Question 11.26: A counterflow heat exchanger is used to cool a flow of 400 l...

Thermodynamics and Heat Power

A counterflow heat exchanger is used to cool a flow of 400 lb./min of lubricating oil. Hot oil enters at 215°F and leaves at 125°F. The specific heat of the oil is 0.85 Btu/lb.·°F, and the overall coefficient of heat transfer of the unit is 40 Btu/(h· $ft .^{2}$ ·°F) (of the outside tube surface). Water enters the unit at 60°F and leaves at 90°F. Determine the outside tube surface required.

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