280
R. Kumar et al.
14.3 Results and Discussion
14.3.1 Thermal Performance Evaluation of PCM Heat Pack
The metallic disk, consisting of multiple grooves, is used to start nucleation in the
PCM heat pack at the desired temperature. The process of the heat release from PCM
heat pack is explained in Fig. 14.2. The metastable supercooled liquid PCM based
heat pack containing 300 g MSLPCM and a metallic disk is shown in Fig. 14.2a. The
solid particles of SAT entrapped between two opposite surfaces of the metallic disk
is released after pressing the metallic disk and nucleation is started in metastable
supercooled liquid, shown in Fig. 14.2b. The nuclei in MSLPCM grow at a fast rate
due to the stability of SAT phase below its melting temperature i.e. solid phase.
Initially, the PCM heat pack is kept inside a T-history air chamber at 80 °C
temperature, above melting temperature ~56 °C of PCM for complete melting of
PCM. After ensuring the complete melting of PCM, the air chamber temperature is
reduced to 0 °C. The PCM pack surface temperature in conjunction with ambient
temperature is measured using K type thermocouple at every 10 s time interval, and
the recorded temperature-history data is plotted in Fig. 14.3.
The heat pack has shown initially cooling from 70 to 35 °C without any solidification and at this temperature the nucleation is initiated by pressing the metallic
disk. The temperature of PCM heat pack is increased from 35 to 53 °C after initiating
solidification due to the heat release, stored in the form of latent heat of fusion in
SAT, Fig. 14.3. The MSLPCM solidifies in the phase change region and temperature
of heat pack remain in the phase change temperature range of MSLPCM (56–46 °C)
during phase change process. After complete solidification of PCM, the PCM pack
releases heat in the form of specific heat of PCM. The PCM heat pack took about
210 min to cool from 70 to 30 °C.
Fig. 14.2 Actual photographs of a PCM in metastable supercooled liquid state in a PVC pack, b initiating nucleation in MSLPCM by pressing metallic disk, and c growth of nucleation (solidification)
in PCM heat pack after 5 s
R. Kumar et al.
14.3 Results and Discussion
14.3.1 Thermal Performance Evaluation of PCM Heat Pack
The metallic disk, consisting of multiple grooves, is used to start nucleation in the
PCM heat pack at the desired temperature. The process of the heat release from PCM
heat pack is explained in Fig. 14.2. The metastable supercooled liquid PCM based
heat pack containing 300 g MSLPCM and a metallic disk is shown in Fig. 14.2a. The
solid particles of SAT entrapped between two opposite surfaces of the metallic disk
is released after pressing the metallic disk and nucleation is started in metastable
supercooled liquid, shown in Fig. 14.2b. The nuclei in MSLPCM grow at a fast rate
due to the stability of SAT phase below its melting temperature i.e. solid phase.
Initially, the PCM heat pack is kept inside a T-history air chamber at 80 °C
temperature, above melting temperature ~56 °C of PCM for complete melting of
PCM. After ensuring the complete melting of PCM, the air chamber temperature is
reduced to 0 °C. The PCM pack surface temperature in conjunction with ambient
temperature is measured using K type thermocouple at every 10 s time interval, and
the recorded temperature-history data is plotted in Fig. 14.3.
The heat pack has shown initially cooling from 70 to 35 °C without any solidification and at this temperature the nucleation is initiated by pressing the metallic
disk. The temperature of PCM heat pack is increased from 35 to 53 °C after initiating
solidification due to the heat release, stored in the form of latent heat of fusion in
SAT, Fig. 14.3. The MSLPCM solidifies in the phase change region and temperature
of heat pack remain in the phase change temperature range of MSLPCM (56–46 °C)
during phase change process. After complete solidification of PCM, the PCM pack
releases heat in the form of specific heat of PCM. The PCM heat pack took about
210 min to cool from 70 to 30 °C.
Fig. 14.2 Actual photographs of a PCM in metastable supercooled liquid state in a PVC pack, b initiating nucleation in MSLPCM by pressing metallic disk, and c growth of nucleation (solidification)
in PCM heat pack after 5 s