Teaching--- I taught “Theory of Combustion” for about 300 undergraduate students from 2003 to 2008. The textbook for this course was revised and the experimental apparatus was redesigned. From 2011, I taught “Engineering Heat Transfer” for undergraduate students. I participated in the teaching reform project of the course “Theory and Method of Engineering Testing” for graduate students, which won the second prize of the Seventh Session of Higher Education Tianjin Municipal Teaching Achievement Award in 2013. I also undertook the graduate courses “Thermodynamic Cycle Analysis and Advanced Development” and “Modern Refrigeration and Heat Pump Technology”. By now, I have supervised 15 undergraduate students, among which six students’ theses were rated as excellent, and I was awarded excellent graduation thesis supervisor twice as well. I also supervised 7 groups of undergraduate students to complete their innovation training projects, among which two projects were awarded the second prize in The Seventh National College Students’ Social Practice and Science and Technology Competition of Energy Saving and Emission Reduction in 2014 and the first prize in The Third Embraco Innovation Contest in2015, respectively. I have supervised 13 master students and assisted in supervising 6 PhD students. Among them, a master student, Miss Yang Yingying, won the scholarship of Weichai Engine Co. Ltd. and the national scholarship for studying abroad in 2014, and a PhD student, Mr Dai Baomin, was awarded the doctoral graduate national scholarship in 2015.

Research--- I am engaged in the application study of new environment-friendly working fluids in refrigeration and heat pump systems, especially the development of CO2 transcritical systems. I developed the prototype of rolling piston expander and swing expander to replace throttling valves in traditional CO2 transcritical cycles for the first time inChina. The efficiency of the CO2 transcritical cycle with throttling valves is always lower than those of conventional refrigerants cycles and the improvement in efficiency by using the expander prototype was about 10% with a maximum efficiency of about 55%. In 2014, the two-cylinder rolling piston expander was prototyped and the efficiency of this expander is above 60%. This research provides a promising direction for the development of CO2 systems. I analyzed the expansion process in the expander and proposed that the phase change delay exists in the CO2 expansion process, it affects the expansion power output, and the heterogeneous additive can decrease the phase change delay. I also analyzed the influence of oil on the flow boiling heat transfer of CO2. I introduced the thermodynamic properties of lubricant into the prediction model of heat transfer and proposed a new model to predict the heat transfer coefficient of CO2 with a small amount of oil. The above studies were very helpful to the design of CO2 system and therefore were awarded the second prize of Science and Technology Invention Award of China Refrigeration Association. I also investigated the heat transfer characteristics of new low global warming potential (GWP) refrigerants HFO1234ze(E), HFO1234yf, and their mixtures with R32 in mini-channels. HFOs are almost only feasible alternative synthetic refrigerant for the refrigeration field at present. My research about the heat transfer data of HFO1234yf /R32 mixtures were published for the first time in the world. A new model was proposed to predict the heat transfer coefficient of these mixtures with the consideration of the impact of mass transfer resistance. This research helps people in industry understand characteristics of these new refrigerants. I also proposed that the proper amount of low GWP refrigerants can improve the coefficient of performance of CO2 system by adding low GWP refrigerants into the system and these CO2 mixtures can also be used in organic rankine cycles.

Social Service --- I was the reviewer of a dozoen or more international journals and domestic journals such as Energy, Applied Thermal Engineering, Journal of Heat transfer, and CIESC Journal. I participated in the writing of 8.1 chapter in the book entitled “ChinaRefrigeration Industry Strategy Development Research Report” to promote the development of the refrigeration industry in China. My research contributed the understanding and application of CO2 heat pump inChina. CO2 transcritical system has been widely accepted as a new heat pump technology in the refrigeration industry inChina. I am collaborating with a company in Shanghai to develop a CO2 compressor, and with a company in Tianjin to develop a CO2 heat pump for automobiles. The development of our CO2 expander promoted the understanding of two-phase flow expander and the application in the heat recovery system. My research about the heat transfer characteristics of HFOs and R32 mixtures were presented in conferences and help people in industry to understand these new type low GWP working fluids and the status quo of refrigerant substitution in Europe andAmerica.

International cooperation --- I cooperated with Panasonic Co., Ltd. ofJapanto develop CO2 expanders and CO2 systems, and with LG Electric Company ofKoreato study high efficiency CO2 heat pump systems. From 2009 to 2011, I did research in The University of Tokyo as a postdoctoral fellowship and fufilled two projects with Professor Hihara Eiji and Associate Professor Dang Chaobin. Associate Professor Dang Chaobin at the University  of Tokyo and I completed a project supported by National Nature Science Foundation of China together. I also invited Professor Hihara and Professor Dang at the University of Tokyo to give lectures to our students at Tianjin  University. I applied for an international project with University of Hertfordshire in 2016 about the conjunctive utilization of waste heat and solar energy. I visited the University of Bordeaux in 2017 under the financial support of The China Scholarship Council to discuss with Professor Jean-Christophe Batsale about the cooperation in building energy conservation.