| 1. |
- Aichmayer, Lukas
(författare)
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Solar receiver development for gas-turbine based solar dish systems
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Small-scale concentrating solar power plants such as micro gas-turbine based solar dish systems have the potential to harness solar energy in an effective way and supply electricity to customers in remote areas. In such systems, the solar receiver transfers the power of concentrated solar radiation to the working fluid of the power conversion cycle. It is one of the key components as it needs to operate at high temperatures to ensure a high power cycle efficiency and under high flux densities to ensure a high receiver efficiency. In order to address these challenges and to ensure efficient and reliable operation innovative designs are needed.This research work focuses on the complete development of a novel solar receiver applying a new systematic design and analysis methodology. Therefore, a comprehensive receiver design and experimental evaluation process were developed and implemented. The design process includes the identification of technical specifications and requirements, the development of receiver design tools of different investigation levels coupled with multi-objective optimization tools, the evaluation of scaling effects between tests in the KTH high-flux solar simulator and the full-scale solar dish system. As a result of the design process a representative final receiver was established with material temperatures and stresses below critical limits while respecting the design specification.The experimental evaluation includes the enhancement of the KTH high-flux solar simulator to provide stable and reliable operating conditions, the precise characterization of the radiative boundary conditions, the design of a receiver test bed recreating the operating behavior of a gas-turbine, and the final receiver testing for multiple operating points. It was shown that the prototype reaches an efficiency of 69.3% for an air outlet temperature of 800°C and a mass flow of 29.5 g/s. For a larger mass flow of 38.4 g/s a receiver efficiency of 84.8% was achieved with an air outlet temperature of 749°C.The measurement results obtained were then used for a multi-point validation of the receiver design tools, resulting in a high level of confidence in the accuracy of the tools. The validated models were then harnessed to calculate the performance of a full-scale solar receiver integrated into the OMSoP solar dish system. It was shown that a solar receiver can be designed, which delivers air at 800°C with a receiver efficiency of 82.2%.Finally, the economic potential of micro gas-turbine based solar systems was investigated and it was shown that they are ideally suited for small-scale stand-alone and off-grid applications.The results of the receiver development highlight the feasibility of using volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems and no major hurdles were found.
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| 2. |
- Akbari, Keramatollah, 1961-
(författare)
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Simulation of Indoor Radon and Energy Recovery Ventilation Systems in Residential Buildings
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study aims to investigate the effects of ventilation rate, indoor air temperature, humidity and using a heat recovery ventilation system on indoor radon concentration and distribution.Methods employed include energy dynamic and computational fluid dynamics simulation, experimental measurement and analytical investigations. Experimental investigations primarily utilize a continuous radon meter and a detached house equipped with a recovery heat exchanger unit.The results of the dynamic simulation show that the heat recovery unit is cost-effective for the cold Swedish climate and an energy saving of about 30 kWh per floor area per year is possible, while it can be also used to lower radon level.The numerical results showed that ventilation rate and ventilation location have significant impacts on both radon content and distribution, whereas indoor air temperature only has a small effect on radon level and distribution and humidity has no impact on radon level but has a small impact on its distribution.
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| 3. |
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Developments in Combustion Technology
- 2016
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Over the past few decades, exciting developments have taken place in the field of combustion technology. The present edited volume intends to cover recent developments and provide a broad perspective of the key challenges that characterize the field. The target audience for this book includes engineers involved in combustion system design, operational planning and maintenance. Manufacturers and combustion technology researchers will also benefit from the timely and accurate information provided in this work. The volume is organized into five main sections comprising 15 chapters overall: - Coal and Biofuel Combustion - Waste Combustion - Combustion and Biofuels in Reciprocating Engines - Chemical Looping and Catalysis - Fundamental and Emerging Topics in Combustion Technology
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| 4. |
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Developments in Near-Infrared Spectroscopy
- 2017
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Over the past few decades, exciting developments have taken place in the field of near-infrared spectroscopy (NIRS). This has been enabled by the advent of robust Fourier transform interferometers and diode array solutions, coupled with complex chemometric methods that can easily be executed using modern microprocessors. The present edited volume intends to cover recent developments in NIRS and provide a broad perspective of some of the challenges that characterize the field. The volume comprises six chapters overall and covers several sectors. The target audience for this book includes engineers, practitioners, and researchers involved in NIRS system design and utilization in different applications. We believe that they will greatly benefit from the timely and accurate information provided in this work.
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| 5. |
- Gambarotta, Agostino, et al.
(författare)
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Editorial : Smart Energy Systems
- 2022
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Ingår i: FRONTIERS IN MECHANICAL ENGINEERING-SWITZERLAND. - : FRONTIERS MEDIA SA. - 2297-3079. ; 8
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Hosain, Md Lokman, 1984-
(författare)
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Fluid Flow and Heat Transfer Simulations for Complex Industrial Applications : From Reynolds Averaged Navier-Stokes towards Smoothed Particle Hydrodynamics
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optimal process control can significantly enhance energy efficiency of heating and cooling processes in many industries. Process control systems typically rely on measurements and so called grey or black box models that are based mainly on empirical correlations, in which the transient characteristics and their influence on the control parameters are often ignored. A robust and reliable numerical technique, to solve fluid flow and heat transfer problems, such as computational fluid dynamics (CFD), which is capable of providing a detailed understanding of the multiple underlying physical phenomena, is a necessity for optimization, decision support and diagnostics of complex industrial systems. The thesis focuses on performing high-fidelity CFD simulations of a wide range of industrial applications to highlight and understand the complex nonlinear coupling between the fluid flow and heat transfer. The industrial applications studied in this thesis include cooling and heating processes in a hot rolling steel plant, electric motors, heat exchangers and sloshing inside a ship carrying liquefied natural gas. The goal is to identify the difficulties and challenges to be met when simulating these applications using different CFD tools and methods and to discuss the strengths and limitations of the different tools.The mesh-based finite volume CFD solver ANSYS Fluent is employed to acquire detailed and accurate solutions of each application and to highlight challenges and limitations. The limitations of conventional mesh-based CFD tools are exposed when attempting to resolve the multiple space and time scales involved in large industrial processes. Therefore, a mesh-free particle method, smoothed particle hydrodynamics (SPH) is identified in this thesis as an alternative to overcome some of the observed limitations of the mesh-based solvers. SPH is introduced to simulate some of the selected cases to understand the challenges and highlight the limitations. The thesis also contributes to the development of SPH by implementing the energy equation into an open-source SPH flow solver to solve thermal problems. The thesis highlights the current state of different CFD approaches towards complex industrial applications and discusses the future development possibilities.The overall observations, based on the industrial problems addressed in this thesis, can serve as decision tool for industries to select an appropriate numerical method or tool for solving problems within the presented context. The analysis and discussions also serve as a basis for further development and research to shed light on the use of CFD simulations for improved process control, optimization and diagnostics.
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| 7. |
- Hosain, Md Lokman, 1984-, et al.
(författare)
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Smoothed Particle Hydrodynamics modeling of transient conduction and convection heat transfer
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Smoothed Particle Hydrodynamics (SPH) is a mesh-free particle method that has been widely used in the last years to model some complex flows. SPH was mainly used to investigate problems related to hydrodynamics and maritime engineering where heat transfer is of no importance. Thermal problems have seldom been addressed due to the limitation of the main commercial and open-source SPH codes.In this article, the energy equation is implemented in the SPH based open-source code DualSPHysics to solve conduction and forced convection heat transfer problems. Laminar flow cases are simulated as the first validation cases of the implemented model. The studied cases include conduction in an aluminum block, conduction in still water in a cavity, laminar water flow between two infinite parallel plates and tube bank heat exchanger. The thermal solutions obtained from SPH are benchmarked with the solutions from Finite Volume Method (FVM) and also validated using available analytical solutions. The obtained results are in good agreement with FVM and available analytical models, which combined with the advantages of the meshless approach, show the high potential for industrial heat transfer applications.This development is an important step towards thermal optimization of several industrial applications that can’t benefit from the conventional FVM approach due to geometry or process complexities. The demonstrated SPH simulation and visualization capabilities contribute to build the future reliable energy-saving solutions.
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| 8. |
- Iplik, Esin
(författare)
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Energy savings for petroleum processing : Using mathematical models, optimal control and diagnostics
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Petroleum products are widely used as an energy supply, and the total production capacity of petroleum refineries is quite high. In this thesis, an energy intensive refinery process, hydroprocessing, is selected and evaluated in terms of its energy loss contributors. Digital solutions are discussed and demonstrated to reduce losses. Both hydrotreatment and hydrocracking processes are included in the evaluation since both require elevated temperatures due to the relevant reactions. While the former is the removal of undesired atoms, the latter is the production of short chain hydrocarbons from heavy oil. Both these processes contribute to cleaner fuel production.When these processes are carried out in fixed bed reactors, the catalyst ages over time, slowing the reactions. Understanding the changes in system dynamics enables the control system to calculate the necessary temperature adjustments to facilitate stable product quality. The usual response is increasing the temperature, which adds to the heat load. If reaction rates are known, the temperature increase can be kept to a minimum. Obtaining real-time feed quality information can aid flexible feed processing refineries intensely. With real-time feed characterization, it is possible to use a feed forward model predictive control system to optimize reactor temperatures. Therefore, for varying crude oil quality, the control system can estimate the minimum temperature requirements for the product to be in the desired quality interval. Additional notice should be given to the temperature sensors as they supply data to the suggested control architecture. Wrong measurements threaten the optimality of the estimated control response. Faulty sensors should be detected and replaced to minimize the risk and collect correct data.Observations made in this thesis show the possible energy gain for hydroprocessing by understanding the aging catalyst, soft sensor installation, feed forward model predictive control, and sensor fault detection. Hydroprocessing is a relevant topic for biorefineries. Although the demonstrations in this work are only for petroleum refineries, the suggested methods can be used in biorefineries as well as integrated co-processing petroleum and biorefineries.
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| 9. |
- Kyprianidis, Konstantinos, 1984
(författare)
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Future Aero Engine Designs: An Evolving Vision
- 2011
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Ingår i: Advances in Gas Turbine Technology, ed. Ernesto Benini. - 9789533076119 ; , s. 3-24
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Gas turbine engines will still represent a key technology in the next 20-year energy scenarios, either in stand-alone applications or in combination with other power generation equipment. This book intends in fact to provide an updated picture as well as a perspective vision of some of the major improvements that characterize the gas turbine technology in different applications, from marine and aircraft propulsion to industrial and stationary power generation. Therefore, the target audience for it involves design, analyst, materials and maintenance engineers. Also manufacturers, researchers and scientists will benefit from the timely and accurate information provided in this volume. The book is organized into five main sections including 21 chapters overall: (I) Aero and Marine Gas Turbines, (II) Gas Turbine Systems, (III) Heat Transfer, (IV) Combustion and (V) Materials and Fabrication.
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| 10. |
- Kyprianidis, Konstantinos G.
(författare)
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Future Aero Engine Designs : An Evolving Vision
- 2011. - 1st
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Ingår i: Advances in Gas Turbine Technology. - Rijeka, Croatia : InTech. - 9789533076119 ; , s. 3-24
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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