Design of coil-wound heat exchangers for molten chloride salt TES in CSP with sodium receiver and sCO2 cycle Articles uri icon

publication date

  • August 2025

start page

  • 1

end page

  • 17

volume

  • 128

International Standard Serial Number (ISSN)

  • 2352-152X

Electronic International Standard Serial Number (EISSN)

  • 2352-1538

abstract

  • This paper introduces a novel design for heat exchangers and optimization of operating temperatures in the thermal energy storage (TES) system for next generation (Gen3) concentrated solar power (CSP) plants. The proposed system integrates a sodium receiver, molten chloride salt TES, and a supercritical CO2 (sCO2) power cycle, using coil-wound heat exchangers (CWHEs) to enhance both efficiency and reliability. These heat exchangers are selected for their exceptional robustness under large temperature and pressure variations, enhanced heat transfer, improved part-load performance, reduced dead zones and better temperature control of molten salts. For the first time, CWHEs are designed for Na-Salt and Salt-sCO2 heat exchange, optimizing the TES system for Gen3 CSP plants. The design approach addresses critical reliability challenges, including creep at high temperatures and corrosion of surfaces exposed to the ternary eutectic molten chloride salt mixture MgCl2-KCl-NaCl (wt% 45.98¿.91¿.11). Additionally, a multi-stream model is applied to the CWHEs to capture thermal gradients across coil layers. Furthermore, the operating temperatures of the hot and cold tanks are optimized to minimize the total annual cost (TAC) of the TES system, including CWHEs and salt tanks. This optimization reduces TAC by 6.4 % to 4.2 % across solar multiples ranging from 1 to 2.5. The proposed design and optimization methodology provide an efficient and reliable solution for heat transfer between the sodium receiver, molten chloride salt, and sCO2 cycle, enhancing the performance and viability of Gen3 CSP plants.

subjects

  • Industrial Engineering
  • Renewable Energies

keywords

  • coil-wound heat exchangers; concentrated solar power; molten chloride salt; multi-stream heat exchanger; sodium receiver; supercritical co2 cycle; thermal energy storage