Answer: The primary reasons for the deviation of the vapor power cycle with respect to the ideal vapor power cycle are fluid friction and irreversibilities.
Fluid Friction: The frictional losses due to fluid flow (major and minor) inside the boiler, condenser and piping system cause the pressure drops.
Irreversibilities due to Heat Loss: The heat loss from the different components in the cycle to the surroundings increases irreversibilities in the cycle. The increase in efficiency causes a decrease in thermal efficiency.
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