Question

Consider a simple ideal Rankine cycle with fixed boiler and condenser pressures. If the cycle is modified with regeneration that involves one open feedwater heater (select the correct statement per unit mass of steam flowing through the boiler),

(a) the turbine work output will decrease.

(b) the amount of heat rejected will increase.

(c) the cycle thermal efficiency will decrease.

(d) the quality of steam at turbine exit will decrease.

(e) the amount of heat input will increase.

Answer 1

The correct answer is OPTION A (the turbine work output will decrease.)

Step-by-step explanation:

In open feedwater heaters, there is a mixing of cold feedwater and steam which raise the temperature of feed water causing the fluid average temperature to rise and thereby increasing the thermodynamic efficiency of the cycle.

In a simple ideal Rankine cycle, heating of the water is converted into work done by the cycle in potential and kinetic energy forms. If there is a fixed boiler flow rate, and the simple ideal Rankine cycle is modified with regeneration, turbine work output, and heat supplied, will decrease.