Thermofluids (Determine surface temperature)

[Michael24]

Homework Statement

Air flows at a mass flow rate(m) of 0.05kg/s in a thin pipe with a diameter of 0.15m. The air enters the pipe at (T_i)103 deg celc and cools to(T_o) 77 deg celc after traveling 5 m in the pipe. The heat transfer coefficient between the duct outer surface and the ambient air at T_amb = 0 deg celc is h_o = 6W/m²K.

Determine the heat flux(W/m² and the duct surface temperature at x = 5m. The duct wall is thin and conduction effect can be neglected.

Homework Equations

q^''[W/m²] ...Might need this equation ??

The Attempt at a Solution

q [W] = mc_p(T_i-T_o) = 1313 W where c_p = 1010 J/KgK for air flowing through pipe.

If I'm not told that the surface heat flux is constant can I still apply the equation above? Also, without knowing surface conditions such as constant surface heat flux or constant surface temperature is this problem solvable?

 

[Chestermiller]

Have you learned how to determine the heat transfer coefficient for the internal flow? If so, please tell us how you would proceed.

Chet