Applications of differential scanning calorimetry to the study of thermal energy storage

• Main Author: Cantor, S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oak Ridge National Laboratory 1977
• Subjects: Urea; 25 Energy Storage; Other Organic Compounds; Alkali Metal Compounds; Organic Compounds; Thermal Energy Storage Equipment; Amides; Paraffin; Heat Storage; Calorimetry; Sodium Compounds; Materials; Waxes 250600* > Energy Storage > Thermal; Hydrocarbons; Measuring Methods; Sulfates; Sulfur Compounds; Latent Heat Storage; Oxygen Compounds; Storage; Capacity; Carbonic Acid Derivatives; Sodium Sulfates; Organic Nitrogen Compounds; Equipment; Energy Storage; Alkanes; Carbonic acid
• Online Access: https://digital.library.unt.edu/ark:/67531/metadc1446857/

Differential scanning calorimetry (DSC) is a versatile tool for investigating the behavior of materials that store energy by melting or by undergoing solid-state transitions. Heating scans measure the enthalpy that can be stored and cooling scans yield the enthalpy that may be recovered from the material. Exotherms also provide information about supercooling. The automatic and rapid thermal cycling features of the instrument system can be used to greatly accelerate thermal decomposition that may arise from the daily duty cycle of the storage medium. These chemical reactions as well as those with containment or with substances added to improve performance can be detected from changes in the thermal spectra. In this study, DSC methods were applied to sodium sulfate decahydrate, paraffin wax, urea, and phthalimide. For Na/sub 2/SO/sub 4/.10H/sub 2/O, DSC measurements showed a decrease in heat of fusion with thermal cycling and, also, considerable supercooling; with added Na/sub 2/B/sub 4/O/sub 7/.10H/sub 2/O (borax), supercooling was greatly lessened but not entirely eliminated. Paraffin wax did not supercool nor were there any indications that thermal cycling or contact with aluminum degraded its thermal performance. Urea, when thermally cycled, decreased in melting point and in heat of fusion; this compound also supercooled about 50/sup 0/ in DSC experiments. Phthalimide, C/sub 6/H/sub 4/(CO)/sub 2/NH, did not decompose when thermally cycled through its melting point, but it did exhibit marked supercooling. However, lesser supercooling of urea and phthalimide in test-tube scale experiments suggests that supercooling derived from DSC should be applied with caution. For phthalimide, the enthalpy of fusion, determined in this study, equalled 48.1 cal/g.