Pr. Zhongzhu Qiu

Shanghai University of Electric Power, China


Talk Title
Investigation of Heat Transfer and Phase Change in Phase Change Balls Based Thermal Energy Storage Device
Talk Abstract
Cold storage and heat storage technology, acting as the role of reducing operating costs, shifting peak and valley, improving the efficiency of renewable energy utilization and waste heat recovery, have gained applications in air conditioning sector, CCHP energy system, solar energy and waste heat utilization systems.
Aim of this talk is to present a theoretical and experimental investigation into the energy performance of a phase change balls based cold energy storage system,. This involved (1) establishment of a test rig; (2) development of a dedicated mathematical model; (3) validation of the model by using the experiment data. (4) demonstration project, including design, construction and operation. It was found that the established model, based on the rig, is able to predict the energy performance at a good accuracy. Under this conclusion, three new mathematical models have been established to predict their energy performance .The models show a phase change energy storage system containing phase change cold storage balls with different diameters. By changing the calculation parameter of flow velocity and balls diameters in Fluent, the different numerical simulation results have been gained. Analyses of the simulation results indicated that smaller ball diameter can increase the solidication rate, as well as enhance the flow rate can also increase the solidication rate. During the experiment of cold energy storage rig, the phenomenon of super-cooling can be clearly observed. We also studied the effect of graphene quantum dots (GQDs) on the super-cooling of phase change materials. By adding the GQDs into the phase change materials, supercooling has been successfully suppressed.
In conclusion, this investigation verified the mathematical models for heat transfer and phase change processes of a phase change balls based cold energy storage system. And by numerical simulation, the parameters influencing heat transfer and phase change of such balls have been found. Finally, when the GQDs were added into the phase change materials, the super-cooling can be reduced. A small demonstration system was designed, constructed, and being operated. The achievements provide the guide for the modification of phase change materials, the sizing of cold storage balls and the design of energy storage devices and system. 
Phase change balls, cold energy storage system, mathematical model, experiment, design, sizing
Short Biography

Professor&Dr Zhongzhu Qiu is currently the Vice Dean and Professor of the College of Energy and Mechanical Engineering, Shanghai University of Electric Power, China. He is the Expert of China Academic Degrees & Graduate Education Development Center and also the Expert of Shanghai Municipal Science and Technology Commission.

He obtained the PhD degree at Tongji University (China) in 2002. He worked at Tongji University as a Post-Doctoral Research Fellow for two years (2002-2004), and then he moved to Shanghai University of Electrical Power to take a role of Associate Professor and was promoted to the Professor and Director of Thermal and Power Engineering Division at this University at December 2009. During January to August 2008, he went to City University of Hong Kong to work on a project as a Senior Research Fellow. Between December 2012 and November 2014, he did his research as Marie·Curie Research Fellow at the Energy Technologies Laboratory in University of Hull, UK. Professor Qiu is experienced at solar energy, thermal energy storage, building energy efficiency and HVAC technologies, energy efficient & low emission thermal power station technologies, with particular interest in PV/thermal systems. He has over twenty years' research experience in the area of energy technologies in Europe and China. He has been involved in more than 20 research projects funded by governments and industries, undertaken 18 engineering consultancy projects, won 3 distinguished awards, and been awarded 6 national patents. He is the author of more than 70 papers published on national/international referred journals and conference proceedings

Target Audience
Students, Post doctoral, Industry, Doctors and professors
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