An analytical and numerical study of emerging energy-storage/energy-conversion devices to improve their overall performance

Numerical studies involving emerging energy-conversion and energy-storage devices are performed.;Photovoltaic (PV) systems, as one of the most promising energy-conversion devices which convert solar energy into electrical energy, are being widely advocated. A multiphysics, finite element computational model for a hybrid concentrating photovoltaic/thermal (HCPV/T) water collector is developed to calculate the thermal and electrical characteristics of the collector and estimate the fatigue life of the module at different water flow rates. In order to improve the performance and fatigue life of the system, the fluid flow and heat transfer characteristics in a HCPV/T system with tree-shaped channel network heat sink are thus investigated numerically and compared with the straight parallel channel heat sink. The effectiveness of the tree-shaped network configuration in the HCPV/T design is characterized by offering lower maximum PV cell temperature and more uniform temperature distribution between PV cells. Finally, instead of directly cooling PV modules by heat sink (heat extractor), the prospect of constructing PV-TE/thermal hybrid systems by embedding TE converter between PV modules and heat extractors is explored, which has been proved to offer comparable thermal efficiency and much higher overall electrical efficiency.;In addition, supercapacitors are in principle, attractive for high-power applications e.g. electric/hybrid vehicles and electronic devices due to high power densities and efficiencies at low temperatures. However, as energy-storage devices with capability of providing the peak-power requirement, supercapacitors are subject to heavy duty cycling conditions and result in significant heat generation. Hence, thermal management is a key issue concerning lifetime and performance of supercapacitors. The research works are conducted to address transient and spatial temperature distribution in supercapacitors, in which a supercapacitor product with prismatic structure, based on the activated carbon and organic electrolyte technology, is chosen for modeling. Moreover, accurate modeling of temperature field inside supercapacitors is essential for designing an appropriate cooling system. A general multi-dimensional electrochemical-thermal coupled model is developed to investigate the cooling of supercapacitor modules under impinging forced air cooling configuration. Referring to the comparison with conventional forced air stream cooling, numerical results present the improved thermal performance of the module.