| Autor(es): |
Moreira, Tiago A.
;
Ribatski, Gherhardt
Número total de Autores: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | 4TH THERMAL AND FLUIDS ENGINEERING CONFERENCE, ASTFE 2019; v. N/A, p. 11-pg., 2019-01-01. |
| Resumo | |
This paper concerns flow patterns visualization and their characterization under diabatic conditions for convective condensation of R134a inside a horizontal tube. The test section comprises a counter-current tube-in-tube heat exchanger with cold water flowing in the annuli region and R134a in the inner tube. Both inner and outer tubes are transparent and made of borosilicate. Such set up allows visualization of the condensation process under heat transfer conditions, on contrary to most of studies available in literature, based on flow pattern characterization in an adiabatic region located downstream the cooling section. The experiments were performed for mass velocities ranging from 130 to 400 kg/m(2)s, saturation temperature of 35 degrees C and vapor qualities up to 0.93. The following flow patterns were observed: (i) stratified; (ii) wavy; (iii) intermittent; and (iv) annular. Comparisons of the experimental visualizations and the methods of Tandon et al. [5] and El Hajal et al. [6] were performed. Both methods predicted correctly the flow patterns at high vapor qualities. The method of Tandon et al. (1982) is the most accurate at low vapor quality conditions. Moreover, based on analyses of flow images, waves on the liquid film with different characteristics were recognized. Besides the waves with low amplitude and high frequency, typically observed under annular flow conditions, waves of high amplitude and low frequency and intermediary amplitude and frequency were characterized based on analyses of an optical signal. (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: | 11/50176-2 - Mitigação da emissão de gases de efeito estufa em sistemas de refrigeração mediante a utilização de gases com baixo GWP e a aplicação de micro e nanotecnologias |
| Beneficiário: | Gherhardt Ribatski |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Regular |
| 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 |