Study of cooling coatings based on natural materials

Studies of the maximum heating loads for cooling systems coatings made from natural materials have been conducted. To investigate cooling coatings based on natural materials, an experimental setup including a coating spraying tool has been developed. The conditions for spraying the material onto the heating surface, as well as the design principles for nozzles and combustion chambers, have been established. In the area of the steam-generating surface’s limiting state, shielded from burnout by cooling, these investigations are practically significant. Cooling systems with porous coatings have been developed, which make it possible to prevent the development of fractures in the coatings of chambers and nozzles through the use of thermodynamic and acoustic screens from three heating sources, as well as devices for spraying coatings with detonation high-temperature flares emanating from nozzles and combustion chambers that are cooled by capillary-porous coatings. High-speed filming and holography were used during the investigation. Heat fluxes, temperatures, flow rates, and pressures of liquid and gas flows were measured. The degree of unaccounted flow at different pressures was determined. A model of the interaction of an axisymmetric supersonic detonation jet of gases from the thermal tool normal to the coating has been constructed. Thermodynamic characteristics of oxygen-kerosene burners for the generation of supersonic high-temperature detonation flares by spraying of coatings from powders of natural materials have been established, and the granulometric composition of materials has been determined. Hydrodynamic operating modes of the burners were selected for specific heat fluxes in the range of (2·10⁶ ÷ 2·10⁷) W/m² from the jet torch into the coating. The oxidizer-to-fuel ratio varied between 0.3÷0.8; the jet torch temperature was (850÷3000)°C; the jet length was (0÷0.16) m; the jet radius was (3÷10) ·10^-3 m, and the burner axis angle to the coating was (90÷0) degrees. Capillary-porous and flow-through cooling systems showed high reliability, with the former reducing coolant consumption by up to 80 times.

1. Shoukat A. K., Nurettin S., Muammer K. Design, fabrication and nucleate pool-boiling heat transfer performance of hybrid micro-nano scale 2-D modulated porous surfaces. Applied Thermal Engineering. Volume 153, 2019,: 168–180. https://doi.org/10.1016/j.applthermaleng.2019.02.133 (In Eng.).

2. Gang L., Weirong L., Qingzhi W. The convective heat transfer of fractal porous media under stress condition. International Journal of Thermal Sciences. Volume 137, 2019,: 55–63. https://doi.org/10.1016/j.ijthermalsci.2018.11.017 (In Eng.).

3. Chuang T. J., Chang Y. H., Ferng Y. M. Investigating effects of heating orientations on nucleate boiling heat transfer, bubble dynamics, and wall heat flux partition boiling model for pool boiling. Applied Thermal Engineering. Volume 163, 2019, 114358. https://doi.org/10.1016/j.applthermaleng.2019.114358 (In Eng.).

4. Kimihide O., Hosei N. Investigation on liquid-vapor interface behavior in capillary evaporator for high heat flux loop heat pipe. International Journal of Thermal Sciences. Volume 140, June 2019, P. 530–538. https://doi.org/10.1016/j.ijthermalsci.2019.03.008 (In Eng.).

5. Riadh B., Vincent P. Dynamic model of capillary pumped loop with unsaturated porous wick for terrestrial application. Energy. Volume 111, 2016,: 402–413. https://doi.org/10.1016/j.energy.2016.05.102 (In Eng.).

6. Seong W. M., et at. A novel coolant cooling method for enhancing the performance of the gas turbine combined cycle. Energy. Volume 160, 2018,: 625–634. https://doi.org/10.1016/j.energy.2018.07.035 (In Eng.).

7. Genbach А. А., Bondartsev D. Yu., Shelginsky A. Y. [Investigation of nanoscale and microscale structured cooling surfaces of thermal power plants]. Nadezhnost' i bezopasnost' energetiki = Safety and Reliability of Power Industry. 2022, 15, (1),: 38–44 (in Russian). https://doi. org/10.24223/1999-5555-2022-15-1-38-44

8. Genbach А. А., Bondartsev D. Yu., Shelginsky A. Y. [Summary of heat transfer processes and their comparative evaluation for capillary porous coatings in power plants]. Nadezhnost' i bezopasnost' energetiki = Safety and Reliability of Power Industry. 2019, 12, (1),: 29–35 (in Russian). https://doi.org/10.24223/1999-5555-2019-12-1-29-35

9. Xing Y., et al. Turbine platform phantom cooling from airfoil film coolant, with purge flow. International Journal of Heat and Mass Transfer. 2019, 140,: 25–40. https://doi.org/10.1016/j.ijheatmasstransfer.2019.05.109

10. Jiin-Yuh J. A study of 3-D numerical simulation and comparison with experimental results on turbulent flow of venting flue gas using thermoelectric generator modules and plate fin heat sink. Energy. 53, 2013,: 270–281. https://doi.org/10.1016/j.energy.2013.03.010