Problem 3 A steel pipe (k 60 W/m.K) with outer diameter of 100 mm and thickness of 8 mm is used to transport hot water at 50 C between two buildings. On a representative winter day, air flows at -3 C and 3 m/s across the pipe. Air is assumed to have the following properties: p= 1.1614 kg/m3, Cp = 1.007 kJ/kg-K, u = 184.6x10-7 Pa.s and k = 26.3x10-3 W/m.K. 2 a. What is the heat loss per pipe length? Hint: here you need to use some concepts from conduction through cylinders to find the temperature of the outer surface. b. Given the electricity price of 1 USD per kWh, what is the cost of the heat loss (per pipe length)? c. How much savings would be possible by insulating the pipe with a layer of polyurethane with k = 0.026 W/m-K and thickness of 10 mm? Hint: disregard investment costs