QUESTION 4 [20 marks] Lectures in week 5-9 A long horizontal steel pipe with a 5.0-cm ID and 3.2-mm wall thickness passes through a large room maintained at 20C and atmospheric pressure; 0.5 kg/s of hot water enters one end of the pipe at 82C. 1. Assuming the hot water flow is a fully developed turbulent flow and the average water temperature is 80C, determine the convection heat transfer coefficient on the inner surface of the pipe. 2. Assuming an average surface temperature of 70 C on the outer surface of the pipe, use the correlation for free convection in the Formula and Data sheet to estimate the average natural convection coefficient on the outer surface of the pipe. 3. Considering both free convection and radiation heat loss from the outer surface of the pipe, calculate the exit water temperatures when the pipe is 25 m long, and the emissivity of the pipe surfaces is 0.8. 4. Explain how to verify if the calculations in part 3 require further iterations. Thermal-physical properties of the pipe are p = 7800 kg/m, cp = 440 J/kg K, k = 58 W/mK, = 18 x 10-6 m/s, &=0.8, = 5.67 x 10-8 W/mK4