1 reply to this topic

[laudrup]

Hi,

I am working on calculations to estimate the refrigeration electricity savings if some vertical cylindrical stainless steel liquid storage tanks were to be insulated.

To do this, I need a formula to estimate the external heat transfer coefficient for the uninsulated stainless steel tanks. The beverage stored in the tanks is sometimes stored at either 15, 10, 5, or -4 deg C. Therefore, depending on the dew point temperature, water vapour condenses on the outside of the tanks.

Can anybody recommend appropriate external heat transfer coefficient correlations that I might use in estimating heat gains? (Most correlations I have seen for this sort of thing do not apply when there is condensation).

These tanks vary in capacity from 5 to 1,000 kL. Some of them are outside and exposed to the sun, while others are undercover. I imagine wind speed may also influence heat transfer.

The tanks also have dimpled cooling plates for small sections of the tank walls through which an ethanol-propylene glycol-water coolant solution intermittently flows (entering at approximately -7 deg C). Water vapour from the air condenses (and then freezes) on the outer side of these dimpled cooling plate sections of the tank walls. Is anyone also able to recommend appropriate external heat transfer coefficient correlations for this heat transfer process as well?

Thanks for your help.

Cheers,
Laudrup

[ElSid]

Google "Stainless Steel Thermal Conductivity". Read the insulation article in CheResources. Search for Tank insulation in the forums. Here are two:
http://www.cheresour...r-storage-tank/
http://www.cheresour...ss-calcualtion/
Also, free insulation software from http://www.insulation.org

Edited by ElSid, 09 January 2013 - 06:53 PM.