Search results for " Structural"
showing 10 items of 1751 documents
Coupled hydraulic and electronic regulation of cross-flow turbines in hydraulic plants
2017
The potential benefit of coupling hydraulic and electronic regulation to maximize the energy production of a cross-flow turbine in hydraulic plants is analyzed and computed with reference to a specific case. Design criteria of the cross-flow turbine inside hydraulic plants are first summarized, along with the use of hydraulic regulation in the case of constant water head and variable discharge. Optimal turbine impeller rotational speed is derived, and traditional as well as innovative systems for electrical regulation are presented. A case study is analyzed to evaluate the potential energy production according to the expected monthly mean flow distribution and two possible choices: CFT1 wit…
A set of indices to assess the real performance of daylight-linked control systems
2017
Abstract The installation of Building Automation Control Systems (BACs) in general is an effective action to achieve relevant energy savings. Commercial BACs, installed in residential or small offices, often include functions of lighting control, acting as Daylight-Linked Control Systems (DLCSs). Nevertheless, because system performance is strictly dependent on different parameters, BAC’s hardware and software configuration and as well as an inaccurate commissioning do not always allow a perfect execution of the desired tasks; therefore, the system could not work as expected. Moreover, it is well known that energy saving potential is specifically related to the variability of the light envi…
CHP (combined heat and power) retrofit for a large MED-TVC (multiple effect distillation along with thermal vapour compression) desalination plant: H…
2016
Abstract Integrated power plants in “dual purpose” configuration may represent a viable option for energy cost abatement of desalted water produced by MED-TVC (Multiple Effect Distillation along with Thermal Vapour Compression). In this paper an existing large MED-TVC plant with a 36,000 m 3 /day capacity is studied: a plant retrofit is designed, based on a steam power plant with condensation and steam extraction used to drive the steam ejector. As the plant operates in CHP (Combined Heat and Power) mode, the possibility to assess the integrated “CHP + MED-TVC” as high efficiency cogeneration according to Directive 2004/8/EC is discussed. Based on a model developed in Engineering Equation S…
Online optimization of a multi-conversion-level DC home microgrid for system efficiency enhancement
2017
In this paper, an on-line management system for the optimal efficiency operation of a multi-bus DC home distribution system is proposed. The operation of the system is discussed with reference to a distribution system with two conversion stages and three voltage levels. In each of the conversion stages, three paralleled DC/DC converters are implemented. A Genetic Algorithm performs the on-line optimization of the DC network’s global efficiency, generating the optimal current sharing ratios of the concurrent power converters. The overall DC/DC conversion system including the optimization section is modelled using MATLAB/Simulink. Thanks to the implemented online algorithm, considering …
Vegetation and soil – related parameters for computing solar radiation exchanges within green roofs: Are the available values adequate for an easy mo…
2016
Several studies analyze the thermal performance of vegetated roofs, presenting either mathematical models or experimental quantifications of heat transfer process through them, also showing the effect of vegetation and soil parameters on the thermal and energy performance of this type of roofing system. However, presently the level of availability of these parameters, has not been enough considered. This work intends to investigate this underestimated issue of the green roofs’ thermal modeling, through the consideration of the availability of parameters pertinent to the shortwave radiation exchange, which are adopted by models based on leaf area index (LAI) and on the fractional vegetation …
Assessing the feasibility of cogeneration retrofit and district heating/cooling networks in small Italian islands
2017
Sustainability of energy supply strategies in small islands has been emerging as a severe issue, due to the large margins for improvement and rationalization of the most frequently adopted solutions. In most of the European islands, large amounts of heat are wasted by the operation of engine-based power plants; conversely, heat is produced by boilers (supplied by liquid fuels) or by electric equipment for a number of different uses, like domestic hot water production or space heating in winter. In this paper a techno-economic analysis is proposed to assess the feasibility of CHP-retrofit of the existing power plants and the possible utilization of the recovered heat to supply, via a distric…
PCM thermal storage design in buildings: Experimental studies and applications to solaria in cold climates
2017
Abstract As energy availability and demand often do not match, thermal energy storage plays a crucial role to take advantage of solar radiation in buildings: in particular, latent heat storage via phase-change material is particularly attractive due to its ability to provide high energy storage density. This paper analyzes the performance of a building-integrated thermal storage system to increase the energy performances of solaria in a cold climate. A wall opposing a highly glazed facade (south oriented) is used as thermal storage with phase change materials embedded in the wall. The study is based on both experimental and simulation studies. The concept considered is particularly suited t…
Sequential design of multioverlapping controllers for structural vibration control of tall buildings under seismic excitation
2012
In this article, a computationally effective strategy to obtain multioverlapping controllers via the inclusion principle is applied to design a state-feedback multioverlapping linear-quadratic regulator controller for a 20-story building. The proposed semidecentralized controller only requires state information of neighboring stories to compute the corresponding control actions. This particular information exchange configuration allows introducing a dramatic reduction in the transmission range required for a wireless implementation of the communications system. More specifically, just a one-story transmission range is required by the proposed multioverlapping controller, while a full-buildi…
A comparative evaluation of crashworthy composite sandwich structures
2007
Abstract This paper describes an experimental evaluation of the energy absorption properties of a series of novel designs for cost-effective crashworthy composite sandwich structures. All the designs are based on the concept of the “tied-core” sandwich, i.e. the use of additional core reinforcements that act to tie the opposing facings of a sandwich together, thus preventing catastrophic failure under edgewise loading. The design, manufacture and crush testing of hollow rectangular tubes fabricated from six different tied-core concepts is described. Factors that are shown to promote high energy absorption include large, continuous areas of contact between the facings and the ties, non-thin …
The control of indoor thermal comfort conditions: introducing a fuzzy adaptive controller
2004
The control and the monitoring of indoor thermal conditions represents a pre-eminent task with the aim of ensuring suitable working and living spaces to people. Especially in industrialised countries, in fact, several rules and standards have been recently released in order of providing technicians with suitable design tools and effective indexes and parameters for the checking of the indoor microclimate. Among them, predicted mean vote (PMV) index is often adopted for assessing the thermal comfort conditions of thermal moderate environments. Unfortunately, the PMV index is characterised by non-linear features, that could determine some difficulties when monitoring and controlling HVAC equi…