Question

(a) Fluid at a mass flow rate of 0.352 kg/s flows through a tube with a diameter of 15 mm and a length of 25 m. The inner surface of the tube is heated with a uniform heat flux of 1000 W/m2. Measurements shown that the inlet temperature of the fluid is 30 ˚C. Assume the outer surface of the tube is perfectly insulated. Consider the thermophysical properties of the fluid are as follows: density ρ = 1000 kg/m3, specific heat capacity cp = 0.15 kJ/kg·K, dynamic viscosity μ = 0.01 kg/m·s, thermal conductivity k = 0.12 W/m·K. Contact resistances do not occur. Additionally, all effects of thermal radiation may be neglected.

1. Calculate the exit temperature of the fluid.

2. What are the minimum and maximum surface temperatures on the inner surface of the tube?

(b) Consider laminar flow over a flat surface, will the heat flux be higher at the leading edge or at the trailing edge of the plate? Explain your answer in details.

Answer 1