This work investigates the solidification characteristics of deionized water in a stainless steel spherical capsule fitted with rectangular fins immersed in a constant temperature bath. Experiments are carried at three different bath temperatures (-6,-9, and -12°C). Four rectangular fins of size 20.6mm length, width 10.6 mm, and 1mm thick made of copper are fixed on the inner surface of the spherical capsule. Results indicated that fin had a significant reduction in total solidification time. A reduction of 13% in total solidification duration is achieved at -9 and -12°C. However a decrease of 87-90 % in freezing duration is observed while considering 50% of PCM mass at bath temperatures of -6°C,-9°C, and -12°C. It is concluded that fins can be employed in CTES systems at lower bath temperatures to achieve expected energy savings of 9-12% under the partial charging method.
The current research examines the findings of the freezing features of PCM in an LDPE spherical capsule fitted with and without fins. De-ionized water is used as phase change material to store energy in form of latent heat. Four fins of length 14mm are inserted in LDPE spherical capsule of same dimension. The effect of fins on the freezing time has been analyzed at various heat transfer fluid temperatures. The experimental results indicated that 50% of the mass of PCM has frozen in 21% and 16% of freezing time with the help of fins when compared to LDPE capsule without fins at -6°C and -9°C bath temperatures. There is not a significant reduction in total freezing time for LDPE spherical capsule with inclusion of fins at all the bath temperatures. A marginal increase in surface heat flux value is observed in case of LDPE finned spherical capsule. Along with heat transfer enhancers, the container material’s thermal conductivity is critical in increasing the freezing rate of PCM.
This study aims at investigating the solidification characteristics in a spherical capsule with pin fins and rectangular fins of same length and volume immersed in a constant temperature bath (-6°C, -9°C, -12°C). The fins are made of copper and are attached to the inner surface of the spherical capsule. The fin lengths correspond to the annulus fill volume margin of 75% taken on the inside wall of the spherical container. The findings showed that the overall solidification period of the capsules with rectangular fins was reduced. Also, the subcooling phenomena is completely eliminated at bath temperature of -6°C. Results also indicated that 50% PCM mass is reduced effectively with the provision of fins. Thus, with the employment of rectangular fins better potential energy savings can be attained when operated at partial charging mode at higher bath temperature.
The purpose of this study is to analyze the impact of the material of the spherical capsule on the solidification characteristics of deionized water as the phase change material(PCM) filled with 90% of its fill volume. The experiment was performed with two same sized balls measuring 86mm diameter made of LDPE(Low density polyethylene) and Stainless Steel kept at distinct bath temperatures(-6,-9 and -12°C). It was noticed that the material of the spherical capsule had an influence on the solidification characteristics of the PCM. The Stainless Steel capsule froze significantly faster than the LDPE capsule for all the mass fractions. This effect was prominent in the lower mass fraction of 50%. It was also inferred that the percentage by which the Stainless Steel capsule froze faster than the LDPE capsule escalated by 32.63%, 40.90% and 43.18% at higher potential temperatures for 50% mass fraction.
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