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  • 251.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    On the trade-off between aviation NOx and energy efficiency2017Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 185, s. 1506-1516Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study aims to assess the trade-off between the ever-increasing energy efficiency of modern aero-engines and their   performance. The work builds on performance models previously developed to optimise the specific fuel consumption of future aero-engine designs. As part of the present work a simple and adaptable   emissions correlation for Rich-burn Quick-quench Lean-burn combustor designs is derived. The proposed model is computationally inexpensive and sufficiently accurate for use in aero-engine multi-disciplinary conceptual design tools. Furthermore, it is possible to adapt the correlation to model the   emissions of combustors designed for very aggressive future cycles. An approach to lean-burn combustor   emissions modelling is also presented. The simulation results show that improving engine propulsive efficiency is likely to have a benign effect on  emissions at high altitude; at sea-level conditions   emissions are particularly likely to reduce. Improving engine thermal efficiency however has a detrimental effect on   emissions from RQL combustors, both at high altitude and particularly at sea-level conditions. LDI combustor technology does not demonstrate such behaviour. Current legislation permits trading   emissions engine efficiency and hence reduce   emissions. If we are to reduce the contribution of aviation to global warming, however, future certification legislation may need to become more stringent and comprehensive.

  • 252.
    Kyprianidis, Konstantinos G.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik. Cranfield University.
    Dynamic Simulation of Aircraft Propulsion Systems2006Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 253.
    Kyprianidis, Konstantinos G.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University.
    Future Aero Engine Designs: An Evolving Vision2011Ingår i: Advances in Gas Turbine Technology / [ed] Ernesto Benini, Rijeka, Croatia: InTech, 2011, 1st, s. 3-24Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 254.
    Kyprianidis, Konstantinos G.
    Cranfield University, UK.
    Multi-Disciplinary Conceptual Design of Future Jet Engine Systems2010Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes various aspects of the development of a multi-disciplinary aero engine conceptual design tool, TERA2020 (Techno-economic, Environmental and Risk Assessment for 2020), based on an explicit algorithm that considers: engine performance, engine aerodynamic and mechanical design, aircraft design and performance, emissions prediction and environmental impact, engine and airframe noise, and production, maintenance and direct operating costs.

    As part of this research effort, a newly-derived semi-empirical NOx correlation for modern rich-burn single-annular combustors is proposed. The development of a numerical methods library is also presented, including an improved gradient-based algorithm for solving non-linear equation systems. Common assumptions made in thermo-fluid modelling for gas turbines and their effect on caloric properties are investigated, while the impact of uncertainties on performance calculations and emissions predictions at aircraft system level is assessed. Furthermore, accuracy limitations in assessing novel engine core concepts as imposed by current practice in thermo-fluid modelling are identified.

    The TERA2020 tool is used for quantifying the potential benefits from novel technologies for three low pressure spool turbofan architectures.  The impact of failing to deliver specific component technologies is quantified, in terms of power plant noise and CO2 emissions. To address the need for higher engine thermal efficiency, TERA2020 is again utilised; benefits from the potential introduction of heat-exchanged cores in future aero engine designs are explored and a discussion on the main drivers that could support such initiatives is presented. Finally, an intercooled core and conventional core turbofan engine optimisation procedure using TERA2020 is presented. A back-to-back comparison between the two engine configurations is performed and fuel optimal designs for 2020 are proposed.

    Whilst the detailed publications and the work carried out by the author, in a collaborative effort with other project partners, is presented in the main body of this thesis, it is important to note that this work is supported by 20 conference and journal papers.

  • 255.
    Kyprianidis, Konstantinos G.
    et al.
    Cranfield University, Bedfordshire, England, UK.
    Colmenares Quintero, Ramon F.
    Cranfield University, Bedfordshire, England, UK.
    Pascovici, Daniele S.
    Cranfield University, Bedfordshire, England, UK.
    Ogaji, Stephen O. T.
    Cranfield University, Bedfordshire, England, UK.
    Pilidis, Pericles
    Cranfield University, Bedfordshire, England, UK.
    Kalfas, Anestis I.
    Aristotle University of Thessaloniki, Thessaloniki, Greece.
    EVA: A Tool for EnVironmental Assessment of Novel Propulsion Cycles2008Ingår i: ASME Turbo Expo 2008: Power for Land, Sea, and AirVolume 2: Controls, Diagnostics and Instrumentation; Cycle Innovations; Electric PowerBerlin, Germany, June 9–13, 2008, 2008, s. 547-556Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the development of a tool for EnVironmental Assessment (EVA) of novel propulsion cycles implementing the Technoeconomical Environmental and Risk Analysis (TERA) approach. For nearly 3 decades emissions certification and legislation has been mainly focused on the landing and take-off cycle. Exhaust emissions measurements of NOx, CO and unburned hydrocarbons are taken at Sea Level Static (SLS) conditions for 4 different power settings (idle, descent, approach and take-off) and are consecutively used for calculating the total emissions during the ICAO landing and take-off cycle. With the global warming issue becoming ever more important, stringent emissions legislation is soon to follow, focusing on all flight phases of an aircraft. Unfortunately, emissions measurements at altitude are either extremely expensive, as in the case of altitude test facility measurements, or unrealistic, as in the case of direct in flight measurements. Compensating for these difficulties, various existing methods can be used to estimate emissions at altitude from ground measurements. Such methods, however, are of limited help when it comes to assessing novel propulsion cycles or existing engine configurations with no SLS measurements available. The authors are proposing a simple and fast method for the calculation of SLS emissions, mainly implementing ICAO exhaust emissions data, corrections for combustor inlet conditions and technology factors. With the SLS emissions estimated, existing methods may be implemented to calculate emissions at altitude. The tool developed couples emissions predictions and environmental models together with engine and aircraft performance models in order to estimate the total emissions and Global Warming Potential of novel engine designs during all flight phases (i.e. the whole flight cycle). The engine performance module stands in the center of all information exchange. In this study, EVA and the described emissions prediction methodology have been used for the preliminary design analysis of three spool high bypass ratio turbofan engines. The capability of EVA to radically explore the design space available in novel engine configurations, while accounting for fuel burn and global warming potential during the whole flight cycle of an aircraft, is illustrated.

  • 256.
    Kyprianidis, Konstantinos G.
    et al.
    Chalmers University of Technology, Sweden.
    Grönstedt, Tomas
    Chalmers University of Technology, Sweden.
    Barbosa, Joao R.
    Instituto Tecnológico de Aeronáutica - ITA, Sao Paolo, Brazil.
    Lessons Learned from the Development of Courses on Gas Turbine Multi-disciplinary Conceptual Design2012Ingår i: Proc. ASME. 44694; Volume 3: Cycle Innovations; Education; Electric Power; Fans and Blowers; Industrial and Cogeneration. GT2012-70095, 2012, s. 513-523Konferensbidrag (Refereegranskat)
    Abstract [en]

    Despite the need for highly qualified experts, multi-disciplinary gas turbine conceptual design has not been a common study topic in traditional post-graduate curriculums. Although many courses on specialised topics in gas turbine technology take place, limited attention is given on connecting these individual topics to the overall engine design process. Teaching conceptual design as part of a post-graduate curriculum, or as an intensive short course, may help to address the industrial need for engineers with early qualifications on the topic i.e., prior to starting their careers in the gas turbine industry.

    This paper presents details and lessons learned from: (i) the integration of different elements of conceptual design in an existing traditional MSc course on gas turbine technology through the introduction of group design tasks, and (ii) the development of an intensive course on gas turbine multi-disciplinary conceptual design as a result of an international cooperation between academia and industry.

    Within the latter course, the students were grouped in competing teams and were asked to produce their own gas turbine conceptual design proposals within a given set of functional requirements. The main concept behind the development of the new design tasks, and the new intensive course, has been to effectively mimic the dynamics of small conceptual design teams, as often encountered in industry. The results presented are very encouraging, in terms of enhancing student learning and developing engineering skills.

  • 257.
    Kyprianidis, Konstantinos G.
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University.
    Sethi, Vishal
    Cranfield University.
    Ogaji, Stephen O. T.
    Cranfield University.
    Pilidis, Pericles
    Cranfield University.
    Singh, Riti
    Cranfield University.
    Kalfas, Anestis I.
    Aristotle University of Thessaloniki.
    Thermo-Fluid Modelling for Gas Turbines-Part I: Theoretical Foundation and Uncertainty Analysis2009Ingår i: ASME TURBO EXPO 2009 Proceedings, GT2009-60092, 2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this two-part publication, various aspects of thermo-fluidmodelling for gas turbines are described and their impact onperformance calculations and emissions predictions at aircraftsystem level is assessed. Accurate and reliable fluid modellingis essential for any gas turbine performance simulation softwareas it provides a robust foundation for building advanced multidisciplinarymodelling capabilities. Caloric properties forgeneric and semi-generic gas turbine performance simulationcodes can be calculated at various levels of fidelity; selection ofthe fidelity level is dependent upon the objectives of thesimulation and execution time constraints. However, rigorousfluid modelling may not necessarily improve performancesimulation accuracy unless all modelling assumptions andsources of uncertainty are aligned to the same level. Certainmodelling aspects such as the introduction of chemical kinetics,and dissociation effects, may reduce computational speed andthis is of significant importance for radical space explorationand novel propulsion cycle assessment.

    This paper describes and compares fluid models, based ondifferent levels of fidelity, which have been developed for anindustry standard gas turbine performance simulation code and an environmental assessment tool for novel propulsion cycles.The latter comprises the following modules: engineperformance, aircraft performance, emissions prediction, andenvironmental impact. The work presented aims to fill thecurrent literature gap by: (i) investigating the commonassumptions made in thermo-fluid modelling for gas turbinesand their effect on caloric properties and (ii) assessing theimpact of uncertainties on performance calculations andemissions predictions at aircraft system level.

    In Part I of this two-part publication, a comprehensiveanalysis of thermo-fluid modelling for gas turbines is presentedand the fluid models developed are discussed in detail.Common technical models, used for calculating caloricproperties, are compared while typical assumptions made influid modelling, and the uncertainties induced, are examined.Several analyses, which demonstrate the effects of composition,temperature and pressure on caloric properties of workingmediums for gas turbines, are presented. The working mediumsexamined include dry air and combustion products for variousfuels and H/C ratios. The errors induced by ignoringdissociation effects are also discussed.

  • 258.
    Kyprianidis, Konstantinos G.
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University.
    Sethi, Vishal
    Cranfield University.
    Ogaji, Stephen O. T.
    Cranfield University.
    Pilidis, Pericles
    Cranfield University.
    Singh, Riti
    Cranfield University.
    Kalfas, Anestis I.
    Aristotle University of Thessaloniki.
    Thermo-Fluid Modelling for Gas Turbines-Part II: Impact on Performance Calculations and Emissions Predictions at Aircraft System Level2009Ingår i: ASME TURBO EXPO 2009 Proceedings, GT-2009-60101, 2009, s. 483-494Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this two-part publication, various aspects of thermo-fluidmodelling for gas turbines are described and their impact onperformance calculations and emissions predictions at aircraftsystem level is assessed. Accurate and reliable fluid modellingis essential for any gas turbine performance simulation softwareas it provides a robust foundation for building advanced multidisciplinarymodelling capabilities. Caloric properties forgeneric and semi-generic gas turbine performance simulationcodes can be calculated at various levels of fidelity; selection ofthe fidelity level is dependent upon the objectives of thesimulation and execution time constraints. However, rigorousfluid modelling may not necessarily improve performancesimulation accuracy unless all modelling assumptions andsources of uncertainty are aligned to the same level. Certainmodelling aspects such as the introduction of chemical kinetics,and dissociation effects, may reduce computational speed andthis is of significant importance for radical space explorationand novel propulsion cycle assessment.

    This paper describes and compares fluid models, based ondifferent levels of fidelity, which have been developed for anindustry standard gas turbine performance simulation code and an environmental assessment tool for novel propulsion cycles.The latter comprises the following modules: engineperformance, aircraft performance, emissions prediction, andenvironmental impact. The work presented aims to fill thecurrent literature gap by: (i) investigating the commonassumptions made in thermo-fluid modelling for gas turbinesand their effect on caloric properties and (ii) assessing theimpact of uncertainties on performance calculations andemissions predictions at aircraft system level.

    In Part II of this two-part publication, the uncertaintyinduced in performance calculations by common technicalmodels, used for calculating caloric properties, is discussed atengine level. The errors induced by ignoring dissociation areexamined at 3 different levels: i) component level, ii) enginelevel, and iii) aircraft system level. Essentially, an attempt ismade to shed light on the trade-off between improving theaccuracy of a fluid model and the accuracy of a multidisciplinarysimulation at aircraft system level, againstcomputational time penalties. The results obtained demonstratethat accurate modelling of the working fluid is not alwaysessential; the accuracy/uncertainty for an overall engine modelwill always be better than the mean accuracy/uncertainty of the individual component estimates as long as systematic errors arecarefully examined and reduced to acceptable levels to ensureerror propagation does not cause significant discrepancies.Computational time penalties induced by improving theaccuracy of the fluid model as well as the validity of the idealgas assumption for future turbofan engines and novelpropulsion cycles are discussed.

  • 259.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University, UK.
    Grönstedt, Tomas
    Chalmers University of Technology, Sweden.
    Barbosa, Joao R.
    Instituto Technológico de Aeronáutica, São José dos Campos, Brazil.
    Lessons Learned From the Development of Courses on Gas Turbine Multidisciplinary Conceptual Design2013Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, nr 7, s. Article number 072601-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the need for highly qualified experts, multidisciplinary gas turbine conceptual design has not been a common study topic in traditional postgraduate curriculums. Although many courses on specialized topics in gas turbine technology take place, limited attention is given on connecting these individual topics to the overall engine design process. Teaching conceptual design as part of a postgraduate curriculum, or as an intensive short course, may help to address the industrial need for engineers with early qualifications on the topic, i.e., prior to starting their careers in the gas turbine industry. This paper presents details and lessons learned from: (i) the integration of different elements of conceptual design in an existing traditional Master of Science (MSc) course on gas turbine technology through the introduction of group design tasks and (ii) the development of an intensive course on gas turbine multidisciplinary conceptual design as a result of an international cooperation between academia and industry. Within the latter course, the students were grouped in competing teams and were asked to produce their own gas turbine conceptual design proposals within a given set of functional requirements. The main concept behind the development of the new design tasks, and the new intensive course, has been to effectively mimic the dynamics of small conceptual design teams, as often encountered in industry. The results presented are very encouraging in terms of enhancing student learning and developing engineering skills.

  • 260.
    Kyprianidis, Konstantinos
    et al.
    Cranfield University, United Kingdom.
    Grönstedt, Tomas
    Chalmers University of Technology, Sweden.
    Ogaji, S. O. T.
    Cranfield University, United Kingdom.
    Pilidis, Pericles
    Cranfield University, United Kingdom.
    Singh, Riti
    Cranfield University, United Kingdom.
    Assessment of Future Aero-engine Designs With Intercooled and Intercooled Recuperated Cores2011Ingår i: Journal of Engineering for Gas Turbines and Power, ISSN 0742-4795, Vol. 133, nr 1, artikel-id 011701Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reduction in CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction in engine nacelle drag and weight. Conventional turbofan designs, however, that reduce CO2 emissions—such as increased overall pressure ratio designs—can increase the production of NOx emissions. In the present work, funded by the European Framework 6 collaborative project NEW Aero engine Core concepts (NEWAC), an aero-engine multidisciplinary design tool, Techno-economic, Environmental, and Risk Assessment for 2020 (TERA2020), has been utilized to study the potential benefits from introducing heat-exchanged cores in future turbofan engine designs. The tool comprises of various modules covering a wide range of disciplines: engine performance, engine aerodynamic and mechanical design, aircraft design and performance, emissions prediction and environmental impact, engine and airframe noise, as well as production, maintenance and direct operating costs. Fundamental performance differences between heat-exchanged cores and a conventional core are discussed and quantified. Cycle limitations imposed by mechanical considerations, operational limitations and emissions legislation are also discussed. The research work presented in this paper concludes with a full assessment at aircraft system level that reveals the significant potential performance benefits for the intercooled and intercooled recuperated cycles. An intercooled core can be designed for a significantly higher overall pressure ratio and with reduced cooling air requirements, providing a higher thermal efficiency than could otherwise be practically achieved with a conventional core. Variable geometry can be implemented to optimize the use of the intercooler for a given flight mission. An intercooled recuperated core can provide high thermal efficiency at low overall pressure ratio values and also benefit significantly from the introduction of a variable geometry low pressure turbine. The necessity of introducing novel lean-burn combustion technology to reduce NOx emissions at cruise as well as for the landing and take-off cycle, is demonstrated for both heat-exchanged cores and conventional designs. Significant benefits in terms of NOx reduction are predicted from the introduction of a variable geometry low pressure turbine in an intercooled core with lean-burn combustion technology.

  • 261.
    Kyprianidis, Konstantinos
    et al.
    Aristotle University of Thessaloniki, Thessaloniki, Greece.
    Kalfas, Anestis I.
    Aristotle University of Thessaloniki, Thessaloniki, Greece.
    Dynamic performance investigations of a turbojet engine using a cross-application visual oriented platform2008Ingår i: Aeronautical Journal, ISSN 0001-9240, Vol. 112, nr 1129, s. 161-169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the development of visual oriented tools for the dynamic performance simulation of a turbojet engine using a cross-application approach. In particular, the study focuses on the feasibility of developing simulation models using different programming environments and linking them together using a popular spreadsheet program. As a result of this effort, a low fidelity cycle program has been created, capable of being integrated with other performance models. The amount of laboratory sessions required for student training during an educational procedure, for example for a course in gas turbine performance simulation, is greatly reduced due to the familiarity of most students with the spreadsheet software. The model results have been validated using commercially available gas turbine simulation software and experimental data from open literature. The most important finding of this study is the capability of the program to link to aircraft performance models and predict the transient working line of the engine for various initial conditions in order to dynamically simulate flight phases including take-off and landing.

  • 262.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University, UK.
    Nalianda, Devaiah
    Cranfield University, UK.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    A NOx Emissions Correlation for Modern RQL Combustors2015Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 75, s. 2323-2330Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study begins with a review of existing emissions prediction methodologies for Rich-burn Quick-quench Lean-burn combustors. The need for a simple and adaptable NOx emissions correlation for such combustor designs as used in state-of-the-art civil turbofan engines is discussed. The derivation of a new correlation is consequently presented. The proposed model is computationally inexpensive and sufficiently accurate for use in aero-engine multi-disciplinary conceptual design tools. Furthermore, it is possible to adapt the correlation to model the NOx emissions of combustors designed for very aggressive future cycles. A case study is presented focusing on the NOx performance of advanced future cycles relative to current and future certification limits.

  • 263.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University, UK.
    Rolt, Andrew
    Rolls-Royce plc, UK.
    On the Optimisation of a Geared Fan Intercooled Core Engine Design2015Ingår i: Journal of Engineering for Gas Turbines and Power, ISSN 0742-4795, Vol. 137, nr 4, s. Paper N_GTP-14-1367-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. Thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to further analyse the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. The proposed design methodology is capable, with the utilised tool, of exploring the interaction of design criteria and providing critical design insight at engine-aircraft system level. Previous work by the authors focused on understanding the design space for this particular configuration with minimum specific fuel consumption, engine weight and mission fuel in mind. This was achieved by means of a parametric analysis, varying several engine design parameters - but only one at a time. The present work attempts to identify 'globally' fuel burn optimal values for a set of engine design parameters by varying them all simultaneously. This permits the non-linear interactions between the parameters to be accounted. Special attention has been given to the fuel burn impact of the reduced HPC efficiency levels associated with low last stage blade heights. Three fuel optimal designs are considered, based on different assumptions. The results indicate that it is preferable to trade overall pressure ratio and pressure ratio split exponent, rather than specific thrust, as means of increasing blade height and hence reducing the associated fuel consumption penalties. It is interesting to note that even when considering the effect of HPC last stage blade height on efficiency there is still an equivalently good design at a reduced overall pressure ratio. This provides evidence that the overall economic optimum could be for a lower overall pressure ratio cycle. Customer requirements such as take-off distance and time to height play a very important role in determining a fuel optimal engine design. Tougher customer requirements result in bigger and heavier engines that burn more fuel. Higher overall pressure ratio intercooled engine cycles clearly become more attractive in aircraft applications that require larger engine sizes.

  • 264.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University, UK.
    Rolt, Andrew
    Rolls-Royce plc, UK.
    Grönstedt, Tomas
    Chalmers University of Technology, Sweden.
    Multidisciplinary Analysis of a Geared Fan Intercooled Core Aero-Engine2014Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 136, nr 1, s. Article number 011203-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, along with the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. The thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is very little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to analyze the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. With minimum mission fuel in mind, the results indicate as optimal values a pressure ratio split exponent of 0.38 and an intercooler mass flow ratio of 1.18 at hot-day top of climb conditions. At ISA midcruise conditions a specific thrust of 86 m/s, a jet velocity ratio of 0.83, an intercooler effectiveness of 56%, and an overall pressure ratio value of 76 are likely to be a good choice. A 70,000 lbf intercooled turbofan engine is large enough to make efficient use of an all-axial compression system, particularly within a geared fan configuration, but intercooling is perhaps more likely to be applied to even larger engines. The proposed optimal jet velocity ratio is actually higher than the value one would expect by using standard analytical expressions, primarily because this design variable affects core efficiency at mid-cruise due to a combination of several different subtle changes to the core cycle and core component efficiencies at this condition. The analytical expressions do not consider changes in core efficiency and the beneficial effect of intercooling on transfer efficiency, nor do they account for losses in the bypass duct and jet pipe, while a relatively detailed engine performance model, such as the one utilized in this study, does. Mission fuel results from a surrogate model are in good agreement with the results obtained from a rubberized-wing aircraft model for some of the design parameters. This indicates that it is possible to replace an aircraft model with specific fuel consumption and weight penalty exchange rates. Nevertheless, drag count exchange rates have to be utilized to properly assess changes in mission fuel for those design parameters that affect nacelle diameter.

  • 265.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University, UK.
    Rolt, Andrew
    Rolls-Royce plc, UK.
    Grönstedt, Tomas
    Chalmers University of Technology, Sweden.
    Multi-disciplinary Analysis of a Geared Fan Intercooled Core Aero-Engine2013Ingår i: Proc. ASME. 55133; Volume 2: Aircraft Engine; Coal, Biomass and Alternative Fuels; Cycle Innovations, V002T07A027. GT2013-95474, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. Thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is very little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to analyse the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption.

    With minimum mission fuel in mind, the results indicate as optimal values a pressure ratio split exponent of 0.38 and an intercooler mass flow ratio just below 1.2 at hot-day top of climb conditions. At ISA mid-cruise conditions a specific thrust of 86m/s, a jet velocity ratio of 0.83, an intercooler effectiveness of 55% and an overall pressure ratio value of 76 are likely to be a good choice. A 70,000lbf intercooled turbofan engine is large enough to make efficient use of an all-axial compression system, particularly within a geared fan configuration, but intercooling is perhaps more likely to be applied to even larger engines.

    The proposed optimal jet velocity ratio is actually higher than the value one would expect by using standard analytical expressions primarily because this design variable affects core efficiency at mid-cruise due to a combination of several different subtle changes to the core cycle and core component efficiencies at this condition. Analytical expressions do not consider changes in core efficiency and the beneficial effect of intercooling on transfer efficiency, nor account for losses in the bypass duct and jet pipe, whilst a relatively detailed engine performance model such as the one utilised in this study does.

    Mission fuel results from a surrogate model are in good agreement with the results obtained from a rubberised-wing aircraft model for some of the design parameters. This indicates that it is possible to replace an aircraft model with specific fuel consumption and weight penalty exchange rates. Nevertheless, drag count exchange rates have to be utilised to properly assess changes in mission fuel for those design parameters that affect nacelle diameter.

  • 266.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University, UK.
    Rolt, Andrew M.
    Rolls-Royce plc.
    On the Optimisation of a Geared Fan Intercooled Core Engine Design2014Ingår i: Proc. ASME. 45653; Volume 3A: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration, V03AT07A018. GT2014-26064, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, as well as the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. Thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to further analyse the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. The proposed design methodology is capable, with the utilised tool, of exploring the interaction of design criteria and providing critical design insight at engine-aircraft system level.

    Previous work by the authors focused on understanding the design space for this particular configuration with minimum specific fuel consumption, engine weight and mission fuel in mind. This was achieved by means of a parametric analysis, varying several engine design parameters — but only one at a time. The present work attempts to identify “globally” fuel burn optimal values for a set of engine design parameters by varying them all simultaneously. This permits the non-linear interactions between the parameters to be accounted. Special attention has been given to the fuel burn impact of the reduced HPC efficiency levels associated with low last stage blade heights.

    Three fuel optimal designs are considered, based on different assumptions. The results indicate that it is preferable to trade overall pressure ratio and pressure ratio split exponent, rather than specific thrust, as means of increasing blade height and hence reducing the associated fuel consumption penalties. It is interesting to note that even when considering the effect of HPC last stage blade height on efficiency there is still an equivalently good design at a reduced overall pressure ratio. This provides evidence that the overall economic optimum could be for a lower overall pressure ratio cycle. Customer requirements such as take-off distance and time to height play a very important role in determining a fuel optimal engine design. Tougher customer requirements result in bigger and heavier engines that burn more fuel. Higher overall pressure ratio intercooled engine cycles clearly become more attractive in aircraft applications that require larger engine sizes.

  • 267.
    Kyprianidis, Konstantinos
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Cranfield University.
    Rolt, Andrew M.
    Rolls-Royce plc.
    Sethi, Vishal
    Cranfield University.
    On Intercooled Turbofan Engines2013Ingår i: Progress in Gas Turbine Performance / [ed] Ernesto Benini, Rijeka, Croatia: InTech, 2013, 1st, , s. 268s. 3-24Kapitel i bok, del av antologi (Refereegranskat)
  • 268.
    Kyprianidis, Konstantinos
    et al.
    Chalmers University, Sweden.
    Sethi, Vishal
    Cranfield University, UK.
    Ogaji, S O T
    Cranfield University, UK.
    Pilidis, Pericles
    Cranfield University, UK.
    Singh, Riti
    Cranfield University, UK.
    Kalfas, A I
    Aristotle University of Thessaloniki, Greece.
    Uncertainty in gas turbine thermo-fluid modelling and its impact on performance calculations and emissions predictions at aircraft system level2012Ingår i: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, ISSN 0954-4100, Vol. 226, nr 2, s. 163-181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this article, various aspects of thermo-fluid modelling for gas turbines are described and the impact on performance calculations and emissions predictions at aircraft system level is assessed. Accurate and reliable fluid modelling is essential for any gas turbine performance simulation software as it provides a robust foundation for building advanced multi-disciplinary modelling capabilities. Caloric properties for generic and semi-generic gas turbine performance simulation codes can be calculated at various levels of fidelity; selection of the fidelity level is dependent upon the objectives of the simulation and execution time constraints. However, rigorous fluid modelling may not necessarily improve performance simulation accuracy unless all modelling assumptions and sources of uncertainty are aligned to the same level.

    A comprehensive analysis of thermo-fluid modelling for gas turbines is presented, and the fluid models developed are discussed in detail. Common technical models, used for calculating caloric properties, are compared while typical assumptions made in fluid modelling, and the uncertainties induced, are examined. Several analyses, which demonstrate the effects of composition, temperature, and pressure on caloric properties of working media for gas turbines, are presented. The working media examined include dry air and combustion products for various fuels and H/C ratios. The uncertainty induced in calculations by (a) using common technical models for evaluating fluid caloric properties and (b) ignoring dissociation effects is examined at three different levels: (i) component level, (ii) engine level, and (iii) aircraft system level. An attempt is made to shed light on the trade-off between improving the accuracy of a fluid model and the accuracy of a multi-disciplinary simulation at aircraft system level, against computational time penalties. The validity of the ideal gas assumption for future turbofan engines and novel propulsion cycles is discussed. The results obtained demonstrate that accurate modelling of the working fluid is essential, especially for assessing novel and/or aggressive cycles at aircraft system level. Where radical design space exploration is concerned, improving the accuracy of the fluid model will need to be carefully balanced with the computational time penalties involved.

  • 269.
    Lam, H. L.
    et al.
    Hon Loong Lam Centre of Excellence for Green Technologies, University of Nottingham Malaysia Campus, Malaysia.
    Varbanov, P. S.
    University of Pannonia, Veszprém, Hungary.
    Klemeš, J. J.
    University of Pannonia, Veszprém, Hungary.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology (KTH), Stockholm, Sweden.
    Green Applied Energy for sustainable development2016Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 161, s. 601-604Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    This special issue of Applied Energy contains articles developed from initial ideas related to the 17th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (PRES 2014) held in Prague, Czech Republic, during 23-27 August 2014. The conference has been organised jointly with CHISA 2014. Both events have benefitted from the shared pool of participants as well as the expanded opportunities for exchanging ideas. From all contributions presented at the conference, high-quality ones suitable for Applied Energy, have been invited. Overall, 37 extended manuscripts have been invited as candidate articles. Of those, after a thorough review procedure, 11 articles have been selected to be published. The topics attained in the focus of this Special Issue include Process Integration and Energy Management, CO2 capture, and Green Energy Applications. 

  • 270.
    Landelius, Erik
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Åström, Magnus
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    DISTRICT HEAT PRICE MODEL ANALYSIS: A risk assesment of Mälarenergi's new district heat price model2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Energy efficiency measures in buildings and alternative heating methods have led to a decreased demand for district heating (DH). Furthermore, due to a recent increase in extreme weather events, it is harder for DH providers to maintain a steady production leading to increased costs. These issues have led DH companies to change their price models. This thesis investigated such a price model change, made by Mälarenergi (ME) on the 1st of August 2018. The aim was to compare the old price model (PM1) with the new price model (PM2) by investigating the choice of base and peak loads a customer can make for the upcoming year, and/or if they should let ME choose for them. A prediction method, based on predicting the hourly DH demand, was chosen after a literature study and several method comparisons were made from using weather parameters as independent variables. Consumption data from Mälarenergi for nine customers of different sizes were gathered, and eight weather parameters from 2014 to 2018 were implemented to build up the prediction model. The method comparison results from Unscrambler showed that multilinear regression was the most accurate statistical modelling method, which was later used for all predictions. These predictions from Unscrambler were then used in MATLAB to estimate the total annual cost for each customer and outcome. For PM1, the results showed that the flexible cost for the nine customers stands for 76 to 85 % of the total cost, with the remaining cost as fixed fees. For PM2, the flexible cost for the nine customers stands for 46 to 61 % of the total cost, with the remaining as fixed cost. Regarding the total cost, PM2 is on average 7.5 % cheaper than PM1 for smaller customer, 8.6 % cheaper for medium customers and 15.9 % cheaper for larger customers. By finding the lowest cost case for each customer their optimal base and peaks loads were found and with the use of a statistical inference method (Bootstrapping) a 95 % confidence interval for the base load and the total yearly cost with could be established. The conclusion regarding choices is that the customer should always choose their own base load within the recommended confidence interval, with ME’s choice seen as a recommendation. Moreover, ME should always make the peak load choice because they are willing to pay for an excess fee that the customer themselves must pay otherwise.

  • 271.
    Larsson, David
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Stridh, Bengt
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Karlsson, Björn
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Solar Electricity in Swedish District Heating Areas: Effective Energy Measures in Apartment Buildings to Increase the Share of Renewable Energy in Europe2014Ingår i: Proceedings from the 14th International Symposium on District Heating and Cooling / [ed] Anna Land, Stockholm: Svensk Fjärrvärme , 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    To overcome the climate challenge is one of the greatest tasks of our time. In EU, renovating the existing building stock has been found an effective measure. In Swedish buildings with district heating, lowering heat demand could be questioned, because the energy used is mainly renewable bio energy or waste heat from industries. In addition many district heating systems cogenerate electricity, which could reduce the overall European greenhouse gas emissions.

    The aim of this article is to find effective measures for Swedish apartment buildings, in order to increase the share of renewable energy in European energy consumption. As a basis we use a previous study of energy saving potentials in apartment buildings. Added to this we study the impact of heat savings in 30 of Sweden’s largest district heating systems.

    The results show that on average heat reductions will lead to a decreased share of renewable energy, while electricity reductions will lead to an increased share of renewables. Of the investigated measures, using photovoltaics for local solar electricity generation has the largest potential.

    Our conclusion is that using the potential of solar electricity production should be considered in national energy policy and future building requirements. Heat reduction, on the other hand, could have lower priority in district heating areas, at least for existing buildings.

  • 272.
    Larsson, Donny
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Andersson, Henrik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Utvärdering av labpilot - flödesbatteri: Experimentell studie2012Självständigt arbete på grundnivå (högskoleexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Results have shown that flow batteries may be a solution in the future as an effective and environmental friendly method to an energy storage system (ESS). The technology is reliable and has a high efficiency that comes with low energy losses and a long lifetime. The range of possible fields is suitable for cutting energy peaks in the power grid, by always have a ready and available energy storage that balances the production. By comparing the advantages of flow batteries with conventional batteries it is mainly the fact that they can conserve energy for a long time without being self-discharged thanks to that the storage capacity is in principle endless and limited by the size of the electrolytes tanks that makes them a great energy storage system. The batteries won’t take any damage or decrease in performance when charging or discharging it or if you exhausts it to 100 % and leave it discharged for a long time. The only disadvantages with flow batteries are that they are built upon an advanced design and are built of components made of expensive materials.

    The main objective of this thesis is to develop an experimental basis for assessing a small pilot module of a flow battery with respect to how different concentrations of salts, flow rates and different currents/voltages affect the performance of the battery. We start by performing the experiment with a polymeric ion exchange membrane and see what values and the advantages and disadvantages it entails.

  • 273.
    Larsson, Linda
    et al.
    Volvo Aero Corporation, Trollhättan, Sweden .
    Grönstedt, Tomas
    Chalmers University, Gothenburg, Sweden.
    Kyprianidis, Konstantinos G.
    Chalmers University, Gothenburg, Sweden.
    Conceptual Design and Mission Analysis for a Geared Turbofan and an Open Rotor Configuration2011Ingår i: Proc. ASME. 54617; Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Wind Turbine Technology. GT2011-46451, 2011, s. 359-370Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this multidisciplinary study a geared open rotor configuration is assessed and compared to an ultra high bypass ratio geared turbofan engine. Both designs assume a 2020 entry into service level of technology. The specific thrust level for minimizing block fuel and the resulting engine emissions for a given mission is sought. The tool used contains models that effectively capture: engine performance, mechanical and aerodynamic design, engine weight, emissions, aircraft design and performance as well as direct operating costs. The choice of specific thrust is a complex optimization problem and several disciplines need to be considered simultaneously. It will be demonstrated, through multidisciplinary analysis, that the open rotor concept can offer a substantial fuel saving potential, compared to ducted fans, for a given set of design considerations and customer requirements.

  • 274. Leduc, Sylvain
    et al.
    Schwab, Dagmar
    Dotzauer, Erik
    Mälardalens högskola, Institutionen för samhällsteknik.
    Schmid, Erwin
    Obersteiner, Michael
    Optimal location of wood gasification plants under poly-production2007Ingår i: The 3rd International Green Energy Conference, 2007Konferensbidrag (Övrigt vetenskapligt)
  • 275. Leduc, Sylvain
    et al.
    Schwab, Dagmar
    Dotzauer, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Schmid, Erwin
    Obersteiner, Michael
    OPTIMAL LOCATION OF WOOD GASIFICATION PLANTS UNDER POLY-PRODUCTION2007Konferensbidrag (Refereegranskat)
  • 276.
    Lee, Duu-Jong
    et al.
    Natl Taiwan Univ Sci & Technol, Taiwan.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Inst Technol, Stockholm, Sweden.
    Chou, Siaw-Kiang
    Natl Univ Singapore, Singapore.
    Desideri, Umberto
    Univ Perugia, Perugia, Italy.
    Clean, efficient, affordable and reliable energy for a sustainable future Preface2015Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 102, s. 1-3Artikel i tidskrift (Övrigt vetenskapligt)
  • 277.
    Lee, M.
    et al.
    National Taiwan University, Taipei, Taiwan.
    Keller, A. A.
    University of California, Santa Barbara, CA, United States.
    Chiang, P. -C
    National Taiwan University, Taipei, Taiwan.
    Den, W.
    Tunghai University, Taichung, Taiwan.
    Wang, H.
    Tongji University, Shanghai, China.
    Hou, C. -H
    National Taiwan University, Taipei, Taiwan.
    Wu, J.
    Tongji University, Shanghai, China.
    Wang, X.
    Tongji University, Shanghai, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Tongji University, Shanghai, China; Royal Institute of Technology (KTH), Sweden.
    Water-energy nexus for urban water systems: A comparative review on energy intensity and environmental impacts in relation to global water risks2017Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 205, s. 589-601Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The importance of the interdependence between water and energy, also known as the water-energy nexus, is well recognized. The water-energy nexus is typically characterized in resource use efficiency terms such as energy intensity. This study aims to explore the quantitative results of the nexus in terms of energy intensity and environmental impacts (mainly greenhouse gas emissions) on existing water systems within urban water cycles. We also characterized the influence of water risks on the water-energy nexus, including baseline water stress (a water quantity indicator) and return flow ratio (a water quality indicator). For the 20 regions and 4 countries surveyed (including regions with low to extremely high water risks that are geographically located in Africa, Australia, Asia, Europe, and North America), their energy intensities were positively related to the water risks. Regions with higher water risks were observed to have relatively higher energy and GHG intensities associated with their water supply systems. This mainly reflected the major influence of source water accessibility on the nexus, particularly for regions requiring energy-intensive imported or groundwater supplies, or desalination. Regions that use tertiary treatment (for water reclamation or environmental protection) for their wastewater treatment systems also had relatively higher energy and GHG emission intensities, but the intensities seemed to be independent from the water risks. On-site energy recovery (e.g., biogas or waste heat) in the wastewater treatment systems offered a great opportunity for reducing overall energy demand and its associated environmental impacts. Future policy making for the water and energy sectors should carefully consider the water-energy nexus at the regional or local level to achieve maximum environmental and economic benefits. The results from this study can provide a better understanding of the water-energy nexus and informative recommendations for future policy directions for the effective management of water and energy.

  • 278.
    Lennermo, Gunnar
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Energianalys AB, Sverige.
    Lauenberg, Patrick
    Lund University, Sweden.
    Distributed heat generation in a district heating system2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    District heating (OH) systems need to be improved  regarding integration  of decentralised  heat generation. Micro production, prosumers and smart grids are terms becoming more and more common  in  connection  to  the  power  grid.  Concerning district  heating,  the  development  is slower, although improving. Today there are a number of such decentralised units for heat generation,  mainly  solar,  that have been partly evaluated.  Previous  studies  have shown  that there is a need to develop a better control system for the connection to the district heating grid.

    In principle  there are four different ways to connect  a local heat generator  to a OH grid. The most  common  technology  is Return/Supply   connection  (R/S). In this concept it is necessary to use a feed-in pump and equipment  to get correct temperatures  and flows.

    Evaluatian of solar thermal (ST) installations in Sweden shows that the feed in flow and heat-power  vary considerably;  more than the heat-power  productian  from  the ST plant.  This causes a drop in heat generation from the solarthermal system. However, if the ST installation is small in relation to the OH system, it will not cause any problems  for the OH system. There are more than 20 R/S ST installations in Sweden and up until recently, no complaints from OH Campanies regarding poor performance were recorded.

  • 279.
    Lennermo, Gunnar
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lauenburg, P.
    Lunds universitet, Sverige.
    Brand, L.
    Lunds universitet, Sverige.
    Decentralised heat supply in district heating systems: Implications of varying differential pressure2014Ingår i: Proceedings from the 14th International Symposium on District Heating and Cooling September, 6-10, 2014 Stockholm, SWEDEN ISBN 978-91-85775-24-8 / [ed] Anna Land, Swedish District Heating Association, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    There is a rising interest for the integration of decentralised heat supply in district heating (DH) systems in the form of so-called prosumers, i.e., customers that both can withdraw and supply heat to the grid. The interest comes from a growing interest in local energy supply among owners of property as well as a growing awareness among DH companies about the need to view their customers more like partners rather than just consumers of heat.In a previous study, decentralised solar heat plants in Sweden were mapped out and their performance were evaluated. In general, the performance in terms of delivered heat was at least 20% lower than expected. The main reason for this is deficiencies regarding the feed-in of theheat to the grid, caused by an inability of the control system to handle the variation of the differential pressure between the supply and the return pipe in the DH network. These variations, caused mainly by the rapid load fluctuations caused by consumption of domestic hot water, has so far been overlooked when designing the control system.

    This paper describes and pins down this problem with support from measurements and simulations of differential pressure.There are different ways to connect decentralised heat supply, where a primary return/supply connection is the most common, implying the heat being added to the DH water before the customer's substation or directly to the DH supply pipe. Although the field study-objects utilise solar energy, it must be emphasised that the results from the project will be of general interest for any type of decentralised heat supply, e.g. surplus heat from local cooling machines or industrial processes. Suggestions for improved control strategies is given in the paper and future work will aim to support them.Keywords: Prosumers, decentralised heat supply, differential pressure, return/supply connec

  • 280.
    Lennermo, Gunnar
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Energianalys AB, Alingsås, Sweden.
    Lauenburg, P.
    Lund university, Sweden.
    Werner, S.
    Halmstad university, Sweden.
    Control of decentralised solar district heating2019Ingår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 179, s. 307-315Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of decentralised solar district heating plants is to feed solar heat directly into district heating networks. This decentralised heat supply has to consider two major output conditions: a stable required feed-in supply temperature and a feed-in heat power equal to the heat output from the solar collectors. However, many installations cannot achieve the second output condition, since severe oscillations appear in the feed-in heat power. This problem can be solved by two different control concepts with either temperature- or flow-control. Detailed measurements from two reference plants are provided for these two different control concepts. One main conclusion is that a robust control system is characterized by the ability to provide required flows and temperatures. The major difference between robust and less robust control is that the supply temperatures and/or flows do not fluctuate even if the input conditions are unfavourable. 

  • 281.
    Lennermo, Gunnar
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lauenburg, Patrick
    Lund University, Faculty of Engineering, Energy Sciences, Sweden.
    Feed-in from Distributed Solar Thermal Plants in District Heating Systems2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    A District heating (DH)feed-in system is connected to the DH system outside themain central pumps. There are fourdifferent ways to connect a feed-in system to the DH main line but the most frequently used are return/return (R/R) and return/supply (R/S). R/S is the most beneficial system sinceit influencesthe DH system the least. For an R/S feed-in system, there are two basic control concepts; a temperature controlled system and a flow controlled system. In the temperature controlled system there is always a shunt flow which the flow controlled system lacks. It is possible to build a combination feed-in system but the risk of poor performance increases. More field testswill be done during the summer 2017.

  • 282.
    Lennermo, Gunnar
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Energianalys AB, Sverige.
    Lauenburg, Patrick
    Lunds universitet, Sverige.
    Brange, Lisa
    Lunds universitet, Sverige.
    Små värmekällor: Kunden som prosument2016Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det finns stor potential att ta tillvara lokal, småskalig värme i fjärrvärmesystemen. Små värmekällor kan utgöras av industriell restvärme, solvärmeanläggningar, krematorier och olika sorters kylmaskiner i lokaler, idrottsanläggningar och butiker. Prosument är ett begrepp som blir allt vanligare för att beskriva en fjärrvärmekund som både köper och säljer fjärrvärme. Fjärrvärmeföretagens egna topplast- eller reservpannor är också intressanta ur denna rapports perspektiv som behandlar hur inmatningen av värme från en prosument till fjärrvärmenätet görs på bästa sätt.

    Många mindre värmekällor har uppvisat problem med pendlingar i inmatad effekt och flöde. Detta kan ha direkt negativ inverkan på värmekällans prestanda – exempelvis genom att solfångare får lägre värmeutbyte. I ett framtida scenario där små värmekällor står för ett betydande bidrag till fjärrvärmen, måste lokal värmeinmatning fungera tillfredsställande. Denna studie har syftat till att undersöka varför det uppstår pendlingar i inmatningssystemen och vad som kan göras för att dessa ska undvikas.

    De två vanligaste varianterna för lokal inmatning är retur/retur (R/R) och retur/fram (R/F) vilket innebär att fjärrvärmevatten tas från returledningen, värms av den lokala värmekällan och matas tillbaka in i fjärrvärmesystemets retur- respektive framledning. R/R är mindre komplicerad men behäftad med fler nackdelar, framför allt att den höjer returtemperaturen i fjärrvärmesystemet. R/F är det inkopplingssätt som förefaller vara mest användbart men som samtidigt är mer komplext att reglera. Det är i R/F-system som pendlingar i inmatningen påträffats och skälet är att regleringen inte lyckats ta hänsyn till att det största tryckmotstånd som ska övervinnas i inmatningen är fjärrvärmenätets differenstryck. Differenstrycket beror inte av inmatningsflödets storlek vilket får till följd att när denna tryckskillnad är övervunnen av inmatningssystemet blir flödet väldigt lätt för stort. Ju större differenstryck och ju mindre anläggning desto större är risken för detta förlopp.

    Grundprincipen, som kan tyckas självklar, är att den inmatade effekten ska vara lika stor som den tillgängliga. Om inte ett värmelager används, vilket är mindre önskvärt av praktiska och ekonomiska skäl, kan detta åstadkommas på två olika sätt: antingen med ett flödesreglerat eller med ett temperaturreglerat system.I ett flödesreglerat system ska det inte finnas någon kortslutningsledning (shunt) mellan retur- och framledningen. Det inmatade flödet ska styras med inmatningspumpen med eller utan hjälp av en 2-vägsventil som ligger i serie med pumpen.

    I ett temperaturreglerat system ska det finnas en kortslutningsledning som aldrig får stängas. Stängs den blir det ett flödesreglerat system och det ställer helt andra krav på styrningen av inmatningspumpen. Inmatningspumpens varvtal styrs efter en börvärdeskurva där ärvärdet utgörs av differenstrycket. Eftersom differenstrycket är relativt stort och konstant (ur ett kortsiktigt perspektiv) så är det enklare att balansera det inmatade flödet med en tvåvägsventil än en trevägsventil i kortslutningsledningen.Värmekällor som kräver en given returtemperatur eller som inte kan lyfta hela temperatursteget kan med fördel kan anslutas temperaturreglerat medan värmekällor som ska arbeta vid så låg temperatur som möjligt eller kylas så långt det går bör anslutas flödesreglerat, eventuellt med en temperaturreglerad uppstart.

  • 283.
    Lennermo, Gunnar
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Persson, Tomas
    Högskolan Dalarna, Energi och miljöteknik.
    Perers, Bengt
    Högskolan Dalarna, Energi och miljöteknik.
    Pettersson, Ulrik
    Johansson, Mathias
    Underlag för utökad besiktning av bio- och solvärmesystem: Formulär med analyshjälp2011Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det är svårt att på ett genomarbetat sätt, kontrollera en solvärmeanläggning som är i drift och det blir svårare när solvärmesystemet skall samverka med en biobränsleanläggning, som har sina speciella egenheter. Det enklaste och, som det kan tyckas, bästa sättet att kontrollera om en solvärmeanläggning fungerar, är att beräkna utifrån en värmemängdsmätare, som förhoppningsvis finns i anläggningen, hur mycket energi per m2 aktiv area som solfångaren har producerat per år. Om produktionen ligger mellan 300 – 350 kWh/m2 så är det bra. Det är dock så att en solvärmeanläggning borde kunna producera betydligt mer värme om den bara ges lite bättre förutsättning eller att den faktiskt kan ge mindre, men ändå uppfylla de krav som ställdes. Det behöver inte nödvändigtvis vara antalet producerade solfångar-kWh värme som är högt utan det viktigaste kanske är att antalet inbesparade kWh biobränsle är många. För att kunna få ett grepp om hur en solvärmeanläggning fungerar i sitt sammanhang så bör det totala systemet redovisas framför allt med avseende på: -Värmedistributionssystemets uppbyggnad. Var och när finns kallt vatten som ska värmas samt hur mycket. -Energi- och effektnivåer för olika delar av systemet och fram för allt under sommaren -Vilka pannor och bränslen som används, framför allt med betoning på reglerbarhet Solvärmekretsen, som inte är speciellt annorlunda utformad än i andra lite större solvärmeanläggningar ges i den här rapporten relativt stort utrymme, eftersom den samlade kompetensen bland de som gör besiktningar och kontroller inte är så hög. De delar som berörs mest är: -Trycket i solvärmeanläggningen med avseende på expansionskärlets förtryck, systemets uppfyllnadstryck och driftsfunktioner -Flödet i anläggningen som inriktar sig på luftmedryckning, flödesfördelning och vanliga flödeshastigheter -Solfångarnas energi- och värmeeffektproduktion Huvuddelen av underlagsmaterialet bör ha samlats in före besöket, genom att försöka få tag på: -Förstudier för solvärme- och pannanläggning -Förfrågningsunderlag för i första hand solvärmeanläggningen -Driftstatistik -Data på hur det totala systemet ser ut. Dessa data bör bearbetas innan besöket på plats vilket skall inkludera en genomgång av driftsansvarig vilket kompletteras med en guidad tur genom anläggningen. Besöket bör också vara förberett hos driftsansvariga så att stegar för att komma åt solfångarna finns framtagna och de säkerhetsselar som skall finnas vid okulär inspektion finns tillgängliga. Efter avslutad på platsen kontroll ska en besiktningsrapport skrivas. Mycket underlagsberäkningar ska skickas med som bilaga samt en lista med punkter som syftar till att få en effektivare sol- och biobränsleanläggning.

  • 284.
    Lennermo, Gunnar
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Persson, Tomas
    Högskolan Dalarna, Energi och miljöteknik.
    Perers, Bengt
    Högskolan Dalarna, Energi och miljöteknik.
    Pettersson, Ulrik
    Johansson, Mathias
    Underlag för utökad besiktning av sol- och biovärmesystem2011Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det är svårt att på ett genomarbetat sätt, kontrollera en solvärmeanläggning som är i drift och det blir svårare när solvärmesystemet ska samverka med en biobränsleanläggning, som har sina speciella egenheter. Det enklaste och, som det kan tyckas, bästa sättet att kontrollera om en solvärmeanläggning fungerar, är att beräkna utifrån en värmemängdsmätare, som förhoppningsvis finns i anläggningen, hur mycket energi per m2 aktiv area som solfångaren har producerat per år. Om produktionen ligger mellan 300 – 350 kWh/m2 är det bra. Det är dock så att en solvärmeanläggning borde kunna producera betydligt mer värme om den bara ges lite bättre förutsättning eller att den faktiskt kan ge mindre, men ändå uppfylla de krav som ställdes. Det behöver inte nödvändigtvis vara antalet producerade solfångarkWh värme som är högt utan det viktigaste kanske är att antalet inbesparade kWh biobränsle är många. För att kunna få ett grepp om hur en solvärmeanläggning fungerar i sitt sammanhang bör det totala systemet redovisas framför allt med avseende på: • Värmedistributionssystemets uppbyggnad. Var, när och hur mycket kallt vatten ska värmas? • Energi- och effektnivåer för olika delar av systemet, framför allt under sommaren? • Vilka pannor och bränslen används, framför allt med betoning på reglerbarhet? Solvärmekretsen, som inte är speciellt annorlunda utformad än i andra lite större solvärmeanläggningar, ges i den här rapporten relativt stort utrymme, eftersom den samlade kompetensen bland de som gör besiktningar och kontroller inte är så hög. Mest berörda delar är: • Trycket i solvärmeanläggningen med avseende på expansionskärlets förtryck, systemets uppfyllnadstryck och driftsfunktioner • Flödet i anläggningen som inriktar sig på luftmedryckning, flödesfördelning och vanliga flödeshastigheter • Solfångarnas energi- och värmeeffektproduktion Huvuddelen av underlagsmaterialet bör ha samlats in före besöket, genom att försöka få tag på: • Förstudier för solvärme- och pannanläggning • Förfrågningsunderlag för i första hand solvärmeanläggningen • Driftstatistik • Data på hur det totala systemet ser ut Dessa data bör bearbetas innan besöket på plats, vilket ska inkludera en genomgång av driftsansvarig kompletterat med en guidad tur genom anläggningen. Besöket bör också vara förberett hos driftsansvariga så att stegar för att komma åt solfångarna finns framtagna och de säkerhetsselar, som ska användas vid okulär inspektion, finns tillgängliga. Efter avslutad på-platsen-kontroll ska en besiktningsrapport skrivas. Mycket underlagsberäkningar ska skickas med som bilaga samt en lista med punkter som syftar till att få en effektivare sol- och biobränsleanläggning.

  • 285.
    Li, C.
    et al.
    Hunan Academy of Forestry, Changsha, China.
    Liu, D.
    Tsinghua University, Beijing, China.
    Ramaswamy, S.
    University of Minnesota, United States.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology (KTH), Stockholm, Sweden.
    Biomass energy and products: Advanced technologies and applications2015Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 157, s. 489-490Artikel i tidskrift (Refereegranskat)
  • 286.
    Li, H.
    et al.
    Royal Institute of Technology, Stockholm, Sweden .
    Ji, X.
    Royal Institute of Technology, Stockholm, Sweden .
    Yan, Jinyue
    Mälardalens högskola, Institutionen för samhällsteknik.
    A new modification on RK EOS for gaseous carbon dioxide2005Ingår i: ECOS 2005 - Proceedings of the 18th International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, 2005, s. 733-739Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mitigation technologies including CO2 capture and storage in various energy conversion systems have been intensively developed in recent years. However, it is of importance to develop an equation of state (EOS) with simple structure and reasonable accuracy for engineering application for both pure CO2 and CO2 mixtures. In this paper, Redlich-Kwong equation of state was modified for gaseous CO2. In the new modification, parameter 'a' was correlated as a function of temperature and pressure from reliable experimental data in the range: 220K to 750K and 0.1MPa to 400MPa. To verify the accuracy of the new parameters, densities were calculated and compared with experimental data. The average error is 1.68 %. Other thermodynamic properties of CO2, such as enthalpy and heat capacities, were also calculated; results fit experimental data well except critical region. This method can be further developed for CO2 mixture systems.

  • 287.
    Li, H.
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Ji, X.
    Royal Institute of Technology, Stockholm, Sweden.
    Yan, Jinyue
    Mälardalens högskola, Institutionen för samhällsteknik.
    Quantitative evaluations on available models for calculating thermodynamic properties of humid air2005Ingår i: ECOS 2005 - Proceedings of the 18th International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, 2005, s. 889-896Konferensbidrag (Refereegranskat)
    Abstract [en]

    Engineering calculation of the thermodynamic properties for cycle simulation and design requires simple but reliable models. This has been proved to be of importance for the research and development on humidified gas turbines, such as humid air turbine (HAT) cycles and compressed air energy storage (CAES). This paper has made a comprehensive review and comparison among different models for calculating thermodynamic properties of the humid air mixtures, including ideal gas model (IG), ideal mixing model (IM), and real gas model (RG); and based on temperature and pressure range, gave quantitative evaluations on saturated water vapor composition and enthalpy. Based on performance conditions of an HAT cycle, several suggestions were given for the use of the today's available models for engineering cycle calculations, which can provide accurate results for cycle performance analysis and design while keeping the methods straightforward.

  • 288. Li, H.
    et al.
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Comparative study of equations of state (EOS) for CO2 transportation in pipeline2006Konferensbidrag (Refereegranskat)
  • 289.
    Li, H.
    et al.
    Chemical Engineering and Technology /Energy Processes, Royal Institute of Technology, Stockholm, Sweden.
    Yan, Jinyue
    Chemical Engineering and Technology /Energy Processes, Royal Institute of Technology, Stockholm, Sweden.
    Preliminary Study on CO2 Processing in CO2 Capture from Oxy-fuel Combustion2007Ingår i: PROCEEDINGS OF THE ASME TURBO EXPO: VOL 3, 2007, Vol. 3, s. 353-361Konferensbidrag (Refereegranskat)
  • 290.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Ningbo RX New Materials Tch. Co. Ltd., China; KTH, Stockholm, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Ningbo RX New Materials Tch. Co. Ltd., China.
    Berretta, Sara
    Tan, Yuting
    Ningbo RX New Materials Tch. Co. Ltd., China; KTH, Stockholm, Sweden.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH, Stockholm, Sweden.
    Dynamic performance of the standalone wind power driven heat pump2016Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 103, s. 40-45Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reducing energy consumption and increasing use of renewable energy in the building sector is crucial to the mitigationof climate change. Wind power driven heat pumps have been considered as a sustainable measure to supply heat forthe detached houses, especially those that even don’t have access to the grid. This work is to investigate the dynamic performance of a heat pump system directly driven by a wind turbine. The heat demand of a detached single familyhouse was simulated in details. To handle the intermittent characteristic of wind power, an electric energy storage system was included. According to the simulations, the wind turbine itself cannot always satisfy the electricity demand of the heat pump, and a larger size of the energy storage system can reduce the probability of load loss. However, it is different from the energy storage system that increasing the capacity of wind turbines may increase the probability of load loss instead, due to the different start-up speed of wind turbines. In order to maximize the system benefit, the capacity of the wind turbine and the size of the energy storage system should be optimized simultaneously based on dynamic simulations.

  • 291.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Ningbo RX New Materials Tch. Co. Ltd., Ningbo, China.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Ningbo RX New Materials Tch. Co. Ltd., Ningbo, China.
    Tan, Y.
    Ningbo RX New Materials Tch. Co. Ltd., Ningbo, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Department of Chemical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Feasibility study about using a stand-alone wind power driven heat pump for space heating2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 228, s. 1486-1498Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reducing energy consumption and increasing the use of renewable energy in the building sector are crucial to the mitigation of climate change. Wind power driven heat pumps have been considered as a sustainable measure to supply heat to the detached houses, especially those that even do not have access to the electricity grid. This work is to investigate the dynamic performance of a heat pump system driven by wind turbine through dynamic simulations. In order to understand the influence on the thermal comfort, which is the primary purpose of space heating, the variation of indoor temperature has been simulated in details. Results show that the wind turbine is not able to provide the electricity required by the heat pump during the heating season due to the intermittent characteristic of wind power. To improve the system performance, the influences of the capacity of wind turbine, the size of battery and the setpoint of indoor temperature were assessed. It is found that increasing the capacity of wind turbines is not necessary to reduce the loss of load probability; while on the contrary, increasing the size of battery can always reduce the loss of load probability. The setpoint temperature clearly affects the loss of load probability. A higher setpoint temperature results in a higher loss of thermal comfort probability. In addition, it is also found that the time interval used in the dynamic simulation has significant influence on the result. In order to have more accurate results, it is of great importance to choose a high resolution time step to capture the dynamic behaviour of the heat supply and its effect on the indoor temperature.

  • 292. Li, Hailong
    et al.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    Dynamic Modeling of a PV Pumping System with Special Consideration on Water Demand2012Konferensbidrag (Refereegranskat)
  • 293.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Daheem, Mehmood
    University of Stavanger, Norway.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zhixin, Yu
    University of Stavanger, Norway.
    Biomethane production via anaerobic digestion and biomass gasification2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, s. 1172-1177Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The transport sector accounts for the second biggest greenhouse gas emissionin the European Union (EU). In order to achieve the target of CO2 emission reduction there is a rapid growing interest in using biomethane as fuel for transport applications. Biomethane can be produced through anaerobic digestion or biomass gasification. Anaerobic digestion is a biochemical process. Since the raw gas contains approximately 65 vol% CH4 and 3 5vol%, an upgrading process is needed to remove CO2. Göteborg biomass gasification project (GoBiGas) is the world's first demonstration plant for large-scale production of biomethane through the gasification of forest residues. To achieve high purity CH4, a methanation process is required after gasification. This work compares these two technologies from the perspective of energy efficiency. Simulation results show that they have similar efficiencies: 62-64% for AE and ~65% for GoBiG.

  • 294.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Ditaranto, Mario
    SINTEF Energy Res,Trondheim, Norway.
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Carbon capture with low energy penalty: Supplementary fired natural gas combined cycles2012Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 97, nr SI, s. 164-169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Enhancing CO2 concentration in exhaust gas has been considered as a potentially effective method to reduce the penalty of electrical efficiency caused by CO2 chemical absorption in post-combustion carbon capture systems. Supplementary firing is an option that inherently has an increased CO2 concentration in the exhaust gas, albeit a relatively low electrical efficiency due to its increased mass flow of exhaust gas to treat and large temperature difference in heat recovery steam generator. This paper focuses on the methods that can improve the electrical efficiency of the supplementary fired combined cycles (SFCs) integrated with MEA-based CO2 capture. Three modifications have been evaluated: (I) integration of exhaust gas reheating, (II) integration of exhaust gas recirculation, and (III) integration of supercritical bottoming cycle. It is further showed that combining all three modifications results in a significant increase in electrical efficiency which is raised from 43.3% to 54.1% based on Lower Heating Value (LHV) of natural gas when compared to the original SFC. Compared with a conventional combined cycle with a subcritical bottoming cycle and without CO2 capture (56.7% of LHV), the efficiency penalty caused by CO2 capture is only 2.6% of LHV.

  • 295.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Han, Song
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Thorin, Eva
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Potentials of energy saving and efficiency improvement from lighting and space heating: a case study of SAAB2012Konferensbidrag (Refereegranskat)
  • 296.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Hu, Yukun
    KTH, Sweden.
    Ditaranto, Mario
    SINTEF Energy Research, Trondheim, Norway .
    Willson, D
    Stanbridge Capital, New York, United States.
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Optimization of cryogenic CO2 purification for oxy-coal combustion2013Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 37, s. 1341-1347Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Oxyfuel combustion is a leading potential CO2 capture technology for power plants. As the flue gas (FG) consists of mainly H2O and CO2, a simpler and more energy-efficient CO2 purification method can be used instead of the standard amine-based chemical absorption approach. For the system of oxyfuel combustion with cryogenic CO2 purification, decreasing the oxygen purity reduces the energy consumption of the Air Separation Unit (ASU) but increases the energy consumption for the downstream cryogenic purification. Thus there exists a trade-off between the energy consumption of the ASU and that for cryogenic purification. This paper investigates the potential efficiency improvement by optimizing this trade-off. The simulated results show that there exists an optimum flue gas condensing pressure for the cryogenic purification, which is affected by the flue gas composition. In addition, decreasing the oxygen purity reduces the combined energy consumption of the ASU and the cryogenic purification, and therefore can improve the electrical efficiency. In summary, prior oxyfuel combustion analyses have assumed a high oxygen purity level of 95 mol% or 99 mol% for the combustion air, which achieves a high CO2 concentration in the flue gases. In this Paper, we demonstrate that a lower level of oxygen purity, such as 80 mol%, in conjunction with a more extensive cryogenic purification of the flue gases can lower the total energy consumption, thereby yielding a significant benefit. However, for oxygen purity levels lower than 75 mol%, it may not be possible to still use the two-stage flash system shown here to achieve a CO2 purity of 95 mol% and a CO2 recovery rate of 90% simultaneously.

  • 297.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Larsson, Eva K.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thorin, Eva
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yu, Xinhai
    E China Univ Sci & Technol, Shanghai, Peoples R China.
    Feasibility study on combining anaerobic digestion and biomass gasification to increase the production of biomethane2015Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 100, s. 212-219Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is a rapid growing interest in using biomethane as fuel for transport applications. A new concept is proposed to combine anaerobic digestion and biomass gasification to produce biomethane. H-2 is separated from the syngas generated by biomass gasification in a membrane system, and then is used to upgrade raw biogas from anaerobic digestion. Simulations have been conducted based on the real operation data of one full scale biogas plant and one full scale biomass gasification plant in order to investigate the feasibility of the new concept. Results show that although less power and heat are generated compared to the gasification plant, which results in a lower overall efficiency, much more biomethane can be produced than the biogas plant; and the new concept can achieve a higher exergy efficiency. Due to the increasing price of biomethane, the novel concept demonstrates a big potential of income increase. For example, at a biomethane price of 12.74SEK/kg, the annual income can be increased by 53% compared to the total income of the biogas and gasification plant. (C) 2015 Elsevier Ltd. All rights reserved.

  • 298.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindmark, Johan
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Nordlander, Eva
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thorin, Eva
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dahlquist, Erik
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zhao, Li
    Tianjin University, China.
    Using the solid digestate from a wet anaerobic digestion process as an energy resource2013Ingår i: Energy technology, ISSN 2194-4296, Vol. 1, nr 1, s. 94-101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wet anaerobic digestion process is a widely used method to produce biogas from biomass. To avoid the risks involved with using the digestion waste as a fertilizer, this work investigates the possibilities to use the solid digestate as an energy resource to produce heat and electricity, which could save some energy currently consumed by the plant and, therefore, may increase the overall efficiency of a biogas plant. Simulations were conducted based on real data from the Växtkraft biogas plant in Västerås, Sweden as a case study. Results show that it is necessary to dry the solid digestate before combustion and include flue-gas condensation to recover enough heat for the drying process. When a steam turbine cycle is integrated, the generated electricity could cover 13–18 % of the total electricity consumption of the plant, depending on the degree of dryness. In addition, reducing the digestion period can increase the carbon content (ultimate analysis), the heating value, and the mass flow of the solid digestate. As a result, the production of electricity and heat is augmented in the steam turbine cycle. However, the production of biogas is reduced. Therefore, a comprehensive economic evaluation is suggested to optimize a biogas plant that uses the solid digestate from a wet anaerobic digestion process as an energy resource.

  • 299.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Song, Jingjing
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Sun, Q.
    Institute of Thermal Science and Technology, Shandong University, Jinan, China.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zhang, Q.
    China Petroleum University, Beijing, China.
    A dynamic price model based on levelized cost for district heating2019Ingår i: Energy, Ecology and Environment, ISSN 2363-7692, Vol. 4, nr 1, s. 15-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    District Heating (DH) is facing a tough competition in the market. In order to improve its competence, an effective way is to reform price models for DH. This work proposed a new dynamic price model based on the levelized cost of heat (LCOH) and the predicted hourly heat demand. A DH system in Sweden was used as a case study. Three methods were adopted to allocate the fuel cost to the variable costs of heat production, including (1) in proportion to the amount of heat and electricity generation; (2) in proportion to the exergy of generated heat and electricity; and (3) deducting the market price of electricity from the total cost. Results indicated that the LCOH-based pricie model can clearly reflect the production cost of heat. Through the comparison with other market-implemented price models, it was found that even though the market-implemented price models can, to certain extent, reflect the variations in heat demand, they cannot reflect the changes in production cost when different methods of heat production are involved. In addition, price model reforming can lead to a significant change in the expense of consumers and consequently, affect the selection of heating solution.

  • 300.
    Li, Hailong
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Tan, Y.
    Royal Institute of Technology, Stockholm, Sweden.
    Ditaranto, M.
    SINTEF Energy, Trondheim, Norway.
    Yan, J.
    Royal Institute of Technology, Stockholm, Sweden.
    Yu, Z.
    University of Stavanger, Norway.
    Capturing CO2 from Biogas Plants2017Ingår i: Energy Procedia, Elsevier Ltd , 2017, s. 6030-6035Konferensbidrag (Refereegranskat)
    Abstract [en]

    As a renewable energy, biogas produced from anaerobic digestion and landfill is playing a more and more important role in the energy market. Capturing CO2 from biogas can result in a negative CO2 emission. Depending on how biogas is utilized, there are different routes to capture CO2. A biogas plant that uses raw biogas to produce power and heat can be retrofitted by integrating CO2 capture. In order to identify the best option, three retrofits were compared from both technical and economic perspectives, including SYS-I, which captures CO2 from raw gas and produces biomethane instead of electricity and heat, SYS-II, which captures CO2 using MEA-based chemical absorption after the combustion of raw gas, and SYS-III, which captures CO2 by using oxy-fuel combustion of the raw gas. In general, SYS-I can achieve the highest profit and shortest payback time, mainly due to the high price of biomethane. SYSII and SYS-III are clearly influenced by carbon credit. In order to have positive profits for the retrofits of SYS-II and SYS-III, carbon credit needs to exceed 750SEK (or 100USD)/ton CO2 and 113 SEK (or 15USD)/ton CO2 respectively.

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