| Summary: | 碩士 === 國立中央大學 === 機械工程研究所 === 99 === This study analyzes one-dimensional spherical phase change material
(PCM) heat transfer formula which derives from the concept of thermal
resistance. The viability of this formula is validated by experimental data.
In the analysis of thermal resistance, the heat which absorb by PCM is
assumed equal to the heat which transfer from the heat transfer fluid
(HTF). In the system, there are three types of thermal resistance in series
connection, including HTF to capsule outside surface, capsule outside
surface to inside surface, and capsule inside surface to PCM. Due to the
specific heat of capsule is very small, the sensible heat of capsule is
neglected. The heat transfer within liquid PCM is considered as two
different types – only conduction and only convection.
As the results, the parameters which affect the melting time include
size and thickness of capsule, and thermal physical properties of capsule,
PCM, and HTF. By the parameter analysis, the melting time is reduced as
the Nusselt number of HTF is increasing, and the thermal conductivity of
capsule is enhanced.
To predict the melting time, it has good agreement by using the heat
transfer formula with considering convection. To predict the melting
surface location, when the melting location coefficient is larger than 0.37,
using the heat transfer formula without considering convection has good
agreement. But when the melting location coefficient is smaller than 0.37,
using the heat transfer formula with considering convection has good
agreement.
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