Enhancement of melting performance in a shell and tube thermal energy storage device under different structures and materials

Abstract

• Melting performance enhancement in a shell and tube device was studied. • Four different enhancement approaches were comparatively evaluated. • Both experiments and simulation were carried out for investigation. • Economic efficiency was assessed to determine the optimal enhanced structure. This paper concerns enhancement of melting performance in a shell and tube thermal energy storage device containing different structures and materials. Four enhanced approaches including topology optimized fin, metal foam, longitudinal fin and form-stable composite phase change material (PCM) were evaluated and compared numerically. Two sets of publish data from literatures were used to validate the numerical codes for the longitudinal fin and metal foam, and two experiments were built to verify the models for the topology fin and composite PCM. A criterion of TES rate per unit cost referring to the ratio of TES rate to material price was employed to assess the economic efficiency of these enhancement approaches from the perspective of material cost. The results indicated that the device melting process can be significantly accelerated by the use of enhancement structure with the melting time respectively being shortened by 88%, 86%, 84% and 83% for the devices containing topology fin, metal foam, longitudinal fin and composite PCM compared with the device containing no enhancement configuration. The use of metal foam or composite PCM in the topology fin based device could achieve a further enhancement on the melting performance. For the topology fin device containing the composite PCM and metal foam, the total melting time can be respectively reduced by 10% and 15% in comparison with the device containing only topology fin. The selection of optimal enhancement structure can be related to the price ratio of the additive to the PCM, and the implementation of topology fin would be an economical solution to realize the combined enhancement of heat transfer rate and material utilization efficiency if the price ratio of the topology fin to the PCM can be controlled to less than 8.