Energy and exergy assessment of heavy-duty mining trucks. Discussion of saving opportunities

Heavy-duty mining trucks are essential for open-pit mining and are significant energy consumers, stressing the need for the mining industry to improve the fuel economy of mining trucks. However, there is a limited discussion on this topic in the specialized literature, mainly focusing on light-duty vehicles. This article discusses the energy and exergy balances of heavy-duty mining trucks operating in an open pit mine in Colombia. Results show saving opportunities by either using batteries or producing hydrogen with the power from regenerative brakes, reducing heat losses in the engine, recovering heat losses with combustion gases using thermoelectric generators, and replacing mechanical pumps with electrical pumps. The assessment shows that reducing engine heat losses by coating the cylinder, cylinder head, and piston crown can reduce fuel consumption between 1.8 % and 9.1 %. Moreover, the production of hydrogen, while economically feasible, needs to assess the implementation of electrolyzers in mining trucks. Other measures are not economically viable. Using batteries, which requires adding 12 t of weight to the truck, reduces truck productivity. Finally, using thermoelectric generators and replacing mechanical pumps shows marginal opportunities to reduce fuel consumption

Data supporting the assessment of biomass based electricity and reduced GHG emissions in Cuba

Assessing the biomass based electricity potential of developing nations like Cuba can help to reduce the fossil fuels dependency and the greenhouse gas emissions. The data included in this study present the evolution of electricity production and greenhouse gas emissions in Cuba. Additionally, the potentialities to produce biomass based electricity by using the most significant biomass sources in Cuba are estimated. Furthermore, estimations of the potential reductions of greenhouse gas emissions, resulting from implementing the biomass based electricity potential of the different sources discussed in the study, are included. Results point to the most promising biomass sources for electricity generation and their potential to reduce GHG emissions

Environmental assessment of pig production in Cienfuegos, Cuba: alternatives for manure management

status: publishe

Improved selection of the functional unit in environmental impact assessment of cement

The outcome of Life Cycle Assessment (LCA) studies is strongly influenced by the selection of the functional unit, which must be defined in such a way that, when products are compared, the amounts compared have identical utilities. LCA studies of cements mostly use mass based functional units (MFU). However, since different cements have a different composition and binding capacity, they result in different compressive strength and durability in their applications, so that MFUs are inadequate. Therefore, this study introduces as functional unit the Cement Functional Performance (CFP): mass of cement needed to obtain 1 MPa of compressive strength during one year of durability (kg/(MPa∙year. To evaluate the effect of the CFP, the environmental performance of three cements is compared. Results show that adding 5% of zeolite to cement results in a similar strength and 1.78 times higher durability of the produced concrete, which is explained by the reduction of chloride diffusion. Moreover, adding 19% of zeolite to cement increases its durability 2.75 times, but reduces compressive strength by 29%. As a result, cement with 5 and 19% of zeolite added has respectively 54 and 36% of the environmental impacts of Portland cement.status: publishe

Selection of HVAC technology for buildings in the tropical climate case study

In this paper, the integral performance indicator for selecting HVAC systems (ACPI) is applied to select the Air Conditioning (AC) system with better results in their life cycle for a typical building in Barranquilla, Colombia. The AC systems under study were: direct expansion system (Split and VRF), air-cooled system (VAC and VAV), and water-cooled system (Chiller). Of the six selection criteria of ACPI, the energy consumption index (EC) and thermal comfort (TC) were calculated through energy simulation of buildings, the regulations were used for IAQ and carbon emissions (CE), and were estimated the investment costs (IC) and operating and maintenance costs (OMC). The best-performance AC system for the building was the air-cooled AC system got the best ACPI values between 25 % and 22.4 %, followed by the water-cooled system with 22.3 %, and finally the direct expansion systems between 16.8 % and 13.5 %, influencing in this level of priority the IAQ and IC criteria. This study contributes to introducing in Colombia a multifactorial analysis to select the more proper AC system technology according to the building and location conditions

Diseño de un controlador difuso para un sistema de generación híbrido

This paper presents the design of a control system for the automatic connection/disconnection and distribution of load, between an asynchronous alternator and a generator, in a hydroelectric central that works in isolated mode. The design of a control algorithm based on fuzzy logic is exposed, as this is a flexible method to be used in different installations with a variety of technology. The controller is supported on the Arduino Mega 2560 platform, in order to develop a low-cost system with its own technology, it is tested by computer simulation using the professional software Proteus v7.7, which guarantees that once validated the correct operation of the controller can be migrated to another system, say for example a PLC. The results obtained are shown and the simulations performed to the different blocks of the system are explained.Este trabajo presenta el diseño de un sistema de control para la automática conexión / desconexión y distribución de carga, entre un alternador asíncrono y un Generador, en central hidroeléctrica que funciona en modo aislado. El diseño de un control Se expone un algoritmo basado en lógica difusa, ya que este es un método flexible para ser utilizado en diferentes instalaciones con variedad de tecnología. El controlador es compatible con Arduino Mega 2560 plataforma, para desarrollar un sistema de bajo costo con tecnología propia, se prueba por computadora simulación utilizando el software profesional Proteus v7.7, que garantiza que una vez validado el correcto funcionamiento del controlador se puede migrar a otro sistema, digamos por ejemplo un PLC. Se muestran los resultados obtenidos y se realizan las simulaciones a los diferentes bloques del se explica el sistema

Evaluación de fallas en un transportador de cangilones. Caso de estudio

A failure in the bottom sheet of a bucket conveyor (KZBQ. AUMUND) during service was investigated. Sheets are coupled to the chain throught a screw connection; they operate in variable load scenarios causing fatigue. A chemical and microstructural analysis was made showing that sheet was built in steel with 0.15 % of Carbone without alloying elements that contribute to the refined grain and resistance increase. Strength calculation, used to determinate safety factor, consider load system and type material. Results concluded that geometry and thickness value do not provide an adequate fatigue resistance coefficient.Es investigada la falla en las láminas del fondo de un transportador de cangilones KZB-Q.AUMUND durante su servicio. Las láminas están acopladas a una cadena a través de uniones atornilladas y operan bajo un régimen de cargas variables causándoles fatiga. Se realiza un análisis químico y microestructural el cual evidencia que las láminas fueron elaboradas de un acero con 0,15 % de carbono sin elementos de aleación que contribuyan al afinamiento del grano y al incremento de la resistencia. Se calculan las tensiones para determinar el coeficiente de seguridad a la fatiga considerando el sistema de cargas y el material de las láminas. Los resultados concluyen que la geometría y los valores de espesor no le proporcionan a las láminas un adecuado coeficiente de resistencia a la fatiga

Experiencias en la utilización de información meteorológica para el pronóstico y control del consumo de electricidad en hoteles

Ponencia presentada en: XI Congreso de la Asociación Española de Climatología celebrado en Cartagena entre el 17 y el 19 de octubre de 2018.[ES]Los hoteles se encuentran entre las instalaciones turísticas de mayor consumo de energía. Para supervisar y controlar el consumo mensual y anual de energía en los hoteles se han propuesto diferentes indicadores. Estos indicadores, desarrollados en base anual, no permiten la rápida detección y mitigación de las malas prácticas y sobreconsumos en las instalaciones del hotel. Este estudio analiza el uso de indicadores de desempeño energético para evaluar y controlar el consumo de electricidad en los hoteles. Para este fin se introduce un nuevo indicador teniendo en cuenta la temperatura exterior. Sobre la base de este indicador se desarrollan las gráficas de control diarios, lo que permite una detección más rápida de sobreconsumos y malas prácticas hacia una mayor eficiencia de la electricidad. Una ventaja de este enfoque es que no se requieren inversiones para ponerlo en práctica. Las herramientas se aplicaron en dos hoteles cubanos de diferentes características, donde se alcanzaron importantes reducciones del consumo de electricidad.[EN]Hotels are among the most energy intensive tourism facilities. To monitor and control the monthly and yearly energy consumption in hotels, different indicators have been proposed. These indicators do not consider the influence of physical parameters such as outdoor temperature, or, when they do, rather complex coefficients are used, precluding implementation in hotel facilities. This study discusses the use of Energy Performance Indicators to assess and control the electricity consumption in hotels. To this end a new indicator considering the outdoor temperature is introduced. Based on this indicator daily control graphs are developed, allowing a more rapid detection of overconsumptions and malpractices towards higher electricity efficiency. The tools were implemented in two Cuban hotels of different characteristics, where significant reductions of the electricity consumption were achieved