Parallel Flow vs Serpentine Evaporators

[Z2TT]

Hello,

I have two different evaporator types, they are both the same size and fit the same application, just the design of the core is different. Since both can fit I am wondering which one would provide better efficiency.

One is Parallel flow and the other is a Serpentine Type.

Thankyou.

[Peter_1]

I should say that with parallel flow you have as many times superheat in the tubes as you have flows while with a serpentine you only have some tubes, not necessarily as many feet or meters lost in your coil to create superheat.

[desA]

It depends what you call a 'parallel flow' evaporator - there are different types - some work & others don't.

[Z2TT]

In my parallel flow evaporator, the gas enters the evaporator through one long tube. The long tube has many tubes branching off it that flow parallel to eachover, they join up again into a common tube at the exit.

[desA]

In my parallel flow evaporator, the gas enters the evaporator through one long tube. The long tube has many tubes branching off it that flow parallel to eachover, they join up again into a common tube at the exit.

Put up a picture, if you can - it will make it easier.

To qualify - if its is made in aluminium, the comments below will be appropriate:
It sounds like a parallel flow condenser, you have on hand.
If it is indeed a parallel flow evaporator, then it will be fairly new technology. Sounds like an automotive device.

If made in copper - conventional technology - then, again, please post a picture.

[Z2TT]

I'll get some pictures tommorow, I have the cores outside so I'll take some pictures.

They are 20 year old cores made by Denso from a Toyota Soarer.

[desA]

^ Excellent. We'll get to it when we see the pics.

Good stuff. :)

[Peter_1]

Big coils have a distributor and refrigerant is injected parallel to each other. There are as many flows as there are injections on the distributor. small coils without a distributor only have one flow. It all depends on the max allowable length/circuit.
Or he's having a liquid overfeed evaporator

[Z2TT]

Hi,

Here are the pictures of the two cores :

http://img21.imageshack.us/img21/102/evapss.jpg

Also I have noticed they have different Thermal expansion valve part numbers.

The Serpentine Core has a Denso 047500-0480 and the Parallel flow has a Denso 047500-0770, I Wonder what the differences are in the Expansion valves and why they are different.

[desA]

^ Evaps, for sure.

The parallel flow evap (not truly // flow, though, since has multi-pass plates), has a lower fin height, giving improved heat-transfer. These are generally more modern than the serpentines.

The evap efficiency drops off as the air passes over the serpentine flat tube, leaving the heat-transfer in the last multi-port a fair bit lower than the port closest to the airside.

I'd clean up the plate unit. It should have a higher W/m3 than the serpentine.

[desA]

Do you have any idea of the refrigeration capacity of each unit?

[tonyelian]

hi
those evaporators look like a car a/c and one of them bigger than the other 0ne so maybe that the difference in exp valves
i am leaning toparallel flow as others mention

[Z2TT]

When put side by side they are almost the same, But if the internal volume is different (total volume of the tubes), i'd assume that would mean a different expansion valve that has a larger orifice inside would be used.

I'm paranoid about evaporator cracks, so I'd prefer to use one that is less likely to leak, I was thinking that the Serpentine core would be less likely to leak as it has less points that it can leak from compared to the plate type.

[desA]

The serpentine tubes suffer from 'grain popout' on the large radii at the ends. Aluminium really doesn't like to be bent too much, due to the large grain sizes.

The corrosion life of the serpentine evap is probably les than a well-made plate evap.