Question

Fully developed (both hydrodynamic and thermal) laminar flow is pushed through a thin-walled circular pipe of diameter 13 mm. The fluid flows through the pipe at a velocity of 0.1 m/sec, has a density of 1000 kg/m^3, a dynamic viscosity of 855 x 10^-6 Pa-sec, a specific heat of 4000 J/kg-K, a Prandtl number of 8, and a thermal conductivity of 0.613 W/(m-K).

The outside of the pipe is subjected to uniform cross flow where the free-stream velocity is 5 m/sec, the density is 1 kg/m^3, the dynamic viscosity is 180 x 10^-7 Pa-sec, the Prandtl number is 0.7, the specific heat is 1000 J/(kg-K), and the thermal conductivity is 0.02 W/(m-K).

The pipe (remember the flow is fully developed everywhere) is 10 m long and is wrapped with a thin heater that is generating uniform flux around the periphery of the pipe.

A) What is the specific thermal resistance (K-m^2/W) at a point 5 m into the pipe from the interior surface of the wall to the mean fluid temperature?

B) Using the conditions outlined above for the isoflux pipe in cross-flow, what is the specific thermal resistance (K-m^2/W) from the outside surface of the pipe (or thin heater surface if you want to think of it like that) to the free stream cross-flow fluid?

Answer 1