In a Rankine cycle, what is the correct sequence of the main processes?

• A. Pump water to high pressure; boil it into high-pressure steam; expand it in a turbine to produce work; condense the steam back to liquid.
• B. Boil water first, then pressurize it, then compress steam in a turbine.
• C. Expand steam in a turbine, then pump water, then condense.
• D. Condense water and then burn it directly in a boiler.

Answer: (A)

In a Rankine cycle the working fluid is treated as a closed loop that must be pressurized, heated to create steam, expanded to extract work, and then condensed back to liquid to repeat the cycle. The pump raises the liquid water to high pressure with minimal temperature change, preparing it for efficient heat addition in the boiler. The boiler then adds heat to turn that high-pressure liquid into high-pressure steam. The turbine takes that steam and expands it, converting most of its energy into useful work. Finally, the condenser cools and condenses the steam back into liquid, ready to be pumped again. This sequence—pump, boiler (heat), turbine (expand and do work), condenser (condense and reject heat)—is essential for the cycle to operate properly.

Other sequences fail because they disrupt the required order of energy input, work extraction, and energy rejection. Boiling before pumping skips the necessary high-pressure liquid stage; turbines do not compress steam (they extract energy by expansion); and condensing with an immediate combustion step isn’t part of the Rankine loop, which relies on a clean cycle of pumping, heating, expanding, and condensing.