# Mechanical Integrity Analysis of a Printed Circuit Heat exchanger with Channel Misalignment
## 4 Conclusions  
In this study, two-dimensional FEM simulations were performed to observe the effects of primary channel misalignment in the PCHE under five different misalignment conditions.  
1. The highest stress intensity was located at the tip edge of the water channel for the higher-pressure intensity compared to that in the sodium channel;
2. The stress intensity increases as the misalignment increases, causing the utilization factor to increase, which is less safe compared to the condition without misalignment;
3. The proposed geometry design can comply with the design limit condition up to 700\({}^{\circ}\) C in terms of the ASME code. This means the for the SFR application, which has an average temperature of 550\({}^{\circ}\) C, the geometry design can comply with the design limit conditions. However, the design can comply with the acceptance criteria up to 725\({}^{\circ}\) C under 30% misalignment condition;
4. The study shows that the design of PCHEs needs to be more precise regarding welding and assembly processes, due to decreasing utilization factor. More strict construction and assembly process monitoring, especially during stacking and welding processes, is needed to avoid this utilization factor degradation due to misalignment conditions.  
Figure 11: Maximum stress for each misalignment condition compared to yield stress of material SS316.  
Figure 12: Yielded section under pressure loading for various temperature conditions.  
**Author Contributions:** Conceptualization, A.P.S. and J.Y.L.; methodology, A.P.S.; software, A.P.S.; validation, A.P.S. and J.Y.L.; formal analysis, data curation, A.P.S.; writing--original draft preparation, A.P.S.; writing--review and editing, A.P.S. and J.Y.L.; visualization, A.P.S.; supervision, J.Y.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported by the National Research Foundation of Korea (NRF) grant, funded by the Korea government (MSIP) (No. 2017M2A8A4018624).  
**Conflicts of Interest:** The authors declare no conflict of interest.  
**Nomenclature**  
_Abbreviations_  
ASME  
American Society of Mechanical Engineers  
PCHE  
Printed Circuit Heat Exchanger  
FEM  
Finite Element Method  
SCO2  
Supercritical Carbon dioxide  
SFR  
Sodium Fast-cooled reactor  
TES  
Thermal Energy Storage  
IHX  
Intermediate Heat Exchanger  
_HTGR_  
High-Temperature Gas Reactor  
_SCL_  
Stress Classification Line  
_Symbol_  
\(S_{m}\)  
The Lowest Stress Intensity value at a given temperature  
\(K\)  
Factor K  
\(S_{o}\)  
Maximum allowable stress intensity  
\(S_{mt}\)  
Maximum allowable stress intensity value time dependent  
\(P_{m}\)  
Primary membrane stress intensity [MPa]  
\(P_{L}\)  
Primary membrane stress local [MPa]  
\(P_{b}\)  
Primary bending stress [MPa]  
\(U_{f}\)  
Utilization factor as the ratio of stress intensity to the maximum allowable stress  
\(m\)  
Misalignment case (mm)  
\(\sigma_{\bar{y},m}\)  
Membrane Stress  
\(\sigma_{\bar{y},b}\)  
Bending Stress  
\(\sigma_{e}\)  
Equivalent Stress  
\(\sigma_{x}\)  
Stress tensor in x direction  
\(\sigma_{y}\)  
Stress tensor in y direction  
\(\sigma_{z}\)  
Stress tensor in z direction  
\(S_{y}\)  
Yield Stress