More Pump Volume / Better AC performance

[kjstamping]

All, Planning on changing out the AC Cooling Pump. Question is , is there any advantage to going with a higher volume (GPH) flow, does this necessarily result in better efficiency from the AC

[Boatsb]

Too much volume pushes the speed of the water beyond where it can efficiently dissipate the heat. It's something you need to match.

[GJH]

What Scott said.

[captainwjm]

I heard this canard when I had to replace my chiler pump, but fail to see how it could be true. Any one know the physics of this claim?

[kjstamping]

Thanks,
Makes sense, there is a balance of flow versus heat transfer and time needed for the water to absorb the heat.
Thanks

[jim rosenthal]

You need a minimum dwell time for the heat to transfer, I think. Above a certain point, more flow doesn't make the AC work any better.

[scallywag]

I have heard this many, many times before, but have never heard the science behind it. The question is, how many BTU per second can be transferred to a specific volume of water.

Imagine you have a very hot piece of metal that you want to cool off with a garden hose. Is it likely that cooling this hot piece of metal will be less effective if you give it too much water? No.

[scallywag]

You need a minimum dwell time for the heat to transfer, I think. Above a certain point, more flow doesn't make the AC work any better.

I would totally agree with this point. As you increase pump capacity, at a certain point there is diminishing returns. Or no quantifiable returns at all.

[kingsley_oasis]

We see this with our heat exchangers a lot. There is a flow point where you hit the optimium heat transfer capacity. Which is a function of surface area, thermal conductivity, and temperature gradient between both mediums. Any flow above this gives you no real benefit. But where issues can arise is if increased flow causes cavitation or airpockets to develop. These can act to reduce the effective surface area available to transfer the heat energy and as such a loss off efficiency is seen.

[scottinsydney]

I was taught that the flow of liquids in a heat exchanger should be opposite due to friction increasing the transfer rate of heat. Is this argument valid?