Simultaneous charging and discharging of the storage could be of importance in certain system configurations. This has also been examined and one set of experimental results are shown in Fig. 6.

Fig. 6. Simultaneous charging and discharging of HEATPACK initially at 50 °C. Charging temperature and flow rate 70 °C and 0,15 m3/h, respectively. Discharging temperature and flow rate 13 °C and 0.10 m3/h, respectively.

Here, the tank is initially not fully charged, with and average PCM temperature at 50 °C. Part of the PCM is molten whereas other sections are still in solid form. The storage was then continuously charged with 70 °C water flowing at 0.15 m3/h, and simultaneously discharged by water at approximately 13 °C, flowing at 0.10 m3/h. As shown, the hot water temperature leaving the storage had a usable temperature of over 40 °C for over two hours.