4. (20 points) A geothermal heat pump carries steam at 150°C underwater, where the
surrounding temperature and pressure are measured as 15°C and 200 kPa, respectively.
Currents in the water maintain a consistent velocity of 1 cm/s. The pipe outer diameter is
20 cm, and the system can be assumed to be at steady-state.
Water, T = 15°C,
U = 1 cm/s
Touter = 85°C
Steam, T =
150°C
Douter = 20 cm
(a) (10 points) Determine the convection coefficient between the pipe surface and the
surrounding water.
(b) (10 points) The conductivity of the pipe is 15 W/(m*K), and it has a thickness of 2.5 cm.
Determine the temperature at the inner surface of the pipe.
HINT 1: You will need to set up a thermal circuit here to evaluate.
HINT 2: You may assume a pipe length to help you set up/solve the problem.
Use EES to solve and submit formatted equations and solution. Screenshots for either will
be fine as long as the text is sufficiently legible.