PDA

View Full Version : modifying ashp? Evaporator question







northbridge
16-07-2009, 08:09 PM
The ashp's have a large flat area evaporator. Is there any reason why they cannot be a smaller surface area but more layers (if you know what I mean)

Sorry, I'm an installer not a techie!

thank you for any guidance.

Brian_UK
16-07-2009, 10:43 PM
Probably to do with the heat transfer rate.

Compare an air conditioner coil and a freezer coil and the number of rows within them.

desA
17-07-2009, 02:43 AM
The ashp's have a large flat area evaporator. Is there any reason why they cannot be a smaller surface area...

The main reason for current evaporator designs being so large is that they are based on archaic heat-transfer technology. Plate-fin + tube evaporator assemblies are incredibly inefficient in terms of overall performance. The main reason for their continued manufacture seems to be their relatively low cost.

I have a new technology project in the R&D phase, where we plan to reduce the current evaporator volumes by at least 50%. This development has the potential to be a disruptive (industry-changing) technology. The heat-transfer side has a few small technical tricks to be smoothed, but, in principle it is doable.

So the answer to your question is that within the next few years, it is possible that evaporators will drastically reduce in footprint & volume.

RefrigNoob
17-07-2009, 07:46 AM
I'll just post bits from a table I got from our coil manufacturer.

On a 2 row coil:
1st row does 57% of the work
2nd row does the remaining 43% of the work

6 row coil:
Row 1 to 3 does 66% of the work
Row 4 to 6 does 34% of the work

10 row coil:
Row 1 to 5 does 66% of the work
Row 6 to 9 does 32% of the work
Row 10 does 2% of the work

northbridge
18-07-2009, 07:34 AM
Thank you for that table, it answers a lot of questions.

I have a unit that we need to modify into a smaller package, so am looking at smaller evaporator, increased fanspeed/

here goes!