Economical comparison of CHP systems for industrial user with large steam demand

In this paper cogeneration benefits applied to a user with a high steam demand are analyzed. The methodology for the feasibility study and the economical analysis of the investment is presented under the Italian legislative framework. The methodology is applied to an actual case and a detailed description and discussion of all data input is provided. Especially this last key point will be faced using starting data usually available in these kind of studies (i.e., not very detailed for thermal consumption). Finally a comparison of different CHP technologies and a sensitivity analysis is done

High-performance magnetic shielding solution for extremely low frequency (ELF) sources

Some particular aspects related to open shields with high performance are presented. The magnetic flux density targets related to the protection of sensitive devices are quite low, <0.2 µT. The problem to reach high magnetic field attenuation is more complicated by the fact that open shields have to be adopted instead of closed solutions. After some general considerations about open shields two practical examples are presented and discussed

Mitigation Solutions for the Magnetic Field Produced by MFDC Spot Welding Guns

Among the different welding technologies, portable welding guns are one of the most critical devices in relation to human exposure to electromagnetic fields. This paper focuses on medium frequency (MF) direct current guns proposing two actions aimed to the mitigation of the magnetic field generated during the welding process. The first action consists in the adoption of a passive shield for the on-board MF transformer. The analysis points out that the transformer alone produces a magnetic field that can exceed the prescribed limits. Therefore, a suitable mitigation system is identified. The second action aims to mitigate the predominant magnetic field that is generated by the electrodes of the welding gun. The analysis of the field waveforms shows that the rise time of the welding current pulse is the main parameter affecting the exposure index. The effect of the increase of the rise time is investigated through experimental and numerical analyses. The results prove that a small increase of the rise time causes a significant reduction of the exposure level. It is noteworthy that the two mitigation actions can be adopted on both existing and newly developed welding guns as they do not require any structural modification of the welding device

A proposal for performance evaluation of low frequency shielding efficiency

The present work aims to propose a methodology for evaluating the performance of low-frequency magnetic shields used for the shielding of complex sources such as MV/LV substations. Today there is no standard procedure for testing shields based on the use of a single-coil for generating artificial MF (MF: Magnetic Field) as is the case for high-frequency anechoic chambers. In the case of shielding for industrial frequency sources, these are generally open shields with sources of various types: 3D transformers, switch-gear, and power lines. These kinds of sources and shields are better checked if the artificial MF has all three components in space. The work proposes a methodology based on the use of a tri-axial source, capable of generating a rotating magnetic field. The supports of the coils are made using a 3D printing process. The paper presents the design steps, the analytical evaluation of the performance of the source and as an application a test of a magnetic shielding plate was presented

Use of weaning concentrate in the feeding suckling kids: effects on meat quality

The effect of a feeding supplementation with starter concentrate on “Capretto” meat production and its qualitative characteristics was investigated. The results showed that the effect of concentrate supplementation did not influence the slaughter weight, slaughter and dissection data, tissue composition and meat chemical composition of the pelvic limb. No differences were found for rheological characteristics of LD meat, except cohesiveness values, which were higher in the concentrate group kids

Magnetic field in an apartment located above 10/0.4 kV substation: Levels and mitigation techniques

The paper presents a real case of non-ionising radiation testing in an apartment located directly above a 10/0.4 kV substation in Serbia. In order to check the compliance with national regulations on protection of population from non-ionising radiation, it was necessary to perform measurements of magnetic flux density in the apartment. After the first measurements were performed, the distribution company implemented a mitigation technique by placing a passive conductive shield inside the substation in order to decrease magnetic field levels in the apartment. Measurements performed after the mitigation technique had been implemented have shown that the applied shield had an impact on magnetic field reduction to a certain extent. However, since the obtained shielding factor was not very high, the authors analysed another possible shielding solution which would provide higher shielding factor and consequently lower magnetic field levels in the apartment. Both shielding solutions and the results they provide are presented and analysed

Uncertainty quantification in energy management procedures

Complex energy systems are made up of a number of components interacting together via different energy vectors. The assessment of their performance under dynamic working conditions, where user demand and energy prices vary over time, requires a simulation tool. Regardless of the accuracy of this procedure, the uncertainty in data, obtained both by measurements or by forecasting, is usually non-negligible and requires the study of the sensitivity of results versus input data. In this work, polynomial chaos expansion technique is used to evaluate the variation of cogeneration plant performance with respect to the uncertainty of energy prices and user requests. The procedure allows to obtain this information with a much lower computational cost than that of usual Monte-Carlo approaches. Furthermore, all the tools used in this paper, which were developed in Python, are published as free and open source software

Influence of posture and coil position on the safety of a WPT system while recharging a compact EV

In this study, the human exposure to the magnetic field emitted by a wireless power transfer (WPT) system during the static recharging operations of a compact electric vehicle (EV) is evaluated. Specifically, the influence of the posture of realistic anatomical models, both in standing and lying positions, either inside or outside the EV, is considered. Aligned and misaligned coil configurations of the WPT system placed both in the rear and front position of the car floor are considered as well. Compliance with safety standards and guidelines has proven that reference levels are exceeded in the extreme case of a person lying on the floor with a hand close to the WPT coils, whereas the system is always compliant with the basic restrictions, at least for the considered scenarios