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Q6. Hot oil of 0.564 kg/s at 91°C enters a pipe heat exchanger and is cooled to 37°C. The water enters at 10℃ and is warmed to 330℃.

(a) Sketch the exchanger showing counter flow. (2)

(b) Calculate the log mean temperature difference for the counter flow arrangement. (3)

(c) Calculate the rate of heat transfer. (2)

(d) Calculate the mass flow rate of water. (2)

(e) If the overall heat transfer coefficient is 2500 W /m²K and the diameter is 50 mm, calculate the length of the tubes.

(f) Explain the difference for each of the calculated values above if a parallel flow arrangement was used.

Note: C_p of hot oil = 2.2 kJ/kgK C_p of water = 4.18 kJ/kgK