Optimization of Natural Circulation District Heating Reactor Primary Heat Exchangers

Jussi Saari (), Heikki Suikkanen, Clara Mendoza-Martinez and Juhani Hyvärinen
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Jussi Saari: Department of Energy Technology, School of Energy Systems, Lappeenranta-Lahti University of Technology LUT, 53850 Lappeenranta, Finland
Heikki Suikkanen: Department of Energy Technology, School of Energy Systems, Lappeenranta-Lahti University of Technology LUT, 53850 Lappeenranta, Finland
Clara Mendoza-Martinez: Department of Energy Technology, School of Energy Systems, Lappeenranta-Lahti University of Technology LUT, 53850 Lappeenranta, Finland
Juhani Hyvärinen: Department of Energy Technology, School of Energy Systems, Lappeenranta-Lahti University of Technology LUT, 53850 Lappeenranta, Finland

Energies, 2023, vol. 16, issue 6, 1-27

Abstract: Small modular reactors (SMRs) are gaining interest as a potential solution for cost-effective, carbon-neutral district heat (DH) production. The low pressures and temperatures permit much lighter and cheaper designs than in power plants, and efficiency is high as all heat generated can be sold to customers. In this work, the optimization of the primary heat exchangers in a natural-circulation 50-MW heating reactor concept was carried out to obtain an initial feasibility estimate for the concept for both baseload and load-following operation, as well as to obtain information on the characteristics of an optimized design. Studies on small natural circulation heat-only SMRs and the impact of heat exchanger design on the overall dimensions and economics have not been published before. Although a detailed heat exchanger cost model was used, the results should be considered tentative initial estimates, as much of the cost impact from the heat exchanger design comes from the effect the design has on the pressure vessel dimensions. While more detailed pressure vessel designs and cost functions are needed for final optimization, the feasibility of the concept is shown. Optimization for different load profiles produced near-identical designs, with the downcomer divided approximately in half between the heat exchanger at the top and an empty space at the bottom to maximize the pressure difference available for natural circulation. Although conservative, even pessimistic estimates were used in the absence of detailed cost functions, cost prices of 30–55 EUR/MWh DH at a 10% interest rate were obtained, or only 20–40 EUR/MWh DH at a 5% interest rate. This indicates potentially good competitiveness for the considered DH SMR concept.

Keywords: small modular reactors; district heating; shell-and-tube heat exchangers; optimization; cuckoo search (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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