Coal, natural gas, and petroleum-based fuel emissions are significant contributors to air pollution and, as a result, global warming. Solar energy holds promise in attempts to transition to a sustainable, carbon-neutral energy economy.
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Solar energy, which is abundant and environmentally beneficial, has the potential to minimize human reliance on traditional energy sources if harnessed effectively.
In this context, phase change materials (PCMs) are a favorable choice for solar energy storage devices because they absorb enough energy at phase transition (in the form of latent heat) to offer useful heating or cooling.
According to research, a solar-powered PCM-based cooling system can lower the ambient temperature by 30 °C. However, realistic PCMs have leakage and corrosion problems. Furthermore, because of their limited thermal conductivity, they have poor heat transfer qualities. While metal PCMs can overcome this problem, they are more expensive and heavier.
According to research, one option to avoid these challenges is to enclose the PCMs in microcapsules with high-conductivity fillers, like nanoparticles. This can shield them from the harmful effects of light, heat, moisture, and oxygen while also improving their heat transfer qualities. Numerous researchers have used low-density, non-metallic, high thermal conductivity nanoparticles for this purpose, which eliminates the problems associated with metallic nanoparticles.
Scientists from China and the United States recently created PMC microcapsules with remarkable photothermal conversion and heat transmission using n-Octadecane (ODE) as the PCM core and silicon carbide (SiC) nanoparticle-doped crosslinked polystyrene (CLPS) as the outside shell.
Phase change microcapsule materials have been the focus of our research. In a previous study, we found that a single organic shell has defects in thermal conductivity and stability, while a single inorganic shell is not satisfactory in compactness and coverage. Therefore, we began to focus on doping organic shells with inorganic nanoparticles to obtain organic-inorganic hybrid shells.
Jifen Wang, Study Author and Professor, Shanghai Polytechnic University
The research was published on September 29th, 2022 in the Energy Storage and Saving journal.
The researchers created a series of four microcapsules using a technique known as “suspension polymerization.” They then used energy-dispersive X-Ray spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy to analyze the microcapsules.
The findings demonstrate that the microcapsules were spherical, and the SiC nanoparticles were implanted in the CLPS shells, enhancing the microcapsules’ heat transfer and photothermal conversion efficiency.
The scientists next investigated the thermal properties of the microcapsules, discovering that they outperformed non-doped samples in photothermal conversion and thermal conductivity. Among the four types of doped microcapsules tested, the one with 1.25 wt% nano-SiC doping performed best, with a 54.9% photothermal conversion efficiency, 146% better than its non-doped counterpart!
With such promising results, the innovative PCM microcapsule shells might serve as a firm base for future research on energy materials with high solar energy storage and conversion efficiency. The research also paves the way for the practical use of multifunctional phase change microcapsules.
These microcapsules can have significant potential applications as energy storage materials in solar energy devices, intelligent thermal insulation equipment, and energy-saving buildings.
Jifen Wang, Study Author and Professor, Shanghai Polytechnic University
Journal Reference:
Zhao, K., et al. (2022) Enhanced photothermal conversion and thermal conductivity of phase change n-Octadecane microcapsules shelled with nano-SiC doped crosslinked polystyrene. Energy Storage and Saving. doi.org/10.1016/j.enss.2022.09.003.