Design, Modelling and Analysis of the Discharge of a High-Temperature Concrete Thermal Energy Storage System Coupled to a Power Plant Turbine
Authors
Sørensen, Stephanie Sigvert ; Gade, Camilla Nødbak
Term
4. term
Education
Publication year
2017
Submitted on
2017-06-01
Pages
137
Abstract
Dette speciale undersøger et termisk energilagringssystem (TES), der bruger et betonbaseret materiale kaldet Heatcrete som lagringsmedie og vand/damp som varmeoverførselsvæske (HTF). Fokus er afladningsprocessen, hvor den lagrede varme frigives, og TES-udgangen kobles til en simpel kraftværksturbine for at estimere elproduktionen. Der udvikles to dynamiske modeller: en Lumped-Mass-Model, som beregner gennemsnitstemperaturer for betonen og HTF’en i rørene under afladning, og en FVM-Model, som simulerer temperaturfordelingen (temperaturgradienten) gennem betonen og beregner en gennemsnitlig temperatureffektivitet. Modellerne kobles, så betonens temperaturgradient indgår i Lumped-Mass-Model. Der undersøges også forskellige afladningsscenarier med varierende tid og temperatur. Resultaterne viser, at betonens og HTF’ens temperaturer falder over tid, når systemet aflades. Betonens effektivitet påvirker varmeoverførslen kun begrænset, men en lavere effektivitet reducerer den noget. Forskellige valg af tid og temperatur giver forskellige udgange for TES-systemet og turbinen, og et TES-system med dobbelt størrelse giver omtrent dobbelt varmeoverførsel og turbineydelse.
This thesis examines a thermal energy storage (TES) system that uses a concrete-based material called Heatcrete as the storage medium and water/steam as the heat transfer fluid (HTF). The work focuses on the discharge process, when stored heat is released, and connects the TES output to a simple power plant turbine to estimate electricity production. Two dynamic models are developed: a Lumped-Mass Model, which computes average discharge temperatures for the concrete and the HTF in the pipes, and an FVM-Model, which simulates how temperature varies through the concrete (a temperature gradient) and calculates an average temperature efficiency. The models are coupled so that the concrete’s temperature gradient informs the Lumped-Mass Model. Several discharge scenarios with different time and temperature settings are investigated. The results show that the concrete and HTF temperatures decrease over time during discharge. The concrete’s efficiency has a limited effect on the heat transfer rate, although lower efficiency does reduce it somewhat. Different time and temperature choices lead to different TES and turbine outputs, and doubling the size of the TES system yields approximately double the heat transfer rate and turbine output.
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