In a surface condenser, what are in direct contact with each other?

In a surface condenser, the cooling water and steam are in direct contact with each other, but not in the way one might think. In this system, steam from the turbine enters the condenser, where it transfers its heat to the cooling water circulating through the condenser tubes. This process allows the steam to condense into water while the cooling water absorbs the heat.

The design of the surface condenser ensures that the steam does not mix with the cooling water. Instead, they are separated by tube walls, which effectively transfers heat from the steam to the cooling water without allowing any contaminants to enter the steam side. This heat exchange is crucial for efficiently condensing the steam back into water, which can then be reused in the boiler system.

The other options involve substances that do not directly relate to the specific function of the surface condenser. For instance, oil and steam typically do not come into contact in this context, as oil is generally not used in condensation processes in this manner. Similarly, exhaust gases and water or steam and ambient air do not represent the direct interaction seen in surface condensers, where the primary operation is the heat transfer between steam and cooling water.