Beeswax as a potential replacement of paraffin wax as shape stabilized solar thermal energy storage material: An experimental study

Thermal Energy Storage (TES) using paraffin wax as Phase Change material (PCM) has been widely used for solar to thermal energy conversion and storage application. Being petroleum by-product, production of paraffin wax have embodied environmental impact and high carbon footprint. Beeswax can replace paraffin's as one of the clean, sustainable, eco-friendly and potential TES PCM. However, TES potential of Beeswax was not investigated thoroughly in previous literatures. Also, limited study has been found which evaluates solar to thermal con-version potential of Beeswax. This study presents a comprehensive analysis of TES performance of Beeswax supported by Bentonite clay and loaded with Graphite was evaluated. Bentonite clay was used as supporting material and Graphite powder is used as additive in varying percentage to form Shape Stabilized Composite Phase Change Material (SSCPCM). SSCPCM was initially investigated for anti-leakage behaviour and was found that Bentonite can hold maximum 40 wt% of Beeswax without leakage above phase transition temperature. Thermal energy storage parameters, thermal degradation, solar to thermal conversion performance, chemical stability, surface morphology, and thermal conductivity were evaluated. Bentonite and graphite has shown good morphology to form SSCPCM samples. Also, SSCPCM has proved to be chemically and physically stable thermal energy storage material. Melting enthalpy of 101.79, 100.66, 98.80, 100.43, 96.51, and 105.01 at melting point of 59.43, 58.88, 58.12, 57.98, 57.36, and 57.11 of SSCPCM-0, SSCPCM-1, SSCPCM-3, SSCPCM-5, SSCPCM-7, and SSCPCM-9 was obtained. Adding Graphite has reduced supercooling of SSCPCM samples maximum by 84.13 %. Increasing additives in PCM improves heating rate and thermal conductivity of the SSCPCM.