Resumo Ainfluência do comportamento dos usuários em edificações é amplamente discutida como uma das causas para discrepâncias entre consumos energéticos esperados, durante a fase de projeto, e consumos durante a operação. Conhecer os principais motivadores para ajustes nos sistemas de edificações é imprescindível para aprimorar a modelagem desses comportamentos. O objetivo deste estudo é avaliar os principais agentes motivadores para o ajuste das janelas, luminárias e aparelhos de ar-condicionado em escritórios. Dois escritórios foram monitorados por meio de sensores que coletaram dados de qualidade do ambiente interno e comportamento de usuário. Foram consideradas influentes para a interação com sistemas de janelas a pluviometria e as temperaturas do ar externo e interno. O aumento das temperaturas interna e externa apresentou ainda mais influência na interaçãocom aparelhos de ar-condicionado. Duas foram as principais conclusões: há influência do layout dos escritórios no compartilhamento e controle das janelas e eficiência de estratégias passivas, como o uso de ventilação natural e cruzada; e há influência do aumento da temperatura interna em comparação à externa na previsibilidade de abertura de janelas e acionamento de aparelhos de ar-condicionado. esperados projeto operação comportamentos arcondicionado condicionado usuário arcondicionado. condicionado. conclusões passivas cruzada

Abstract The influence of occupant behaviour in buildings is widely discussed as one of the causes for the gap between energy use estimated via computer simulation and during building operation. Knowing the main drivers for adjustments in building systems is essential to guide the development of mathematical models for such behaviours. The aim of this study is to evaluate the main motivating agents for adjusting windows, luminaires, and air-conditioning in offices. Two offices were monitored using sensors that collected data from the internal environment and user interaction with such systems. Rainfall and external and internal air temperatures were considered influential for the interaction with window systems. The increase in internal and external temperatures had even more influence on interactions with air-conditioners. The main conclusions were: there is influence of the layout of the offices in the sharing and control of windows and efficiency of passive strategies, such as the use of natural and cross ventilation; and there is an influence of the increase in internal temperature compared to external temperature in the predictability of opening windows and turning air-conditioning devices on. operation behaviours luminaires airconditioning conditioning airconditioners. airconditioners conditioners. conditioners air-conditioners strategies ventilation

Abstract There is a growing interest in reducing energy consumption in the economic sectors, where the residential sector is a substantial consumer of energy in societies and therefore, a focus of attention for efficiency and renewable energy generation policies. In Ecuador, residential consumption represents 1/4 of the total electricity demanded by the socioeconomic system. Household composition has changed due to demographic dynamics, socioeconomic improvements and social justice efforts, which impacts electricity consumption. The aim of this study is to analyze the dynamics of energy consumption in Ecuador´s residential sector based on the construction of household typologies under the hierarchy of demographic, geographic, economic and technical variables using a top-down and bottom-up methodology and the application of MuSIASEM for which statistical information from National Surveys and Censuses was used, which allowed the construction of household typologies and their consumption pattern. The results show heterogeneous electricity consumptions in the 4.5 million households in 2017 hierarchically divided into 240 typologies. The pattern varies from the lowest consumption households with 50 KWh/month to the highest consumption of 350 KWh/month. For example, in the urban area the highest rate is concentrated in households made up of more than 8 people with rates between 150 to 180 KWh/month, while in the rural area the values range from 90 to 120 KWh/month but differ by geographic location and male or female headship. Likewise, the data allowed scaling to aggregate levels where it is shown that, of the total annual electricity consumption of 6,428 GWh, 54% of the consumption was concentrated in the coastal region, which concentrates 51% of the total households in the residential sector of Ecuador.

Resumen Existe un interés creciente por reducir el consumo de energía en los sectores económicos, donde el sector residencial es un consumidor sustancial de energía en las sociedades y por tanto, un foco de atención para las políticas de eficiencia y de generación energética renovable. En Ecuador, el consumo residencial representa un 1/4 del total de electricidad que demanda el sistema socioeconómico. La conformación de los hogares ha cambiado por la dinámica demográfica, mejoras socioeconómicas y los esfuerzos por la justicia social, lo cual impacta en el consumo de electricidad. El objetivo del estudio es analizar la dinámica del consumo de energía en el sector residencial del Ecuador a partir de la construcción de tipologías de hogares bajo la jerarquización de variables demográficas, geográficas, económicas y técnicas utilizando una metodología top-down y bottom-up y la aplicación de MuSIASEM para lo cual se utilizó información estadística de Encuestas y Censos Nacionales, que permitió construir las tipologías de hogares y su patrón de consumo. Los resultados muestran consumos de electricidad heterogéneos en los 4,5 millones de hogares presentes en 2017 divididos jerárquicamente en 240 tipologías. El patrón varía desde los hogares de menor consumo con 50 KWh/mes hasta los de mayor consumo de 350 KWh/mes. Por ejemplo, en la zona urbana la mayor tasa se concentra en los hogares conformados por más de 8 personas con tasas entre 150 a 180 KWh/mes, mientras que en la zona rural los valores oscilan entre 90 a 120 KWh/mes, pero difieren por ubicación geográfica y por su jefatura masculina o femenina. Igualmente, los datos permitieron escalar a niveles agregados donde se muestra que, del total de consumo anual de electricidad de 6,428 GWh, el 54% del consumo se concentró en la región Costa que concentra el 51% del total de hogares del sector residencial del Ecuador.

Abstract: This investigation studied the energy efficiency of a steam system in a hospital, considering the procedure in ASME EA-3-2009 standard. This is the standard for the energy assessment of industrial steam systems and aims to enhance the energy efficiency and sustainability of industrial steam systems by identifying opportunities and providing recommendations to optimize system performance. The obtained boiler energy efficiency was 80.29 %, by applying an energy balance, reaching 15.33 kW for heat losses in the distribution pipes. Two consistent improvement alternatives were proposed, starting by unifying the pipe diameter of the kitchen area of 5 m, generating a reduction of heat loss from 828 to 600 W, which represented a total annual energy saving of around 2.4 GJ/year. The investment cost is USD 47.40, considering the achievement of the break-even point after 9 months, where the insulation of the pipes with glass wool was considered second and it generated a reduction in losses of 5.98 kW, representing a total annual energy saving of about 62.91 GJ/year, which corresponds to approximately USD 1 672. The expenditure for insulating a 49 m pipe amounted to USD 462, factoring in both the NPV calculation and potential savings. The breakeven point was achieved within roughly 4 months, underscoring the economic advantage of implementing the two suggested improvement measures.

Resumen: En esta investigación se analizó la eficiencia energética de un sistema de vapor en un hospital, considerando la norma ASME EA-3-2009. Esta norma se utiliza para la evaluación energética de los sistemas de vapor industriales y busca mejorar la eficiencia energética y la sostenibilidad de estos sistemas identificando oportunidades y proponiendo medidas para optimizar el rendimiento. Se obtuvo una eficiencia energética de la caldera de 80.29 % mediante un balance de energías y las pérdidas de calor en las tuberías de distribución alcanzaron 15.33 kW. Se plantearon dos alternativas de mejora consistentes, iniciando con unificar el diámetro de tubería del área de cocina de 5 m, generando una reducción de pérdida de calor de 828 hasta 600 W, que representó un ahorro de energía anual total de 2.4 GJ/año, aproximadamente. El costo de inversión es de USD 47.40, considerando como alcanzable el punto de equilibrio a los 9 meses, donde se planteó en segundo lugar el aislamiento de las tuberías mediante lana de vidrio y generó la disminución de pérdidas en 5.98 kW, representando un ahorro de energía anual total de alrededor de 62.91 GJ/año, lo que corresponde a USD 1 672, aproximadamente. La inversión para el aislamiento de tuberías con una longitud de 49 m fue de USD 462, considerando el cálculo del VAN y los posibles ahorros, además el punto de equilibrio se alcanza a los 4 meses, aproximadamente, e indica el beneficio económico de aplicar las dos opciones de mejora planteadas.

Abstract: Vertical roller mills, (VRM), are widely used for grinding raw materials in factories engaged in the extraction and processing of minerals. Any machine used for grinding or crushing consumes around 30 to 40% of the energy of a factory. The loading pressure, table rotation speed, moisture content, outlet temperature and pressure rollers are variables that can be controlled to decrease the specific energy consumption Ecs. This paper poses an optimization problem in order to reduce the energy consumption of a VRM used to produce cement and to find the optimal parameters of the operating variables. Several packages are used to solve the nonlinear programming problem, with very good results in terms of accuracy and speed of convergence, but those provided by the Pyomo package are used because it obtains more accurate results. Comparing the result of the objective function with the energy consumption of a well-known cement company in Ecuador, it is concluded that the optimized parameters are able to reduce by 25% the energy consumption guaranteeing a minimum production of 2200 tons of cement per day, so the model is correctly validated.

Resumen: Los molinos verticales de rodillos (VRM), son máquinas muy utilizadas para moler materia prima en fábricas dedicadas a la extracción y procesamiento de minerales. Cualquier máquina ocupada para moler o triturar consume alrededor del 30 o 40% de la energía de una fábrica. La presión de carga, la velocidad de rotación de la mesa, el contenido de humedad, temperatura de salida del molino y presión de los rodillos son variables que se pueden controlar para disminuir el consumo de energía especifica (Ecs). Este trabajo plantea un problema de optimización con el fin de reducir el consumo energético de un VRM utilizado para producir cemento y encontrar los parámetros óptimos de las variables de operación. Se utilizan varios paquetes para resolver el problema de programación no lineal, obteniendo resultados muy buenos respecto a la precisión y velocidad de convergencia, pero se usan aquellos proporcionados por el paquete Pyomo ya que obtienen resultados más exactos. Comparando el resultado de la función objetivo con el consumo energético de una empresa cementera en Ecuador se concluye que los parámetros optimizados son capaces de reducir en un 25% el consumo energético garantizando una producción mínima de 2200 toneladas de cemento diarias por lo que el modelo se valida correctamente.

Abstract This article presents a systematic literature review on the reuse of electric vehicle batteries (EVB) for second-life applications in power systems. The end-oflife of these batteries represents a major environmental problem due to their composition and materials. The study aims to analyze the reuse of EVBs as a sustainable alternative for the environment. Additionally, it seeks to provide complementary services to facilitate the incorporation of intermittent unconventional renewable generation into the electrical grid. Through an exhaustive search of scientific publications indexed in prestigious digital catalogs and their subsequent systematic treatment, a selected group of 49 scientific articles published between 2018 and 2023 have been found in which the different opportunities, benefits and limitations of second-life energy storage systems oriented to boost a circular economy have been identified. The study concludes that, although the reuse of batteries has not yet been fully addressed or implemented due to existing challenges in terms of technology, costs, and regulations, it is of utmost importance to delve deeper into its analysis to improve efficiency and reduce the environmental impacts associated with the manufacturing, use, and disposal of such batteries.

Resumen Este artículo presenta una revisión sistemática de literatura relativa al tópico reutilización de baterías de vehículos eléctricos (BVE) para aplicaciones de segunda vida en sistemas eléctricos de potencia. El fin del ciclo de vida de estas baterías representa un gran problema ambiental debido a su composición y materiales. El estudio tiene por objeto analizar la reutilización de las BVE como una alternativa sostenible para el medioambiente y, además, para brindar servicios complementarios que faciliten la incorporación de generación renovable no convencional de carácter intermitente a la red eléctrica. A través de una búsqueda exhaustiva de publicaciones científicas indexadas en catálogos digitales prestigiosos y de su posterior tratamiento sistemático, se ha llegado a un número selecto de 49 artículos científicos publicados entre 2018 y 2023. En ellos ha sido posible identificar las diferentes oportunidades, beneficios y limitaciones de los sistemas de almacenamiento de energía de segunda vida orientadas a impulsar una economía circular. El estudio concluye que, si bien la reutilización de baterías no está plenamente tratada ni implementada, debido a que aún enfrenta desafíos en términos de tecnología, costos y regulaciones, es de gran importancia profundizar su análisis para mejorar la eficiencia y disminuir los impactos ambientales que provocan su fabricación, uso y desecho.

Abstract: The results of a proposal for a high-efficiency photovoltaic system with multipurpose applications implemented along a road are presented. This system is designed to address issues related to lighting, telecommunications, and electric vehicle charging. The need for an isolated system arises from sudden power outages in the country that affect road safety and reliability, as well as the lack of phone signal in some areas. In the field of lighting, an analysis is conducted using DiaLux software to ensure compliance with appropriate lighting standards for different types of roads. Furthermore, the multipurpose system includes electric vehicle charging, which is becoming increasingly relevant due to the shift towards more eco-friendly vehicles. Providing electric vehicle charging along roads resolves the issue of limited electric vehicle range and promotes their reliable use. The evaluation of the energy resource using the Glover and McCulloch method is essential for designing an efficient system capable of meeting various user needs. Additionally, reducing carbon dioxide emissions is a significant consideration, as electric vehicles can significantly contribute to reducing greenhouse gas emissions compared to fossil fuel vehicles. Abstract highefficiency high efficiency presented telecommunications reliability areas Furthermore ecofriendly eco friendly use needs Additionally consideration

Resumen: Se presentan los resultados de una propuesta de un sistema fotovoltaico de alta eficiencia con aplicaciones multipropósito, implementado a lo largo de una carretera. Este sistema está diseñado para abordar cuestiones relacionadas con la iluminación, las telecomunicaciones y la carga de vehículos eléctricos. La necesidad de un sistema aislado surge de los apagones repentinos en el país que afectan la seguridad vial, el excesivo uso de vehículos de combustibles fósiles que emiten gases que contaminan el planeta, así como la falta de señal telefónica en algunas zonas. En el ámbito de la iluminación, se realiza un análisis utilizando el software DiaLux para garantizar el cumplimiento de los estándares adecuados de iluminación para diferentes tipos de carreteras. Además, el sistema multipropósito incluye la carga de vehículos eléctricos livianos de uso particular, que se está volviendo cada vez más relevante debido al cambio hacia vehículos más ecológicos. La provisión de carga de vehículos eléctricos a lo largo de las carreteras resuelve el problema de la autonomía limitada de los vehículos eléctricos y promueve su uso confiable. La evaluación del recurso energético mediante el método Glover y McCulloch es fundamental para diseñar un sistema eficiente capaz de satisfacer diversas necesidades del usuario. Además, la reducción de las emisiones de dióxido de carbono es un aspecto importante, ya que los vehículos eléctricos pueden contribuir significativamente a la reducción de las emisiones de gases de efecto invernadero en comparación con los vehículos de combustibles fósiles Resumen carretera vial planeta zonas Además particular ecológicos confiable usuario importante

Abstract: Globally, the residential building stock shows different levels of obsolescence and high energy consumption. Therefore, it is imperative to promote energy savings through measures to improve building efficiency in the rehabilitation and remodeling of housing units. The objective of this work is to analyze the different ways of evaluating energy efficiency through the diachronicity of the renovations introduced during their use, with emphasis on the variations of the building envelope. The method used is a theoretical-qualitative study, structured in two stages that allow addressing the regulatory context in force in 31 countries. It is concluded that the evaluation methods examined apply a synchronic criterion, without considering the dynamics of housing change processes. Together, the regulations of Brazil, Austria, Belgium, Germany, and Cyprus are highlighted for their relevance, potential and approach to the envelope.

Resumen: A nivel global, el parque construido residencial acusa distintos niveles de obsolescencia y elevados consumos de energía. Por tanto, resulta imperativo propiciar el ahorro energético mediante medidas de mejora de la eficiencia edilicia en la rehabilitación y remodelación de las unidades de vivienda. Por esto, el objetivo del trabajo es analizar las diversas maneras de evaluar la eficiencia energética a través de la diacronicidad de las reformas introducidas durante su uso, con énfasis en las variaciones de la envolvente. El método utilizado es un estudio teórico-cualitativo, estructurado en dos etapas que permiten abordar el contexto normativo vigente en 31 países. Se concluye que los métodos de evaluación examinados aplican un criterio sincrónico, sin considerar la dinámica de los procesos de cambios de las viviendas. Conjuntamente, se rescatan por su relevancia, potencialidad y la particular modalidad de abordaje de la envolvente, las normativas de Brasil, Austria, Bélgica, Alemania y Chipre.

ABSTRACT Ecuador's solar potential was explored, proving high for the favorable implementation of photovoltaic systems, with a greater focus on the Andes mountain range. In the Coastal region, global horizontal irradiation levels maintain the trend of being feasible for energy optimization in establishments through photovoltaic panels. A proposal was developed to improve the energy efficiency of the computer company Altura S.A. via commercial license software, PVsyst 7.2; showing positive technical and economic results, producing an energy surplus of 14.11% with a recovery period of 15.7 years, avoiding the emission of 1.33 tons of CO2 annually. In turn, various barriers were established that prevent the penetration of these systems such as political, social, etc., as well as the great and reinforced use of conventional energy sources despite the feasibility shown in this study.

RESUMEN El potencial solar de Ecuador fue explorado mostrandose elevado para la favorable puesta en marcha de sistemas fotovoltaicos, con un mayor enfoque en la cordillera de los Andes. En la región Costa, los niveles de irradiación global horizontal mantienen la tendencia de ser factibles para la optimización energética en establecimientos por medio de paneles fotovoltaicos. Fue desarrollada una propuesta para mejorar la eficiencia energética de la empresa informática Altura S.A. mediante el software de licencia comercial, PVsyst 7,2; mostrando resultados positivos en lo técnico y económico, produciendo un excedente energético del 14,11% con un periodo de recuperación de 15,7 años, evitandola emisión de 1,33 toneladas de CO2 anualmente. A su vez, se establecieron diversas barreras que impiden la penetración de estos sistemas como las políticas, sociales, etc, así como el gran y reforzado uso de fuentes convencionales de energía a pesar de la factibilidad mostrada en este estudio.

Different concentration techniques were evaluated for preconcentration of a mineral ore at a coarser size to avoid energy and resource wastage. Specifically, the aim was to reduce milling costs and energy required in the beneficiation of tin. In this study, cassiterite (0.17% Sn) was the mineral of interest in a pegmatite ore body associated with quartz (SiO2 > 60%) and alumina (Al2O3 > 20%). Three concentration techniques, namely dense media, shaking table, and flotation, coupled with characterization analysis, were used to assess the concentration response. The results confirmed that particle size and mineral liberation impact the separation process. High recovery and grade were obtained with gravity concentration methods (dense media and shaking table) for coarser (+300 to +212 μm) and intermediate (+150 to +53 μm) particle sizes. Lower recovery and grade were identified for much finer sizes (-53 to -38 μm). Flotation produced a high-grade product at a relatively low recovery and appeared to be only applicable to finer grains. Separation efficiency based on Schulz's equation measured a segregation performance of 74.8% for dense medium separation and 60.7% for the shaking table for the coarse and intermediate particle sizes. Flotation only achieved a separation of 30%-40%. The results suggest that use of dense media separation as a rough preconcentration method prior to further grinding, and the utilization of a more advanced concentration technique for mineral recovery and upgrade, constitute a successful approach to improve process economics.

Abstract: This investigation was a case of study in the powder detergent packaging line and aimed to reduce all those wastes that do not add value to the product, increasing the cost of production. Reducing or eliminating waste within the manufacturing industry becomes necessary for sustainable businesses over time and keeps generating development. To achieve it, the Lean Six Sigma DMAIC methodology was implemented in a detergent powder packaging line, to identify the problems that afflicted and made production more expensive. By using quality tools (such as Pareto and Ishikawa diagrams, 5S application, Poka-Yokes, SMED, training personnel, and standardizing processes) it was possible to reduce unproductive times. Energy consumption was reduced by up to 20 %, also efficiency and machine availability increased by 10.98 % and 7.32 %, respectively. The general performance of the line increased by 15.16 %, which translates into significant monthly savings of USD 71 442.05. By applying these improvement techniques, the most significant efficiency was registered in 1 kg packages, going from 47 % to 89 %, approximately. To maintain this productivity and even to perfect it, it is necessary to hire specialized personnel who know the production processes and industrial operations.

Resumen: Esta investigación fue un estudio de caso en una línea de empaque de detergente, con el objetivo de reducir todos los desperdicios que no añaden valor al producto y que aumentan el costo de producción. La disminución o eliminación de desperdicios de cualquier tipo dentro de la industria manufacturera se convierte en una necesidad para que los negocios continúen siendo sustentables en el tiempo y generan desarrollo. Para alcanzar este objetivo, se implementó la metodología Lean Six Sigma DMAIC en una línea de envasado de polvo detergente, permitiendo descubrir los problemas que agobiaban y encarecían la producción. Al utilizar herramientas de calidad (como Diagramas de Pareto e Ishikawa, la aplicación de la metodología 5S, Poka-Yokes, SMED, capacitando al personal, y estandarizando procesos) se logró reducir tiempos improductivos. El consumo de energía se redujo hasta en un 20 %, la eficiencia y la disponibilidad de la máquina aumentaron en 10.98 % y 7.32 %, respectivamente. También se incrementó el rendimiento general de la línea en 15.16 %, lo cual se tradujo en un ahorro significativo mensual de USD 71 442.05. Mediante la aplicación de estas técnicas de mejora, la eficiencia más significativa se registró en los empaques de 1 kg, pasando de 47 hasta 89 %, aproximadamente. Para mantener esta productividad y perfeccionarla, es necesario contratar personal especializado, que conozca los procesos productivos y operaciones industriales.

Resumo Este trabalho tem como objetivo analisar a sustentabilidade nos hotéis de 5 estrelas do Algarve, determinando como é que comunicam o seu comportamento sustentável nos seus websites, quais são as práticas mais adotadas e os principais motivadores/obstáculos. Foram analisados os websites e motores de reserva dos hotéis. E um questionário foi usado para recolher informações sobre as suas práticas sustentáveis. É possível perceber um pouco de comunicação sustentável nos sites desses hotéis. Essa percentagem é superior no motor Booking.com, um canal mais competitivo. As principais áreas de intervenção são a gestão de energia, gestão de água/resíduos e responsabilidade social. A maioria das práticas implementadas são as menos dispendiosas. E os principais impulsionadores são a responsabilidade ambiental, visão estratégica e ganho de eficiência. Embora o principal obstáculo referido seja o custo do investimento, a falta de pessoal qualificado e questões técnicas são outros constrangimentos. A dimensão “mais fraca” da tríade da sustentabilidade é a social (com resultados menores). E a mais limitante para se avançar na área é a económica, pela perceção de custos associados. O crescimento de novos negócios e empregos na área, bem como o uso de um relatório padronizado e de certificação, poderá superar os entraves.

Abstract This work aims to analyze sustainability in 5-star hotels in Algarve, determining how they communicate their sustainable behavior on their websites, what are the most adopted practices and the main motivators/obstacles. Hotel websites and booking engines were analyzed. And a questionnaire was used to gather information about their sustainable practices. It is possible to notice a bit of sustainable communication on the sites of these hotels. This percentage is higher in the Booking.com engine, a more competitive channel. The main areas of intervention are energy management, water/waste management and social responsibility. Most of the implemented practices are the least expensive. And the main drivers are environmental responsibility, strategic vision and efficiency gains. Although the main obstacle referred to is the investment cost, the lack of qualified personnel and technical issues are other constraints. The “weakest” dimension of the sustainability triad is social (with lower results). And the most limiting to develop the area is the economic one, due to the perception of associated costs. The growth of new businesses and jobs in the area, as well as the use of standardized reporting and certification, could overcome the barriers.

RESUMEN La eficiencia energética de los sistemas de riego es un aspecto de gran importancia en todos los procesos de diseño y manejo; por este motivo se desarrolló una investigación en la finca “Tío Pedro” ubicada en el municipio de Venezuela, provincia Ciego de Ávila durante los años 2021 y 2022 con el objetivo de estimar el rendimiento energético general en el sistema de riego por surcos. Durante este periodo la unidad de bombeo funcionó con el siguiente régimen de operación promedio: caudal de bombeo de 61,1 L s-1; tiempo de bombeo de 2,8 horas y carga de bombeo de 18,2 m. Este comportamiento determinó una potencia hidráulica de 10,9 kW y rendimiento de la bomba de 85,2%. La energía suministrada en el bombeo fue de 429,4 kWh y la energía absorbida en el periodo evaluado de 631,9 kWh. En relación con los parámetros energéticos del sistema se obtuvo un balance energético del suministro de 7,4 m; un índice de carga energética del sistema de 15,2 m; un rendimiento energético del bombeo de 68,2% (excelente) y un rendimiento energético general del sistema de 34,0% (normal).

ABSTRACT The energy efficiency of irrigation systems is an aspect of great importance in all design and management processes; For this reason, an investigation was carried out in the "Tío Pedro" farm located in the municipality of Venezuela, Ciego de Ávila province during the years 2021 and 2022 with the objective of estimating the general energy yield in the furrow irrigation system. During this period, the pump unit offers the following average operating regime: pump flow rate of 61.1 L s-1; pumping time of 2,8 hours and pumping head of 18.2 m. This behavior reduces a hydraulic power of 10.9 kW and a pump efficiency of 85.2%. The energy supplied in pumping was 429.4 kWh and the energy absorbed in the evaluated period was 631.9 kWh. In relation to the energy parameters of the system, an energy balance of the supply of 7,4 m was obtained; a system energy load index of 15.2 m; an energy efficiency of the pumping of 68.2% (excellent) and a general energy efficiency of the system of 34.0% (normal).

RESUMEN El estudio se realizó en la finca Tío Pedro en el municipio de Venezuela, en la provincia de Ciego de Ávila, tuvo como objetivo proponer modelos matemáticos para estimar los parámetros hidráulicos de un sistema de bombeo utilizando la técnica de riego por surcos para el cultivo del frijol negro. Los resultados mostraron fluctuaciones esperadas en los parámetros hidráulicos como caudal, carga, potencia hidráulica, tiempo de bombeo y volumen bombeado. Se encontraron relaciones funcionales entre el caudal y la carga de bombeo, así como entre la potencia hidráulica, el caudal y la carga de bombeo. Estas relaciones pueden mejorar el funcionamiento del sistema de bombeo, ahorrar energía y aumentar la eficiencia de la bomba. Además, se desarrollaron funciones para predecir las curvas características de la carga, la eficiencia de la bomba y del sistema en general. Estos resultados pueden mejorar la eficiencia energética y la gestión del agua en la agricultura.

ABSTRACT The study was carried out at the Tío Pedro farm in the municipality of Venezuela, in the province of Ciego de Ávila, with the objective of proposing mathematical models to estimate the hydraulic parameters of a pumping system using the furrow irrigation technique for the cultivation of black bean. The results showed expected fluctuations in hydraulic parameters such as flow rate, head, hydraulic power, pumping time, and pumped volume. Functional relationships were found between flow and pumping head, as well as between hydraulic power, flow and pumping head. These ratios can improve pump system performance, save energy, and increase pump efficiency. In addition, functions were developed to predict the characteristic curves of the load, the efficiency of the pump and the system in general. These results can improve energy efficiency and water management in agriculture.

Rainwater harvesting (RWH) provides a unique opportunity for water conservation. This research aimed to assess the performance of two types of RWH systems (gravity and pump-driven) at a local public school in replacing non-potable water for toilet flushing. The volume of harvested water, efficiency to meet demand, expenses involved and associated environmental burdens were key criteria of performance. Economic considerations included capital costs and return periods, while the environmental aspects encompassed simplified life cycle assessments (LCAs) as well as specific carbon footprints. The gravity-fed system supplied 452.5 kL/annum and covered 31.8% of the demand for flushing water for toilets for the school investigated. The pumped system provided 476.8 kL/annum representing 33.5% of the demand. Together they would be able to supply 65.3% of the demand. The catchment area of these two systems differed and there was no overlap. As expected, the gravity-fed system outperformed the pumped system, both economically and environmentally, because no energy for pumping was needed. In terms of costs, the difference was small, and the payback periods of both systems were similar. However, environmentally, the LCA scores for the pumped system were an order of magnitude higher for all 18 impact categories considered. Carbon footprints showed that in the construction stage both systems have similar footprints. For the operation stage, the comparison was extended, as there were higher energy requirements for the pumped system (about 4 times higher than those from the provision of municipal potable water), but in the same range or lower when compared with other alternative sources of water like groundwater abstraction, recycling of municipal water and desalination. The gravity-fed system required no energy for pumping. This study shows how trade-offs in assessing the overall performance of RWH systems can be considered, leading to better decision making.

The present research used a combination of experimental and numerical methods to investigate energy dissipation blocks of different heights placed downstream of a sluice gate in an open channel flow. Numerical model simulations were performed using a 3D computational fluid dynamics (CFD) technique, using the Reynolds-averaged Navier-Stokes (RANS) equations with the volume of fluid (VOF) and k-ε turbulence models. The accuracy of the numerical model and the grid sensitivity was assessed according to a recommended procedure in the literature. Different hydraulic and geometry conditions were investigated to understand the energy dissipation behaviour of the blocks. The hydrodynamic effects of different block spacings, heights and configurations were analysed by means of CFD simulations. The results show that the variable size blocks have a high energy dissipation efficiency in sluice gate flows, particularly at high Froude numbers. The energy dissipation efficiency of the blocks downstream of a sluice gate can reach up to 55% for high discharges (Q = 35 L/s). Interestingly, the energy dissipation performance of small gate openings exceeds that of large gate openings, reaching a peak efficiency of 40% for the same discharge. In addition, the block spacing has a minimal effect on the energy dissipation, while smaller block spacing results in a smoother water surface profile.