Heat transfer study of phase change materials with graphene nano particle for thermal energy storage Karunesh Kant a,⇑ , A. Shukla a , Atul Sharma a , Pascal Henry Biwole b,c a Rajiv Gandhi Institute of Petroleum Technology, Jais, Amethi, UP, India b Department of Mathematics and Interactions, University of Nice Sophia-Antipolis, Nice, France c Mines Paris Tech, PSL Research University, Center for Processes, Renewable Energies and Energy Systems, Sophia Antipolis, France article info Article history: Received 21 January 2017 Received in revised form 27 February 2017 Accepted 6 March 2017 Keywords: PCM Graphene nanoparticles Melt fractions Streamlines Melting Fronts abstract The thermal conductivity of commonly used phase change materials (PCM) for thermal energy storage (TES), such as, fatty acids, paraffin etc., is relatively poor, which is one of the main drawbacks for limiting their utility. In the recent past, few attempts have been made to enhance the thermal conductivity of PCM by mixing different additives in the appropriate amount. Graphene nanoparticles, having higher thermal conductivity may be a potential candidate for the same, when mixed appropriately with different PCM. In present study authors have carried out the numerical investigation for the melting of graphene nano- particles dispersed PCM filled in an aluminum square cavity heated from one side. In this work, the gra- phene nanoparticles are mixed in three different volumetric ratios (1%, 3%, and 5%), with three different commonly used categories of organic, inorganic and paraffin PCM (namely, Capric Acid, CaCl 2 Á6H 2 O, and n-octadecane) to see the effect on melting of composite PCM developed. The resulting transient iso- therms, velocity fields, and melting front and melt fractions thus have been deliberated in detail. These results clearly indicate that the addition of graphene nanoparticles increases melting rate but can also hamper the convection heat transfer within large cavities. The study also shows that such enhanced PCM can be effectively used for different TES applications in different fields. The prediction of temperature variation and rate of melting or solidification may be found useful especially for designing such TES devices. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction The growth of the civilization in general and global economic growth, in particular, has largely depended on human efforts to efficiently produce, store and convert to a new form. This is deeply motivating research area and requires development efforts from several spheres of engineering, science and technology, and espe- cially from material sciences. TES related research is mainly con- centrated towards efficient use of thermal energy, generally, the solar energy but has considerable interest for thermal energy managing in industries too. One of the main concerns in thermal energy management is to practice materials having high energy storage capacity with high reliability and less aging effect. In the recent past there has been huge amount of research efforts devoted to developing such novel materials for variety of applications, such as buildings, textiles, and space heating. These materials are com- monly known as PCM, are promising thermal storage materials for storing and discharging bulk amounts of latent heat throughout phase change process (Fang et al., 2009; Hasnain, 1998; Kant et al., 2016a; Murat Kenisarin and Mahkamov, 2006) with regu- lated time intervals associated as per energy demand. Though, the criteria for the choice of PCM for a specific application is its melting temperature, but other properties such as the latent heat of fusion, thermal conductivity, thermal stability, density and lower volume change, also play significant role in better designing of a product and therefore these are essential to be considered (Ling and Poon, 2013; Mehling and Cabeza, 2007). Hence, the opti- mization of material properties as per requirement is quite chal- lenging and novel materials with better efficiency are being continuously explored with time. Additionally, most applications of PCM require high thermal conductivity, though numbers of PCM usually employed lack the same. The lower thermal conduc- tivity of PCM leads to the increase of heat transfer time for the stor- age materials causing the poor TES system performance. To increase the rate of heat transfer, several experimental and numer- ical studies have been performed, for enhancing thermal conduc- tivity using metal matrix, metallic fins, thermal conductive http://dx.doi.org/10.1016/j.solener.2017.03.013 0038-092X/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: k1091kant@gmail.com (K. Kant). Solar Energy 146 (2017) 453–463 Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener