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Extend and assessment of the accuracy of current liquid film thickness measurement technique for flat surfaces to a curved geometry

Grant number: 18/06057-8
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): January 15, 2019
Effective date (End): July 14, 2019
Field of knowledge:Engineering - Mechanical Engineering
Principal Investigator:Gherhardt Ribatski
Grantee:Tiago Augusto Moreira
Supervisor abroad: Gregory Nellis
Home Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
Local de pesquisa : University of Wisconsin-Madison (UW-Madison), United States  
Associated to the scholarship:16/16849-3 - Theoretical and experimental analysis of heat transfer coefficient, pressure drop and flow patterns during condensation of hydrocarbons ZEOTROPIC mixtures inside tubes, BP.DR

Abstract

The estimation of the liquid film thickness (LFT) during annular flows is a critical issue in heat transfer processes involving two-phase flows, since the heat conduction through the liquid film is the main thermal resistance for both flow boiling and convective condensation. Moreover, the frictional pressure drop is also associated to the liquid film characteristics. Therefore, the correct estimation of the liquid film is a crucial tool to the development of predictive methods for the heat transfer coefficient, pressure drop and critical heat flux (dryout). Currently, the Multiphase Flow Visualization and Analysis Laboratory (MFVAL) coordinate by Prof. Gregory F. Nellis at the University of Wisconsin-Madison (ranked as the 40th best according to the Times Higher Education ranking in the area of engineering and education) is working on the improvement of a technique, initially proposed by the Shedd and Newell (1998), for the measurement of LFT on flat surfaces. In this context, the present internship proposal intends that the Doctorate student learn the current know how on the LFT measurements developed by the Multiphase Flow Visualization and Analysis Laboratory at the University of Wisconsin-Madison. It is also expected that, during his internship, the student extends and assesses the accuracy of the technique developed for flat surfaces to a curved geometry. After his return to Brazil, the student will implement and use the same technique to evaluate the LFT for in-tube condensation in the facility built at the Heat Transfer Research Group (HTRG) at EES-USP. Based on the LFT results, and experimental data obtained for the heat transfer coefficient and pressure drop previously to his internship, new phenomenological models for void fraction, heat transfer coefficient and pressure drop will be proposed. It is expected, based on LFT measurements, to segregate the condensation process as vapor-shear and gravity-controlled, allowing the development of accurate prediction methods. It is important to highlight that this proposal allows to combine technology transfer to a research group in Brazil and provide international experience to a Brazilian student presenting high academic performance.