Maximizing Vanadium Redox Flow Battery Efficiency: Strategies of Flow Rate Control

Vanadium redox flow batteries (VRFBs) are one of the most promising technologies for large-scale energy storage due to their flexible energy and power capacity configurations. The energy losses evaluation assumes a very important rule on the VRFB characterization in order increase the efficiency of the battery. Very few papers describe the relations between hydraulic, electrical and chemical contributions to the system energy losses, especially in a large size VRFB system. In the first part a fluid dynamics characterization of a 9kW / 27 kWh VRFB test facility has been conducted. In particular, we will consider the internal resistance as the sum of an ohmic and a transport resistance. Secondly, an overall loss assessment based on both numerical and experimental results has been carried out. Finally, some improvements in the battery management strategy and in stack engineering are proposed, that results from this work and can help the future designer to develop more efficient VRFB stack with a compact design

Enhancing the efficiency of kW-class vanadium redox flow batteries by flow factor modulation: An experimental method

he paper presents a control method of the electrolyte flow factor in kW-class Vanadium Redox Flow Batteries that minimizes transport losses without affecting the battery's electrical performance. This method uses experimental data acquired on a 9 kW/27 kWh test facility at varying operating conditions. The effects of overpotentials on the polarization curves are then modeled as non-linear electrical resistances that vary with the stack current, state of charge and electrolyte flow rates. Our analysis of these variables shows that the optimal performance is found if the flow factor is modulated during operation according to stack current and the battery state, so as to minimize the overall flow-dependent losses. The optimal profiles have been identified as functions of the battery's operating conditions. Based on these results, a dynamic control for the electrolyte flow rates has been implemented at a software level (i.e. without modifying the hardware of the test facility), which is capable of maximizing the round-trip efficiency and exceeds the performance achieved with a constant flow factor strategy, as proposed in previous literature. The implementation of the optimal flow rate control requires a preliminary test campaign to collect performance data, which are then used in the control protocol to manage the battery's operation. This scheme is easily implementable at a software level in other industrial redox flow batteries

A validated dynamical model of a kW-class Vanadium Redox Flow Battery

The development of redox flow batteries depends on the research on new materials as well as on the technological development, but also on appropriate models which allow to simulate their performance in operative conditions. Very few investigations are reported in the literature concerning the technology, modeling and simulation of large-scale Vanadium Redox Flow Battery systems, built around multi-cell stacks. This paper regards the modeling of an industrial-sized 9 kW test facility. In particular, a complete dynamic model is presented, that takes into account all thermal effects occurring inside the stack, resulting in a complex non-linear coupled formulation, that allows to simulate the battery operation in any realistic conditions. The model is able to simulate the thermal behavior both in standby, i.e. without power and reactant flow, as well as in load operation, i.e. in charge and discharge. The numerical implementation of the model is described in detail. The model validation is also described, consisting in comparing computed data with experimental measurements taken on the available test facility

Estudo cromossomico em raças naturalizada de bovinos.

Estudo da metafase de linfocitos de animais pertencentes a raça carac

Disponibilidade de cobre na rotação soja-trigo em sistema de plantio direto.

A matéria orgânica (MO) é um quelante natural com capacidade de diminuir a disponibilidade de cobre (Cu) para as plantas, principalmente, quando cultivadas em sistema de plantio direto (SPD). O objetivo deste trabalho foi avaliar os efeitos de doses de Cu sobre a produção e fertilidade do solo na rotação trigo (Triticum aestivum) e soja (Glycine max) em SPD. O delineamento experimental foi o blocos casualizados em parcelas subdividida com quatro repetições. As parcelas consistiram na aplicação de cinco doses de Cu (0, 1, 2, 4 e 8 kg ha-1) em cobertura e a subparcelas os períodos de cultivo. As doses de Cu influenciaram a produção de grãos de trigo e soja. Em solo com alto teor de MO, os extratores DTPA-TEA e Mehlich 1 apresentaram correlação significativa na determinação do Cu disponível, sendo que o DTPA-TEA teve o melhor ajuste (R2) em função das doses de Cu aplicada

Atributos biológicos do solo numa cronossequência de pastagens em sistema ILP no Cerrado.

Neste estudo, objetivou-se avaliar as alterações exercidas pela dinâmica de rotação de culturas anuais e pastagem sobre o componente biológico do solo, com ênfase na cronossequência da fase pastagem, dentro do sistema de integração lavoura-pecuária.bitstream/item/35587/1/comt-198.pd

RI-abitare l’oggi : intorno al progetto di riuso

Interi paesi fantasma, un patrimonio demaniale in disuso e in cerca di valorizzazione, caserme e carceri obsolete o abbandonate collocate all’interno dei centri urbani, capannoni industriali vuoti e un numero crescente di centri commerciali poco o per niente frequentati nelle aree di connessione tra città e campagna, interi complessi industriali abbandonati, palazzi pubblici e privati di dimensione, organizzazione e dotazione di servizi non adeguati alle esigenze odierne. E ancora, chiese, barchesse, scuole, ex colonie ma anche edifici residenziali del tessuto storico urbano e non, architetture storiche e monumentali dal grande valore culturale da rendere funzionali per i diversi usi attuali: sono diversi e sempre più evidenti gli esempi di un patrimonio da riconsiderare, in un’ottica di riutilizzo sostenibile del costruito inteso come risorsa da non sprecare, su cui convergono molteplici obiettivi europei, quali l’incremento dell’efficienza energetica legata al Green New Deal e il raggiungimento del traguardo di zero consumo di suolo, mediante un riuso selettivo e appropriato dell’esistente. In Italia, per la storia plurimillenaria e la forte tradizione identitaria caratterizzata dal ruolo significativo del costruito storico, in cui affondano le radici culturali del Paese, queste sfide richiedono lo sviluppo di un pensiero evoluto sul progetto, in cui l’innovazione e la continuità possano integrarsi, confrontandosi con i principi della Dichiarazione di Davos 2018 Verso una Baukultur di alta qualità per l’Europa e del New European Bauhaus. Sono questi i nuovi temi – o temi noti da riconsiderare – che l’architettura contemporanea deve affrontare, sollecitando una riflessione sui modi di intervenire sul patrimonio costruito e sul ruolo esercitato dalle diverse discipline