극초음속 비행체의 재생 냉각 시스템에서는 연료의 열분해를 통해 추가적인 흡열 성능을 확보할 수 있으나, 이 과정에서 생성되는 코크는 열전달 저하와 유로 막힘을 유발한다. 본 연구에서는 JP-7급 열안정성 연료를 대상으로 SS316, Inconel 600, Ti Grade 9 반응기 및 실리카 코팅 SS316 반응기에서 열분해 실험을 수행하여 반응기 재질 및 코팅이 흡열 특성과 코크 생성에 미치는 영향을 평가하였다. 또한 분산제, 산화방지제, 금속 비활성화제를 적용하여 재질별 코크 저감 최적 첨가제 조합을 도출하였다. 실험 결과, 무첨가 조건에서 인코넬과 티타늄 반응기는 SS316 대비 코크 생성이 크게 감소하였고, 실리카 코팅 튜브 역시 유의미한 코크 저감 효과를 나타냈다. 첨가제는 반응기 재질에 따라 최적 조합이 다르게 나타났으며, 코크 저감과 화학적 흡열량 향상이 동시에 확인되었다. 이러한 결과는 반응기 표면 재질 및 코팅층의 화학적 특성이 코크 형성 경로와 첨가제 효과에 영향을 미침을 보여준다.

In regenerative cooling systems for hypersonic vehicles, fuel pyrolysis provides additional endothermic cooling capacity; however, coke formation during this process can deteriorate heat transfer and block flow channels. In this study, pyrolysis experiments were conducted using a Synthetic JP-7 Surrogate in SS316, Inconel 600, Ti Grade 9, and  silica-coated  SS316  reactors  to  evaluate  the  effects  of  reactor  material  and  internal  coating  on  endothermic characteristics and coke formation. In addition, a dispersant, an antioxidant, and a metal deactivator were applied to determine the coke reduction optimal additive formulation for each reactor material. The results revealed that, in the absence of additives, the Inconel 600 and Ti Grade 9 reactors produced substantially less coke than SS316, and the silica-coated SS316 tube also effectively suppressed coke deposition. The most effective additive combination varied with the reactor material; nevertheless, the optimized formulations simultaneously reduced coke formation and increased the chemical heat sink. These findings suggest that the surface chemistry of the reactor wall and coating layer plays a critical role in determining the dominant coking pathway and additive performance.

Synthetic JP-7 surrogate, Regenerative cooling, Hypersonic vehicles, Coke reduction, Reactor materials, Sil- ica-coated reactor, Dispersants, Antioxidants, Metal deactivators

1. Peters, A. B., Zhang, D., Chen, S., Ott, C., Oses, C., Curtarolo, S., McCue, I., Pollock, T. M. and Eswarappa Prameela, S., “Mate- rials Design for Hypersonics,” Nature Communications, 15(1), 3328 (2024).
2. Blevins, R. D., Holehouse, I. and Wentz, K. R., “Thermoacous- tic Loads and Fatigue of Hypersonic Vehicle Skin Panels,” J. Aircr., 30(6), 971-978(1993).
3. Qin, J., Bao, W., Zhang, S. and Zhou, W., “Comparison During a Scramjet Regenerative Cooling and Recooling Cycle,” J. Ther- mophys. Heat Transfer, 26(4), 612-618(2012).
4. Jiang, R., Liu, G. and Zhang, X., “Thermal Cracking of Hydro- carbon Aviation Fuels in Regenerative Cooling Microchannels,” Energy Fuels, 27(5), 2563-2577(2013).
5. Xu, K. and Meng, H., “Modeling and Simulation of Supercriti-cal-Pressure Turbulent Heat Transfer of Aviation Kerosene with Detailed Pyrolytic Chemical Reactions,” Energy Fuels, 29(7), 4137-4149(2015).
6. Pan, Y., Zhang, H., Zhang, C., Wang, H., Jing, K., Wang, L., Zhang, X. and Liu, G., “Supercritical Pyrolysis and Coking of JP-10 in Regenerative Cooling Channels,” Energy Fuels, 34(2), 1627- 1638(2020).
7. Tao, Z., Hu, X., Zhu, J. and Cheng Z., “Numerical Study of Flow and Heat Transfer of N-Decane with Pyrolysis and Pyrolytic Coking Under Supercritical Pressures,” Energy Fuels, 31(8), 8698-8707
(2017).
8. Towfighi, J., Sadrameli, M. and Niaei, A., “Coke Formation Mecha- nisms and Coke Inhibiting Methods in Pyrolysis Furnaces,” J. Chem. Eng. Japan, 35(10), 923-937(2002).
9. Edwards, T., “Cracking and Deposition Behavior of Supercritical Hydrocarbon Aviation Fuels,” Combustion Sci. Technol., 178(1-
3), 307-334(2006).
10. Baker, R., Yates, D. and Dumesic, J. A., Filamentous carbon for- mation over iron surfaces, ACS Publications(1982).
11. Muñoz Gandarillas, A. E., Van Geem, K. M., Reyniers, M. and Marin, G. B., “Influence of the Reactor Material Composition on Coke Formation During Ethane Steam Cracking,” Ind. Eng. Chem. Res., 53(15), 6358-6371(2014).
12. Symoens, S. H., Olahova, N., Muñoz Gandarillas, A. E., Karimi, H., Djokic, M. R., Reyniers, M., Marin, G. B. and Van Geem, K. M., “State-of-the-Art of Coke Formation During Steam Cracking: Anti-Coking Surface Technologies,” Ind. Eng. Chem. Res., 57(48), 16117-16136(2018).
13. Marek, J. C. and Albright, L. F., “Formation and Removal of Coke Deposited on Stainless Steel and Vycor Surfaces from Acetylene and Ethylene,” ACS Publications(1982).
14. Mahmoudi, E., Hafizi, A., Rahimpour, M. R., Bolhasani, A. and Shariati, A., “Inhibition Effect of CeO2 Promoted SiO2 Coating on Coke Growth During Steam Cracking of Ethane,” Chem. Eng. Res. Design, 136, 271-281(2018).
15. Liu, J., Wang, X., Wang, H., Xu, H. and Yang, J., “Preparation and Anti-Coking Application of Sol–Gel SiO2 Coating in a Delayed Coking Furnace,” RSC advances, 11(17), 9849-9855(2021).
16. Zhou, J., Wang, Z., Luan, X. and Xu, H., “Anti-Coking Property of the SiO2/S Coating During Light Naphtha Steam Cracking in a Pilot Plant Setup,” J. Anal. Appl. Pyrolysis, 90(1), 7-12(2011).
17. Kim, Y., Kim, J., Hyeon, D. H., Han, J. S., Chun, B., Jeong, B. H. and Kim, S. H., “Development of PIBSI Type Dispersants for Carbon Deposit from Thermal Oxidative Decomposition of Jet A-1,” Fuel, 158, 91-97(2015).
18. Dubois-Clochard, M., Durand, J., Delfort, B., Gateau, P., Barré, L., Blanchard, I., Chevalier, Y. and Gallo, R., “Adsorption of Polyisobutenylsuccinimide Derivatives at a Solid−Hydrocarbon Interface,” Langmuir, 17(19), 5901-5910(2001).
19. Jia, T., Zhao, M., Pan, L., Deng, C., Zou, J. and Zhang, X., “Effect of Phenolic Antioxidants on the Thermal Oxidation Stability of High-Energy–Density Fuel,” Chemical Engineering Science, 247, 117056(2022).
20. Morris, R. E., Hasan, M. T., Su, T. C., Wechter, M. A., Turner, N. H. and Schreifels, J. A., “Significance of Copper Complex Ther- mal Stability in the Use of Metal Deactivators at Elevated Tem- peratures,” Energy Fuels, 12(2), 371-378(1998).21. Waynick, J. A., “The Development and Use of Metal Deactiva- tors in the Petroleum Industry: A Review,” Energy Fuels, 15(6), 1325-1340(2001).
22. Loegel, T. N., Morris, R. E. and Leska, I., “Detection and Quan- tification of Metal Deactivator Additive in Jet and Diesel Fuel by Liquid Chromatography,” Energy Fuels, 31(4), 3629-3634(2017).
23. Jones, E. G. and Balster, L. M., “Impact of Additives on the Autoxidation of a Thermally Stable Aviation Fuel,” Energy Fuels, 11(3), 610-614(1997).
24. Gough, R. V., Widegren, J. A. and Bruno, T. J., “Thermal Decompo- sition Kinetics of the Thermally Stable Jet Fuels JP-7, JP-TS and JP-900,” Energy Fuels, 28(5), 3036-3042(2014).
25. Esmailian, M., “Corrosion Resistance of Welds in Type 316L Stainless Steel,” Mater. Perform., 56(3), 58-61(2017).
26. Bonnet, F., Ropital, F., Berthier, Y. and Marcus, P., “Filamentous Carbon Formation Caused by Catalytic Metal Particles from Iron Oxide,” Materials and Corrosion, 54(11), 870-880(2003).
27. Wang, S., Cui, L., Wang, G., Zheng, Y., Wang, H. and Jia, J., “Prop- erties of Oxide Films Grown on 25Cr20Ni Alloy in Air-H2O and H2-H2O Atmospheres,” Petroleum Science, 11(1), 147-154(2014).
28. Xiao, J., Prud’Homme, N., Li, N. and Ji, V., “Influence of Humid- ity on High Temperature Oxidation of Inconel 600 Alloy: Oxide Layers and Residual Stress Study,” Appl. Surf. Sci., 284, 446- 452(2013).
29. Altin, O. and Eser, S., “Pre-Oxidation of Inconel Alloys for Inhi- bition of Carbon Deposition from Heated Jet Fuel,” Oxidation Metals, 65(1), 75-99(2006).
30. Zhu, C., Ma, F., Dai, Z. and Ma, D., “Atomic Layer Deposition of TiO2 Thin Films on the Inner Walls of Steel Tubes Increases Anti-Coking Properties,” ACS Omega, 5(49), 32102-32111(2020).
31. Tang, S., Liu, T., Duan, S., Guo, J. and Tang, A., “Comparison of Growth Characteristics and Properties of CVD TiN and TiO2 Anti-Coking Coatings,” Processes, 7(9), 574(2019).
32. Park, C., Aum, H., Ji, S., Jeong, B., Choi, H., Park, D. and Jung, J., “Endothermic Properties and Coke Reduction of Thermally Stable Fuels Using Antioxidants and Metal Deactivators,” Korean Chemi- cal Engineering Research, 63(1), 34-41(2025).
33. Park, C., Aum, H., Kim, D., Kim, Y., Jeong, B., Choi, H., Park, D. and Jung, J., “Endothermic Properties and Coke Reduction of exo- THDCPD Using Antioxidants and Metal Deactivators,” Korean Chemical Engineering Research, 64(1), 105147.1-105147.10(2026).
34. Linne, D., Meyer, M., Edwards, T. and Eitman, D., “Evaluation of Heat Transfer and Thermal Stability of Supercritical JP-7 Fuel,” 33, 3041(1997).
35. Wang, J., Jin, H., Gao, H. and Wen, D., “Cooling Capacity Opti- mization of Hydrocarbon Fuels for Regenerative Cooling,” Appl. Therm. Eng., 200, 117661(2022).
36. Mun, J., Kim, N., Jeong, B. and Jung, J., “Endothermic Properties of Liquid Fuel Decomposition Catalyst Using Metal Foam Sup- port,” Korean Chemical Engineering Research, 59(4), 481-486 (2021).
37. Kim, N., Park, C., Cho, S., Jeong, B. and Jung, J., “Decomposi- tion of Thermally Stable Fuel Using a Cerium-Modified Zeolite Catalyst and Endothermic Characteristics,” ACS Omega, 8(45), 43130-43138(2023).
38. Jones, E. G., Balster, W. J. and Balster, L. M., “Evaluation of the Effectiveness of a Metal Deactivator and Other Additives inReducing Insolubles in Aviation Fuels,” Journal of Engineering for Gas Turbines and Power, 119(4), 830-835(1997).
39. Balster, W. J. and Balster, L. M., “Use of MDA, BHT, and Dis- persant Singly and in Combination as Jet-Fuel Additives,” OSTI, (1996).
40. Zhi, H., Fu, Y., Gang, X., Zhang, L., Wang, J. and Xu, G., “Inves- tigation on Thermal Oxidation Coking Inhibition of Aviation Kerosene RP-3 Using Additives and Surface Modification Method,” Fuel, 406, 136957(2026).
41. Altin, O. and Eser, S., “Characterization of Carbon Deposits from Jet Fuel on Inconel 600 and Inconel X Surfaces,” Ind. Eng. Chem. Res., 39(3), 642-645(2000).
42. Guo, X., Vanhaecke, E., Vullum, P. E., Ma, J., Gunawardana, P. D. S., Walmsley, J. C., Chen, D. and Venvik, H. J., “Effects of Metal Dusting Relevant Exposures of Alloy 601 Surfaces on Carbon Formation and Oxide Development,” Catalysis Today, 369, 48-61(2021).
43. Finkelstein-Shapiro, D., Davidowski, S. K., Lee, P. B., Guo, C., Holland, G. P., Rajh, T., Gray, K. A., Yarger, J. L. and Calatayud, M., “Direct Evidence of Chelated Geometry of Catechol on TiO2 by a Combined Solid-State NMR and DFT Study,” The Journal of Physical Chemistry C, 120(41), 23625-23630(2016).
44. Sonström, A., Boldrini, B., Werner, D., Maichle-Mössmer, C., Rebner, K., Casu, M. B. and Anwander, R., “Titanium (IV) Surface Complexes Bearing Chelating Catecholato Ligands for Enhanced Band-Gap Reduction,” Inorg. Chem., 62(2), 715-729(2023).
45. Sudarsanam, P., Li, H. and Sagar, T. V., “TiO2-Based Water-Tol- erant Acid Catalysis for Biomass-Based Fuels and Chemicals,” ACS Catalysis, 10(16), 9555-9584(2020).
46. Vicente, H., Liu, C., Gayubo, A. G., Castano, P. and Pidko, E. A., “Improving the Dehydrogenation Function and Stability of Zn- Modified ZSM-5 Catalyst in Methanol-to-Aromatics Reaction by Ca Addition,” Applied Catalysis A: General, 683, 119854(2024).
47. Tang, S., Wang, J., Zhu, Q., Chen, Y. and Li, X., “Preparation of Rutile TiO2 Coating by Thermal Chemical Vapor Deposition for Anticoking Applications,” ACS Applied Materials & Interfaces, 6(19), 17157-17165(2014).
48. Rane, N., Kersbulck, M., Van Santen, R. A. and Hensen, E., “Cracking of n-Heptane over Brønsted Acid Sites and Lewis Acid Ga Sites in ZSM-5 Zeolite,” Microporous and Mesoporous Materials, 110(2-3), 279-291(2008).
49. Liu, D., Cao, L., Zhang, G., Zhao, L., Gao, J. and Xu, C., “Cata- lytic Conversion of Light Alkanes to Aromatics by Metal-Contain- ing HZSM-5 Zeolite Catalysts—A Review,” Fuel Process. Technol., 216, 106770(2021).
50. Wang, H. and Shiju, N. R., “A Mini Review on Aromatization of n-Alkanes,” Reaction Chemistry & Engineering, 10(4), 768-776
(2025).
51. Wang, Z., Ding, X., Guo, X., Dou, B., Zhou, J., Wang, B. and Wang, M., “Investigation into the Anticoking Performances of Sol–Gel- Derived SiO2 and SiO2–CeO2 Coatings During Thermal Pyrolysis of Light Naphtha,” Energy Fuels, 35(3), 2562-2578(2021).
52. Okoye-Chine, C. G., Mbuya, C., Ntelane, T. S., Moyo, M. and Hildebrandt, D., “The Effect of Silanol Groups on the Metal- Support Interactions in Silica-Supported Cobalt Fischer-Tropsch Catalysts. A Temperature Programmed Surface Reaction,” Jour- nal of Catalysis, 381, 121-129(2020).53. Zhou, J., Wang, Z., Luan, X. and Xu, H., “Anti-Coking Property of the SiO2/S Coating During Light Naphtha Steam Cracking in a Pilot Plant Setup,” J. Anal. Appl. Pyrolysis, 90(1), 7-12(2011).
54. Lemmens, A. K., Rap, D. B., Thunnissen, J. M., Willemsen, B. and Rijs, A. M., “Polycyclic Aromatic Hydrocarbon Formation Chemistry in a Plasma Jet Revealed by IR-UV Action Spectros- copy,” Nature Communications, 11(1), 269(2020).