Development of pentadecane/diatomite and pentadecane/sepiolite nanocomposites fabricated by different compounding methods for thermal energy storage

Abstract

Summary Global warming is one of the most important consequences of excess energy consumption. Phase change materials (PCMs) have prominent advantages in thermal energy storage owing to their high latent heat capacities and small temperature variations during the phase change process. However, leakage is a major problem that limits the use of PCMs. Leakage may occur in encapsulated PCMs or in composites where the PCM is attached to the surface of a supporting material or within the pores of that material. In this study, pentadecane/diatomite and pentadecane/sepiolite nanocomposites were fabricated by using unmodified and microwave‐irradiated diatomite and sepiolite samples and by using different compounding processes, such as direct impregnation, vacuum impregnation, and ultrasonic‐assisted impregnation methods. The microstructures and the chemical and thermal properties of the composites were characterized by scanning electron microscopy, Fourier‐transform infrared spectroscopy, and differential scanning calorimetry. Subsequently, the thermal reliability and stability and the thermal conductivity of the PCM composites were also investigated. A melting temperature of 9.25°C and a latent heat capacity of 58.73 J/g were determined for the pentadecane/diatomite composite that was prepared with the direct impregnation method using a microwave‐treated diatomite sample. The pentadecane/sepiolite composite prepared in the melting temperature range 7.98°C to 8.53°C and latent heat capacity range 41.05 to 46.02 J/g. The results of the thermal analysis indicate that fabricated diatomite‐based or sepiolite‐based PCM composites have good potential as thermal energy storage materials.

Clay Composites for Thermal Energy Storage: A Review

“…The measured thermal conductivity was 0.59 W/mK. Further, Konuklu et al figured out that an ultrasound treatment had a negative effect on sepiolite due to its tubular structure while the microwave treatment promotes the preparation of the composites with improved thermal conductivity [76]. Additionally, Konuklu and Ersoy compared the thermal properties of the composites prepared by mixing paraffin or dodecanoic acid with sepiolite [77].…”

“…In turn, the thermal conductivity was increased by 70 to 105% compared to pure salt hydrates by the addition of 10 wt% of graphite into the composition. Konuklu et al compared the properties of pentadecane/diatomite composites prepared by direct impregnation, vacuum impregnation, and ultrasonic-assisted impregnation methods and estimated the effect of microwave treatment of the resulted composites [76]. The composites prepared with direct impregnation of pentadecane demonstrated the highest LHS capacity and thermal conductivity with no supercooling.…”

Carbonized waste hazelnut wood‐based shape‐stable composite phase change materials for thermal management implementations

“…One of the methods for solving these problems is to encapsulate PCMs with polymer or some inorganic shells in micro or macro scale to prevent seepage. But here, the main deficiencies are complexity of the encapsulation process, relatively high cost and easy break of capsule shells 10,11 . A second method is the production of shape‐stable composite PCMs by using a supporting material.…”

“…During the melting and solidification phase transformations, PCMs perform LHTES function, while the supporter materials prevents PCM seepage in liquid state and ensures the solid shape to be fully preserved 12‐16 . Some of the porous materials commonly used in the production of shape stable composites are attapulgite, 17 expanded perlite, 18 sepiolite, 11 vermiculite, 19 diatomite 14,20 and silica fume 8,21 . However, many of these materials themselves have low thermal conductivity and hence it is obvious that they cannot help increase the thermal conductivity of PCMs.…”

Phase change material impregnated wood for passive thermal management of timber buildings

“…Each PCM possesses different characteristics in term of their thermal behavior and latent heat storage. [21][22][23][24][25][26] Organic PCMs including fatty acids, fatty alcohols, PEGs, paraffins and their eutectic mixtures have been generally used for latent heat storage due to their high latent heat capacity, proper phase change temperature within wide range, non-corrosivity, non-toxicity, good thermally/chemically stability, low vapor pressure, very small volume change and mostly no supercooling. 16,[27][28][29][30][31][32] PCMs can be integrated in building materials by using impregnation and encapsulation.…”