Performance characteristics of PCM based thermal energy storage system for fluctuating waste heat sources

Abstract

The large temperature fluctuations of industrial waste heat pose great economic and operational challenge for the feasibility of industrial waste heat recovery systems. In this regard, Phase Change Material (PCM) based Thermal Energy Storage (TES) systems can effectively dampen large thermal fluctuations during the charging cycle. The current work focuses on the assessment of the performance of a shell and tube latent TES unit when subjected to fluctuating thermal cycles of waste heat from clinker cooling process (420K − 600K) as Cycle 1 & 2 and internal combustion engines (360K − 780K) as Cycle 3–5, using HITEC® industrial salt as PCM. The complete melting time of PCM for Cycle 1 is 41.6% higher than Cycle 2 whereas the average PCM temperature for Cycle 1 is found to be 9.3% lower than for Cycle 2. Similarly, Cycle 5 accelerates the PCM melting by 37.4% and 33.3% as compared to Cycle 3 and Cycle 4. The sharp dips in source temperatures decelerate the melting process and cause localized re-solidification of PCM. The PCM dampens the source temperature fluctuations by more than 80%. The constant overall PCM melting time for both fluctuating and mean temperature sources indicate the effectiveness of latent TES system.

Keywords

• Thermal fluctuations
• Phase change materials
• Clinker cooling
• IC engines
• Waste heat recovery