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Proceedings of Symposium on Energy Engineering in the 21<sup>st</sup> Century (SEE2000) Volume I-IV

ISSN:
1-56700-132-7 (Print)

HIGH TEMPERATURE LATENT HEAT THERMAL ENERGY STORAGE SYSTEM FOR SOLAR RANKINE ENGINES

Takeo S. Saitoh
Department of Aeronautics and Space Engineering, Tohoku University, Sendai 980 Japan

Akira Hoshi
Professor of Dept. of Aeronautics and Space Engineering Tohoku University, Sendai 980-8579, Japan

Abstract

Thermal energy storage is of importance in effective use of thermal energy for many application to utilize such as renewable energies including solar, geothermal, sky radiation, and load leveling to reduce peak electricity demand. Among several thermal energy storage technologies, the latent heat thermal energy storage (LHTES) system using phase change material (PCM) is useful in charging and discharging a large amount of heat during melting and solidification. The LHTES systems are also considered to be very promising to reduce carbon dioxide (C02) emissions and to mitigate global warming. Man's activities have exceeded a critical level at which their effects give an impact to earth's environment.

A lot of investigations concerning the LHTES systems have been reported in recent years. However, almost all of the past investigations have been well classified into category of a low temperature range. In the future, the high-density heat storage system for industrial applications, space crafts and automobiles will be of importance. The high-temperature LHTES systems are capable of having the high-density TES and permit heat extraction at a constant high-temperature condition. But some investigations are necessary for the heat transfer enhancement since thermal conductivity of the PCM is relatively low. In the present paper, the charging characteristics of the high-temperature LHTES system are discussed numerically. As an application, the present LHTES system is applied to solar Rankine engine will be introduced and the possible thermal performance and validity of this engine will be also discussed.