Gravitational separation of liquid and vapor also plays an important part in the functioning of condensers, of which many designs exist, their nature determined largely by the ratio of the condensed to the uncondensed components in the fluid stream being cooled.
Even when the cooled stream is nominally wholly condensable, as is true of stream condensers for power stations, inward leakage of air may make it necessary to extract some uncondensed fluid, and the flow velocities must be such that the upward flow of air will not entrain any of the (nominally) downward-flowing water. This requirement is met by the provision of lanes between banks of tubes; and baffles are employed to ensure that
There is not short-circuiting from the steam inlet to the air outlet. In power station condensers, the steam is usually on the shell side, and the cooling water runs through horizontal tubes. In the process industry, tube-side condensation is common, and, in those circumstances, the tubes are usually vertical.