4th Class Power Engineering Part A Practice Exam 2026 - Free Power Engineering Practice Questions and Study Guide

The water-tube boiler is designed for quick startup and high thermal efficiency primarily due to its construction and operation characteristics. In a water-tube boiler, water flows through tubes that are surrounded by hot gases produced by combustion. This design allows for a larger surface area for heat transfer, enhancing thermal efficiency as the water is often heated more rapidly than it would be in a fire-tube boiler, where hot gases travel through tubes surrounded by water.

This kind of boiler can reach high pressures and temperatures quickly, making it suitable for applications requiring immediate steam generation. Additionally, the efficient heat transfer in a water-tube boiler contributes to less fuel consumption, further elevating its standing for high thermal efficiency.

The other types of boilers have specific characteristics that may not align with quick startups or high thermal efficiency. Fire-tube boilers, for example, typically have a larger volume of water that needs to be heated before steam can be generated, which may lead to longer startup times. Electric boilers are highly efficient in terms of electricity use, but they may not achieve the thermal efficiency and rapid startup capabilities of water-tube designs when large quantities of steam are needed quickly. Combination boilers serve both heating and hot water needs but are not optimized solely for the high thermal efficiency and rapid