Question 6

A phase change fluid at 74°C is pumped

through 7 m of a multi-layered pipe,

which is exposed to an external fluid

current at 22°C. The innermost layer is

made of steel (thermal conductivity 13

W/m/K), with inner and outer radii 40

mm and 52 mm, respectively. The

second layer is made of insulating

material (thermal conductivity 0.6

W/m/K), with outer radius equal to 70

mm. The convective heat transfer

coefficients associated to the internal

and external fluids are respectively

1,166 W/m2/K and 150 W/m2/K.

Calculate the heat transfer (absolute

value) through the pipe thickness in kW

to 1 decimal place.

Note: use pi=3.1415