A dynamic analytical model to predict and parametrically analyze charging and discharging process of tube-in-tank PCM systems

Tube-in-tank PCM systems, which have high energy storage density and packing factor, have been highlighted in previous studies on making use of heat and cold thermal energy. However, dynamic variation of working conditions, such as switch between charging/discharging process and fluctuation of inlet temperature of the tube, have irreversible influences on the whole working process. To the optimization of the system, in this study, an analytical model is proposed by using time-dependent differential equation of energy and effectiveness-NTU method. Meanwhile, to improve prediction accuracy of discharging process, an equation to calculate effective thermal conductivity of the melted PCM layer that affect by natural convection is introduced. With diversified tube inlet temperatures, transient features of phase change heat transfer process can be numerically solved. This model is validated by a set of experiments. Similar tendencies and values of tube outlet temperatures are obtained. The prediction errors of energy storage capacity are between 1.86% and 8.81%. The parametric analysis of geometric parameters and tube materials of the system are also discussed.

Automated summary

The study proposed an optimization analytical model for tube-in-tank PCM systems and validated it through experiments, with prediction errors of energy storage capacity between 1.86% and 8.81%. Parametric analysis of geometric parameters and tube materials of the system were also discussed.