Optimisation of a portable phase-change material (PCM) storage system for emerging cold-chain delivery applications

Increasing consumer demand for home grocery delivery is introducing new challenges to the cold chain logistics of fresh produce distribution. A potential solution to enable efficient, flexible, and cheap temperature management of delivered groceries is through a portable phase change material (PCM) container system. In this study, the optimum layout and properties of PCMs in a packed container are determined through experimental and numerical analysis. Three PCM layouts are evaluated, from which placing PCMs along the top, bottom, and long side walls of the insulative container is the most effective configuration with a threshold time of 15.8 h and discharge efficiency of 80%. Combinations of four PCM materials are compared, with higher latent heat found to increase threshold time and lower melting temperature found to increase discharge efficiency and temperature inhomogeneity. Sensitivity analysis of content thermophysical properties show a negatively proportional relationship between thermal diffusivity coefficient and time to reach the average threshold temperature. Finally, an analysis of environmental conditions impact shows that tote performance decreases more significantly with the increase in the ambient temperature as compared to forced convection coefficient-68% decrease in the time reaching the average threshold temperature by increasing the ambient temperature from 15 degrees C to 50 degrees C.