A 4-m-long tube is subjected to uniform wall heat flux. The tube has an inside diameter of 0.0149 m and a flow rate of 7.8 × 10^-5 m³/s. The liquid flowing inside the tube is ethylene glycol-distilled water mixture with a mass fraction of 0.5. Determine the apparent (developing) friction factor at the location x/D = 20 if the inlet configuration of the tube is:
(a) Re-entrant

(b) Square-edged. At this location, the local Grashof number is Gr = 28,090 and the properties of the mixture of distilled water and ethylene glycol are: Pr = 20.9, v = 2.33 × 10^-6 m²/s, and μ_b /μ_s = 1.25.