Investigation of the critical heat flux and film boiling applied for high temperature compact heat exchangers

• Grant number: 21/10323-8
• Support Opportunities: Scholarships in Brazil - Master
• Effective date (Start): December 01, 2021
• Effective date (End): November 30, 2023
• Field of knowledge: Engineering - Mechanical Engineering - Thermal Engineering
• Principal Investigator: Cristiano Bigonha Tibirica
• Grantee: Thalles Coimbra Borba Roldão
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

This research proposal is about the experimental and theoretical investigation of the critical heat flux and the film boiling during convective boiling in the context of applications of compact heat exchangers at high temperatures. The critical heat flux is the maximum heat flux that can be applied in a fluid before the starting of the film boiling, characterized by a low heat transfer coefficient. One of the applications that are being highlighted in the scientific community is the development of efficient heat exchangers for power cycles used in wasted heat recovery, like organic Rankine cycle. These heat exchangers operate at high temperatures and they are exposed to situations of critical heat flux and film boiling. In this context it is important a better comprehension of the physical mechanisms of the critical heat flux and film boiling. Critical heat flux and the film boiling in internal forced flows will be studied and measured for fluids used in organic Rankine cycles. By the end of the experiments it will be evaluated a compact heat exchangers heated by hot gases in the condition of critical heat flux and of film boiling. It is expected within this project, (i) new data for high levels of critical heat flux; (ii) new measurements for film boiling under convective boiling; and (iii) the development of prediction tools that will help the design of compact heat exchangers used in new applications of waste heat recovery.