Re: Heat dissipation calculation

[sreejith2088]

Hi
I am in requirement of a heat dissipation calculation for a battery room to design the cooling requirements for the room. The details are as follows:
No of strings: 6
No of blocks/string: 40 = 240 blocks in total
Ah of battery: 157
End load: 900kVA UPS
Discharge Current: 13.1A
Discharge Time: 10 minutes.
Battery type: VRLA
I have contacted the manufacturer and they have come up with a value of 1024 Watts but another manufacturer has come up with 6586 W for a similar set up. But I am not sure if this is right and feel its quite less because at present we have induced a lot of cooling. Could someone help me with the process, and explain how he got this value or if you feel there is a change in the total output please let me know.
Cheers

 

[itsmoked]

You could try doing the math yourself.

The batteries dissipate heat via their internal resistance.
Power is current squared times the resistance.
P = I² x R

You have the current already.

The resistance of the batteries is given on a chart somewhere that shows the resistance verse the current being extracted from the battery.(Data sheet for battery) The greater the current you demand the higher the resistance.

Keep in mind that the heat generated is generated inside the battery electrolyte and so doesn't instantly show up in the room. If your bank gets heavily discharged for say 10 minutes the heat generated will likely take two hours to find most of its way into the room air.

Keith Cress
kcress -

http://www.flaminsystems.com