IRIS Pol. Torinohttps://iris.polito.itIl sistema di repository digitale IRIS acquisisce, archivia, indicizza, conserva e rende accessibili prodotti digitali della ricerca.Fri, 23 Jul 2021 19:49:03 GMT2021-07-23T19:49:03Z1031Optimized synthesis/design of the carbonator side for direct integration of thermochemical energy storage in small size Concentrated Solar Powerhttp://hdl.handle.net/11583/2787391Titolo: Optimized synthesis/design of the carbonator side for direct integration of thermochemical energy storage in small size Concentrated Solar Power
Abstract: Two of the most attractive characteristics of Concentrated Solar Power are the high-quality heat exploitable and its capacity for thermal energy storage, which enhance the energy dispatchability in comparison with other renewable sources such as photovoltaics or wind. Consistent efforts are therefore direct to the research of suitable thermodynamic cycles and energy storage systems with low thermal losses and high operating temperatures. However, in the most developed technologies, based on sensible and latent heat storage, high thermal losses are the direct consequence of high operating temperatures. As alternative, Thermochemical Energy Storage systems are gaining attention in the last years.
The present work investigates the adoption of a novel Calcium-Looping system for Thermochemical Energy Storage, focusing on the integration on carbonator side. This key integration is directly linked to the energy delivery from the energy storage system and therefore power generation capacity of the plant. An optimization of the carbonator side plant is performed for a direct integration layout, where carbon dioxide from the carbonator evolves through the power block. This analysis aims to maximize the system efficiency acting both on the process components operation and on the thermal transfer between the involved streams. The optimization relies on a novel method based on a genetic algorithm. The pinch analysis is adopted for this study and proper constraints are provided to obtain a configuration exploiting only the renewable energy source. A multi-objective optimization is performed to find out the heat exchanger network topology changes that occur for different operating conditions and derived from this analysis suggestion for systems integration are provided.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/11583/27873912019-01-01T00:00:00ZIntegration of thermochemical energy storage in concentrated solar power. Part 1: Energy and economic analysis/optimizationhttp://hdl.handle.net/11583/2842818Titolo: Integration of thermochemical energy storage in concentrated solar power. Part 1: Energy and economic analysis/optimization
Abstract: Coupling of Concentrated Solar Power and Thermo-Chemical Energy Storage is a very interesting option because of the high efficiencies attainable with a renewable source and the large variation of solar radiation. Thermo-Chemical Energy Storage based on Calcium-Looping represents a promising opportunity thanks to high operating temperature, high energy density, null thermal losses and cheap calcium oxide precursor exploitable. The large variety of suitable power blocks and the importance of their integration in the discharging process makes it necessary to perform a coherent analysis of the selected alternatives, in order to compare them and establish the most convenient integration. Many aspects must be taken into account, such as system efficiency, investment costs and layout complexity. The purposes of the present work are: the development of a methodology to simulate the entire plant operations; the synthesis of heat recovery systems for both the charging and discharging processes; the execution of an economic analysis and the development of economic optimizations for the design/dimensioning of solar side and calciner side. Between the options investigated, power blocks based on supercritical CO2 are the most convenient both in terms of global efficiency (higher than 19%) and capital investment, keeping this advantage also for higher plant sizes. The methodology here developed and the results obtained are useful information for a deeper analysis of the most promising integration alternative, which is performed in the second part of this study.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/11583/28428182020-01-01T00:00:00ZIntegration of thermochemical energy storage in concentrated solar power. Part 2: Comprehensive optimization of supercritical CO2 power blockhttp://hdl.handle.net/11583/2842814Titolo: Integration of thermochemical energy storage in concentrated solar power. Part 2: Comprehensive optimization of supercritical CO2 power block
Abstract: Among the various options of Thermo-Chemical Energy Storage, Calcium-Looping represents a promising alternative for Concentrated Solar Power plants, thanks to high operating temperatures, high energy density and absence of thermal losses. Finding the most suitable power cycle for this system is a task that has still to be solved and is not trivial because it consists in a complex process synthesis problem. From a preliminary analysis (Part 1), supercritical CO2 cycles results to be the most promising option. In the present work, the integration of this power block (pilot plant size, 2 MWe) is deeply investigated through a comprehensive analysis. Numerous thermal cycle layouts are considered and two options for the power block thermal feeding are assumed. The HEATSEP methodology (comprising genetic algorithm, pinch analysis and bisection) is adopted to optimize both components operating conditions and heat transfer processes in the discharging phase. The plant section devoted to the charging process is optimized and dimensioned taking into account the transient operation. Thanks to the complex problem structure developed, the algorithm is free to find the most suitable configuration between a huge set of feasible combinations. Both energy and economic optimizations are performed for the complete plant and, being in contrast between them, a multi-objective optimization is executed. The independent variables influence on the resulting configuration is assessed and intermediate layouts obtained from the Pareto curve are commented. Carbonator inlet temperature of reactants are observed to increase with plant efficiency. The maximum efficiency (21%) is obtained with the most complex power block (recompression, intercooling and reheating) exchanging heat directly on the carbonator wall. Less performing discharging processes are cheaper but determine higher costs of charging sections; the resulting effect is positive and the integration of simpler power blocks results economically convenient. A power cycle with single intercooling and thermal feeding performed on the carbonator outflows is the result of economic optimization (efficiency equal to 16.3%). The algorithm gives precedence to power block thermal feeding and then to reactants preheating. Novel plant layouts are designed for these configurations and data useful for further investigations are provided in the last part of this work.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/11583/28428142020-01-01T00:00:00Z