Thermal energy storage technology has evolved as one of the prominent methods of storing thermal energy when it is available and utilized as per the requirements. In recent years, thermal energy storage has found a variety of applications for thermal management, such as buildings, batteries, electronics, cold storage, textiles, and solar thermal systems. Phase Change Material (PCM) has taken the lead among all other thermal energy storage materials because of various merits such as high energy density, ease of use, low cost, low volume change, environmental friendliness, easy availability, and chemical stability. However, limitations such as poor thermal conductivity and leakage during phase transformation limit their applicability. In this study, Shape Stabilized Composite PCM (SSCPCM) was developed to overcome these drawbacks. Paraffin wax and soya wax were used as PCMs and multi-walled carbon nanotubes and graphene oxide were used as nano-additives. High-Density Polyethylene (HDPE) is used as a supporting matrix. Leakage test suggest maximum loading of 40 wt% and 35 wt% of paraffin wax and soya wax in HDPE without any leakage at elevated temperature. The prepared SSCPCM shows substantially better thermal energy storage capacity along with improved thermal conductivity. A maximum rise of 260.8% in thermal conductivity was observed in paraffin wax supported by HDPE and loaded with 3 wt% of multi-walled carbon nanotube nanoparticles. The heating and cooling performance suggests an improvement in the heating and cooling rate by adding nano-additives. The prepared SSCPCM are also thermally stable at elevated temperatures up to 150 °C.

During Diwali festival, extensive burning of crackers and fireworks is made. Weeklong intensive observational campaign for aerosol study was carried out at a representative urban location in the eastern Indo-Gangetic Plain (IGP), Varanasi (25.3°N, 83.0°E), from October 29 to November 04, 2005 (Diwali on November 01, 2005), to investigate behavioral change of aerosol properties and radiative forcing between firework affected and nonaffected periods. Results show a substantial increase (~27%) in aerosol optical depth, aerosol absorption coefficients, and aerosol scattering coefficients during affected period as compared to non-affected periods. Magnitudes of radiative forcing at top of atmosphere during affected and non-affected periods are found to be +10 ± 1 and +12 ± 1 Wm⁻², respectively, which are −31 ± 7 and −17 ± 5 Wm⁻², respectively, at surface. It suggests an additional cooling of ~20% at top of atmosphere, ~45% cooling at surface, and additional atmospheric heating of 0.23 Kday⁻¹during fireworks affected period, which is ~30% higher than the non-affected period average.

Nanofluids represent a promising frontier in materials science and engineering, offering unprecedented opportunities to enhance heat transfer efficiency, mechanical properties, and biomedical applications. Nanofluids, which are suspensions of nanomaterials in base fluids, have garnered significant interest due to their unique properties and potential applications across various fields. This chapter overview of recent advancements, preparation methods, stability evaluation, stability enhancement and current applications for nanofluids. Continued research and innovation in nanotechnology will play a crucial role in unlocking the full potential of nanofluids across diverse fields, paving the way for more efficient and sustainable technological advancements in the future.