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The technical feasibility of an innovative solar collector is studied in this paper. A phase change material (paraffin) is used in the solar collector to store solar energy. This type of system combines both collection and storage of thermal energy into a single unit. The major advantages of the phase change stores are their large heat storage capacity and isothermal behavior during the melting and solidifying processes. A negative aspect of paraffin is its low thermal conductivity which increases the melting and solidifying time for paraffin energy storage. In this paper, new aluminum foams infiltrated with paraffin are presented. It presents a two dimensional model describing the melting and solidifying processes of paraffin while accounting for both phase change heat transfer and natural convection. Apparent heat capacity method was used to simulate the melting and solidifying processes of paraffin. The simulation results show that the motion of the hot liquid paraffin plays an important role in increasing the heat transfer between paraffin and top surface of solar collector. The shape profile of the pure paraffin solid-liquid interface is determined by the synergistic relationship between its temperature and velocity field. Though aluminum foams impregnated with paraffin will limit motion of the hot liquid paraffin, the heat transfer ability is greatly improved. The distributions of the temperature in the paraffin with aluminum foams are more homogeneous compared with that of the paraffin without aluminum foams. Thus, use of aluminum foams infused with paraffin improves heat transfer and enhances paraffin’s melting and solidifying rates.


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Numerical simulation of phase change heat transfer of a solar flat-plate collector with energy storage

Show Author's information Donghua PengZhenqian Chen( )
School of Energy and Environment, IIUSE, Southeast University, Nanjing 210096, China

Abstract

The technical feasibility of an innovative solar collector is studied in this paper. A phase change material (paraffin) is used in the solar collector to store solar energy. This type of system combines both collection and storage of thermal energy into a single unit. The major advantages of the phase change stores are their large heat storage capacity and isothermal behavior during the melting and solidifying processes. A negative aspect of paraffin is its low thermal conductivity which increases the melting and solidifying time for paraffin energy storage. In this paper, new aluminum foams infiltrated with paraffin are presented. It presents a two dimensional model describing the melting and solidifying processes of paraffin while accounting for both phase change heat transfer and natural convection. Apparent heat capacity method was used to simulate the melting and solidifying processes of paraffin. The simulation results show that the motion of the hot liquid paraffin plays an important role in increasing the heat transfer between paraffin and top surface of solar collector. The shape profile of the pure paraffin solid-liquid interface is determined by the synergistic relationship between its temperature and velocity field. Though aluminum foams impregnated with paraffin will limit motion of the hot liquid paraffin, the heat transfer ability is greatly improved. The distributions of the temperature in the paraffin with aluminum foams are more homogeneous compared with that of the paraffin without aluminum foams. Thus, use of aluminum foams infused with paraffin improves heat transfer and enhances paraffin’s melting and solidifying rates.

Keywords: numerical simulation, solar energy, paraffin, aluminum foams

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Publication history
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Acknowledgements

Publication history

Received: 24 February 2009
Revised: 01 November 2009
Accepted: 02 November 2009
Published: 04 December 2009
Issue date: December 2009

Copyright

© Tsinghua University Press and Springer-Verlag 2009

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant No. 50776015) and the National Key Technologies R&D Program of China (Grant No. 2007BA000875-04).

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