Experimental results and thermodynamic analysis of a natural gas small scale cogeneration plant for power and refrigeration purposes

In this work, experimental results are reported for a small scale cogeneration plant for power and refrigeration purposes. The plant includes a natural gas microturbine and an ammonia/water absorption chiller fired by steam. The system was tested under different turbine loads, steam pressures and chiller outlet temperatures. An evaluation based on the 1st and 2nd Laws of Thermodynamics was also performed. For the ambient temperature around 24°C and microturbine at full load, the plant is able to provide 19 kW of saturated steam at 5.3 bar (161 °C), corresponding to 9.2 kW of refrigeration at -5 °C (COP = 0.44). From a 2nd law point-of-view, it was found that there is an optimal chiller outlet temperature that maximizes the chiller exergetic efficiency. As expected, the microturbine presented the highest irreversibilities, followed by the absorption chiller and the HRSG. In order to reduce the plant exergy destruction, it is recommended a new design for the HRSG and a new insulation for the exhaust pipe. © 2013 Elsevier Ltd. All rights reserved.

Acceso al poder y participación en la toma de decisiones en América Latina y el Caribe: políticas de equidad de género hacia el año 2000 = Access to power and participation in decision-making in Latin America and the Caribbean: policies for gender equity looking to the year 2000

Incluye Bibliografía

Informe del Seminario-Taller sobre Políticas para el Control y la Fiscalización de la Contaminación Atmosférica de las Fuentes Fijas de los Sectores Productivo y Energético = Report of the Seminar-Workshop on Policies for the Regulation and Control of Air Pollution from Fixed Sources in the Production and Energy Sectors

Contiene antecedentes, asistencia y organización de los trabajos y resumen de las presentaciones de la reunión que tuvo como objetivo analizar los aspectos jurídicos, institucionales, económicos y tecnológicos de la política de descontaminación ambiental. Incluye lista de documentos presentados y de participantes.

Economical use of hydro power, steam power and system interconnections

Includes bibliography

Report of the Workshop on Investment Funding for Renewable Energy and Energy Efficiency Projects in the Caribbean

Includes bibliography

Antecedentes para la formulación e implementación de una política para el control y la fiscalización de la contaminación atmosférica de las fuentes fijas de los sectores productivo y energético = Background information for the formulation and implementation of a policy on the regulation and control of air pollution from fixed sources in the production and energy sectors

Incluye Bibliografía

Critical factors to be considered when planning the implementation of environmental improvements and energy saving

To identify the critical success factors in the adoption of energy efficiency actions in Brazilian hospitals and describe their behaviour are the objectives of this paper. In order to achieve these goals, a literature review was performed on green management and energy efficiency. This was the basis to define the questions of the interview script applied to two hospitals located in the state of Sao Paulo, Brazil. The interview script application was complemented by secondary data and direct observation. The results showed that: a) the studied hospitals are embracing environmental management actions more often and, whenever possible, energy efficiency actions are taken as well; and b) in the cases analysed top management support, commitment with the environment, green process design and employee empowerment were some of the most relevant critical success factors to the accomplishment of energy efficiency actions. These findings may be of interest to emerging countries, including BRICS (Brazil, Russia, India, China and South Africa).

Chemical Composition, Rumen Fermentation Kinetics, Digestibility and Energy Value of Cassava Leaves Hay at Different Storage Times

Cassava leaves have been widely used as a protein source for ruminants in the tropics. However, these leaves contain high level of hydro-cyanic acid (HCN) and condensed tannins (CT). There are evidences that making hay can eliminate more than 90% of HCN and that long-term storage can reduce CT levels. A complete randomized design with four replicates was conducted to determine the effect of different storage times (0-control, 60, 90 and 120 days) on chemical composition, in vitro rumen fermentation kinetics, digestibility and energy value of cassava leaves hay. Treatments were compared by analyzing variables using the GLM procedure (SAS 9.1, SAS Institute, Inc., Cary, NC). Crude protein (CP) and ether extract (EE) of the cassava hay were not affected (P > 0.05) by storage time (17.7% and 3.0%, respectively). Neutral detergent fiber, acid detergent fiber, total carbohydrate and non-fiber carbohydrate were not affected either (P>0.05) by storage time (47.5, 32.6, 72.3 and 25.8% respectively). However, other parameters were influenced. CT was lower (P<0.05) in hay after 120 days of storage compared with control (1.75% versus 3.75%, respectively). Lignin and insoluble nitrogen in neutral detergent, analyzed without sodium sulfite, were higher (P<0.01) after 120 days of storage, compared with the control (11.22 versus 13.57 and 1.65 versus 3.81% respectively). This suggests that the CT has bound to the fiber or CP and became inactive. Consequently, the in vitro digestibility of organic matter (50.36%), total digestible nutrients (44.79%) and energy (1.61 Mcal/KgMS), obtained from gas production data at 72 h of incubation, has increased (P<0.05) with storage times (56.83%, 51.53% and 1.86 Mcal/KgMS, respectively). The chemical composition and fermentative characteristics of cassava hay suffered variations during the storage period. The best values were obtained after 90 days of storage. This is probably due to the reduction in condensed tannins.

Capacity of Active Power Reserve for Frequency Control Enhanced by Distributed Generators

Usually, ancillary services are provided by large conventional generators; however, with the growing interest in distributed generation to satisfy energy and environmental requirements, it seems reasonable to assume that these services could also be provided by distributed generators in an economical and efficient way. In this paper, a proposal for enhancement of the capacity of active power reserve for frequency control using distributed generators is presented. The goal is to minimize the payments done by the transmission system operator to conventional and distributed generators for this ancillary service and for the energy needed to satisfy loads and system losses, subject to a set of constraints. In order to perform analysis, the proposal was implemented using data of the IEEE 30-bus transmission test system. Comparisons were performed considering conventional generators without and with distributed generators installed in the system.

Optimal Reactive Power Planning Using Risk Analysis

In this paper, the optimal reactive power planning problem under risk is presented. The classical mixed-integer nonlinear model for reactive power planning is expanded into two stage stochastic model considering risk. This new model considers uncertainty on the demand load. The risk is quantified by a factor introduced into the objective function and is identified as the variance of the random variables. Finally numerical results illustrate the performance of the proposed model, that is applied to IEEE 30-bus test system to determine optimal amount and location for reactive power expansion.

Nickel exposure promotes osmoregulatory disturbances in Oreochromis niloticus gills: histopathological and energy dispersive spectrometry analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sex and reproductive stage differences in the growth, metabolism, feed, fecal production, excretion and energy budget of the Amazon River prawn (Macrobrachium amazonicum)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)