Title: Influence of orifice in entropy generation and exergy analysis under transient condition for large diameter natural circulation loops

Authors: D.N. Elton; U.C. Arunachala; A.C. Rajat

Addresses: Department of Mechanical and Manufacturing Engineering, Renewable Energy Center, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal – 576104, Karnataka, India ' Department of Mechanical and Manufacturing Engineering, Renewable Energy Center, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal – 576104, Karnataka, India ' Hexagon Capability Center, Madhapur, Hyderabad – 500081, Telangana, India

Abstract: Stable power generation is of concern due to instability in NCL. The entropy generation analysis in a 38.89 mm diameter loop identified the flow reversals by a drop in its value after a peak. Orifice plates and operating procedures lead to a change in threshold value. During unsteady state, the least entropy generation was observed with β = 0.77. At higher power, constant power generation is possible with low orifice as it exhibits better exergy efficiency. The entropy generated due to friction was negligible compared to that by heat transfer.

Keywords: natural circulation systems; single-phase; instantaneous entropy generation; instability; orifice; large-diameter loop; exergy analysis.

DOI: 10.1504/IJEX.2021.118722

International Journal of Exergy, 2021 Vol.36 No.2/3/4, pp.298 - 314

Received: 27 Jan 2021
Accepted: 25 Mar 2021

Published online: 29 Oct 2021 *

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