Project Details
Projekt
Ericsson Battery – Conception of an Ericsson Pumped Thermal Energy Storage System
Applicant
Professorin Dr.-Ing. Christiane Thomas
Subject Area
Technical Thermodynamics
Term
since 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 526159167
In Carnot batteries, mainly Rankine or Brayton cycles have been used so far to realize heat supply and regeneration. In the proposed project, an Ericsson process will be targeted for the first time for cases where only the Rankine process has been considered so far. Therefore, this concept is called Ericsson battery. The background is that the Rankine cycle differs from the Carnot cycle, which leads to exergy losses. In heat pump mode, expansion losses, and in power generation mode, preheating losses dominate. In Carnot batteries, these have so far been countered by the use of an additional sensible heat storage. As an alternative, a cycle is now to be used instead, in which these types of losses do not occur. In principle, the Ericsson cycle is suitable for this purpose, but the technical implementations have not yet been successful so far, since the volumetric power density is low due to the gas used as the working fluid and the necessary heat transfer is low due to the lack of a phase change. For this reason, a new approach is being used, whose basic features have been developed at the Bitzer Chair of Refrigeration, Cryogenics and Compressor Technology in recent years. It is a Recuperative Two-Phase Cycle (RTPC), in which complete recuperation is enabled by the use of a zeotropic mixture with a highly nonlinear profile in the two-phase area. This cycle can adopt the shape of the Ericsson cycle, while still having the desired phase change. The goal is to use it in thermal electricity storage systems, resulting in a storage concept that is based only on latent heat storage and does not require additional sensible storage. In the proposed project, this concept will be investigated for the first time. For this purpose, the optimal cycle process parameters with the required working fluid mixtures have to be identified first. This requires a parallel optimization of process parameters, mixture components and mixture composition. As a result, the most important thermodynamic characteristics of the Ericsson battery are obtained, such as the ideal storage temperature and the specific heat flow. In the next step, the functionality of the mixture will be verified on a demonstrator, although the experiment is intended to represent only part of the desired overall process. The project is being carried out in cooperation with other partners. Thereby, energy-economical requirements (A) are received, methodical approaches (B) are integrated into the own calculation tools and requirements for necessary components (C) are passed on. In a final part, all theoretical and experimental findings will be used to quantify the potential of a technical implementation of the Ericsson battery.
DFG Programme
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