A molten mixture of salt (NaNO3-KNO3) is used as the heat transfer fluid for application in a parabolic trough solar field. The molten salt at 300oC is flown through a steel pipe (k = 14 W/moC) whose inner and outer diameters are 9 cm and 10 cm, respectively, in an environment at 32oC. If the heat transfer coefficients on the inside and the outside of the pipe are 150 and 30 W/m2C, respectively:
a. Determine the rate of heat loss from the molten salt per meter length of the pipe.
b. If the pipe is insulated with 5-cm-thick SiO2 wool insulation (k = 0.017 W/moC), what would be the rate of heat loss per meter length of the pipe. What is the reduction in heat loss (in %) if we use the insulation.