MEMS Seminar: Efficient Energy- Conversion Systems: The Critical Role of Phase-Change Thermo Fluid Phenomena

Oct 27

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Thursday, October 27, 2016 - 1:00pm to 2:00pm


Professor Jocelyn Bonjour

In the context of the need for a higher efficiency of thermo-mechanical energy conversion systems, some thermodynamic cycles face a renewed interest. Among others, the Organic Rankine Cycle (ORC) can be a valuable option to recover waste heat energy from internal-combustion engines, while absorption chillers are now spreading and adsorption chillers are at an early stage of commercialization in a number of countries.

The aim of the present seminar is to highlight the critical role of one field of mechanical engineering / thermal science in the development of such energy-conversion technologies, namely phase-change thermofluidics. For instance, in ORCs, the thermodynamic conditions that the working fluid meets in the evaporator (evaporating temperature of 100°C and more, i.e. high reduced temperature) are fairly different from standards relevant to refrigeration or air-conditioning systems, for which a certain degree of knowledge has been reached owing to past efforts of research. Regarding the improvement of sorption chillers in which water is the refrigerant (e.g. in LiBr sorption chillers), the most crucial component is the evaporator for which a higher compacity is to be sought. However, the design of compact evaporators is constrained by the vaporization of the refrigerant under a very low pressure (i.e. close to triple point) which has not been widely studied in the past.

In his presentation, Prof. Bonjour will summarize his recent research results for boiling in extended ranges of thermodynamic conditions: he will describe the experimental efforts and development to study boiling in such conditions; he will show how such research led to the discovery of new physical phenomena and how they affect the design strategy of evaporators.

Prof. Bonjour has been active in the field of phase­change heat transfer for more than 20 years. His research line has always been to develop a virtuous cycle that originates from applied problems (e.g. refrigeration and air­conditioning; heat pumps; heat pipes; etc.), to identify scientific challenges and develop new knowledge (boiling in confined spaces; thermocapillary evaporation; boiling of refrigerant ­ oil mixtures; etc.), prior to proposing improvement in the components and systems useful for the application. He has publishied more than 80 articles in peer-reviewed journals and as many communication in conference proceedings.

Prof. Bonjour is currently the Director of his research center (CETHIL), a joint center of ca. 120 individuals (40 professors, 40 PhD students, and engineers / post­docs / administrative or technical staff) shared between INSA de Lyon (an independent engineering school), Université Claude Bernard Lyon 1 ­ the medical, science and engineering university in Lyon­ and the National Center for Scientific Research (CNRS).

Prof. Bonjour has been one of the Regional Editors of the International Journal of Refrigeration since Oct. 2012. He has also been the Secretary (2003­2007) and the Vice­President (2007­now) of Commission B1 (“Thermodynamics and transfer processes”) of the IIR (International Institute of Refrigeration, an intergovernmental agency (funded by more than 60 countries) in charge of the diffusion of scientific and technological knowledge in the field of refrigeration). He was elected in June 2016 as the Chairman of the Committee on the International Heat Pipe Conferences, an international body in charge of the organization of the conference of reference in the field of heat pipes.

Lunch will be served from 12:30 - 1:00 pm.