Flow boiling of hydrocarbons and their zeotropic binary mixtures under pre- and post-dryout conditions

Autor(es)

Oliveira, Guilherme H. S. ^[1] ; Moreira, Tiago Augusto ^[1] ; Ayub, Zahid H. ^[2] ; Ribatski, Gherhardt ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sao Carlos Sch Engn EESC, Dept Mech Engn, Heat Transfer Res Grp HTRG, 400 Trabalhador Sao Carlense Ave, BR-13566590 Sao Carlos, SP - Brazil

^[2] Isotherm Inc, 7401 Commercial Blvd East, Arlington, TX 76001 - USA

• Tipo de documento: Artigo Científico
• Fonte: APPLIED THERMAL ENGINEERING; v. 198, NOV 5 2021.
• Citações Web of Science: 0

Resumo

This paper concerns an experimental evaluation of the flow boiling heat transfer coefficient of R290, R600a and R1270 focusing on the replacement of R134a in commercial, and residential air-conditioning and refrigeration applications. Moreover, new zeotropic binary mixtures (R600a/R290, 70/30% molar fraction, and R600a/ R1270, 75/25% molar fraction) with similar range of temperature applications than R134a are proposed and evaluated. Experiments are performed inside a conduit with a diameter of 9.43 mm for mass velocity ranging from 50 to 300 kg/(m2 s), local heat flux from 10 to 30 kW/m2, vapor quality from 0 to 1, and saturation temperature of 5 degrees C. In general, higher heat transfer coefficients are obtained for pure hydrocarbons, followed by the mixtures, therefore, showing a better heat transfer performance than R134a. Similar heat transfer coefficients are noticed among pure hydrocarbons, with R600a presenting slightly higher values under certain conditions. A behavior typical of heat transfer dominated by convective effects is noticed for the hydrocarbons with increasing quality at mass velocities higher than 100 kg/(m2 s), while for R134a such a behavior is verified only for mass velocities higher than 200 kg/(m2 s). Nucleate boiling dominated heat transfer is noticed only for mass velocities lower than 100 kg/(m2 s) and 200 kg/(m2 s) for hydrocarbons and R134a, respectively. In general, the heat transfer coefficient increases with mass velocity and heat flux. The heat transfer coefficient and dryout incipience vapor quality data are compared against prediction methods from literature, however, none predicting the current data. Generally, lower dryout incipience vapor qualities are noticed for the hydrocarbons compared to R134a, with the R600a presenting the lowest values. The dryout is delayed in terms of vapor quality for the mixtures compared to the pure hydrocarbons. (AU)

• 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
• 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