(Solved): Question Two: (40 marks) a) Forced convection heat transfer analysis normally involves non-dimensio ...

Question Two: (40 marks) a) Forced convection heat transfer analysis normally involves non-dimensional groups, i) Reynolds number (Re) ii) Nusselt number \( (\mathrm{Nu}) \) (4 marks) iii) Prandili number \( (\mathrm{Pr}) \) (4 marks) Define each group and discuss what it represents. b) An air heater consists of a thin tube of \( 25 \mathrm{~mm} \) internal diameter through which water at a mean bulk temperature of \( 90^{\circ} \mathrm{C} \) flows at \( 8 \mathrm{~m} / \mathrm{s} \). Air, at a temperature of \( 14^{\circ} \mathrm{C} \) flows across the tube at \( 14 \mathrm{~m} / \mathrm{s} \). i) Determine the convective heat transfer coefficient on the water side. ( 12 marks) ii) Determine the convective heat transfer coefficient on the air side. ( 6 marks) iii) Neglecting the resistance due to the tube wall, determine the rate of heat loss from the surface of the tube per metre length. (10 marks)