In an external heat combustion engine, what is primarily heated to generate energy?

In an external heat combustion engine, the primary method of generating energy involves heating water in a boiler. This process typically works by burning fuel in a separate combustion chamber, which produces hot gases that transfer their heat to the water. As the water heats up, it turns into steam, and this steam is then used to drive a turbine or another mechanism to generate energy.

Heating water is particularly efficient in this context because steam can be produced at high pressures and temperatures, allowing for more energy to be extracted during its expansion as it moves through the engine. The use of water also provides a consistent and effective medium for energy transfer.

While a mixture of fuel and air is essential for combustion to take place, it is the heated water that ultimately serves as the energy carrier in an external heat combustion engine setup. Oil in a furnace may also relate to energy generation, but in the context of an external heat engine, it is typically not the primary focus compared to the steam cycle. Similarly, metal components in the engine are important for the structure and operation, but they do not directly generate energy themselves.