Author
Theoklis Nikolaidis
Bio: Theoklis Nikolaidis is an academic researcher from Cranfield University. The author has contributed to research in topics: Turbine & Gas compressor. The author has an hindex of 11, co-authored 80 publications receiving 461 citations.
Papers
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TL;DR: In this paper, the authors examined the environmental competence of Bio-Synthetic Paraffinic Kerosene (Bio-SPKs) against conventional Jet-A, through development of a life cycle GHG model (ALCEmB) from a "cradle-grave" perspective.
Abstract: Biojet fuels have been claimed to be one of the most promising and strategic solutions to mitigate aviation emissions. This study examines the environmental competence of Bio-Synthetic Paraffinic Kerosene (Bio-SPKs) against conventional Jet-A, through development of a life cycle GHG model (ALCEmB – Assessment of Life Cycle Emissions of Biofuels) from “cradle-grave” perspective. This model precisely calculates the life cycle emissions of the advanced biofuels through a multi-disciplinary study entailing hydrocarbon chemistry, thermodynamic behaviour and fuel combustion from engine/aircraft performance, into the life cycle studies, unlike earlier studies. The aim of this study is predict the “cradle-grave” carbon intensity of Camelina SPK, Microalgae SPK and Jatropha SPK through careful estimation and inclusion of combustion based emissions, which contribute ≈70% of overall life cycle emissions (LCE). Numerical modelling and non-linear/dynamic simulation of a twin-shaft turbofan, with an appropriate airframe, was conducted to analyse the impact of alternative fuels on engine/aircraft performance. ALCEmB revealed that Camelina SPK, Microalgae SPK and Jatropha SPK delivered 70%, 58% and 64% LCE savings relative to the reference fuel, Jet-A1. The net energy ratio analysis indicates that current technology for the biofuel processing is energy efficient and technically feasible. An elaborate gas property analysis infers that the Bio-SPKs exhibit improved thermodynamic behaviour in an operational gas turbine engine. This thermodynamic effect has a positive impact on aircraft-level fuel consumption and emissions characteristics demonstrating fuel savings in the range of 3–3.8% and emission savings of 5.8–6.3% (CO2) and 7.1–8.3% (LTO NOx), relative to that of Jet-A.
68 citations
TL;DR: In this article, the authors examine and analytically review the thermal management systems proposed over the past six decades for gas turbine civil aero engines and identify the remaining research questions that need to be addressed to enable this important technology to be adopted by next generation of aero engine with complicated designs.
Abstract: This paper examines and analytically reviews the thermal management systems proposed over the past six decades for gas turbine civil aero engines. The objective is to establish the evident system shortcomings and to identify the remaining research questions that need to be addressed to enable this important technology to be adopted by next generation of aero engines with complicated designs. Future gas turbine aero engines will be more efficient, compact and will have more electric parts. As a result, more heat will be generated by the different electrical components and avionics. Consequently, alternative methods should be used to dissipate this extra heat as the current thermal management systems are already working on their limits. For this purpose, different structures and ideas in this field are stated in terms of considering engines architecture, the improved engine efficiency, the reduced emission level and the improved fuel economy. This is followed by a historical coverage of the proposed concepts dating back to 1958. Possible thermal management systems development concepts are then classified into four distinct classes: classic, centralized, revolutionary and cost-effective; and critically reviewed from challenges and implementation considerations points of view. Based on this analysis, the potential solutions for dealing with future challenges are proposed including combination of centralized and revolutionary developments and combination of classic and cost-effective developments. The effectiveness of the proposed solutions is also discussed with a complexity-impact correlation analysis.
46 citations
TL;DR: The potential solutions for the remaining research challenges for application to aerospace engineering problems in the future include the implementation of enhanced and modified optimization algorithms and hybrid optimization algorithms in order to achieve optimal results for the advanced engine modelling and controller design procedure with affordable computational effort.
38 citations
TL;DR: In this paper, the authors investigated the technical performance of turboshaft engine cycles based on existing simple cycle and its projected modified cycles for civil helicopter application and found that the modified engine cycles with unconventional components exhibit better performance in terms of thermal efficiency and specific fuel consumption than the traditional simple cycle engine.
34 citations
TL;DR: In recent years, the increase in marine fuel prices coupled with stricter regulations on pollutant emissions set by the International Maritime Organization have promoted the research in new propuls... as mentioned in this paper.
33 citations
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TL;DR: The Thermophysical Properties Research Literature Retrieval Guide as discussed by the authors was published by Y. S. Touloukian, J. K. Gerritsen and N. Y. Moore.
Abstract: Thermophysical Properties Research Literature Retrieval Guide Edited by Y. S. Touloukian, J. K. Gerritsen and N. Y. Moore Second edition, revised and expanded. Book 1: Pp. xxi + 819. Book 2: Pp.621. Book 3: Pp. ix + 1315. (New York: Plenum Press, 1967.) n.p.
1,240 citations
TL;DR: Although the breadth of research in camelina over the last few years is impressive, several areas that would benefit from further research were identified and compiled and summarized new and existing information in order to identify gaps in knowledge and areas for future research.
213 citations
TL;DR: In this paper, the authors provided an overview on the conversion technologies, economic assessment, environmental influence and development status of bio-jet fuels, and suggested that hydrogenated esters and fatty acids, and Fischer-Tropsch synthesis can be the most promising technologies for biojet fuels production in near term.
195 citations
TL;DR: In this paper, the current state of development of drop-in alternative jet fuels including various Fisher-Tropsch synthetic jet fuels and bio-jet fuels is reviewed and discussed.
Abstract: With the growing air transport demand and concerns about its environmental impacts, alternative jet fuels derived from non-conventional sources have become an important strategy for achieving a sustainable and green aviation. In the past 10 years, governments around the world along with aviation industry have invested significant efforts into exploring all sorts of alternative jet fuels that can be used to power aircraft engines. Among all the alternative jet fuels explored, the aviation sector has agreed that hydrocarbon-based ‘drop-in’ replacement fuels, which are fully interchangeable and compatible with current conventional jet fuels, would be the best choice in the near future, as they can be used without any modifications to today׳s aircraft or fuel infrastructure. This paper reviews the current state of development of ‘drop-in’ alternative jet fuels including various Fisher–Tropsch synthetic jet fuels and bio-jet fuels. Recent advances in research activities on alternative jet fuels, including fuel property evaluations, combustor component tests, engine tests, and flight tests, are highlighted. Furthermore, basic research needs for understanding the combustion characteristics of alternative jet fuels are underlined and discussed by reviewing recent fundamental combustion studies on ignition, extinction, flame propagation, emissions, and species evolution of various conventional and alternative jet fuels. Recognizing that the use of ‘simpler’ surrogate fuels to emulate the behavior of ‘complex’ alternative jet fuels is of fundamental and practical importance for the development of physics-based models to enable quantitative emissions and performance predictions using combustion modeling, recent studies on surrogate formulation for alternative jet fuels are also reviewed and discussed. This review concludes with a brief discussion of future research directions.
173 citations
TL;DR: A comprehensive literature review has been performed to analyse which tools have been used by the scientific community for the sustainability evaluation of renewable energy systems during the past ten years and shows that LCA and MCDM applied individually do not achieve a comprehensive sustainability evaluation.
Abstract: Sustainability is a concept that integrates at least three dimensions: environmental, economic and social. Energy systems are usually evaluated as a key contributor for sustainable development, needing the methodology used for their evaluation to address many indicators, some are quantitative, while others are qualitative. It is therefore a challenge to choose the best methodology to accomplish this task. In this article, a comprehensive literature review has been performed to analyse which tools have been used by the scientific community for the sustainability evaluation of renewable energy systems during the past ten years (2007–2017). The purpose of this work focuses on verifying that the methodological framework integrated by the Life Cycle Analysis (LCA) and Multi-Criteria Decision Making (MCDM) combination is the right tool for the sustainability evaluation of renewable energy systems and obtaining a set of sustainable indicators, evaluation methods and the context where they are applied (such energy policies, electrical supply and evaluation of projects). A knowledge database has been built from the scientific experience of 154 cases of sustainability evaluation in renewable energy systems, with special focus on photovoltaic systems. The results of this revision show that LCA and MCDM applied individually do not achieve a comprehensive sustainability evaluation, due to their intrinsic high degree of uncertainty and the different kinds of analysed parameters. The hybrid framework of LCA and MCDM applied in combination appears as the most appropriate approach for this purpose, and specifically the combination of LCA and Analytic Herarchic Process (AHP), the most frequently used by the scientific community, for its simplicity and robustness for sustainable evaluation in energy systems.
152 citations