A row of 10 parallel pipes that are 5 m long and have an outer diameter of 6 cm are used t...

A row of 10 parallel pipes that are 5 m long and have an outer diameter of 6 cm are used to transport steam at 145°C through the concrete floor (k = 0.75 W/m · °C) of a 10-m × 5-m room that is maintained at 20°C. The combined convection and radiation heat transfer coefficient at the floor is 12 W/m2 · °C. If the surface temperature of the concrete floor is not to exceed 35°C, determine how deep the steam pipes should be buried below the surface of the concrete floor.