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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

EXPERIMENTAL INVESTIGATION ON THE EFFECT OF FIN LENGTH ALLOCATION FOR THE PCM MELTING ENHANCEMENT

Get access (open in a dialog) DOI: 10.1615/IHTC16.ctm.023264
pages 3955-3963

Sinopsis

Latent heat thermal energy storage (LHTES) with phase change materials (PCMs) has been increasingly demanded in various energy systems. To overcome PCMs poor thermal conductivity, metal fins are always inserted for heat transfer enhancement. We propose setting the fin length allocation to enhance phase change melting. Five schemes for a combination of two horizontal parallel fins with different length allocations are designed. To investigate their effects on the phase change thermal storage, the experimental tests are carried out in a self-designed rectangular LHTES unit. The heat source is uniformly added from the vertical side of the enclosure. RT42, used as thermal storage medium, is filled into the container to store the thermal energy. The melt photographs for each case are captured by the camera in a time sequence. The detailed melting processes, divided at two different stages, are firstly compared and analyzed. The melt fraction evolution with time is then calculated. By comparing the fin-PCM cases, the results show that in the premise of total fins length invariant, the allocation of each partial fin length has a significant influence on the PCM melting process and the instantaneous shape of the solid-liquid interface forming. The PCMs with fin length allocation 2 which composes of a top longer fin and lower shorter fin, perform a slight melting improvement, while the PCMs with fin length allocation 5 with an opposite length allocation melt slower than others. The maximum relative difference can reach to 11% on the basis of fin length allocation 3. However, the total PCM melting time is not obvious influenced at all cases. Besides, the melting front length is also calculated at each time step. Results show that melting front length with fin length allocation 5 is totally different with other designs during the whole process, which results from the heat transfer distribution by different fin length allocation schemes. Another finding is revealed that the PCM melting rate is linearly increasing with the length of melting front formed at the PCM solid-liquid interface, no matter how the fin length allocation is set.