Prof. Lingai LUO
National Center for Scientific Research (CNRS), France
Recent progress in compact heat exchanger and their functionality integration

Heat exchangers are devices that provide heat transfer from one medium to another. They are essential unit elements in chemical and process engineering including power production process, chemical and food industries, electronics, environmental engineering, waste heat recovery, manufacturing industry, air conditioning, refrigeration and space applications. In these applications, thermal–hydraulic balance and energy usage play dominant roles. Heat exchangers having high efficiency are expected to save energy and material. 

Our research interests are centered on the study of compact heat exchangers with high performance: key issues, design, fabrication, modeling, and experimental studies. Beginning with the concept of micro heat exchangers and its advantages and disadvantages, we illustrate the notion of heat transfer intensification by several innovative designs of mini-scale heat exchangers proposed during our research work. Distinct from other approaches, we do not seek extra fine channel size. On the contrary, we work on how to effectively manage the hydrodynamic aspects and the geometric organization of heat transfer surface to intensify heat transfer with acceptable increase of total pressure drop, for example, using internal (chaotic) mixing, multi-passage configuration and multi-scale geometries. 

Another trend is the development of multi-functional heat exchanger-reactors. Such a conception comprising arborescent (tree-like) distributors and collector, 16 mini-channels in parallel and T-mixers is proposed and realized. Thermal performance of proposed heat exchanger-reactor are experimentally tested and discussed. High global heat transfer coefficients ranging from 2000 to 5000 W∙m-2∙K-1 are obtained under our working conditions. The volumetric heat exchange capability (UA/V) is found to be around 200 kW∙m-3∙K-1, showing a high heat exchange capability with compact design. A typical fast exothermic reaction, neutralization between acid and basic solutions, is carried out to test the thermal control capability of the studied heat exchanger-reactor. Results indicate that isothermal condition could be realized by circulating appropriate flowrate of coolant through the heat exchanger. The design of heat exchanger-reactor with arborescent distributor and collector makes possible the application of multi-channel systems.


Pr. Lingai LUO received her Ph.D. degree (1991) in mechanic and thermal engineering from National Polytechnic Institute of Lorraine (INPL), Nancy, France. She worked as associate professor at University of Nancy I and at INPL, France. From 2003 until 2012 she was a full professor at University of Savoie, France. She is now senior research director of French National Center for Scientific Research (CNRS) at the laboratory of thermo-kinetics, Nantes (LTN), France. 

Pr. Luo is mainly engaged in the intensification of heat and mass transfer and shape optimization in different energy components, systems and processes. She proposed a multi-scale approach for energy efficiency optimization of processes. To improve the global performance, intensification should necessarily be implemented at three scales: local scale, component scale and system scale. The internal links between these scales should be carefully examined for performance maximization with minimization of dissipations.

Pr. Luo is the author of 2 books and over 100 journal articles. From 2007 until 2012, She is supervisor of 20 graduated PhD and 6 Doctoral students. she was the head of laboratory of design optimization and environmental engineering (LOCIE) of CNRS and University of Savoie. She was the cofounder and coordinator of Sino-French Collaboratory for Environmental and Process Engineering (1998 - 2006) and is the head of its successor Sino-French Laboratory for Sustainable Energy (since 2008) of French CNRS and Chinese Academy of Sciences. She is also an invited professor at 5 Chinese universities/institutions, and Leuphana University at Lüneburg, Germany.

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