rad E. Three or five passes may explain the apparently high resistance. (seven or more passes seems odd to me with a 30 tube rad, but could be 4,4,4,4,4,4,6.)

I've been playing around with numbers towards adding a 'barb ID factor' to the spreadsheet. I'm not familiar with the correct equations for this stuff. (Involves someone named Darcy right?)

I've just been fiddling around in Excel trying to match Bill's 2 gpm data from the chart here. The equation:

dP = .00156 * ID^-5

gives the match shown here:



I like my equation. It's simple and hits half the points dead on, unfortunately, I have no idea whether there is any justification for it in fluid dynamics.

Les, would you mind detailing how you applied the correction for Big Momma's barbs? Or, rework the spreadsheet to take a barb ID as user input?

Do you think a 'barb factor' should replace the 'overhead factor' completely or only partially?

[Les]

Originally posted by Since87
LOL, was wondering.

1)I've been playing around with numbers towards adding a 'barb ID factor' to the spreadsheet. I'm not familiar with the correct equations for this stuff. (Involves someone named Darcy right?)

I've just been fiddling around in Excel trying to match Bill's 2 gpm data from the chart here. The equation:

dP = .00156 * ID^-5

gives the match shown here:



I like my equation. It's simple and hits half the points dead on, unfortunately, I have no idea whether there is any justification for it in fluid dynamics.

2) Les, would you mind detailing how you applied the correction for Big Momma's barbs? Or, rework the spreadsheet to take a barb ID as user input?

3) Do you think a 'barb factor' should replace the 'overhead factor' completely or only partially?

1) Think I prefer (From visual inspection of same Billa data)

From distant memory think fourth power has some justification in fluid dynamics( have to check)

2) Again from visual inspection of same Billa data.
Difference at 2gpm between 2x( 0.488"ID) and 2x(0.3" ID) = 1.3 psi = 8.96KPa.
Did rough convert to ~ 0.896m(H20) should be 0.9149m(H2O).

Simply used the 0.015972. Have been using this for the "Cathar Big Arse" v "Big Momma" and has been giving results.
Whether correct is another question - eg using 2 Barb correction (and is Billa data single Barb - think it is but not sure).

3) Ugh and dunno. I am possibly the last person to ask for conciseness/simplification.Think prob wait for more data with which to play(torture).

EDIT1: Deleted inane comment.

EDIT2: Corrected explanation of arrival at. 0.015972 "fudge factor". Used 0.3"(not 0.25" or 0.25- 0.3") as ID of 3/8" Barb. Excuse is it is a long time since did it.

[Les]

Edited previous post.
Used 0.3"(not 0.25" or 0.25- 0.3") as ID of 3/8" Barb. Excuse is it is a long time since did this work.
Am making hard work of this.

[BillA]

sorry for the delay, bit too much on my plate





data being sent to Les and Since87

[Les]

Originally posted by unregistered
sorry for the delay, bit too much on my plat

data being sent to Les and Since87

Delay? . Was not expecting anything.
Data received.Thanks.
Before I dig too deep a hole , am I understanding correctly? :- The differential is the PD differences between radiators fitted with two(2) specimen Barbs(entry and exit) and two(2) reference 12.83mm ID Barbs.

Les

EDIT: Corrected 0.583" ID to 12.83mmID . See Unregistered below.

[Roscal]

BillA > Hi , do you have some news about testing the rad in the two way possible?

[BillA]

no Les
the ref connectors are a pair of 3/8"NPT x 5/8" barb (in brass) with an ID of 12.83mm/0.505in.

this is something of a gap between the 1/2"CTS (5/8" OD copper pipe) which has an ID of 0.572"
- or thereabouts, depends on the schedule as it is OD based

the only difference in pressure drop between 0.468" and 0.505" was 0.01psi @ 3gpm
would suggest that going to 0.572" ID is not huge, but something rather small

I will dig through my old data for a correlation

Roscal
will try, but am a bit pressed for time (for reasons which will be known shortly)

[Les]

Originally posted by unregistered
no Les
the ref connectors are a pair of 3/8"NPT x 5/8" barb (in brass) with an ID of 12.83mm/0.505in.

Typo (re 0.583"ID Barbs, 12.83mm).
I stay in the kitchen,maybe only for the spinach.

[Les]

Originally posted by unregistered
.......
data being sent to Les and Since87

The usual Dog's Dinner.
Probably only a selfish indulgence and completely useless for "The Simulator"
The best fits with Simulated Data from "SF Pressure Drop5" *:-



Have been using the "Green" simulations in previous graphs.
Maybe OK for small ID Differences( <2mm).

* http://www.pressure-drop.com/

[BillA]

and here the real problem of the measurand being smaller than the rounding error/uncertainity becomes apparent
0.01psi (using a scaling indicator with offset) is too large an increment for this work

an omitted 'note' (sorry Les)
all connector inlets and outlets were chamfered
- am not suggesting that a radius be defined, typically a slope with rounded edges