Experimental study on the cascaded thermal energy storage system using MWCNT-enhanced phase change materials

Abstract

The proposed work is about the effectiveness of latent heat dispersion on energy storage using phase change materials with modified thermal stratifiers on charging inlet of the tank. A novel flow-governing nozzle with swirl flow injection is designed and fabricated to enhance the steady state of heat flow inside the cascaded thermal energy storage (TES) system. Spherical phase change materials (PCM) capsules with added multiwall carbon nanotubes (MWCNT) particles used as an energy storage material inside the TES tank. Experimentation conducted for the variable process parameters with mass flow rates, temperature, and injection pressure to differentiate the initial stratification of the thermocline system. Results obtained from the analysis clarify that with the increase in swirl number through injection pressure, temperature, and flow rate increases the steady state stratification behavior inside the cascaded TES tank. It is clear that the effective charging rate of 35 min observed from the system at 1 wt% of MWCNT with the increase in injection pressure and flow rate of 4 bar and 3 L/min. It also noted that the swirl effect increases the heat dissipation on the PCM capsules by maintaining a concentric heat transfer with the radial flow over the layers of the PCM capsules. Discharging trials are carried out by the batch-wise process to recover the stored thermal energy. Moreover, the cascaded latent heat thermal energy storage system using MWCNT-filled PCM is best suitable for water heating applications to overcome the intermittency.