Experimental and numerical analyses of a phase change storage unit

Abstract

Thermal storage technologies are key components for increasing energy efficiency and assisting the integration of regenerative energy sources in the energy market. One type of thermal energy storage is latent heat storage, which makes use of the large amount of enthalpy that can be stored during the phase change of a storage material, and is an interesting storage technology for both high temperature and process steam processes. However, the rate of heat transfer into and out of the storage is a limiting factor for fast discharges, due to the inherently low rate of heat transfer of the storage materials. In order to enhance the rate of heat transfer in latent heat storage units, heat transfer structures have been developed and tested at DLR. Various fin designs have been analyzed and tested. To analyze the effectiveness of more complex geometries, a finite element method analysis method has been developed. Concurrently, physical storage units have been tested. Based on the results from the testing of a fin design in a demonstration storage unit, a new fin was designed. This fin shows good results in the laboratory environment. In this paper, the results from the finite element method analysis and those of a lab-scale latent heat storage unit with the new fin design are compared and discussed.