Tank Cooling Time 1

[PuffJr]

I would appreciate help in estimating the time required for the contents of an insulated liquid storage tank to cool from a know maximum temp. to a known minimum temp.

The ultimate goal is to determine the number of heating pads to install. I have easily determined the number of pads needed to maintain my target temp, given a minimum expected ambient temp. However, I suspect that I can get away with fewer pads. If, for instance, a week passes before the contents cool to an unpumpable temperature, I will need fewer pads. In that time I will either receive additional warm fluid into the tank, or the cold snap will have ended.

Ideas?

 

[25362]

Try

http://www.ogdenmfg.com/pdf/tech16.pdf

Is this for a continuous process ? If so, have you checked the capitalized cost of energy against the cost of the pads ?

 

[vpl]

Star for you 25362!

Puffjr, before you reduce the number of heating pads, I'd give some serious consideration to the following:

1. What are the consequences if there are localized sections of "unpumpable" liquid? (i.e., do you have to worry only about bulk temperature or also localized temperatures?)

2. How positive are you that you will always get sufficient warm fluid into the tank to maintain an adequate temperature? (Do you know the minimum influx necessary?)

3. How positive are you that the "cold snaps" will always recover in a week?

4. Did you account for changes in tank volume or use worst case level?

5. How often and for how long will you need to use the heating pads?

6. Are there adverse consequences to overheating the fluid?

I'm sure there are other things to consider, and others will probably be along to chime in.

Patricia Lougheed

Please see FAQ731-376 for tips on how to make the best use of the Eng-Tips Forums.