The alcohol in wine can be distilled into brandy by heating the wine to approximately 78° C ---

hot enough to evaporate the alcohol, but not hot enough to evaporate the water. The resulting

vapour, which is mostly alcohol, is then run through a concentric tube parallel flow heat

exchanger where it condenses.

The alcohol enters the heat exchanger as a saturated vapour at 78°C, and leaves as a saturated

liquid at the same temperature.

The coolant (constant specific heat = 3.1kJ/kgK) enters the heat exchanger at 18° C with a

mass flow rate of 0.3kg/s.

The overall heat transfer coefficient is U = 72W/m² K and the heat-exchanger surface area is

A =3.5m².

Determine the temperature (°C) at which coolant leaves the heat exchanger.