Title: Enhancing performance by incorporating solar feedwater heating instead of steam bleeding of an existing steam power plant: energy and exergy analyses

Authors: Sayan Mandal; Sudip Simlandi; Nilkanta Barman

Addresses: Department of Mechanical Engineering, Jadavpur University, Kolkata – 700032, India ' Department of Mechanical Engineering, Jadavpur University, Kolkata – 700032, India ' Department of Mechanical Engineering, Jadavpur University, Kolkata – 700032, India

Abstract: This study presents energy and exergy analyses to improve the performance of a 500 MW thermal power plant by adding a direct solar feedwater heating system, rather than steam bleedings, resulting in a significant increase in energy efficiency. The energy efficiency increases from 44.33% to 48.50%, if off-bleeding is considered at the reheater inlet or at low- and intermediate-pressure turbines. A lower solar energy requirement of 134 MW is found when off-bleeding is established at the reheater inlet, but it demands an increase in temperature to 337.40°C. The approach enhances energy efficiency and introduces a new concept.

Keywords: existing thermal power plant; reduce bleedings; direct solar heating; increasing efficiency; energy and exergy analyses.

DOI: 10.1504/IJEX.2026.151866

International Journal of Exergy, 2026 Vol.49 No.2, pp.112 - 121

Received: 02 Aug 2025
Accepted: 09 Oct 2025
Published online: 24 Feb 2026 *

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