Generally whenever you prepare some calculation model in excel for evaluating different scenarios or for simulating some process conditions, it is very frustrating that each time you have to input some or the other fluid property manually.

The basic purpose of developing an excel model is defeated & it can not give the flexibility & options you need for identifying all possible scenarios. Speed of work is also slow....What to do?

You need to develop some correlation for that relevant property so that a formula can be used which can give you all results at just a click of mouse.

Here is one such property i.e. thermal conductivity of air vs its correlation with temperature. The equation is...

k = 1.5207 x 10^(-11) x T^3 - 4.8574 x 10^(-8) x T^2 + 1.0184 x 10^(-4) x T - 0.00039333

Where k is in W/m/K

and T is in K

The range of use is T = 100 to 1600 K

Now you can use it in any calculation for example if you designing any air heater, you can use it to find out Nusselt no of air side & accordingly your U will vary in the Excel sheet automatically. Thus you will get better results.

The basic purpose of developing an excel model is defeated & it can not give the flexibility & options you need for identifying all possible scenarios. Speed of work is also slow....What to do?

You need to develop some correlation for that relevant property so that a formula can be used which can give you all results at just a click of mouse.

Here is one such property i.e. thermal conductivity of air vs its correlation with temperature. The equation is...

k = 1.5207 x 10^(-11) x T^3 - 4.8574 x 10^(-8) x T^2 + 1.0184 x 10^(-4) x T - 0.00039333

Where k is in W/m/K

and T is in K

The range of use is T = 100 to 1600 K

Now you can use it in any calculation for example if you designing any air heater, you can use it to find out Nusselt no of air side & accordingly your U will vary in the Excel sheet automatically. Thus you will get better results.

## 8 comments:

Thanks, where does this equation come from and what is its temperature range of applicability?

The equation comes from the equation fit of actual air properties data from std book. The equation fit was developed by myself earlier during my initial engineering days.

The range of temp applicability is already given in the post as T =100 K to 1600 K

hi Profaster if i need to reference this equation, what reference should i used

Thank you so much.

It is so accurate and helpful.

i need to reference this equation, what reference should i used???

i need to reference this equation, what reference should i used??? plz do rply

How this empirical equation derived

How above equation is derived

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