Design of High Temperature Thermal Energy Storage for High Power Levels - Abstract, Methodology, and Integration into a Cogeneration Plant

Oct 29, 2026

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A latent heat thermal energy storage unit is modeled, simulated, and designed for integration into a cogeneration plant delivering steam to industrial customers in Saarland, Germany. The design features a vertical bundle of extended finned tubes inside a shell filled with phase change material, with water/steam flowing through tubes between upper and lower headers. A new fin geometry targets high power requirements, supported by an iterative multi-step analysis linking fin design, cross-sectional heat transfer, and coupled 2D axial-radial storage behavior.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages16

Reading Time40 min

AccessFree to download

Abstract

1 Introduction

2 Methodology

2.1 Preliminary Design

Design of High Temperature Thermal Energy Storage for High Power Levels Maike Johnson 1 *, Julian Vogel 1, Matthias Hempel 1, Bernd Hachmann2, Andreas Dengel3 1German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569 Stuttgart, Germany 2F.W. Brökelmann GmbH & Co. KG, Oesterweg 14, 59469 Ense-Höingen, Germany 3 Steag New Energies, St. Johannerstraße 101-105, 66115 Saarbrücken, Germany *[Corresponding email: maike.johnson@dlr.de](Corresponding email: maike.johnson@dlr.de) Keywords: Latent heat ; thermal energy storage; PCM; extended fin ; integration ; cogeneration ABSTRACT A latent heat thermal energy storage unit has been modeled, simulated and designed for integration into a cogeneration plant that supplies steam to industrial customers in Saarland, Germany. The design consists of a vertical bundle of extended finned tubes surrounded by phase change material in the shell. The heat transfer fluid water/steam flows through the tubes between the upper and lower headers. A new fin design was developed to achieve the required high power levels. The storage system was designed and analyzed with the development of an iterative multi-step method. The method spans from the design of the fin, based on both empirical and geometrical information, to the heat transfer analysis of a storage system. The analysis is comprised of several steps: a heat transfer analysis of the cross-section of one tube without modeling the heat transfer fluid, a transfer from the cross-section to a simplified onedimensional radial model and a two-dimensional axial and radial analysis coupling the axial flow of the heat transfer fluid and the radial heat transfer into the storage. The developed analysis method and the resulting storage system are presented and the comparison of different fin designs shows the suitability of each fin for different applications. 1 INTRODUCTION A thermal energy storage unit is to be integrated into a cogeneration plant. This storage will act as an intermediate back-up to a gas turbine coupled with a heat recovery steam generator (HRSG), so it is situated in parallel to the HRSG, between the feedwater pump and the steam main. This layout is shown in Figure 1. This plant produces steam for several customers, including one with very specific and constant steam quality requirements. Water injection Steam main to customer Figure 1 : Layout of the cogeneration plant showing the latent heat thermal energy storage integrated in parallel to the HRSG and the back-up boiler. Currently, a fossil-fuel fired standby boiler is maintained at warm load and in the case of a turbine trip, is heated from warm to full load in two minutes. The storage unit will be integrated so that it is kept on standby and the backup boiler will be reduced to cold load, which requires significantly less fossil fuel. From cold load, the backup boiler needs 15 minutes to reach full load. During this time, the storage unit will produce the required 6 MW of superheated steam at 26 bar and a minimum of 300 °C for the industrial customer. This combination of parameters leads to a minimum required capacity of 1.5 MWh. The standby storage unit is being developed as a latent heat energy storage unit. Using the latent heat of fusion of the storage material side with a solidification temperature near the required steam temperature, the volume of the entire storage unit is reduced in comparison to a sensible heat storage unit. Latent heat energy storage allows for a leveling of the discharge temperature due to isothermal phase change. The planned integration is discussed in more detail by Johnson et al. [1] . 2 METHODOLOGY Preliminary design considerations and a combination of heat transfer simulation methods are used for the development of a latent heat thermal energy storage unit for a specific application, and moreover one that produces superheated steam, . 2.1 PRELIMINARY DESIGN The system into which the storage unit is to be integrat

FAQs

What is the proposed energy storage concept and where is it integrated?

The document proposes a latent heat thermal energy storage unit integrated into a cogeneration plant in parallel to the HRSG. It acts as an intermediate back-up between the feedwater pump and the steam main.

How is the heat transfer unit constructed?

A vertical bundle of extended finned tubes is placed in a shell containing phase change material. Water/steam flows through the tubes between upper and lower headers, while the PCM surrounds the bundle.

What methodology is used to design and analyze the storage system?

An iterative multi-step method is used. It starts from fin design using empirical and geometrical information, then progresses through cross-sectional heat transfer analysis, conversion to a simplified 1D radial model, and finally a coupled 2D axial-radial analysis including axial flow and radial heat transfer.

Oct 29, 2026

Upload by aboduw