ABSTRACT
Stratified tanks are being widely used for thermal energy storage (TES), allowing a decoupling between the energy source (commonly a renewable energy source or heat rejected by some industrial process) and the demand. A high degree of stratification is required to make more efficient use of the stored energy, and several design configurations have been developed in order to create and maintain a good stratification. Numerical and experimental approaches are used to monitor and design the process, and also to predict the behavior of these tanks under different conditions. Detailed numerical simulation, however, is computationally expensive and not suitable for the long-time simulations (typically years) required to assess the performance and the economics of energy systems which include TES tanks.
In this paper, a relatively simple, computationally inexpensive numerical approach, called Multi-node model, is used to simulate the energy transfer and the stratification inside the tank. The results obtained are compared to a software package for simulation of energy systems called TRNSYS and some experimental results to validate the model.