Two Condensers connected in series

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racecar
Posts: 11
Joined: Mon Nov 13, 2017 3:23 pm

Two Condensers connected in series

Postby racecar » Mon Nov 13, 2017 3:29 pm

Hello all....

Had a question about a custom car build we are doing. We have limited space and the factory condenser will not fit.

The factory condenser has a surface area of 344 sq. in. If we had two condensers made that are 13 x 13 and connected with a 6 inch AC hose......will it work the same since the surface area is almost identical.

Each condenser will have a 12 x 12 constant running 2,500 cfm fan on them.

Thanks.
ice-n-tropics
Posts: 50
Joined: Sat Apr 23, 2016 3:40 pm

Re: Two Condensers connected in series

Postby ice-n-tropics » Tue Nov 14, 2017 11:17 am

I fabbed a dual condenser, supped up A/C'd Humvee.
Condenser Basic Design Principals:
A single condenser installation can be analyzed as 3 heat dissipators in series.
1) Initial heat disippator #1: Large internal flow flow cross sections for SENSIBLE heat transfer of superheated high vevocity gas only. (Ref "How to Air Condition Your Hot Rod" pg. 16 Cool Science Concept 8 : Latent Heat; available from Vintage Air). Gas gives up it's superheat with temperature reduction.
2) Mid heat disippator or actual Latent condensing section #2: Gradually reducing internal flow cross sections to optimize refrigerant velocity as LATENT heat transfer occurs and warm gas becomes 100% warm liquid with no basic temperature change.
3) Final Sensible heat transfer disippator #3: Temperature change is effective to cool Warm liquid as subcooling occurs and liquid becomes colder than the liquid exiting the condenser section (#3).
Now the first decision is series plumbing verses parallel of a 2 condenser A/C system?
I choose a series design because :
1) Was building a optimized custom system with minimal plumbing connections and weight/cost.
2) Would build the first heat X with the first 1/3 large multiple flow path for basically gas volume only and gradually transition to fewer flow paths as gas condensed to liquid.
3) Second condenser would have less cross section initially transitioning to a small crossection at the outlet for subcooled liquid only.
Converesly, if you go with off the shelf condensers then parallel flow is optimal.
I didn't want the unbalance of all of the 5% oil clogging one parallel circuited condenser and not the other and to avoid one heat X exiting some gas while the other heat X exited over subcooled liquid so series layout was used.
So your on the right track if the first condenser has larger flow cross sections than the downstream second condenser in an efficient manner.
If off the shelf convensional condensers are used then parallel is the best option because most condenser types have smaller flow areas approaching the outlet and this restriction on refrigerant which is not yet half condensed into liquid is unacceptable for flow restriction when used 2X.
Concerning system balance the condensing capacity should be approximately 130%of the evaporator capacity due to the heat equivalent of the compressor power input.
But condenser capacity is very dependant on air flow and fan ratings are dubious. A shrouded fan which utilizes the entire condenser is preferred.
Reminder: For high rev engines choose a compressor drive ratio that complies with less than the compressor rated crpm
Hope this helps,
hotrodac
racecar
Posts: 11
Joined: Mon Nov 13, 2017 3:23 pm

Re: Two Condensers connected in series

Postby racecar » Tue Nov 14, 2017 11:33 am

ice-n-tropics wrote:I fabbed a dual condenser, supped up A/C'd Humvee.
Condenser Basic Design Principals:
A single condenser installation can be analyzed as 3 heat dissipators in series.
1) Initial heat disippator #1: Large internal flow flow cross sections for SENSIBLE heat transfer of superheated high vevocity gas only. (Ref "How to Air Condition Your Hot Rod" pg. 16 Cool Science Concept 8 : Latent Heat; available from Vintage Air). Gas gives up it's superheat with temperature reduction.
2) Mid heat disippator or actual Latent condensing section #2: Gradually reducing internal flow cross sections to optimize refrigerant velocity as LATENT heat transfer occurs and warm gas becomes 100% warm liquid with no basic temperature change.
3) Final Sensible heat transfer disippator #3: Temperature change is effective to cool Warm liquid as subcooling occurs and liquid becomes colder than the liquid exiting the condenser section (#3).
Now the first decision is series plumbing verses parallel of a 2 condenser A/C system?
I choose a series design because :
1) Was building a optimized custom system with minimal plumbing connections and weight/cost.
2) Would build the first heat X with the first 1/3 large multiple flow path for basically gas volume only and gradually transition to fewer flow paths as gas condensed to liquid.
3) Second condenser would have less cross section initially transitioning to a small crossection at the outlet for subcooled liquid only.
Converesly, if you go with off the shelf condensers then parallel flow is optimal.
I didn't want the unbalance of all of the 5% oil clogging one parallel circuited condenser and not the other and to avoid one heat X exiting some gas while the other heat X exited over subcooled liquid so series layout was used.
So your on the right track if the first condenser has larger flow cross sections than the downstream second condenser in an efficient manner.
If off the shelf convensional condensers are used then parallel is the best option because most condenser types have smaller flow areas approaching the outlet and this restriction on refrigerant which is not yet half condensed into liquid is unacceptable for flow restriction.
Reminder: For high rev engines choose a compressor drive ratio that complies with less than the compressor rated crpm
Hope this helps,
hotrodac


Thanks for the reply.....

So if I understand, the first condenser should simply be 33% larger in its total surface area then the second condenser. Both should be parallel type. Then to run them in series is good.

.
ice-n-tropics
Posts: 50
Joined: Sat Apr 23, 2016 3:40 pm

Re: Two Condensers connected in series

Postby ice-n-tropics » Tue Nov 14, 2017 11:45 am

This is not about the surface area of the condensers, but of the refrigerant tube internal restriction, e. g., for a 3/8" tube fabbed condenser:
entry could be 2 parallel 3/8" tubes throughout. The second condenser could be 2 parallel tubes entry and half way a transition to a single 3/8" tube.
So what condenser tube type will you use so we can make nails with heads on them this time instead of pins?
Heck I was building a watch but you asked the time.
Your Texas friend
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bohica2xo
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Location: Las Vegas, NV

Re: Two Condensers connected in series

Postby bohica2xo » Tue Nov 14, 2017 12:05 pm

Actually, Chrysler used a series condenser in production. The 1996 Town & Country minivan added a second condenser in series when they put in rear A/C.

4" x 26" , and obviously intended for series cooling. P/N 4682591
racecar
Posts: 11
Joined: Mon Nov 13, 2017 3:23 pm

Re: Two Condensers connected in series

Postby racecar » Tue Nov 14, 2017 12:24 pm

ice-n-tropics wrote:This is not about the surface area of the condensers, but of the refrigerant tube internal restriction, e. g., for a 3/8" tube fabbed condenser:
entry could be 2 parallel 3/8" tubes throughout. The second condenser could be 2 parallel tubes entry and half way a transition to a single 3/8" tube.
So what condenser tube type will you use so we can make nails with heads on them this time instead of pins?
Heck I was building a watch but you asked the time.
Your Texas friend


LOL....OK......where would I get these made?

Or where can I buy these 2 condensers with the tube sizes you recommend?

I'll give your idea a try.......

.
racecar
Posts: 11
Joined: Mon Nov 13, 2017 3:23 pm

Re: Two Condensers connected in series

Postby racecar » Tue Nov 14, 2017 12:26 pm

bohica2xo wrote:Actually, Chrysler used a series condenser in production. The 1996 Town & Country minivan added a second condenser in series when they put in rear A/C.

4" x 26" , and obviously intended for series cooling. P/N 4682591


Well, I'm glad to at least hear the series idea works.....Now I have to package it correctly.

I have a 1,200 HP turbo Trans Am going together and I live in Ft. Lauderdale, so A/C is a must. As long as the condenser(s) are away from the radiator, engine cooling and the cooling for the condenser(s) will be sufficient.

The way its been set up there's no way the factory single 26 x 15 condenser will fit anywhere.....So I need two smaller ones.



.
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bohica2xo
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Location: Las Vegas, NV

Re: Two Condensers connected in series

Postby bohica2xo » Tue Nov 14, 2017 1:34 pm

Are there intercoolers in the cooling air path?

Is there room for the condensers you plan to use in the front of the car? Or are they going someplace else?
racecar
Posts: 11
Joined: Mon Nov 13, 2017 3:23 pm

Re: Two Condensers connected in series

Postby racecar » Tue Nov 14, 2017 1:45 pm

bohica2xo wrote:Are there intercoolers in the cooling air path?

Is there room for the condensers you plan to use in the front of the car? Or are they going someplace else?


No, the two separate condensers will have permanent fans attached, with shrouds so all of the air being pulled through actually goes through the entire surface area of the condenser. The factory had the single condenser laying up against the factory radiator. With the modded, larger displacement engine and the block being iron instead of aluminum.....the radiator must get all of the incoming ram air from the lower air dam. Otherwise in slow moving traffic on a hot day the temps will slowly creep up and not stop....and then overheat.

The fans on each of the condensers will be be 2,500 cfm flowing fans. 13 x 13 condenser.......12 x 12 diameter fans.

.
ice-n-tropics
Posts: 50
Joined: Sat Apr 23, 2016 3:40 pm

Re: Two Condensers connected in series

Postby ice-n-tropics » Tue Nov 14, 2017 6:32 pm

As Bohica indicated the a CAC, a hefty charge air cooler, is pretty basic for your higher temp and pressure intake air if you expect that HP and any engine life.
You said lower ram air is for the radiator which leaves upper ram air for CAC and then Radiator.
But not enough height for condensers w/o preheating and restricting air for the rad CAC pack.
That may leave just wheel wells and trunk for condenser location?
E. G., Porsche 911 rear lid mounted condenser (with ambient air temp) scoop. Just brain storming.
hotrodac

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