E. Granada

Fuel lignocellulosic briquettes, die design and products study

Briquetting of biomass can be done through various techniques. The present work describes the process of designing a taper die and its optimisation for use in a hydraulic machine. The application of an experimental design technique, and the later statistical analysis of the results is presented, applied to a laboratory hydraulic press densification process of lignocellulosic biomass. The most appropriate experiment type is determined for a first set of experiments; calculating, among other things: minimum number of tests to carry out to obtain binding conclusions, most influential factors, and search paths to improve fuel quality. Another experiment type is determined for a second set of experiments, taking account of the most influential factors [1, 3] (pressure, temperature and moisture content), and also the number of tests to carry out considering the improvement of density and friability. Finally, an approximation study of the best product allows conclusions to be reached on product behaviour beyond the experimental design range factors.

Biomass Thermogravimetric Analysis: Uncertainty Determination Methodology and Sampling Maps Generation

The objective of this study was to develop a methodology for the determination of the maximum sampling error and confidence intervals of thermal properties obtained from thermogravimetric analysis (TG), including moisture, volatile matter, fixed carbon and ash content. The sampling procedure of the TG analysis was of particular interest and was conducted with care. The results of the present study were compared to those of a prompt analysis, and a correlation between the mean values and maximum sampling errors of the methods were not observed. In general, low and acceptable levels of uncertainty and error were obtained, demonstrating that the properties evaluated by TG analysis were representative of the overall fuel composition. The accurate determination of the thermal properties of biomass with precise confidence intervals is of particular interest in energetic biomass applications.

Heterogenic Solid Biofuel Sampling Methodology and Uncertainty Associated with Prompt Analysis

Accurate determination of the properties of biomass is of particular interest in studies on biomass combustion or cofiring. The aim of this paper is to develop a methodology for prompt analysis of heterogeneous solid fuels with an acceptable degree of accuracy. Special care must be taken with the sampling procedure to achieve an acceptable degree of error and low statistical uncertainty. A sampling and error determination methodology for prompt analysis is presented and validated. Two approaches for the propagation of errors are also given and some comparisons are made in order to determine which may be better in this context. Results show in general low, acceptable levels of uncertainty, demonstrating that the samples obtained in the process are representative of the overall fuel composition.

Potential effect of uncertainty on the GRG interpretation

Purpose – The purpose of this paper is to propose an interpretation of the grey relational grade taking into account its variation range on the basis of the error propagation theory.Design/methodology/approach – The paper uses error propagation theory to calculate the uncertainty of the grey relational grade, exploring how errors are propagated through the sequential operations of the grey relational analysis.Findings – The non‐consideration of the error associated to the measurement of the experimental data that is transferred to the grey relational grade may have a potential effect on the interpretation of the grey relational rank. Data uncertainty quantification provides information about how well measurement fits to the value of the measured quantity and determines its validity. Therefore, this might lead one to consider that some sequences are less attractive than other lower‐ranked ones.Practical implications – The combination of the grey and error propagation theories is a tool to choose the most a...

A Refrigerated Web Camera for Photogrammetric Video Measurement inside Biomass Boilers and Combustion Analysis

This paper describes a prototype instrumentation system for photogrammetric measuring of bed and ash layers, as well as for flying particle detection and pursuit using a single device (CCD) web camera. The system was designed to obtain images of the combustion process in the interior of a domestic boiler. It includes a cooling system, needed because of the high temperatures in the combustion chamber of the boiler. The cooling system was designed using CFD simulations to ensure effectiveness. This method allows more complete and real-time monitoring of the combustion process taking place inside a boiler. The information gained from this system may facilitate the optimisation of boiler processes.

Uncertainty Determination Methodology, Sampling Maps Generation and Trend Studies with Biomass Thermogravimetric Analysis

This paper investigates a method for the determination of the maximum sampling error and confidence intervals of thermal properties obtained from thermogravimetric analysis (TG analysis) for several lignocellulosic materials (ground olive stone, almond shell, pine pellets and oak pellets), completing previous work of the same authors. A comparison has been made between results of TG analysis and prompt analysis. Levels of uncertainty and errors were obtained, demonstrating that properties evaluated by TG analysis were representative of the overall fuel composition, and no correlation between prompt and TG analysis exists. Additionally, a study of trends and time correlations is indicated. These results are particularly interesting for biomass energy applications.

Combustion Behavior of Spanish Lignocellulosic Briquettes

If briquettes are to be used efficiently and rationally as fuel, they must be characterized to determine such technological parameters as their reactivity, moisture content, density, ashes, volatile matter, and heat value, along with their major component elements. Traditionally, research has centered on small particles of coal that do not reflect the combustion behavior of briquettes as heterogeneous solids. The objective of this work is to compare experimental data on the reactivity of biomass briquettes and to analyze the results. From the reactivity and the rest of the data available, it will be possible to asses what kind of briquette is suitable for a particular application by matching its behavior to specific requirements, including pollutant emissions.

CFD analysis of a TG–DSC apparatus : Application to the indium heating and phase change process

A ThermoGravimetric analyser with differential scanning calorimetry (TG–DSC) has been studied during the fusion of an indium sample using both an experimental procedure and a CFD simulation. To do so, a CAD model of the real device was built and meshed in detail, in order to take into account the small scale processes which occur inside the crucibles. Several theoretical models, some previously existing in the CFD software used and others developed ad hoc, were applied to simulate the whole facility. Therefore, realistic boundary conditions and a PID-based control system already developed for previous studies had to be used. The validation of the CFD model was done by comparing the outcome of the resulting simulation to the results obtained by experimental procedure in a case where natural convection is the main heat and mass transfer mechanism. This comparison was made for two different heating rates inside the furnace. Typical characteristics of phase change process inside a TG-DSC as thermal lag, onset temperature or heat flow exchange during the fusion could be analysed. As well, a more detailed approach to physical phenomena taking place inside the furnace could be done, since CFD simulations allow to obtain data which is not achievable experimentally. Besides, a valid CFD model for a TG-DSC could be later used in further CFD simulations.

Exhaust Emissions from Diesel, LPG, and Gasoline Low-power Engines

Abstract In a way similar to the automotive industry, outboard emissions limits are being constantly revised, which strongly effects the development of the new engines and their compliance. During the last ten years, conventional two-stroke outboard engines, which are used for fishing and recreational boats, have thus been replaced by four-stroke engines or direct-injection two-stroke engines. The objective of this article is to compare various outboard engines and the technical solutions developed for the reduction of exhaust emissions, with special emphasis being placed on the low-power gasoline and diesel outboard engine range. A gasoline outboard engine was also transformed to allow the use of liquefied petroleum gas (LPG) and showed that this technique could be an alternative solution for the future emission limit compliance.

Contribution of Renewable Energy Sources to Electricity Production in Galicia (Spain)

The use of renewable energy offers a decrease in external energy dependence; a boost to local and regional component manufacturing industries; promotion of regional engineering; increased R&D, decrease in impact of electricity production and transformation; increase in the level of services for the rural population; creation of employment, etc. To achieve these benefits, a series of actions are required, among which the following are particularly important: creation of a suitable climate for performing R&D; training of technicians in design, production, and maintenance of equipment; motivation for establishing a new market; proper financing; fostering of appropriate technologies; practical demonstration of results; etc. This article reviews the progress made in the Autonomous Community of Galicia in terms of the introduction of renewable energy technologies (RETs) and examines the possibility of meeting a target of 90% coverage (practical electrical self-sufficiency) by 2010.