the specific mass of about 20% (55 kg/kWe). We expect to use the abovementioned numerical simulations to further optimize the configuration of the LTES system and minimize the specific mass of the receiver. Composite Type Thermal Energy Storage Composite Materials Design and development of the solar receiver for future space missions will require innovative concepts that achieve higher efficiency and lighter weight. We are engaged not only in development of conventional receivers such as the metallic containment canisters with PCMs as described above, but also the development of advanced LTES systems. Our particular interest is in incorporating the PCMs in a submicron-sized porous structure. In this system, the distribution of voids can be controlled. Porous media can also provide the PCM with a continuous conduction path resulting in an increase in effective thermal conductivity. Moreover, the direct absorption of concentrated sunlight minimizes temperatures gradients. System weight is also reduced. The composite LTES storage materials proposed in this study use porous silicon carbide (SiC) for the structure and fluoride salts (LiF and MgF2) as the thermal storage media. The thermal conductivity of SiC is so high that further thermal devices are unnecessary. Simple configurations for the composite system also improve long life reliability. A scanning electron micrograph (SEM) of the SiC-LiF composite material is shown in Fig. 9. The weight fraction of LiF is 0.35. We also constructed a high temperature SiC/MgF2 composite, which could be combined with an advanced gas turbine with a 1500 K inlet temperature. Thermal stability verification on these composite materials has been performed. The results revealed the SiC porous structure is not damaged after several tens of melting and solidification cycles. However, we realized that a very serious drawback is the evaporation of fluoride salts from the composite surface. Some technical approaches are under evaluation to prevent evaporation. Thermal analysis of the
RkJQdWJsaXNoZXIy MTU5NjU0Mg==