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View Full Version : Desingning and sizing a coil for a custom air conditioner



davidk
29-07-2021, 11:25 AM
Hi,
I need to build and install a packaged AC unit into a very confined location on a vehicle. Previously the vehicle had two Tricool packaged AC's and I need to replace these, as these are old R22 and very corroded units. Me and the owners reached the conclusion we have to build from scratch two custom units that can fit exactly in the original location. These units needs to have the air inlets and outlets in the same location as the old units.

My main problem is I need to find condensers and evaporators of the same physical sizes.
For example, I need to calculate how many rows, fin density and pipe dimension for a 24000BTU condenser. The old R22 condenser was 580x310mm for finned area, 2.5mm fin pitch, 5 pipe rows and 10mm pipe O.D.

I'm not asking for someone to calculate this, I'd like to know if there's an easy or practical method for me to calculate a new condenser for, let's say, R32 refrigerant I intend to use.
Thanks!

RANGER1
29-07-2021, 08:44 PM
David,
You need to find a manufacturer in your part of the world who will do most of the work for you to guarantee performance & match components.
Below some information which might be helpful in your search in your area.

Repairs & Replacements - Products - Beehive Coils Ltd (https://www.beehivecoils.co.uk/products/repairs/)

Spec Data - Evap.doc (austcoil.com.au) (https://austcoil.com.au/wp-content/uploads/2020/10/austcoil-spec-data-evap-2015.pdf)

Coil Specifications (austcoil.com.au) (https://austcoil.com.au/coil-specifications/)

NH3LVR
29-07-2021, 09:37 PM
I would think that the Condenser would be easier than the evaporator.
I have had some experience with changing refrigerants (One example was R13B1 to R22). This of course required a Compressor change to maintain capacity)
The expansion valve had to be changed of course. But we never could get the low load feed correct. I suspect that the Distributer and perhaps the Evap tubing size was a bit too large. Fortunately we were able to devise a work around. I worked for a Coil Manufacturer once upon a time. I always considerer the Design Engineers as practicing a Black Art. We had a test room for new designs and sometimes they need tweaking. Evap design best left to the Pros as RANGER1 says.