2 replies to this topic

[SAprocessGD]

Good morning,

 

This post is in response to the thread “Storage Tank Heat Loss Calculation Based on Kumana and Kothari Article.” As the storage tank forum is closed to posts I’m going to ask the question here.

 

http://www.cheresour...othari-article/

http://www.cheresour...ss-calculators/

 

I found both the paper and spreadsheet very informative and detailed, but I have one question on the spreadsheet which is in regards to the end of the spreadsheet where the time is found to drop the tank temperature.

 

I understand that you need to solve the differential equation U_tot x A_tot x ΔT = m x Cp x dΔT/dt, solving for time. However, I’m having a difficult time trying to understand how you can add up the total overall heat transfer co-efficients (i.e. U_{dry wall}, U_{wet wall}, U_roof, U_bottom) and multiply them by the sum of the different areas (i.e. A_{dry wall}, A_{wet wall}, A_roof, A_bottom) as done so in the spreadsheet. Please note, from the spreadsheet, the overall heat transfer co-efficients and areas for each component of the vessel have already been determined. See cell C416 for the calculations.

 

If anyone could please clear this up and/or provide a better understanding of the matter, it would be much appreciated.

 

Regards,

 

SAprocessGD

[AlertO]

Hi SAprocessGD

 

i haven't  gone through the calculation sheet deeply; however, i try to explain you about the calculation concept.

 

The calculation seperate the heat transfer to 4 sections (wet wall, dry wall, roof and bottom). the reason is each section has a difference environment leading to different heat transfer rate as well. So, the overall heat transfer coeff. and area in each section have to be seperated. After calculation for all section, the total will come from the summation of them.

 

Hope this can help you.

[SAprocessGD]

Hey AlertO,

 

That is what I thought you had to do; take the summation of the total heat rate (from the 4 sections) and then determine the tanks overall heat transfer coefficient based on Q=UA deltaT. I believe the calculation in the spreadsheet is wrong where the over all heat transfer coefficients (wet wall, dry wall, roof and bottom) are all added up to provide the tanks overall heat transfer coefficient.

 

Cheers!