Internal Flow Calculator

1. Internal Flow Calculator Melissa Armstrong Micah Christiansen

2. Objective Create a calculator to obtain values of the Nusselt number and convective coefficient for fluids and liquid metals inside a circular tube using the methods found in section 8.5 (Dittus, Sieder, Gnielinski, Skupinski, and Seban) .

3. Using the Calculator • Open Excel file • Enable Macros • Select which method to use • Input all data in the method box you selected • Select conditions in the orange box • Press Run • Read Results (Green-Good, Red-Bad)

4. Example Water at a flow rate = 0.215 kg/s is cooled from 70⁰C to 30⁰C by passing it through a thin-walled tube of diameter D = 50 mm and maintaining coolant at 15⁰C in cross flow over the tube. Find the convective coefficient (h) for the interior of the tube.

5. Example We can find the following properties for water at our average temperature (323 K) and surface temperature (298 K).

6. Example We can now select the appropriate method (Method 2 in this case) and input our data.

7. Example Now we select the conditions (in this example we are cooling a fluid) and hit run.

8. Example We can now read our results and select the appropriate (green) Nusselt number and convective coefficient.

9. Recommendations When calculating the Nusselt number or convective coefficient for the internal flow of a circular tube, use the calculator (rather than doing the work by hand) to save time.

10. Appendix Fundamentals of Heat and Mass Transfer by Incropera, DeWitt, Bergman, and Lavine, 6th Edition, Section 8.5.