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

• Grant number: 19/11066-9
• Support Opportunities: Regular Research Grants
• Duration: October 01, 2019 - September 30, 2022
• Field of knowledge: Engineering - Mechanical Engineering - Transport Phenomena
• Principal Investigator: Cristiano Bigonha Tibirica
• Grantee: Cristiano Bigonha Tibirica
• 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 is being highlighting in the scientific community is 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. This project proposes the integration of two test facilities developed by the researcher, where the critical heat flux and the film boiling in internal forced flows will be studied and measured for fluids used in organic Rankine cycle. 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. To achieve theses goals, new equipments like pumps, flow meters and instrumentation are necessary. It is expected within this project, (i) new data for high level critical heat flux; (ii) new measurements for film boiling under convective boiling; (iii) the development of prediction tools that will help the design of compact heat exchangers used in new applications of waste heat recovery and (iv) enable a Brazilian laboratory to test a wide range of critical heat flux and film boiling conditions including high temperatures. (AU)