Session: 6.1.1 - Student Competition

Paper Number: 108746

108746 - Investigation of Melting of Pcm Dispersed With Nanoparticles in a Square Enclosure Integrated With Fins Subjected to a Uniform Magnetic Field: A Numerical Study 

Due to global warming, snow cover will decrease, and sea levels will rise, which will have disastrous consequences for human life. The primary contributor to global warming is the combustion of fossil fuels. There is an exponential increase in the use of renewable and clean energy sources to minimise dependence on fossil fuels. To meet the energy demands of future generations, it is vital to capture and utilise waste heat from residential and industrial activities as well as readily accessible renewable energy sources from nature. Thermal storage using a PCM can buffer fluctuating heat loads, balance renewable energy output and demand, store grid-scale energy, recover waste heat, and contribute to carbon neutrality. For this, extensive work is being done on latent thermal energy storage systems (LHTES) and waste heat recovery (WHR) The PCM-based latent heat TES systems are highly advantageous among various TES systems because of higher density of energy storage associated with phase transition from solid to liquid . Also, the solid-liquid phase transition in phase change materials (PCM) occurs with very small volume change.TES/WHR systems based on PCM absorb heat energy and melt during their charging phase, while they release heat energy and solidify during their discharging phase. The major performance hamper in the use of  phase change materials is their low thermal conductivity. Low thermal conductivity decreases the heat transfer performance of PCM during melting and solidification process. In order to increase the thermal conductivity of PCM, various thermal conductivity enhancers such as extended surfaces, nanoparticles, and metallic foams are embedded with PCM. Enhancing the heat transfer rate in PCM based thermal  energy storage systems can in turn increase the energy storage rates.  Thus, it becomes important to study the melting and solidification characteristics of Nano enhanced phase change materials.

PCM is also used in battery heat management, where it is exposed to an electromagnetic field generated by the batteries. PCM may also be subjected to an external magnetic field in a number of other applications, including WHR and energy storage systems. Several investigations indicate that the application of an external magnetic field can alter convective heat transport in an electrically conductive fluid. The incorporation of nanoparticles into phase change material enhances its electrical conductivity, making it sensitive to an external magnetic field. In addition, the modulation of the external magnetic flux can be utilised to regulate the melting and solidification rates of electrically conductive PCM.

Here in the present work, the melting characteristics of lauric acid dispersed with Cu nanoparticles in a square cavity integrated with rectangular and triangular double fin are investigated for different nanoparticle concentration. Position of fins is also altered. Constrained melting conditions are assumed. Two-dimensional transient numerical simulation based on the enthalpy porosity technique will be employed. Transport of nanoparticles by convection will not be considered. The nanoparticles will be assumed to be distributed uniformly in the cavity at all times. In effect, the nanoparticles' presence only affects the PCM's thermophysical properties. The thermal characteristics of nano enhanced PCM (NePCM) are estimated through empirical corelations. Left wall of the enclosure is isothermally heated at a constant temperature. Further, the effect of hybrid nanoparticles (combination of Al₂0₃ and Cu) on melting characteristics is also investigated. Nanoparticles are found to increase the melting rate of PCM but at the cost of decrease in latent heat. Thus, the concentration of nanoparticles is to be optimized depending upon a particular application. Influence of uniform magnetic field on the thermal performance of NePCM is investigated by the incorporation of Lorentz force term in the momentum equation. Magnetic field is found to decrease the phenomenon of natural convection and hence melting rate. However, the influence of magnetic field is found be insignificant during the early stages of melting due to weak natural convection. The present work could be used for the optimization of LHTES units integrated with fins and subjected to magnetic field in industries

Presenting Author: Akhalesh Sharma Indian Institute of Technology Indore

Presenting Author Biography: Akhalesh Sharma is a PhD scholar at the Indian Institute of Technology, Indore, India. He works in the area of energy storage systems.