Liquid-film thickness, flow pattern, and void fraction of hydrocarbons and their zeotropic mixtures during convective condensation

Autor(es)

Moreira, Tiago Augusto ; Baptistella, Victor Eduardo Corte ; Ribatski, Gherhardt

• Tipo de documento: Artigo Científico
• Fonte: INTERNATIONAL JOURNAL OF MULTIPHASE FLOW; v. 159, p. 23-pg., 2022-12-06.

Resumo

The present study concerns an experimental investigation of the liquid-film thickness, flow patterns, and void fraction during convective condensation of hydrocarbons and their zeotropic mixtures. Experiments were performed for R600a, R290, R1270, R600a/R290 (70/30 molar fraction) and R600a/R1270 (75/25 molar fraction) in a horizontal tube with an internal diameter of 9.43 mm. In the experiments, the saturation temperature was kept at 35 degrees C, mass velocities ranged from 50 to 250 kg/m2s, vapor qualities from 0 to 1, and heat fluxes from 5 to 60 kW/m2. It was noticed that the transition from gravitational to shear-driven flow patterns can be quantitatively characterized by a peak in the newly defined base liquid-film thickness measured at the top region of the channel at a certain vapor quality. At mass velocities higher than 100 kg/m2s, shear-driven flow patterns were dominant, and noticed in a wider range of vapor qualities, presenting a sharp transition from gravitational-driven flow patterns, which is independent of the refrigerant. At lower mass velocities, R290 and R1270 showed a higher vapor quality associated with the transition from gravitational to shear-driven flow patterns than the other fluids. Such behavior was associated with the lower vapor specific volumes of R290 and R1270. Gravitational to shear-driven transition prediction methods were compared against the data from the present study based on the peak of the base liquid-film thickness, showing reasonable results for flow pattern prediction methods developed based on heat transfer data. The void fraction was estimated based on the LFT measurements for annular flows, and the results compared with several prediction methods with two of them providing accurate predictions. (AU)

• Processo FAPESP: 16/16849-3 - Análise teórica-experimental do coeficiente de transferência de calor, perda de pressão e padrão de escoamento durante a condensação de misturas zeotrópicas de hidrocarbonetos no interior de tubos
• Beneficiário: Tiago Augusto Moreira
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 20/10923-2 - Avaliação do comportamento hidrodinâmico e dos mecanismos de transferência de calor durante a ebulição convectiva em microcanais em condições de secagem de parede
• Beneficiário: Victor Eduardo Corte Baptistella
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 18/06057-8 - Desenvolvimento e avaliação de um método para determinação experimental da espessura de filmes líquidos no interior de superfícies circulares
• Beneficiário: Tiago Augusto Moreira
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 19/08577-1 - EMU concedido no processo 16/09509-1: câmera de alta velocidade phantom V2012
• Beneficiário: Gherhardt Ribatski
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários