Water flows on the inside of a steel pipe with an inner diameter of 2.5cm. The wall thickness is 2mm, and the convection coefficient on the inside is 500 W/m2oC. The convection coefficient on the outside is 12 W/m2oC. Calculate the overall heat transfer coefficient, U and comment on what is the most significant determining factor for U. If the pipe is covered with a layer of asbestos (k=0.18 W/moC) while still surrounded by a convection coefficient with h=12 W/m2oC, what is the critical insulation radius? Will the heat transfer increase or decrease by adding a layer of asbestos insulation with a thickness of a) 0.5 mm, b) 10 mm?