Question on AC condensors, can they be run in series? Options

[boxsterfan]

Suppose a crazy person was thinking of A/C in their 914. Could such a crazy person run condensors in series behind the fog light grills?

Basically, the refrigerant (R134) would come from the compressor all the way up to the right front under the headlight, go through a condensor, come out of that condensor across the front of trunk, into a second condensor under the left head light area, and then back out to a receiver/dryer and through the rest of the system.

Obviously, there are some cuts you need to make in the front area behind the fog light grills, the condensors have to be small enough to fit under the headlights when close and for good enough air flow you have to have cut holes in the front wheel well behind the condensors.

I know someone on this board mounted some oil coolers in these locations (can't find the thread).

914 A/C reference from http://www.914world.com/bbs2/index.php?sho...=192917&hl= (thanks dlee6204).

[Mike Bellis]

If you could make it work, put two in parallel. That way they condense at the same rate.

[boxsterfan]

I was thinking I would run parallel flow condensors in series.

[ThePaintedMan]

But how would you ever be able to put fans on them?

[76-914]

Why? Saving trunk space? Are you H20 or air cooled?

[stugray]

I know someone on this board mounted some oil coolers in these locations (can't find the thread).

http://www.914world.com/bbs2/index.php?showtopic=56102

Goto page 13

[Dave_Darling]

You can run condensors in series. The 911s did that. Each one you add gets less effective at removing heat, since the earlier ones will have removed some heat already. But the later ones will have some effect.

Running them in parallel would seem, to me, to raise issues of flow balance that I'd really rather not think about.

--DD

[boxsterfan]

Why? Saving trunk space? Are you H20 or air cooled?

I'm just exploring the idea. For my build, I'm willing to get rid of the foglights and go with a "plain" grill there. Also willing to move the horns if they are in the way. Given the space there, I could also mount them pseudo-flush with the front of the chassis in that spot.

I'll be a Type IV 2270 when I finish my rustoration.

[boxsterfan]

You can run condensors in series. The 911s did that. Each one you add gets less effective at removing heat, since the earlier ones will have removed some heat already. But the later ones will have some effect.

Running them in parallel would seem, to me, to raise issues of flow balance that I'd really rather not think about.

--DD

I guess the question is "how less effective will they be in series?" Seems like if it was good enough for the 911 (and the boys in Stuttgart) then it will be good enough for me. :-)

[Dave_Darling]

There were differences, though. Both condensers on the 911 had fans pulling air through them (electric on the front-mounted one; the engine fan on the rear one). They were also much larger than the 914 foglight grilles. But the 911 has more interior space to cool than the 914 does.

Oh, and the 911 was not known for highly-effective air conditioning. At least, not without modifications to the system (like the Kuehl Air system I installed on my wife's car).

--DD

[Spoke]

Griffiths.com does this for the 911. It's called Mr Ice Project or something like that. I got a quote for my 930 for over $3k.

[Mike Bellis]

Running them in parallel would seem, to me, to raise issues of flow balance that I'd really rather not think about.

--DD

Flow balance isn't that hard if you keep equal lengths of tubing and equal number of elbows. The tubing systems should be mirror images and meet in the middle at a T. You could fine tune from there if needed.

[76-914]

Running them in parallel would seem, to me, to raise issues of flow balance that I'd really rather not think about.

--DD

Flow balance isn't that hard if you keep equal lengths of tubing and equal number of elbows. The tubing systems should be mirror images and meet in the middle at a T. You could fine tune from there if needed.

Wouldn't the catch be whether the condensers were exactly the same. We know the pipe and fittings will all be congruent but what are the odds all of those fintubes flow equally.
Didn't Dlee in Houston just add AC to an air cooled teener last year? Might be some good info in his thread.

[Chris914n6]

The question is can you find a pair of 11x13 condensers? Or Y fittings?

Plus for the amount of work involved, mounting in the trunk floor or engine lid makes a lot of sense.

[boxsterfan]

The question is can you find a pair of 11x13 condensers? Or Y fittings?

Plus for the amount of work involved, mounting in the trunk floor or engine lid makes a lot of sense.

I can definitely find condensors in that size or have them made custom. I believe the opening of the fog light grill is about 8.5" by 6".

[914_teener]

The question is can you find a pair of 11x13 condensers? Or Y fittings?

Plus for the amount of work involved, mounting in the trunk floor or engine lid makes a lot of sense.

I can definitely find condensors in that size or have them made custom. I believe the opening of the fog light grill is about 8.5" by 6".

You need to figure the temperature split first as a basis for design and then the condensor size.

Then figure the size and then a location where you can get adequate heat transfer.....free flow....inductive......ect.
.

[stugray]

I chose to put my oil coolers in series because I figured the peace of mind that it will never become "unbalanced" outweighs the relatively small difference in cooling efficiency.

I think the concept behind the series coolers being less efficient is the following:
As hot oil enters cooler 1 the cooling efficiency is proportional to the temperature difference between the oil and the air moving through the cooler.
As the hot oil is cooled by cooler #1, it enters cooler #2 at a lower temperature than when it entered cooler #1 so the 2nd cooler is less efficient.

But to me it seems like a long skinny cooler would have the same effect. The cooling efficiency goes down as the fluid travels from one end to the other anyway.

[914_teener]

[quote name='stugray' date='Aug 6 2015, 04:48 PM' post='2219841']
I chose to put my oil coolers in series because I figured the peace of mind that it will never become "unbalanced" outweighs the relatively small difference in cooling efficiency.

I think the concept behind the series coolers being less efficient is the following:
As hot oil enters cooler 1 the cooling efficiency is proportional to the temperature difference between the oil and the air moving through the cooler.
As the hot oil is cooled by cooler #1, it enters cooler #2 at a lower temperature than when it entered cooler #1 so the 2nd cooler is less efficient.

But to me it seems like a long skinny cooler would have the same effect. The cooling efficiency goes down as the fluid travels from one end to the other anyway.
[/quote

Stu...now I know how you got us to Pluto!

There is most probably no advantage to configure them like that. My 02.

[914_teener]

.....I quess my statement needs context. There is probably no advantage to configure a condensing coil(s) in a series with that size as described like Stu configured his for cooling oil.

The interesting thing to me is that nobody tried getting the re-heat on the coils. At least not that I know of from the posts and threads. This would make a big difference in humid environments. I read and noticed though that the guy that eliminated the heat gain from the windows and radiant heat got the greater splits because of the heat gain.

I won't get into the thermodynamics......my wife rolls her eyes up in the back of her head when I start that.

This is the garage. (IMG:style_emoticons/default/beerchug.gif)

[Dave_Darling]

What do you mean "re-heat on the coils"?

--DD