Maintenance of fire sprinkler systems based on the dynamic assessment of its condition

Safety is one of the major concerns of process safety engineers in most industrial facilities all over the world. To this scope, some events play an important role once the effect of their consequences can be assumed as totally undesirable. One of these events refers to the occurrence of a fire. Such event can result in catastrophic consequences for life, equipment, and continuity of activities or even leading to environmental damage. A fire protection equipment with low reliability means that this equipment are often unavailable and thus the risk of a fire increases. Maintenance of fire protection equipment is very important because this kind of systems is mostly in a dormant mode, which gives uncertainty about their operability when demanded in a real situation of fire. This article outlines the importance of tests, inspection, and maintenance operations in the context of a fire sprinkler system and proposes a methodology based on international standards and supported by test/inspection reports to correct the frequency of these actions according to the level of degradation of the components and regarding safety purposes. © 2015 American Institute of Chemical Engineers.

Modelling a cable structure for a new wind energy production device

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Mecânica Especialização em Concepção e Produção

Energy-dispersive x-ray fluorescence analysis of modern coloured glasses from Marinha Grande (Portugal)

X-Ray Spectrom. 2003; 32: 396–401

CMOS indoor light energy harvesting system for wireless sensing applications

This book discusses in detail the CMOS implementation of energy harvesting. The authors describe an integrated, indoor light energy harvesting system, based on a controller circuit that dynamically and automatically adjusts its operation to meet the actual light circumstances of the environment where the system is placed. The system is intended to power a sensor node, enabling an autonomous wireless sensor network (WSN). Although designed to cope with indoor light levels, the system is also able to work with higher levels, making it an all-round light energy harvesting system. The discussion includes experimental data obtained from an integrated manufactured prototype, which in conjunction with a photovoltaic (PV) cell, serves as a proof of concept of the desired energy harvesting system. © 2016 Springer International Publishing. All rights are reserved.

Energy transduction by respiratory complex I

Dissertation presented to obtain a PhD degree in Biochemistry at the Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa

Estudo da Viabilidade Técnico-Económica de umm Sistema de Cogeração para um Complexo de Piscinas Interiores

A presente dissertação centrou-se no estudo técnico-económico de dois cenários futuros para a continuação de fornecimento de energia térmica a um complexo de piscinas existente na região do vale do Tâmega. Neste momento a central de cogeração existente excedeu a sua licença de utilização e necessita de ser substituída. Os dois cenários em estudo são a compra de uma nova caldeira, a gás natural, para suprir as necessidades térmicas da caldeira existente a fuelóleo, ou o uso de um sistema de cogeração compacto que poderá estar disponível numa empresa do grupo. No primeiro cenário o investimento envolvido é cerca de 456 640 € sem proveitos de outra ordem para além dos requisitos térmicos, mas no segundo cenário os resultados são bem diferentes, mesmo que tenha de ser realizado o investimento de 1 000 000 € na instalação. Para este cenário foi efetuado um levantamento da legislação nacional no que toca à cogeração, recolheram-se dados do edifício como: horas de funcionamento, número de utentes, consumos de energia elétrica, térmica, água, temperatura da água das piscinas, temperatura do ar da nave, assim como as principais características da instalação de cogeração compacta. Com esta informação realizou-se o balanço de massa e energia e criou-se um modelo da nova instalação em software de modelação processual (Aspen Plus® da AspenTech). Os rendimentos térmico e elétrico obtidos da nova central de cogeração compacta foram, respetivamente, de 38,1% e 39,8%, com uma percentagem de perdas de 12,5% o que determinou um rendimento global de 78%. A avaliação da poupança de energia primária para esta instalação de cogeração compacta foi de 19,6 % o que permitiu concluir que é de elevada eficiência. O modelo criado permitiu compreender as necessidades energéticas, determinar alguns custos associados ao processo e simular o funcionamento da unidade com diferentes temperaturas de ar ambiente (cenários de verão e inverno com temperaturas médias de 20ºC e 5ºC). Os resultados revelaram uma diminuição de 1,14 €/h no custo da electricidade e um aumento do consumo de gás natural de 62,47 €/h durante o período mais frio no inverno devido ao aumento das perdas provocadas pela diminuição da temperatura exterior. Com esta nova unidade de cogeração compacta a poupança total anual pode ser, em média, de 267 780 € admitindo um valor para a manutenção de 97 698 €/ano. Se assim for, o projeto apresenta um retorno do investimento ao fim de 5 anos, com um VAL de 1 030 430 € e uma taxa interna de rentabilidade (TIR) de 14% (positiva, se se considerar a taxa de atualização do investimento de 3% para 15 anos de vida). Apesar do custo inicial ser elevado, os parâmetros económicos mostram que o projeto tem viabilidade económica e dará lucro durante cerca de 9 anos.

Estudo comparativo entre o sistema convencional de arrefecimento e o arrefecedor evaporativo para os edifícios industriais portugueses

Em Portugal existem muitos espaços comerciais e industriais em que as necessidades térmicas de arrefecimento são muito superiores às necessidades de aquecimento devido aos ganhos internos que advêm da existência de equipamentos e da iluminação dos edifícios, assim como, da presença das pessoas. A instalação de sistemas convencionais de ar condicionado para espaços comerciais e industriais de grande dimensão está geralmente associada ao transporte de grandes caudais de ar, e consequentemente, a elevados consumos de energia primária, e também, elevados custos de investimento, de manutenção e de operação. O arrefecedor evaporativo é uma solução de climatização com elevada eficiência energética, cujo princípio de funcionamento promove a redução do consumo de energia primária nos edifícios. A metodologia utilizada baseou-se na criação de uma ferramenta informática de simulação do funcionamento de um protótipo de um arrefecedor evaporativo. Foi efetuada a modelação matemática das variáveis dinâmicas envolvidas, dos processos de transferência de calor e de massa, assim como dos balanços de energia que ocorrem no arrefecedor evaporativo. A ferramenta informática desenvolvida permite o dimensionamento do protótipo do arrefecedor evaporativo, sendo determinadas as caraterísticas técnicas (potência térmica, caudal, eficiência energética, consumo energético e consumo e água) de acordo com o tipo de edifício e com as condições climatéricas do ar exterior. Foram selecionados três dimensionamentos de arrefecedores evaporativos, representativos de condições reais de uma gama baixa, média e elevada de caudais de ar. Os resultados obtidos nas simulações mostram que a potência de arrefecimento (5,6 kW, 16,0 kW e 32,8 kW) e o consumo de água (8 l/h, 23,9 l/h e 48,96 l/h) aumentam com o caudal de ar do arrefecedor, 5.000 m3/h, 15.000 m3/h e 30.000 m3/h, respetivamente. A eficácia de permuta destes arrefecedores evaporativos, foi de 69%, 66% e 67%, respetivamente. Verificou-se que a alteração de zona climática de V1 para V2 implicou um aumento de 39% na potência de arrefecimento e de 20% no consumo de água, e que, a alteração de zona climática de V2 para V3 implicou um aumento de 39% na potência de arrefecimento e de 39% no consumo de água. O arrefecedor evaporativo apresenta valores de consumo de energia elétrica entre 40% a 80% inferiores aos dos sistemas de arrefecimento convencionais, sendo este efeito mais intenso quando a zona climática de verão se torna mais severa.

Characterisation of noisy speech channels in 2G and 3G mobile networks

As the wireless cellular market reaches competitive levels never seen before, network operators need to focus on maintaining Quality of Service (QoS) a main priority if they wish to attract new subscribers while keeping existing customers satisfied. Speech Quality as perceived by the end user is one major example of a characteristic in constant need of maintenance and improvement. It is in this topic that this Master Thesis project fits in. Making use of an intrusive method of speech quality evaluation, as a means to further study and characterize the performance of speech codecs in second-generation (2G) and third-generation (3G) technologies. Trying to find further correlation between codecs with similar bit rates, along with the exploration of certain transmission parameters which may aid in the assessment of speech quality. Due to some limitations concerning the audio analyzer equipment that was to be employed, a different system for recording the test samples was sought out. Although the new designed system is not standard, after extensive testing and optimization of the system's parameters, final results were found reliable and satisfactory. Tests include a set of high and low bit rate codecs for both 2G and 3G, where values were compared and analysed, leading to the outcome that 3G speech codecs perform better, under the approximately same conditions, when compared with 2G. Reinforcing the idea that 3G is, with no doubt, the best choice if the costumer looks for the best possible listening speech quality. Regarding the transmission parameters chosen for the experiment, the Receiver Quality (RxQual) and Received Energy per Chip to the Power Density Ratio (Ec/N0), these were subject to speech quality correlation tests. Final results of RxQual were compared to those of prior studies from different researchers and, are considered to be of important relevance. Leading to the confirmation of RxQual as a reliable indicator of speech quality. As for Ec/N0, it is not possible to state it as a speech quality indicator however, it shows clear thresholds for which the MOS values decrease significantly. The studied transmission parameters show that they can be used not only for network management purposes but, at the same time, give an expected idea to the communications engineer (or technician) of the end-to-end speech quality consequences. With the conclusion of the work new ideas for future studies come to mind. Considering that the fourth-generation (4G) cellular technologies are now beginning to take an important place in the global market, as the first all-IP network structure, it seems of great relevance that 4G speech quality should be subject of evaluation. Comparing it to 3G, not only in narrowband but also adding wideband scenarios with the most recent standard objective method of speech quality assessment, POLQA. Also, new data found on Ec/N0 tests, justifies further research studies with the intention of validating the assumptions made in this work.

Energy resources management in three distinct time horizons considering a large variation in wind power

The intensive use of distributed generation based on renewable resources increases the complexity of power systems management, particularly the short-term scheduling. Demand response, storage units and electric and plug-in hybrid vehicles also pose new challenges to the short-term scheduling. However, these distributed energy resources can contribute significantly to turn the shortterm scheduling more efficient and effective improving the power system reliability. This paper proposes a short-term scheduling methodology based on two distinct time horizons: hour-ahead scheduling, and real-time scheduling considering the point of view of one aggregator agent. In each scheduling process, it is necessary to update the generation and consumption operation, and the storage and electric vehicles status. Besides the new operation condition, more accurate forecast values of wind generation and consumption are available, for the resulting of short-term and very short-term methods. In this paper, the aggregator has the main goal of maximizing his profits while, fulfilling the established contracts with the aggregated and external players.

SCADA House Intelligent Management for Energy Efficiency Analysis in Domestic Consumers

The implementation of smart homes allows the domestic consumer to be an active player in the context of the Smart Grid (SG). This paper presents an intelligent house management system that is being developed by the authors to manage, in real time, the power consumption, the micro generation system, the charge and discharge of the electric or plug-in hybrid vehicles, and the participation in Demand Response (DR) programs. The paper proposes a method for the energy efficiency analysis of a domestic consumer using the SCADA House Intelligent Management (SHIM) system. The main goal of the present paper is to demonstrate the economic benefits of the implemented method. The case study considers the consumption data of some real cases of Portuguese house consumption over 30 days of June of 2012, the Portuguese real energy price, the implementation of the power limits at different times of the day and the economic benefits analysis.

Modified Discrete PSO to Increase the Delivered Energy Probability in Distribution energy Systems

This paper proposes a PSO based approach to increase the probability of delivering power to any load point by identifying new investments in distribution energy systems. The statistical failure and repair data of distribution components is the main basis of the proposed methodology that uses a fuzzyprobabilistic modeling for the components outage parameters. The fuzzy membership functions of the outage parameters of each component are based on statistical records. A Modified Discrete PSO optimization model is developed in order to identify the adequate investments in distribution energy system components which allow increasing the probability of delivering power to any customer in the distribution system at the minimum possible cost for the system operator. To illustrate the application of the proposed methodology, the paper includes a case study that considers a 180 bus distribution network.

Dispatch of distributed Energy Resources to Provide Energy and Reserve in Smart Grids using a Particle Swarm Optimization Approach

The smart grid concept is a key issue in the future power systems, namely at the distribution level, with deep concerns in the operation and planning of these systems. Several advantages and benefits for both technical and economic operation of the power system and of the electricity markets are recognized. The increasing integration of demand response and distributed generation resources, all of them mostly with small scale distributed characteristics, leads to the need of aggregating entities such as Virtual Power Players. The operation business models become more complex in the context of smart grid operation. Computational intelligence methods can be used to give a suitable solution for the resources scheduling problem considering the time constraints. This paper proposes a methodology for a joint dispatch of demand response and distributed generation to provide energy and reserve by a virtual power player that operates a distribution network. The optimal schedule minimizes the operation costs and it is obtained using a particle swarm optimization approach, which is compared with a deterministic approach used as reference methodology. The proposed method is applied to a 33-bus distribution network with 32 medium voltage consumers and 66 distributed generation units.

Intelligent Remuneration and Tariffs for Virtual Power Players

Power systems have been through deep changes in recent years, namely due to the operation of competitive electricity markets in the scope the increasingly intensive use of renewable energy sources and distributed generation. This requires new business models able to cope with the new opportunities that have emerged. Virtual Power Players (VPPs) are a new type of player that allows aggregating a diversity of players (Distributed Generation (DG), Storage Agents (SA), Electrical Vehicles (V2G) and consumers) to facilitate their participation in the electricity markets and to provide a set of new services promoting generation and consumption efficiency, while improving players’ benefits. A major task of VPPs is the remuneration of generation and services (maintenance, market operation costs and energy reserves), as well as charging energy consumption. This paper proposes a model to implement fair and strategic remuneration and tariff methodologies, able to allow efficient VPP operation and VPP goals accomplishment in the scope of electricity markets.

Smart Grid Market Using Joint Energy and Ancillary Services Bids

The power systems operation in the smart grid context increases significantly the complexity of their management. New approaches for ancillary services procurement are essential to ensure the operation of electric power systems with appropriate levels of stability, safety, quality, equity and competitiveness. These approaches should include market mechanisms which allow the participation of small and medium distributed energy resources players in a competitive market environment. In this paper, an energy and ancillary services joint market model used by an aggregator is proposed, considering bids of several types of distributed energy resources. In order to improve economic efficiency in the market, ancillary services cascading market mechanism is also considered in the model. The proposed model is included in MASCEM – a multi-agent system electricity market simulator. A case study considering a distribution network with high penetration of distributed energy resources is presented.

Integration in MASCEM of the Joint Dispatch of Energy and Reserves Provided by Generation and Demand Resources

The provision of reserves in power systems is of great importance in what concerns keeping an adequate and acceptable level of security and reliability. This need for reserves and the way they are defined and dispatched gain increasing importance in the present and future context of smart grids and electricity markets due to their inherent competitive environment. This paper concerns a methodology proposed by the authors, which aims to jointly and optimally dispatch both generation and demand response resources to provide the amounts of reserve required for the system operation. Virtual Power Players are especially important for the aggregation of small size demand response and generation resources. The proposed methodology has been implemented in MASCEM, a multi agent system also developed at the authors’ research center for the simulation of electricity markets.