Development and Analysis of a Multi-Node Dynamic Model for the Simulation of Stratified Thermal Energy Storage

Nora Cadau,Michele Rossi,Mirko Morini,Andrea De Lorenzi,Agostino Gambarotta

doi:10.3390/en12224275

Abstract

To overcome non-programmability issues that limit the market penetration of renewable energies, the use of thermal energy storage has become more and more significant in several applications where there is a need for decoupling between energy supply and demand. The aim of this paper is to present a multi-node physics-based model for the simulation of stratified thermal energy storage, which allows the required level of detail in temperature vertical distribution to be varied simply by choosing the number of nodes and their relative dimensions. Thanks to the chosen causality structure, this model can be implemented into a library of components for the dynamic simulation of smart energy systems. Hence, unlike most of the solutions proposed in the literature, thermal energy storage can be considered not only as a stand-alone component, but also as an important part of a more complex system. Moreover, the model behavior has been analyzed with reference to the experimental results from the literature. The results make it possible to conclude that the model is able to accurately predict the temperature distribution within a stratified storage tank typically used in a district heating network with limitations when dealing with small storage volumes and high flow rates.

Highlights

The continuous increase in the importance of the role of energy over the last few decades, as well as the rise in fuel prices and the need to limit greenhouse gas emissions, have led to a steady growth in the use of energy saving technologies and in a more effective and extensive implementation of renewable energy sources [1]
A number of applications for thermal energy storage can be seen in energy grids, since they allow (i) an effective balance in energy supply vs. demand dynamics, (ii) a decrease in heating system energy losses, reducing the number of start-up and shut-down maneuvers and the need for backup plants, (iii) an increase in deliverable capacity, (iv) a shift in energy purchases to lower cost periods, and (v) an increase in renewable energy source exploitation
Simulations have been conducted on a single heat storage tank both in the charge and discharge

Summary

Introduction

The continuous increase in the importance of the role of energy over the last few decades, as well as the rise in fuel prices and the need to limit greenhouse gas emissions, have led to a steady growth in the use of energy saving technologies and in a more effective and extensive implementation of renewable energy sources [1]. Despite renewable energies representing one of the best alternatives to conventional sources—such as fossil or nuclear—for energy supply in most areas of the world, renewable energies are often hampered by their discontinuous nature during the day and by the actual availability of the source during the year. To improve the availability of renewable energies in remote geographical areas and to overcome their intermittent nature, thermal energy storage (TES) represents a fundamental solution to increase their competitiveness. A number of applications for thermal energy storage can be seen in energy grids, since they allow (i) an effective balance in energy supply vs. demand dynamics, (ii) a decrease in heating system energy losses, reducing the number of start-up and shut-down maneuvers and the need for backup plants,

Objectives

Methods

Results

Conclusion