The honeycombed matrix of SiC has many through holes along the longitudinal axis as shown in Figure 1. Thermal conductivity along the longitudinal direction of the SiC/LiF was calculated on a parallel model [17], because the SiC and LiF components of this composite are continuous along this direction only. On the other hand, LiF is separated by the SiC matrix along the transverse direction of this composite, thus the thermal resistance along this direction was calculated on a two direction continuous model [17], In the CZLiF, C and LiF are continuous along any directions, thus thermal conductivity of this composite was calculated on a three direction continuous model [17], The specific heat and density of the composites were calculated on the basis of proportion of components in them. These thermophysical properties of the composites were calculated as shown in Table 2. Heat from the storage material is transferred to the working fluid by forced convection heat transfer. The heat transfer coefficient is calculated by the Sleicher- Rouse formulae [16] shown as follows. where Nu is the Nusselt number between the working fluid and the wall, Re is the Reynolds number of the working fluid flow, and Pr is the Prandtl number of the working fluid. Moreover a and b are calculated respectively from the following equations. The calculating code for the numerical analysis is ANSYS-R4.4A produced by Swanson Analysis Systems, Inc. The calculating machine is a super computer, CRAY:X-MP216. Results and Discussion Five hours from the start, heat inputs of the heaters were held constant, then a steady state temperature distribution appeared throughout the model storage units. Differences between average temperature of the canister surface and the working fluid temperature in each measuring section at the steady state are compared in Table 3. Heat flow into the working fluid was calculated from the rising value of its temperature at each part of the model storage units as also shown in the table. On the basis of results of the numerical analysis, the experimental results were examined respectively on the measuring sections. Thermal resistance needed to be added between the surface of the canister and the working fluid on the heat transfer model of the numerical analysis in order to obtain same values as the experimental results. The additional thermal resistance is also shown in table 3.
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