Effect of Feedwater Temperature Rise in Heaters on Regenerative Rankine Cycle Performance

Abstract

In this article, the performance of regenerative power plants in terms of second law of thermodynamics is discussed. The performance of the cycle is improved with the addition of backward cascaded-type and open-type feedwater heaters. This improvement is obtained by the reduction in irreversible losses as the number of feedwater heaters increases. A conventional energy-balance approach is used to calculate the irreversible losses in the cycle. The irreversible losses of each component of the cycle is given in a dimensionless ratio and from that ratio one can easily see the fraction of the irreversible losses of each component with respect to the power output, which means the irreversible losses can be obtained directly from the power output. The boiler causes the maximum fraction of the total irreversible losses among the components of the cycle. These losses are reduced by introducing feedwater heaters into the cycle. The irreversibilities in the cycle are examined according to the effect of varying the total temperature rise across the feedwater heaters.