Research On High Temperature Molten-Salt Circulating Phase Change Thermal Energy Storage System

Thermal energy storage (TES) system is the crucial factor for concentrated solar power (CSP) station to produce dispatchable and steady electrical power. Among the different storage concepts, High Temperature Molten-Salt TES is a preferred technical scheme for large CSP station. This proposal puts forwards a new idea called High Temperature Molten-Salt Circulating Phase Change Thermal Energy Storage System (CPC-TES). Its typical characteristics are:(1) breaking through the traditional idea of encapsulating phase change material (PCM) in latent heat storage system, (2) PCM performs the process of heat (dis)charge using external circulation technology, (3) the combination of circulation characteristic in latent heat storage and phase change characteristic in sensible heat storage.Main contents of the paper:(1) Developing the prototypes of phase change heat exchange, analyzing the thermodynamics-dynamics mechanism of CPC-TES, and constructing a laboratory heat (dis)charge ’flow-loop’ setup to test the CPC-TES concept. (2) According to the 40% KNO3 and 60% NaNO3 molten-salt in the 563K-838K temperature range, analyzing the physical properties, migration characteristics and the distribution of solar energy flow. (3) Developing the thermal calculation program for tower type receiver, simulating single module/tube temperature rise, convective heat loss, radiation heat loss, overall heat loss and average thermal efficiency under different conditions.Research results can offer a possible solution to the existing problems of complicated structure, low heat conductivity in latent heat storage, and small heat storage density, large heat exchange temperature difference in sensible heat storage. CPC-TES will be able to provide an attractive option and theoretical support for large-scale latent heat storage in commercial application.