Tube-Side Heat Transfer Coefficient and Pressure Drop Single Phase

TUBE-SIDE HEAT-TRANSFER COEFFICIENT AND PRESSURE DROP (SINGLE PHASE) 

Heat-transfer data for turbulent flow inside conduits of uniform cross-section are usually correlated by an equation of the form  

Gt = mass velocity, mass flow per unit area, kg/m2s, fj, = fluid viscosity at the bulk fluid temperature, Ns/m2, 

Equation 12.12 is applicable at Reynolds numbers greater than 10,000. 

In some texts the equivalent (hydraulic mean) diameter is defined differently for use in calculating the heat transfer coefficient in a conduit or channel, than for calculating the pressure drop. The perimeter through which the heat is being transferred is used in place of the total wetted perimeter. In practice, the use of de calculated either way will make 

Re = Reynolds number = putdelix) = Ctdelfx), Pr = Prandtl number = (Cpfx/kf) and hi = inside coefficient, W/m °C, 

Butterworth (1977) gives the following equation, which is based on the ESDU work  

If the variation in the physical properties is too large for these simple methods to be used, it will be necessary to divide the temperature-enthalpy profile into sections and evaluate the heat transfer coefficients and area required for each section. 

The index for the Reynolds number is generally taken as 0.8. That for the Prandtl number can range from 0.3 for cooling to 0.4 for heating. The index for the viscosity factor is normally taken as 0.14 for flow in tubes, from the work of Sieder and Tate (1936), but some workers report higher values. A general equation that can be used 

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