A combined multi-criteria decision-making approach for the selection of carbon-based nanomaterials in materials

Phase change materials (PCMs) provide renewable and sustainable energy by storing non-continuous renewable energy sources and enabling them to be used on demand. PCMs used in thermal energy storage must provide certain properties to efficiently charge and discharge energy when needed. Because of their unique properties, carbon-based nanomaterials are of interest in improving the properties of PCMs. There are critical parameters for the selection of carbon-based nanomaterials as a PCM additive. At this point, Multi-Criteria Decision Making (MCDM) methodology is very useful. In this study, Multi-Objective Optimization based on Ratio Analysis plus full multiplicative form (MULTIMOORA) and Weighted Aggregated Sum Product Assessment (WASPAS) as the MCDM methods were used for the rating of carbon-based additives in PCMs. Seven evaluation criteria were determined, namely melting point temperature change, latent heat change, thermal conductivity enhancement, leakage, greenhouse gas, cost, and agglomeration. The criterion weights were determined by objective and subjective methods, namely entropy and ranking methods, respectively. According to the results accomplished by the entropy method, the greenhouse gas was determined as the most important criterion, while the most important criterion according to the ranking was thermal conductivity. With each of these criteria weights, the alternatives were ranked by using MULTIMOORA and WASPAS methods. Expanded graphite was found to be the most suitable material to be added to PCMs according to MCDM results. In addition, a sensitivity analysis was carried out to see the effect of changes that may occur between the criteria determined to define each alternative, and according to the results of the sensitivity analysis, expanded graphite was found to be the best alternative.