For boilers, what typically happens to efficiency when stack temperature decreases?

The relationship between stack temperature and boiler efficiency is crucial to understanding how systems operate. When the stack temperature decreases, it typically indicates that more heat is being transferred from the combustion gases to the water or steam produced by the boiler.

This heat transfer is essential for improving the boiler's overall efficiency. A lower stack temperature means that less energy is being wasted as hot gases exit the system. Therefore, as the stack temperature drops, one can generally expect the boiler's efficiency to increase because more of the produced energy is utilized.

The concept here hinges on the principle of heat recovery and waste heat minimization. Efficient boilers aim to lower stack temperatures to ensure that as much heat as possible is transferred to the water or steam, minimizing energy loss.

The answer indicating that efficiency usually decreases contradicts the fundamental understanding of thermal dynamics in this context. Lower stack temperatures should correlate with improved efficiency, not a decline. Thus, an accurate assessment of this scenario leads to the conclusion that the right choice is that efficiency increases as stack temperature decreases.