What principle governs the efficiency of heat exchange in boilers?

The principle that governs the efficiency of heat exchange in boilers is thermal conductivity. This principle refers to the ability of a material to conduct heat. In the context of boilers, the materials involved—such as the water, steam, and the metal surfaces of the boiler itself—must effectively transfer heat. Good thermal conductivity ensures that heat generated in the combustion process is efficiently transferred to the water, converting it to steam without significant losses.

Heat retention, while important for maintaining temperature, does not directly affect the process of heat exchange as much as thermal conductivity does. Pressure differentials are relevant in some aspects of boiler operation, such as in circulation or steam generation, but they do not directly govern the efficiency of the heat transfer process. Meanwhile, fluid dynamics plays a role in the movement and behavior of fluids within the system but does not focus specifically on the efficiency of heat exchange itself. Thus, thermal conductivity is the key principle in this context.