The effect of aspect ratio on PCM melting behaviour in rectangular enclosure

The effect of Aspect ration on melting process of PCM (polyethylene glycol 1500 (PEG 1500)) in a rectangular encloser was investigated using CFD modelling. The CFD model was validated by experimental measurement performed for one case of aspect ratio of 2.31 with height = 155 mm, width = 67 and depth = 200 mm. The study was conducted in two phases: i) constant height enclosure, ii) constant volume enclosure. The main conclusions from this study are: i) the conduction heat transfer is the only mode of heat transfer in the first 250 secs from the start of heating of PCM. Then, the evolution of natural circulation starts at the hot wall and developed to a complete steady cycle after 2000 secs. ii) the results indicate a clear effect of the aspect ratio (AR) on melting percentage with peak at AR = 2,31 for both cases of constant heght and constant volume. iii) the results also show that there is a limiting width of the encloser where the circulation velocity reduced to low values (<0.3 mm/s) regardless of the enclosure heht.