A thermal-hydraulic analysis model of printed circuit heat exchangers for system simulation using Modelica

ABSTRACT

Supercritical CO₂ (S-CO₂) Brayton cycle is one of the alternative energy conversion technologies for generation IV nuclear energy systems. Printed circuit heat exchanger (PCHE) is one of the key components in S-CO₂ Brayton cycle. Although PCHE has dedicated steady-state models, transient models that can be applied to precise analysis of systems remain to be developed. The deviations brought by different flow and heat transfer correlations needs to be studied in simulations of PCHE, considering that the disparity of results obtained by various correlations under different working conditions are more obvious in iterative calculations. We developed a PCHE model in Modelica according to the existing S-CO₂ flow and heat transfer correlations. To benchmark the model, steady-state results are compared with the results obtained by Fluent. The deviations caused by various flow and heat transfer correlations are analyzed. Transient analysis is performed to compare different control strategies when reducing the power of PCHE. According to the results of the transient simulation, PCHE used as a pre-cooler in S-CO₂ Brayton cycle can quickly respond to transient variations. Both steady-state and transient results verified the reliability of the PCHE model, which suggests that the model can be utilized for the system analysis of S-CO₂ Brayton cycle.

KEYWORDS:

• Thermal-hydraulic analysis
• printed circuit heat exchangers
• supercritical CO₂
• Modelica

Nomenclature

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Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by the Energy Development Foundation of College of Energy [Grant No. 2018NYFZ01].