Enhancing the thermal behaviour of phase change materials by doping with wheat husk and prosophis juliflora bio-carbon nanoparticles / Aman Yadav

Faculty of Mechanical and Automotive Engineering Technology

Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2025

Includes bibliographical references

Battery cells have temperature rise problem during the charging and discharging process. So, in the present research work, Polyethylene glycol (PEG-1000) phase change materials (PCM) is integrated with a battery thermal management system. Nevertheless, (PEG-1000) PCM has challenges during the thermal energy storage, notably poor thermal conductivity and a limited temperature range. To resolve the aforementioned problems, commercialized carbon-based multiwalled carbon nanotubes (MWCNTs) particles are dispersed with the base (PEG-1000) PCM. However, the cost of the commercialized MWCNT particles is too high and nonbiodegradable. Hence, an ongoing study's primary objective is synthesizing bio-based particles derived from the prosophis juliflora plant (PJ) and wheat husk (WH) to reduce the use of expensive carbon-based particles with base (PEG-1000) PCM for battery thermal management systems. The PJ and WH microparticles are synthesized through pyrolysis at a temperature of 1000 ˚C. Further, a two-step ultrasonication method was employed to develop composites by dispersing MWCNT, PJ, and WH particles into the base (PEG-1000) PCM to enhance thermal properties. Moreover, the developed composites morphology, chemical stability, optical absorptivity and transmissivity, thermal stability, and heat transfer rate are comprehensively explored in the experiments. Remarkably, the results of the current research demonstrated that the highest thermal conductivity values were found to be 0.58 W/m⋅K, 0.49 W/m⋅K, and 0.55 W/m⋅K, in PEG-MWCNT, PEG-PJ and PEG-WH composites respectively. The highest final decomposition temperature enhancements by 3.7 % in WH dispersed PCM composite as compared with the base PCM. The highest latent heat values and melting points were observed in the WH dispersed PCM composite. Moreover, based on the results, the WH dispersed PEG composite shows better chemical and thermal stability after thermal cycles as compared with the MWCNT and PJ-dispersed PEG composite. The highest heat transfer rates is observed in PEG-WH composites, as determined by ENERGY-2D software. Hence, WH dispersed PEG composite was selected to integrate with the battery cell to improve the thermal performance of the battery cell during the charging and discharging process due to its higher thermal properties and improved heat transmission rates than PJ and MWCNT dispersed PEG composites. The experimental results show the thermal performance of PEG-1.0 wt.% WH composite in lowering battery temperature to 47.9 ˚C as compared with the base PCM at 3C during the charging and discharging process. Thus, PEG-WH composites provide a feasible and sustainable alternative to costly and environmentally harmful fillers, providing substantial benefits in battery heat control and promoting material sustainability.