Nikolaos Nikolopoulos

Numerical investigation of the aerodynamic breakup of diesel droplets under various gas pressures

Financial support from the MSCA-ITN-ETN of the European Union’s H2020 programme, under REA grant agreement n. 675676 is acknowledged.

Critical review of current industrial scale lignite drying technologies

Abstract Lignite constitutes a major energy source and has long been used for energy production despite its contribution in greenhouse gas (GHG) emissions, as a fossil fuel. For example, 27.4% of Germany‘s electricity originates from lignite power plants, while in Greece more than 55% of its electric energy consumption is provided by lignite. A total of 45% global coal reserves consist of low-rank coals (LRCs) such as lignite. With this background, the utilization of lignite for energy production is expected to remain a common practice in the decades to come since the availability of lignite is considerable in many countries of Europe and the world (e.g., Germany, Poland, Greece, United States, and Australia). Therefore, problems regarding the combustion and use of lignite should be addressed in a more efficient and environmentally friendly way. One of the main existing problems is the high moisture contained in raw lignite as received from the mine. The high moisture content results in higher CO2 emissions per unit of energy produced and is responsible for high capital and transport costs as well as other technical problems such as reduction in coal friability and difficulties in its blending and pneumatic transportation. Therefore processing of lignite through drying is considered of great interest in the implementation of energy production in lignite power plants. Taking into account the significance of the subject and the usefulness of such an attempt, an overview of the currently existing drying technologies, including both evaporative and nonevaporative drying methods, is reported in the present chapter.

Dynamic Modeling of a Utility Once-Through Pulverized-Fuel Steam Generator

AbstractThis study aims at modeling and simulating the transient operation of a utility supercritical steam generator fired with pulverized hard coal. The present theoretical study focuses on the d...

CFD Simulation of Domestic Gasification Boiler

AbstractThis paper describes the simulation of a wood gasification household boiler operation during the period that synthesis gas (syngas), which is produced after gasification, is further combusted for the production of heat that is transferred to the boiler heating surfaces. The particular boiler was designed by an Austrian company for the benefit of a Greek company based in northern Greece, which is currently manufacturing the boiler to test and further optimize it. The nominal fuel power of the boiler is approximately 50  kWth and its efficiency is about 90 percent (specifically 88.98 percent). The study is oriented toward the use of computational fluid dynamics (CFD) software as a supporting tool during the design phase of a gasification boiler and focuses on the combustion characteristics and the main gas emission concentrations expected at its outlet. In this study, the boiler is simulated under nominal operating conditions, assuming steady-state conditions as these have been defined by the Austri...

Role of heat transfer in bubble dynamics neglecting phase change. A numerical study

Financial support from the MSCA-ITN-ETN of the European Union’s H2020 programme, under REA grant agreement n. 675676 is acknowledged.