How does water circulate in a sterling boiler?

In a sterling boiler, water circulation is a key part of its operation, allowing for efficient heat transfer and steam generation. The correct answer describes the process where water enters the top drum and flows down to the mud drum. This configuration takes advantage of natural convection and the design of the boiler to utilize heat effectively.

When water enters the top drum, it is under high pressure, and as it flows downwards to the mud drum, it absorbs heat from the combustion gases surrounding it. The design of the boiler ensures that water then rises again to the upper drums as it is heated to form steam. This cycle is crucial in maintaining a steady flow of hot water and steam throughout the system, which enhances the overall efficiency of the heating process.

Other options do not accurately capture this fundamental method of water circulation in a sterling boiler. Some may suggest alternatives or misleading paths that do not reflect the typical flow and cycle seen in stationary boiler systems. By understanding this correct flow path, one can better grasp how energy transfer is optimized in these systems, making option B the most valid answer.