Thermal Behaviour of Nanocomposite Phase Change Material for Solar Thermal Applications

The use of solar thermal technologies has shown great prospects towards solar energy conversion into more useful forms of energy and has increasingly expanded solar thermal technology applications. However, the inability to properly store the excess solar energies during peak hours and demands have limited many of their applications. The integration of thermal energy storage (TES) systems with thermal technologies have increased the solar thermal technology performance but the poor thermal characteristics exhibited by phase change materials (PCM) limited the system overall performance. The enhancement of PCM properties by nonadditive have shown increased material performance in TES application and thereby extending the use of solar thermal technology application. Given this narrative and identifies literature gaps, the present study investigated experimentally the enhancement of paraffin PCM using nonadditive metallic of different types and concentrations and analysed their thermal behaviours. The results showed that Cu/paraffin PCM nanocomposites had good thermal reliability in proposed applications even after 150 thermal cycles under different temperatures. Moreover, thermal conductivity was improved significantly as an enhancement of 39% was reported when adding 2.5% of Cu nanoparticles. While specific heat and thermal diffusivity has been enhanced by 16% and 9%, respectively compared to pure paraffin. The obtained results were compared with different theoretical models such as Maxwell mode, Hamilton Crossover model, Jeffery model, and Bruggeman model. The calculated values show a good agreement with experimental ones. As a result, the prepared Cu/Paraffin nanocomposite PCM shows significant promise in thermal energy storage application due to its favourable phase change temperature, comparatively large latent heat, enhanced thermal conductivity and high thermal reliability and conversion. The proposed nanocomposite PCM can be used in many applications such as building materials to reduce interior temperature swings, enhance thermal comfort, and conserve electricity consumption.

Paraffin Wax [As a Phase Changing Material (PCM)] Based Composites Containing Multi-Walled Carbon Nanotubes for Thermal Energy Storage (TES) Development

Thermal energy storage (TES) technologies are considered as enabling and supporting technologies for more sustainable and reliable energy generation methods such as solar thermal and concentrated solar power. A thorough investigation of the TES system using paraffin wax (PW) as a phase changing material (PCM) should be considered. One of the possible approaches for improving the overall performance of the TES system is to enhance the thermal properties of the energy storage materials of PW. The current study investigated some of the properties of PW doped with nano-additives, namely, multi-walled carbon nanotubes (MWCNs), forming a nanocomposite PCM. The paraffin/MWCNT composite PCMs were tailor-made for enhanced and efficient TES applications. The thermal storage efficiency of the current TES bed system was approximately 71%, which is significant. Scanning electron spectroscopy (SEM) with energy dispersive X-ray (EDX) characterization showed the physical incorporation of MWCNTs with PW, which was achieved by strong interfaces without microcracks. In addition, the FTIR (Fourier transform infrared) and TGA (thermogravimetric analysis) experimental results of this composite PCM showed good chemical compatibility and thermal stability. This was elucidated based on the observed similar thermal mass loss profiles as well as the identical chemical bond peaks for all of the tested samples (PW, CNT, and PW/CNT composites).

Thermal Modification by High Speed In Situ Mixing for Nanoparticles TiO2 and SDS Surfactant to Paraffin Based PCM Nano Enhanced Composite

The use of liquid-solid type phase change material (PCM) is increasing due to the importance of having a good storage for latent heat, which can be attributed to its wide range of application, such as electronics, buildings, textiles, and the automotive sector. This study employed an experimental procedure through in situ mechanical mixing of paraffin-based PCM and 4Wt% Titanium dioxide (TiO2) rutile to form nanocomposite PCM with high-speed agitation (900 rpm at 90°C for 60 minutes) and mixed with Sodium Dodecyl Sulphate (SDS) as the dispersant. It was conducted by applying premixing of polar solution (distilled H20 + 4Wt% SDS dispersant) to the aforementioned non-polar paraffin-based solution (paraffin wax + 4Wt% TiO2) in a 1:4 ratio, then cooled naturally. The Fourier Transient Infrared (FTIR) spectrum and the X-Ray Diffraction (XRD) pattern indicated a characteristic typical of composite systems, in which. there is no new material system composed. The typical wavenumbers of composite PW+TiO2 (2918 cm-1, 2851cm-1, 1471 cm-1, 720cm-1 and 469 cm-1) were also seen in the FTIR, while high intensity peaks 2θ = 21.4°, 23.8 and low intensity peaks 27.4°, 36.074°, XRD patterns could be tied to monoclinic paraffin crystal with the typical plane diffractions of (110) and (200) and TiO2. The thermal properties of the composite were measured using Differential Scanning Calorimetry. The findings showed that the paraffin based PCM comprised a higher thermal storage capacity of 144.3 J/g compared to its common 104.5 J/g typology. Scanning Electron Microscope observation showed a better dispersion of TiO2 clusters (smooth, spherical, and spreading). The results ultimately showed that optimizing the agitation speed at the prompt temperature contributes to the increase of the crystallite size and the capacity to isolate the temperature of nanoparticles, which may elicit a growing interest for more practical applications of the nanocomposites PCM.

Study on Dispersion Stability Characteristics of TiO2 Nanoparticles in PCM for Use in Cold Storage Air-Conditioning

A new organic phase change materials (PCM) for cool storage was developed for use in cold storage air-conditioning. The thermal properties of the new organic PCM were measured with a differential scanning calorimeter (DSC). To improve the thermal conductivity of the new organic PCM, the further research of using nanocomposite technology to the organic PCM SSW-4 was made. The effects of nanoparticles concentration on dispersion, ultrasonic time and consistence of dispersant in the best ultrasonic time on the dispersion were investigated by experiment. The results showed that the thermal conductivity of the nanocomposite PCM TiO2 /SSW-4 increased by approximately 16.27% compared to that of the organic PCM SSW-4. The best dispersion condition of preparation for TiO2 /SSW-4 was confirmed.