Selection of phase change material for solar thermal storage application: a comparative study

The study of five paraffin waxes and wood resin was carried out to investigate their thermo-physical properties. The investigation aimed at selection of a phase change material (PCM), for its potential use as a thermal energy reservoir (TER) in a fabricated solar dryer. Differential scanning calorimeter was used to determine the melting point, solidification point, latent heat of fusion and solidification of these PCM. The T-history analysis was carried out to determine the effective thermal conductivity and specific heat in liquid and solid states. Bulk density of these PCMs was determined using standard pycnometer method. A comparative analysis was done for the selection, and PW1 was selected among the paraffin waxes, while wood resin was rejected. The selected PCM was used in the flat plate collector of solar dryer to identify the thermal zones and to validate its capability as a TER. Maximum temperature achieved at outlet of flat plate collector was 50 degrees C. The temperature profile built in different zones was determined with and without using PCM. It was found that after 18:00 IST evening, the average flat plate collector chamber temperature with PCM PW1 was found to be 23.5% higher than that without using PCM.