An oil with Pr = 1960, = 860 kg/m3, = 1.6 104 m2/s, and

Question:

An oil with Pr = 1960, ρ = 860 kg/m3, ν = 1.6 × 10−4 m2/s, and k = 0.14W/m· oC enters a 2.5-mm-diameter tube 60 cm long. The oil entrance temperature is 20oC, the mean flow velocity is 30 cm/s, and the tube wall temperature is 120oC. Calculate the heat-transfer rate.