ANS:D - all (a), (b) and (c)

The Dittus-Boelter equation is an empirical correlation used to estimate the convective heat transfer coefficient (ℎh) in forced convection heat transfer, particularly in flow through pipes. It relates the Nusselt number (Nu) to the Reynolds number (Re) and Prandtl number (Pr). The general form of the Dittus-Boelter equation for turbulent flow in smooth pipes is: =0.023×0.8×0.4Nu=0.023×Re0.8×Pr0.4 Where:

• Nu is the Nusselt number,
• Re is the Reynolds number,
• Pr is the Prandtl number.

This equation is applicable for a wide range of Reynolds numbers typical of turbulent flow, and it provides an estimate of the convective heat transfer coefficient based on the fluid properties and flow conditions. It's worth noting that variations of the Dittus-Boelter equation exist for different flow geometries and conditions, and adjustments or corrections may be necessary for specific applications.