Dount fan rpm

[cecil87]

Which USB fan for TVbox is more efficient in terms of exhaust: 120mm fan 1200rpm x 80mm fan 2500rpm? Which one can lower the temperature of the TVbox more?

 

[KlausST]

Hi,

Look at the datasheet at air volume flow.
For sure you need to ensure identical conditions (pressure) at the fan air input and output.

Klaus

 

[cecil87]

I don't have much information, I only have the purchase links for the 120mm 1200rpm and 80mm 2500rpm fans
80mm https://www.aliexpress.com/item/100...o.order_list.order_list_main.5.74381802WVCrNq

120mm https://www.aliexpress.com/item/329....order_list.order_list_main.16.6ecc1802cdYBFm

 

[KlausST]

You get what you pay for....

If the vendor does not specify ... I won´t be surprised if tomorrow you get a different device than today.
And: you even can´t complain about it.

Klaus

 

[cecil87]

If you analyze only the size of the fan 80mm and the photo of the air outlet of the TVBOX T95 Max Plus, the 80mm cooler fan has a good or bad size for good cooling and good exhaustion of this TVBOX (TVBOX 10cm wide x 10cm long)

 

[D.A.(Tony)Stewart]

Efficiency is hard to define when there are grills that block flow and create eddy current noise.

I can tell you that while volume flow is important in laminar cooling, hot power supply parts depend on the linear air velocity directly over the hot spots. Flow restricted by the grill is such that flow depends on pressure drop varies for different fans.

When I had to tackle this problem in a 1U rack design I once did for Lucent/Avaya which used an open frame 40 mm 180W supply. I chose to create a spoiler for intake air to create eddy currents over the transformer hot spot and with a thermistor regulator the fan speed with temp using an ADJ LDO with an NPN. I used a cigarette smoke flow test with a flashlight to optimize the spoiler with a mylar flap. The effort paid off with a 50% reduction in temperature rise with the spoiler.

Bigger fans can have lower RPM and the chance for lower noise.

However remember that the more air volume flows out, the more dust goes in, so annual cleaning may be necessary.

 

[cecil87]

the 120mm 1200rpm cooler under the TVbox and on the TVbox's USB port in exhaust mode and connected the T95 Max Plus TVbox and used it. The temperature ranged from 49C to 56C. Is this temperature good or bad for the long life of the TVbox? Does this cooler fulfill its function or not and this temperature is still high? 80mm usb hydraulic bearing 2500rpm i not tested result is similar?

 

[D.A.(Tony)Stewart]

That's marginal for hotspots but rather high for air temp.

Every 10-degree C reduction in temp. rise in theory doubles life span or mtbf.

A better plenum design is needed to support linear velocity rise. just above the hot spots.

Then try to reduce case rise to 10'C but allow 15'C.

 

[cecil87]

miy city temperature is 30-35C using cooler 120mm tvbox temperature varies 49C to 56C no cooler temperature up for 76C
cooler temperature is good or bad long term storage?

 

[dick_freebird]

If you believe that airflow follows area times RPM, it looks like a
wash, roughly.

But fan blade design is a thing, trades are made between airflow,
noise dB, current.

Definitely refer to some "selection guides" and datasheets for the
vendor's assertions about airflow.