A series of tests in which water was heated while flowing through a 1 m-long electrically heated tube of 1.3 cm ID yielded the experimental pressure-drop data shown next.





GIVEN

Water flowing through a tube

Isothermal and nonisothermal pressure drop data given above

The dimensionless friction factor



Reynolds number



Inside tube diameter



Tube length





FIND

Dimensionless equation of the form:



SKETCH



PROPERTIES AND CONSTANTS

From Appendix 2, Table 13, for water


The exponent n will be determined from the isothermal data by the least squares fit for log ReD vs. log f



The least squares straight line fit for the data is



The data and straight line fit are shown below



Evaluating ReD (based on the bulk temperature), 0.149 Re–0.1715, f (based on the bulk temperature), and

?s/?f for the non-isothermal case





The linear least square fit for this data is



Therefore:

The data for x and y and the straight line fit are shown below



Comparing the correlation to the experimental data

Physics & Space Science

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