Designing the microturbine engine for waste-derived fuels

Power Electronics for Modern Sustainable Power Systems: Distributed Generation, Microgrids and Smart Grids—A Review

This work presents and discusses the application of power electronics for the integration of several distributed generation sources, as well as those related to it, the microgrids and the smart grids, to the power sector. Trends and challenges are addressed for the area of study and an embracing overview of the main technologies and techniques is presented for future investigation. As there are many power electronics devices available for employment, in each one of these crucial, modern, sustainable electrical systems, it is important for students, researchers and professionals to understand and compare the state of the art of them all, for the right choice in their respective uses. These apparatuses not only allow grid matching, but also provide new functions that enhance these artifacts’ operations, and of the entire power system. Thus, in this paper, the relationship between power electronics and distributed generation is detailed, with the role and classification of each static converter for the improved operation of wind power, photovoltaic systems, fuel cells, small hydro and microturbines exposed. While the first two are more widely covered in the literature, the last three are rarely discussed and differentiated, in terms of their power electronics interfaces. Then, the same is made for microgrids and smart grids, also scarcely approached in other works, with regard to the characteristics of the power converters applied, confirming their superior performances with the use of power electronics. Finally, conclusions are given.

Effects of Pyrolysis Bio-Oils on Fuel Atomisation—A Review

Bio-oils produced by biomass pyrolysis are substantially different from those produced by petroleum-based fuels and biodiesel. However, they could serve as valuable alternatives to fossil fuels to achieve carbon neutral future. The literature review indicates that the current use of bio-oils in gas turbines and compression-ignition (diesel) engines is limited due to problems associated with atomisation and combustion. The review also identifies the progress made in pyrolysis bio-oil spray combustion via standardisation of fuel properties, optimising atomisation and combustion, and understanding long-term reliability of engines. The key strategies that need to be adapted to efficiently atomise and combust bio-oils include, efficient atomisation techniques such as twin fluid atomisation, pressure atomisation and more advanced and novel effervescent atomisation, fuel and air preheating, flame stabilization using swrilers, and filtering the solid content from the pyrolysis oils. Once these strategies are implemented, bio-oils can enhance combustion efficiency and reduce greenhouse gas (GHG) emission. Overall, this study clearly indicates that pyrolysis bio-oils have the ability to substitute fossil fuels, but fuel injection problems need to be tackled in order to insure proper atomisation and combustion of the fuel.

Pelletization of Refuse-Derived Fuel with Varying Compositions of Plastic, Paper, Organic and Wood

The combustible fraction of municipal solid waste (MSW) is called refuse-derived fuel (RDF). RDF is a blend of heterogeneous materials and thus its handling is challenging. Pelletization is an efficient treatment to minimize the heterogeneity. In this research, typical RDF compositions were prepared by mixing several mass fractions of paper, plastic, household organic and wood. The collected compositions were ground, wetted to 20% moisture content (wet basis) and pelletized. Increasing the plastic content from 20% to 40% reduced the pelletization energy but increased the pellet’s calorific value. Pellets with higher plastic content generated more dust when exposed to shaking. Making durable pellets with 40% plastic content needed an increase in die temperature from 80 °C to 100 °C. Increasing the paper content from 30% to 50% increased the durability but consumed higher energy to form pellets. Paper particles increased the friction between pellet’s surface and die wall as was evident from expulsion energy. Force versus displacement curve for material compression revealed that the RDF compositions have rigid material characteristics.