University of Hertfordshire

Exergy optimisation for cascaded thermal storage

Research output: Contribution to conferencePaperpeer-review


  • 906865

    Accepted author manuscript, 220 KB, PDF document

  • Yuan Tian
  • C.Y. Zhao
  • A. Lapkin
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Original languageEnglish
Number of pages8
Publication statusPublished - 2012
Event12th Int Conf on Energy Storage (Innostock 2012) - Lleida, Spain
Duration: 16 May 201219 May 2012


Conference12th Int Conf on Energy Storage (Innostock 2012)


Cascaded thermal storage, consisting of multiple Phase Change Materials (PCMs) with different melting temperatures, has been proposed to solve the problem of poor heat transfer caused by unavoidable decrease of temperature differences during heat exchange process. This paper conducts a theoretical study of the overall thermal performance for a cascaded thermal storage system. Both heat transfer rate and exergy efficiency are taken into account. The main findings are: the cascaded arrangement of PCMs enhances the heat transfer rate by up to 30%, whilst it does not always improve the exergy efficiency (-15 to +30%). Enhanced heat transfer and reduced exergy efficiency can both be attributed to the larger temperature differences caused by the cascaded arrangement. A new parameter hex (exergy transfer rate) has been proposed to measure the overall thermal performance. It is defined as the product of heat transfer rate and exergy efficiency, representing the transfer rate of the utilisable thermal energy. The simulation results indicate that the cascaded thermal storage has higher overall thermal performance than the single-staged storage despite of higher exergy efficiency loss.

ID: 1998130