Solar radiation on a horizontal tank

  • Thread starter eclaisse
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  • #1
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Hello everyone, I'm looking to estimate the variation of degassing on a horizontal tank of VC (vinyl chloride) due to solar radiation.
The feed flow is continuous but the outlet is batch flow. So there is a lot of variation of liquid level in the tank (constant pressure).
To avoid a lot of degassing during big heats, I want to estimate if it is a good idea to put an insulator around the tank.

How can I include a insulating element in my calculation ?
For now, I just have the basic equation of energy balance (convection and solar radiation).

Thanks.
 

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  • #3
Baluncore
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Welcome to PF.

What is your approximate latitude on Earth ?
Is the tank axis N-S or E-W ?

How much variation is there in ambient air temperature ?
What exactly do you mean by “big heats” ?

What is the maximum capacity of the tank ?
 
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  • #4
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Thanks Baluncore.

Here is some information :
Approximate latitude : 51° (Belgium) and the tank axis is N-S with a diameter of 3m and a length of 10 meters.
I want to see the utility of insulating. During summer we have temperature around 30 degrees celsius.

I try to use the basic equation : Q = U*deltaT*A where U = 1/R = 1/hi + lambda/e + 1/he
Then I compare with the addition of 10 cm rockwool as isolation.
So finally I have Q= [T(outside)-T(inside)]*U*A and I can compare and see the difference between both situation.

I have some questions :
1) I use basic data for hi and he (0.17 et 0.04 m^2.K/W) => Is it ok ?
2) Can I include the solar radiation with this method ?
3) After that, Can I use Q=m*Hvap to estimate my degassing ?

PS : I will upload my calculation in few hours (it will be clearer...)
Thank you in advance.
 
Last edited:
  • #5
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After some research, I do these calculations...
It looks okai. But I still need to include the effect of solar radiation...
Thanks for your time...
1603831890479.png
 
  • #6
BvU
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Is the VC at ##\ \ +##14 ##^\circ##C ? or at ##\ \ -##14 ?
 
  • #7
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It is +14°C. It is a calculated value (saturation temperature) from data pressure (2.8bar)
 
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  • #8
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Hello, I update my calcul if someone is interested.
I juste have two questions : My way to estimate my outside surface temperature seems okay ?
And I have a big problem to estimate an average convection coefficient for both situation : (h_out in my first calculation (1/h_out = 0.05 m2.K/W) and h_in in my second (1/h_in = 0.17 m2.K/W). These coefficients change a lot the final result and I am not sure about my values (I just use theoretical value find in literature...).

Thanks a lot.
1606140225181.png
 

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The key to this is to look at a worst case scenario, using upper bounds to the inside and outside heat transfer coefficients. That way the calculation should be conservative, and give an upper bound to the evaporation rate. I think your value for the inside heat transfer coefficient looks low. I would use a much higher value, on the order 500. Your outside heat transfer coefficient looks reasonable. Considering that, in the actual situation, the insulation is going to dominate, I guess these values wouldn't matter much.
 

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