dubulup

I also understand ohm's law, as I'm an electrical engineer...If the load resistance in each branch is the same, the "current" in each branch will be the same.

put the input TEE equal distance between the two, same as your out put TEE?? There you shall have equal flow.


I just don't know how to run the thermo dynamic numbers between series heat exchange and parallel. I believe this would be the answer to an end all debate. I guess I would need specs on flow thru various cooler units...as, the more lbm/hr you can push generally increases your heat xfer

quick search on google yields

In the most basic terms, if you don't have any loss to ambient (which is what we bank on, right? xfer to cooler fins then to air), the heat rate you put into your exchanger must be what is coming out.

m(h2-h1)=m*(h1*-h2*) where m=mass flow rate of fluid 1 in lbm/hr h1=enthalpy of fluid 1 at inlet in btu/lbm h2=enthalpy of fluid 1 at outlet in btu/lbm *=fluid2

dubulup

yeah...I just went looked at it, not sure what I was thinking earlier?!?!...gotham's set-up is looking nicer and nicer, Bang for the buck.

GoodfellaFD3S

iTrader: (213)

Yeah, it looks pretty as hell sitting on my garage shelf . Install should be um, interesting, lol.

Carson, just got the screens in the mail today and will paypal ya the 5 bones. Thanks, big stud daddy

Rich

axr6

Well, I better know ohm's law... I used to teach it for close to 20 years, together with more complex electrical principles...

axr6

Not surprised that you're an engineer. I was too, before I retired. I was an electrical engineer for high voltage (transmission) protection for my local utility.

I used to teach most of their people, from Linemen to Engineers everthing from Basic Electricity to Advanced Protective Relaying courses. As a matter of fact, I still do it under contract and still develop new ones that include the newest microprocessor technologies. Not an easy field to keep abreast of, is it...?

The way you've thrown yourself into the hands-on end of this project I figured that you "might" be an engineer.

Albert

dubulup

Not to get too far off topic...but here are some of my bigger electrical projects I've posted here.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/electron-manipulation-336924/ <-My car

https://www.rx7club.com/showpost.php...7&postcount=87 <-post 87 of the same thread, shop project car in Atlanta. (BIG DOWNLOAD)

axr6

Very impressive project. I love the idea for the harness connector. That alone saves a lot of struggle and cussing when you pull the engine. I'll seriously consider doing it if/when I have to pull my engine again. It was just last November so, hope it won't be any time soon.

Looks like you "like" building things. Same with me, I love to build them and when I get to the point where I feel a project, for all practical purposes, is maxed out, I get bored with it. One thing that I never got bored with is the looks and the feel of my FD! I think this second FD has a long ways to go before I consider it maxed out...

dubulup

four years strong and I'm not bored!! Of course I wanted this car when I first saw it when I was 16, but could only afford a 1991.

teaser video, of my "sleeper"


Click

single turbo and full emissions and a resonator to quite things (barely hear it in the car), If you are quick too look, you'll see the diffuser, and you can catch a view of my electric air pump and AI line running to the outlet of the IC...in the bottom left corner when I'm revving

FDNewbie

iTrader: (10)

Nice! What's the deal w/ the green strut bar tho?

nashman69g

iTrader: (3)

why the emission--your in Lafayette??? Are u just green friendly? Awsome either way...

P.S. u coming to the meet on the 30 Apr.

dubulup

A friend gave it to me...he powder coated to match my TEIN HA's, and feed engine "brace". Bet you never saw one like that before, haha!!

I just moved here from ATL, and emissions make ME smell a whole lot better! No need to disregard them for a street car. Probably won't make it to the meet, I have to prep the car for paint this week...but maybe it will be out.

kashent

Running the oil coolers in parallel will work better.

Remember:

Q = h A ΔT

where

Q = power input or heat lost
h = overall heat transfer coefficient
A = outside surface area of tubing
ΔT = difference in temperature between tubing surface and surrounding area

so the larger the difference in temperature, the more heat is vented to the air.

Just doing a quick back of the envelope calculation:
Let's say we have an area of 50 cm^2, and a coefficient of 1.

If the oil comes in at 250 degrees and ambient air is 80, the first oil cooler gives us:
1 * 50 * (250-80) = 8500

now let's say the oil is some arbritary amount cooler, "z". The second oil cooler gives you:
1 * 50 * ((250-z) - 80) = 8500 - 50z.

This gives you a total heat loss of 1700 - 50z, which tells you that for every degree the first one makes the oil cooler, you lose 50 (really hA) times that in cooling efficiency loss in the second one.

In parallel, you get:

1 * 100 * (250-80) = 1700.

That's 1700 solid, no drop from having it precooled.



So the conclusion: PARALLEL = MAX efficiency.
SERIES = loss of efficiency directly related to each degree the first cooler cools.

(If the first cooler gets near saturated, this means both systems perform nearly the same, but the rest of the time parallel will result in lower temps.)

dubulup

I followed you until this statement...if the first cooler (meaning 1st in series, I assume) gets near saturated (with heat, therefore not cooling as much)...both systems perform nearly the same...meaning when the first cooler isn't doing much the system is generating more heat transfer?

that seems odd, but I think I see your point on..."every degree the first one makes the oil cooler, you lose 50 times that in cooling efficiency loss in the second one." <--is this because the cooler will drop more heat the hotter the oil is?? Not a linear function.

7racer

maybe I'm not understanding it but it seems like from your equation, that the total heat loss in series is 1700-50z

so let's say the oil is cooled only 1 degree then the total heat loss is 1700-50*1 or 1650.

Isn't that lower than the constant amount from parallel at 1700?

dubulup

I think the higher the # the better the cooling

axr6

I can not argue those calculations as they are foreign to me but, as I suggested in my earlier post, the risks of parallel operation are that you basically cut the time the oil is exposed to a cooling surface to roughly one half. That may result in the passing of the oil through the coolers too quickly and not have the time to cool.

I do not see any variables in the equation to account for the exposure time and the oil pressures that define the time it takes for the oil to pass though the coolers. Given the same oil pressures you will pass more oil though the parallel coolers in a given timeframe than if they were in series.

The question is if max heat trasfer can occur faster in a reduced exposure time frame?

93ttwankel

Back to the original topic, you could always do this https://www.rx7club.com/showthread.p...ler+engine+bay the pics are gone but you should be able to figure it out without them. Just a thought.

dubulup

I remember seeing that years ago (whatever happen to Ron?), but never read any actual data recorded...other than, "The ducts feel hot" Anyone do this mod and record any data???

Is pressure the only factor that defines how much time it takes to pass thru a cooler? What about size of the cooler?

Figure first it passes a 10 row, then a 9 row (stock R1/2) and back to the block. So what if you are passing oil at the same pressure thru a 19 row on each side at the same time?? I think the resistance of getting it to the second cooler slows things down a bit...but the oil in parallel is exposed to a total of 38 rows.

Bigger the cooler...more exposure time required??? Bigger the cooler...faster the flow???

I think I'm starting to get confused

Whizbang

im curious if i could adapt some of these ideas to the FC and FB chassis. granted i have no convience premade holes....but technically speaking the same principles should apply.

axr6

In your example you just doubled the total cooling area, therefore, you're liable to get substantially better cooling in any configuration.

I need to say that I am not an expert in flow dynamics but in Electrical Engineering, just as you are. I'd just simply applied the rules of parallel vs. series circuitry in this thinking. Pressure is only one of the variables. The size and length of the oil passeges must also be entered as variables. In a parallel cicuits you basically double the size of passages, compared to a series setup. This will reduce the flow resistance to one half, allowing twice the oil to pass through at a given pressure compared to a series setup where the flow resistances would add.

I am absolutely certain that there is such thing as passing the oil through too fast. I could tell you a long story about this battle that I fought with my Lamborghini cooler; by repeatedly removing and adding flow restrictors to a cooler with too little flow resitance I had proved that a restricted (slower) flow cooled FAR better than a low resistance, unrestricted flow, where the oil simply got through the cooler much too fast to be effectively cooled.

Some one should phone a factory engineer at one of the oil cooler manufacturers to settle this question. I've alway had good luck with going directly to the manufacturer engineers for answers

Albert.

GoodfellaFD3S

iTrader: (213)

Just finished the fender liner cutout mod on my dad's R1. We had the front in the air anyway to do the brakes, so figured why the hell not. I had the wire mesh already sitting here, thanks to dubulup. I'm hoping to have the time to perform the same thing on my FD tomorrow. Thanks again for posting that info up albert

axr6

You're welcome Rich, glad to be able to help.

Albert

dubulup

are you going to get that GR oil cooler kit on as well?

7racer

here is a link about parallel coolers, since it was brought up earlier in the thread, albeit for an ITS race car....

https://www.rx7club.com/forum/showth...9&page=3&pp=15

silverTRD

iTrader: (37)

hey rich, did you ever get any data on if this helped at all? cooler temps, faster top speeds as mentioned earlier?