Autor(es)

Netto, Arlindo T. Souza ; Oliveira, Arthur V. S. ; Gradeck, Michel ; dos Santos, Rogerio Gonsalves

• Tipo de documento: Artigo Científico
• Fonte: INTERNATIONAL JOURNAL OF THERMAL SCIENCES; v. 219, p. 12-pg., 2025-01-25.

Resumo

This work investigates the heating process of a small volume of ethanol under subcritical, critical, and supercritical pressures in a test section representative of real fuel heating systems and using a commercial fuel heater. The heater consists of a cylindrical cartridge resistance with a diameter of 5 mm that operates in horizontal orientation. The experiments were carried out at pressures ranging from 1 to 100 bar. The experimental setup allowed data acquisition including voltage, current, fluid pressure and temperature, and high-speed synchronized imaging of the phenomena. At subcritical pressures, nucleate boiling drove rapid heating of the fluid, promoting intense turbulence and temperature homogenization. On the other hand, heater dryout was observed for pressures up to 5 bar, leading to heater temperatures exceeding 700 degrees C and a decline in heat transfer performance. Heat fluxes were estimated and compared with the critical heat flux predicted by the Zuber correlation adjusted for cylindrical surfaces, confirming dryout conditions. During the cooling process after dryout, the mitigation of the vapor film was also analyzed. At supercritical pressures, the absence of bubble nucleation caused significant degradation of the heat transfer and homogeneity, with pseudo-boiling structures being identified (pseudo-bubbles and pseudo-droplets). These data and information contribute to understanding and optimizing fluid heating systems, especially for applications in advanced internal combustion engines and pollutant emission reduction strategies. (AU)

• Processo FAPESP: 22/06199-2 - Shadowgraphy e PLIF combinadas para caracterização dinâmica e térmica de fluidos
• Beneficiário: Arthur Vieira da Silva Oliveira
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 21/01897-0 - Estudo experimental do impacto de gotas sobre superfícies aquecidas usando técnicas ópticas combinadas: gotas isoladas, múltiplas gotas e sprays
• Beneficiário: Arthur Vieira da Silva Oliveira
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores