Recent advancements in latent heat phase change materials and their applications for thermal energy storage and buildings: A state of the art review

Recent developments in nano-enhanced phase change materials for solar thermal storage

The immersion of nano-encapsulated phase change material (NPCM) in a carrier fluid to form NPCM slurry can ensure of the latent heat absorption and effective heat transfer. Here, the convective heat transfer of the NPCM slurry stream in a double-pipe heat exchanger were studied experimentally. PCM nanocapsules have been prepared via a mini-emulsion polymerization process. The nanocapsules consisting of n-dodecanol as the core, and polymethyl methacrylate (PMMA) as the shell were modified by graphene oxide (GO) nanosheets as an additional protective layer. Morphology as well as thermal and structural features of nanocapsules were examined and analyzed. The least particle size corresponded with a latent heat of 148.5 J/g. The enhancement mechanism of the convective heat transfer of NPCM slurry was studied via the response surface method. The heat transfer features were evaluated based on experiments designed statistically to determine the optimal values of inlet temperature (Tin), NPCM concentration (ϕ), and Reynolds number (Re). The optimization was performed aiming at the maximum enhancement of thermal efficiency (η). The validity of the developed regression models was assessed using the ANOVA technique. It is found that in the turbulent tubular flow of NPCM slurry, the inlet temperature and the mass fraction of nanocapsules have the most significant effects on the heat transfer performance. The optimum values of ϕ, Tin and Rein were found to be 14%, 83 °C and 5046, respectively, resulted in the maximum η of 4.5.

Optimization of the thermal performance of nano-encapsulated phase change material slurry in double pipe heat exchanger: Design of experiments using response surface methodology (RSM)

Experimental investigation of heat transfer enhancement using ionic liquid-Al2O3 hybrid nanofluid in a cylindrical microchannel heat sink

Experimental study on the effects of air blowing and irradiance intensity on the performance of photovoltaic modules, using Central Composite Design

Nano Encapsulated Phase Change Materials (NEPCMs) are a crucial part of solar energy systems due to their high thermal storage density. The particle size of the NEPCMs is especially of great importance due to its effect on heat transfer and long-term use during applications. In this study, nanocapsules containing Phase Change Material (PCM) n-dodecanol as core and polymethyl methacrylate (PMMA) as shell were synthesized by miniemulsion polymerization with Graphene Oxide (GO) nanosheets as an extra protective screen situated at the interface between the core and the shell. The experiments were designed with the Central Composite Design (CCD) of Response Surface Methodology (RSM). The nanocapsules synthesis experiments were conducted as per the statistical design to determine the optimum process conditions. The effect of initiator/Methyl methacrylate(MMA) mass ratio (BPO/MMA wt.%), n-octadecane/MMA mass ratio (PCM/MMA), stabilizer/MMA mass ratio (triton X-100/MMA wt.%), water/MMA mass ratio (H2O/MMA) and GO/MMA ratio on the nanocapsule properties were investigated. The correlation between nanocapsule properties (melting latent heat and average particle size of nanocapsules) and affecting factors were evaluated and verified. The numerical optimization showed that the optimum nanoparticle size (110 nm) and latent heat (148.5 J/kg) can be obtained at H2O/MMA of 11.3 wt%, PCM/MMA mass ratio of 1.88wt%, X-100/MMA of 10.81wt.%, and BPO/MMA of 2.96 wt.% and GO/MMAof 3.79wt%.  The optimized nanocapsules were characterized by Fourier Transform InfraRed (FT-IR) spectroscopy, Transmission Electron Microscope (TEM), Differential Scanning Calorimetry (DSC), ThermoGravimetric Analysis (TGA), and laser particle diameter analyzer. The thermal cycling tests indicate the high thermal resistance of the prepared core-shell system, even after 100 heating/cooling cycles, and have an excellent potential for energy storage and release performance of the system.

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Arman Chananipoor

Papers

Optimization of the thermal performance of nano-encapsulated phase change material slurry in double pipe heat exchanger: Design of experiments using response surface methodology (RSM)

Synthesis and Optimization of GO/PMMA/n-Octadecane Phase Change Nanocapsules Using Response Surface Methodology