61,527 research outputs found
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Integrated Dynamic Facade Control with an Agent-based Architecture for Commercial Buildings
Dynamic façades have significant technical potential to minimize heating, cooling, and lighting energy use and peak electric demand in the perimeter zone of commercial buildings, but the performance of these systems is reliant on being able to balance complex trade-offs between solar control, daylight admission, comfort, and view over the life of the installation. As the context for controllable energy-efficiency technologies grows more complex with the increased use of intermittent renewable energy resources on the grid, it has become increasingly important to look ahead towards more advanced approaches to integrated systems control in order to achieve optimum life-cycle performance at a lower cost. This study examines the feasibility of a model predictive control system for low-cost autonomous dynamic façades. A system architecture designed around lightweight, simple agents is proposed. The architecture accommodates whole building and grid level demands through its modular, hierarchical approach. Automatically-generated models for computing window heat gains, daylight illuminance, and discomfort glare are described. The open source Modelica and JModelica software tools were used to determine the optimum state of control given inputs of window heat gains and lighting loads for a 24-hour optimization horizon. Penalty functions for glare and view/ daylight quality were implemented as constraints. The control system was tested on a low-power controller (1.4 GHz single core with 2 GB of RAM) to evaluate feasibility. The target platform is a low-cost ($35/unit) embedded controller with 1.2 GHz dual-core cpu and 1 GB of RAM. Configuration and commissioning of the curtainwall unit was designed to be largely plug and play with minimal inputs required by the manufacturer through a web-based user interface. An example application was used to demonstrate optimal control of a three-zone electrochromic window for a south-facing zone. The overall approach was deemed to be promising. Further engineering is required to enable scalable, turnkey solutions
Positioning And Design Recommendations For Materials Of Efficient Thermal Storage Mass In Passive Buildings
The role of mass in energy storage has long been a subject of interest in passive buildings. Thermal mass is used to diminish temperature variations for interior spaces in desert or semi- desert climates. Energy from solar and internal gains during the day in winter is often greater than daytime heating requirements. This energy can be stored in materials within the building, and released at night to offset building heat loss. In a similar manner, building mass may allow the interior to remain cooler during the daytime in summer and reduce air conditioning requirements. In this paper, the geometric and energetic positioning of thermal mass has been studied in order to determine most convenient locations. It is found that floors receive direct solar energy for a high percentage of time, usually 70%-90% of the radiation transmitted through the window during the day (9 am to 3 pm solar time). The materials related to the technical efficiency of thermal mass are reviewed specifying the thickness most suitable for storing solar heat in the winter or keeping the interior cool in summer.Fil: Esteves, Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ambiente, Habitat y Energia.; ArgentinaFil: Mercado, Ma. Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ambiente, Habitat y Energia.; ArgentinaFil: Ganem, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ambiente, Habitat y Energia.; Argentina. Universidad Nacional de Cuyo. Facultad de Artes y Diseño; ArgentinaFil: Gelardi, Daniel. Universidad de Mendoza. Instituto Para El Estudio del Medio Ambiente; Argentin
Hierarchical macro-nanoporous metals for leakage-free high-thermal conductivity shape-stabilized phase change materials
Impregnation of Phase Change Materials (PCMs) into a porous medium is a
promising way to stabilize their shape and improve thermal conductivity which
are essential for thermal energy storage and thermal management of small-size
applications, such as electronic devices or batteries. However, in these
composites a general understanding of how leakage is related to the
characteristics of the porous material is still lacking. As a result, the
energy density and the antileakage capability are often antagonistically
coupled. In this work we overcome the current limitations, showing that a high
energy density can be reached together with superior anti-leakage performance
by using hierarchical macro-nanoporous metals for PCMs impregnation. By
analyzing capillary phenomena and synthesizing a new type of material, it was
demonstrated that a hierarchical trimodal macro-nanoporous metal (copper)
provides superior antileakage capability (due to strong capillary forces of
nanopores), high energy density (90vol% of PCM load due to macropores) and
improves the charging/discharging kinetics, due to a three-fold enhancement of
thermal conductivity. It was further demonstrated by CFD simulations that such
a composite can be used for thermal management of a battery pack and unlike
pure PCM it is capable of maintaining the maximum temperature below the safety
limit. The present results pave the way for the application of hierarchical
macro-nanoporous metals for high-energy density, leakage-free, and
shape-stabilized PCMs with enhanced thermal conductivity. These innovative
composites can significantly facilitate the thermal management of compact
systems such as electronic devices or high-power batteries by improving their
efficiency, durability and sustainabilit
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Expert-based development of a standard in CO2 sequestration monitoring technology
Bureau of Economic Geolog
Small-Scale Compressed Air Energy Storage Application for Renewable Energy Integration in a Listed Building
In the European Union (EU), where architectural heritage is significant, enhancing the energy performance of historical buildings is of great interest. Constraints such as the lack of space, especially within the historical centers and architectural peculiarities, make the application of technologies for renewable energy production and storage a challenging issue. This study presents a prototype system consisting of using the renewable energy from a photovoltaic (PV) array to compress air for a later expansion to produce electricity when needed. The PV-integrated small-scale compressed air energy storage system is designed to address the architectural constraints. It is located in the unoccupied basement of the building. An energy analysis was carried out for assessing the performance of the proposed system. The novelty of this study is to introduce experimental data of a CAES (compressed air energy storage) prototype that is suitable for dwelling applications as well as integration accounting for architectural constraints. The simulation, which was carried out for an average summer day, shows that the compression phase absorbs 32% of the PV energy excess in a vessel of 1.7 m(3), and the expansion phase covers 21.9% of the dwelling energy demand. The electrical efficiency of a daily cycle is equal to 11.6%. If air is compressed at 225 bar instead of 30 bar, 96.0% of PV energy excess is stored in a volume of 0.25 m3, with a production of 1.273 kWh, which is 26.0% of the demand
Mathematical modelling of operation modes and performance evaluation of an innovative small-scale concentrated solar organic Rankine cycle plant
In this paper an innovative small-scale concentrated solar 2 kWe organic Rankine cycle plant coupled with a phase change material storage tank equipped with reversible heat pipes is investigated using a simulation analysis. The plant, intended for residential applications, is going to be built and tested under the European funded H2020 Innova MicroSolar project executed by the consortium of several Universities and industrial organizations, led by Northumbria University. The authors of this work used the design of the integrated system, developed by the consortium, to preliminary estimate the overall performance of the system in order to provide useful information for its forthcoming real operation. In particular, according to the varying ambient conditions, the influence of different operation modes of the prototype plant are evaluated. The dynamic simulation analysis has shown an interesting performance of the system in terms of annual operating hours, power production and conversion efficiencies. More precisely, the organic Rankine cycle unit is able to operate for more than 3100 h/year, achieving the design performance when solar power is sufficiently high, producing about 5100 kWhe/year. For the considered operating set-point temperatures of the thermal energy storage, the plant is able to reach high conversion efficiency also when the organic Rankine cycle unit is supplied by discharging the energy stored in the storage tank, for about 800 h/year. Hence, the work has provided some useful insights into the best working conditions of such micro combined heat and power system to be integrated in residential buildings. Moreover, the analysis could serve as a general guide for the design and optimization of the mutual interactions of the different subsystems in small-scale concentrated solar organic Rankine cycle plants
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