Transformerless topologies for grid-connected single-phase photovoltaic inverters

NOTICE: this is the author’s version of a work that was accepted for publication in . Changes resulting from the publishing process, such as peer review, editing, corrections,structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in RENEWABLE AND SUSTAINABLE ENERGY REVIEWS, [VOL 15 , ISSUE 7, (07/2011)] DOI 10.1016/j.rser.2011.03.034[EN] In order to improve the efficiency and reduce the cost of a photovoltaic system, the use of transformerless photovoltaic inverters is an alternative of increasing interest. However, this topology needs to be studied in detail, as it presents some problems related to the galvanic connection between the grid and the photovoltaic generator (e.g. efficiency degradation and safety problems). In this paper, a review of grid-connected single-phase photovoltaic inverters based on transformerless topologies has been carried out. On the one hand, some alternatives based on classical topologies have been presented. On the other hand, alternatives based on multi-level inverter topologies have been studied, showing up that no leakage current is generated in comparison to classical topologies. © 2011 Elsevier Ltd All rights reserved.This work is supported by the Spanish Ministry of Science and Innovation under grant ENE2009-13998-C02-02.Patrao Herrero, I.; Figueres Amorós, E.; González Espín, FJ.; Garcerá Sanfeliú, G. (2011). Transformerless topologies for grid-connected single-phase photovoltaic inverters. Renewable and Sustainable Energy Reviews. 15(7):3423-3431. https://doi.org/10.1016/j.rser.2011.03.034S3423343115

Concentration-Induced Micelle-to-vesicle Transitions in Aqueous Sodium Ricinate Branched Polyoxyethylene Ether Solutions

The aggregation behavior of a novel carboxylate surfactant, sodium ricinate branched polyoxyethylene ether, was studied by dynamic light scattering (DLS), ultraviolet visible spectrophotometer and transmission electron microscope (TEM) measurements. Concentration-induced micelle-to-vesicle transitions were observed when the concentration of surfactant solution was higher than 0.1 mmol/L. And the size of the vesicles decreased with the increasing of the concentration of surfactant. We did a detailed study on this interesting phenomenon and proposed a possible mechanism: intermolecular hydrogen bonds of branched polyoxyethylene ether in the molecule may be the reasons that lead to the formation of vesicles in aqueous solutions of sodium ricinate branched polyoxyethylene ether

Aggregation Behavior of Imidazolium-Based Surface-Active Ionic Liquids with Photoresponsive Cinnamate Counterions in the Aqueous Solution

Two imidazolium-based surface active ionic liquids (SAILs) with photoresponsive cinnamate aromatic counterions, viz. 1-dodecyl-3-methylimidazolium cinnamate ([C₁₂mim]­[CA]) and 1-dodecyl-3-methylimidazolium <i>para</i>-hydroxy-cinnamate ([C₁₂mim]­[PCA]), were newly synthesized, and their self-assembly behaviors in aqueous solutions were systematically explored. Results of surface tension and conductivity measurements show that both [C₁₂mim]­[CA] and [C₁₂mim]­[PCA] display a superior surface activity in aqueous solutions compared to the common imidazolium-based SAIL, 1-dodecyl-3-methylimidazolium bromide (C₁₂mimBr), which implies the incorporation of cinnamate aromatic counterions can promote the micellar formation. Furthermore, [C₁₂mim]­[CA] shows higher surface activity due to the higher hydrophobicity of its counterion in comparison to [C₁₂mim]­[PCA] that has a hydroxyl group. Both hexagonal liquid-crystalline phase (H₁) and cubic liquid-crystalline phase (V₂) were constructed in the [C₁₂mim]­[CA] aqueous solutions. In contrast, the [C₁₂mim]­[PCA]/H₂O system only exhibits a single hexagonal liquid-crystalline phase (H₁) in a broad concentration region. These lyotropic liquid crystal (LLC) phases were comprehensively characterized by polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheometer. Investigation on the temperature-dependent self-assembly nanostructures demonstrates that the higher temperature leads to a looser arrangement. Under UV irradiation, trans–cis photoisomerization of the phenylalkene group results in inferior surface activity of the prepared SAILs in aqueous solution with higher cmc values. Moreover, UV light irradiation induces obvious change of the structural parameters without altering the LLC phases. This work is expected to enrich the investigations of phase behaviors formed in SAILs systems and receive particular attention due to their unique properties and potential applications in drug delivery, biochemistry, materials science, etc

A LOW-COST DATABASE AND SOFTWARE FOR THE MEASUREMENT OF AMMONIA AND GREENHOUSE GAS EMISSIONS OF ANIMAL HOUSES

Measuring the emissions of thousands of animal houses is needed to obtain representative emission factors and relevant categories of animal farms for emission inventories. This scale is also necessary to develop a comprehensive understanding of all facotrs that influence ammonia and greenhouse gas emissions at the farm scale. A robust and low-cost method was developed in France to measure emissions from poultry, bovine and swine houses. A database and associated software is presented here that helps to apply this method to a large number of houses, while protecting the data when the database is used by different companies or institutions. It is based on freeware: an Ubuntu system, OpenOffice for testing equations, PostgreSQL and PgAdmin for database management with “user-only” or “project-only” restricted access to data, and C++ with CodeBlocks and wxWidgets for the calculation and interface modules developed. As for typical Ubuntu software, all messages in the interfaces developed can be translated into several languages using PoEdit. All systems, software and data can be stored on a bootable USB flash drive or SD card with at least two partitions, one for the system (FAT32) compressed into a squashfs file, and one for the modified files (EXT2). The data are divided into three categories: national references (e.g. manure composition), farm references (e.g. specific house characteristics), and observations (e.g. gas concentrations). Training is recommended to begin using the software more quickly. Further development is required to adapt this tool to monitor the results of mitigation strategies and improve their efficiency