Experimental Study on the Strengthen Heat Transfer Performance of PCM by Active Stirring

Abstract

Latent heat storage has higher energy density, but most phase change materials (PCMs) have low thermal conductivity. Current research focuses on conduction dominated heat transfer mechanism to increase the heat transfer performance. However, convection also has important effects on promoting PCM melting and solidification processes. Therefore, an active stirring method with conduction dominated heat transfer mechanism was studied. A shell storage with stirrer inside was constructed and tested. Paraffin was selected as the PCM; the heat transfer fluid (HTF) was water. The results show that average charging rate increased by 32.23 J/s than that without stirring, and the average discharging rate increased by 47.39 J/s. Completion time for charging/discharging with stirring was shortened by 9.61% and 48.61% than that without stirring. In the charging process, the average power of motor was 16.08 W, and the average discharging rate was greater than 500 J/s, accounting for less than 3.2%. In the discharging process, the average power consumption of the motor accounted for less than 5.2% of the discharging rate. It may be considered that convection dominated heat transfer mechanism can effectively improve phase-change heat transfer performance with lower active power consumption

The theoretical approach of the solar organic Rankine cycle integrated with phase change material for the Hungarian region

“…The shell‐and‐tube type of LHTES is the most oftenused configuration as of its benefits, such as simple design, low cost, low‐pressure drop, large heat transfer area, high discharge power, and high efficiency 49 . Furthermore, the PCM will be placed between the two tubes, which directly exchange heat between the heat transfer fluid (HTF) and the working fluid, as proposed by several researchers 50–52 . Aside from that, the industry uses shells and tubes 90% of the time.…”

Effect of Charging and Discharging Process of PCM with Paraffin and Al₂O₃ Additive Subjected to Three Point Temperature Locations

“…In the first ten minutes the temperature of the material was found to be 50 °C and it reached 41 °C at 1 hour; also it was observed that it was not possible to achieve the ambient temperature with the time interval of 1.4 hours, however, the corresponding temperature at 1.4 hours was noted to be 32 °C. This is due to less turbulent motion resulting in slow rapid cooling and lesser stirring rate, as well as less lack of turbulent layer behaviour [Zhang et al, 2020].…”

Standardised methods for the determination of key performance indicators for thermal energy storage heat exchangers

“…Two options are based on the internal energy change. First, time constants based on the total internal energy are referred to as charging time (e.g., [89,93,117,124,[163][164][165]) and are defined by Equation 32. Second, time constants based on the latent heat (e.g., [46, 68, 69, 72, 77, 83, 87, 88, 90, 93, 96, 98, 99, 102, 104, 107-109, 113, 119, 120, 125, 129, 131-134, 136, 149, 165-170]) which are called melting/solidification time and are defined by Equation 33with 𝜆 ̅ the total liquid fraction.…”