Effect of fin material on PCM melting in a rectangular enclosure

•It is reasonable to divide melting process into four stages for fin schemes.•The enhancement in mean power is the highest for copper fin scheme, about 68.6%.•The reduction in energy per mass is the lowest for aluminum fin scheme, about 9.4%.•The cost per energy stored rises except for aluminum fin scheme with reducing by 0.1%.•The selection of fin materials depends on the used evaluation indicators seriously. A comprehensive study was conducted to analyse the effect of fin material on PCM melting in a rectangular enclosure. Four commonly employed indicators, surface averaged Nusselt number, melting time, total stored energy and mean power, and two proposed, stored energy per mass and cost per energy stored, were used to evaluate the influence of fin material roundly. Results show that compared with the no-fin scheme, the PCM melts faster and the melting time is reduced by 41.6%, 41.0%, 40.1% and 37.2% with inserting copper, aluminum, carbon steel and steel302 fins. Significant reduction in stored energy per mass is presented by adding fins and the decline range is the highest for the copper fin scheme and the lowest for the aluminum fin scheme, which is 27% and 9.4% respectively. Among four fin schemes, the cost per energy stored is the largest for the copper, 5.6% higher than the no-fin case. The selection of fin material is affected by adopted indicators. If four commonly used indicators are considered only, the copper and carbon steel fin schemes are highly recommended, while the aluminum fin scheme is highly recommended if six indicators are considered simultaneously. A criterion, selecting fin material with higher thermal conductivity, high specific heat capacity, low density and low cost as fins, is proposed.