| 1. |
- Aslanidou, Ioanna, et al.
(författare)
-
Introduction of a Smartphone Application in an Aeroengine Technology Course
- 2020
-
Ingår i: Proceedings of the ASME Turbo Expo 2020, Sep 21-25. - 9780791884157
-
Konferensbidrag (refereegranskat)abstract
- The main goal of an engineering course is for the students to achieve the defined educational goals, enhance their problem- solving capabilities and develop the essential engineering mindset. The continuous improvement of a course is essential to maintain its challenging nature while improving the course quality. Adapting the teaching methods used to new types of students can provide a significant improvement in student learning. In that context, a digital tool is employed in an advanced course in Aeroengine Technology. A smartphone application that calculates gas turbine performance is introduced in the course to help students understand some of the key concepts. The purpose of the application is to provide the students with an interactive tool to understand the gas turbine thermodynamic cycle. An exercise regarding this application is assigned to note the performance of different engine technologies used in aircraft propulsion through the years. The assignment with the application is combined with a larger assignment on gas turbine performance. The application is also employed in the final exams of the course. The purpose of this paper is to present the use of the application in the course and to address any challenges that arise in the implementation of the app in the learning process. The employed teaching methods received positive feedback from the students who indicated that the app assignment helped them understand some of the key concepts in the course. After all, the main aim of the use of novel teaching methods should be to make learning more interesting, so that students get more involved in a course.
|
|
| 2. |
- Aslanidou, Ioanna, et al.
(författare)
-
Reforming heat and power technology course structure using student feedback to enhance learning experience
- 2021
-
Ingår i: International Journal of Mechanical Engineering Education. - : SAGE Publications. - 0306-4190 .- 2050-4586. ; 49:4, s. 410-434
-
Tidskriftsartikel (refereegranskat)abstract
- The main outcomes of an engineering course should be for the students to achieve the educational goals, enhance their problem solving capabilities and develop essential skills for their future career. In that context, it is important to understand what motivates the students and what helps them develop an engineering mindset. This paper discusses the improvement of a course with the use of student feedback to motivate students and help them develop essential skills. The purpose of the paper is to provide insight into how different aspects of the course are linked to the students’ growth. Different activities have been integrated in the course over the past years. The effect these have on the student motivation to follow the course and develop skills, knowledge and interest in the subject is discussed through the analysis of student performance, student feedback and the experience of the lecturers. The improvements in the course based on the student feedback were received positively by the students, whose learning experience improved, even though the workload of the course was high. Their motivation to successfully complete the course has also increased through the changes in the delivery of the course and the support by the teachers. The combination of student feedback and teacher experience is key for the improvement of a course, while ensuring that the students develop their engineering knowledge. Therefore, the teachers should strike a balance between helping the students find the solution and encouraging them to think on their own in order to develop essential skills.
|
|
| 3. |
- Gkoutzamanis, Vasilis G., et al.
(författare)
-
Conceptual Design and Energy Storage Positioning Aspects for a Hybrid-Electric Light Aircraft
- 2021
-
Ingår i: Journal of engineering for gas turbines and power. - : ASME International. - 0742-4795 .- 1528-8919. ; 143:9
-
Tidskriftsartikel (refereegranskat)abstract
- This work is a feasibility study of a 19-passenger hybrid-electric aircraft, to serve the short-haul segment within the 200-600 nautical miles. Its ambition is to answer some dominating research questions, during the evaluation and design of aircraft based on alternative propulsion architectures. The potential entry into service (EIS) is foreseen beyond 2030. A literature review is performed to identify similar concepts under research and development. After the requirements' definition, the first level of conceptual design is employed. The objective of design selections is driven by the need to reduce CO2 emissions and accommodate aircraft electrification with boundary layer ingestion engines. Based on a set of assumptions, a methodology for the sizing of the hybrid-electric aircraft is described to explore the basis of the design space, incorporating a parametric analysis for the consideration of boundary layer ingestion effects. Additionally, a methodology for the energy storage positioning is provided to highlight the multidisciplinary aspects between the sizing of an aircraft, the selected architecture (series/ parallel partial hybrid), and the storage characteristics. The results show that it is not possible to fulfill the initial design requirements (600 nmi) with a fully-electric aircraft configuration, due to the farfetched battery necessities. It is also highlighted that compliance with airworthiness standards is favored by switching to hybrid-electric aircraft configurations and relaxing the design requirements (targeted range, payload, battery technology). Finally, the lower degree of hybridization (40%) is observed to have a higher energy efficiency (-12% energy consumption) compared to the higher degree of hybridization (50%) and greater CO2 reduction, with respect to the conventional configuration.
|
|
| 4. |
- Nikolaidis, Theoklis, et al.
(författare)
-
Off-Design Performance Comparison between Single and Two Shaft Engines, Part 1 – Fixed Geometry
- 2020
-
Ingår i: Proceedings of the ASME Turbo Expo 2020, Sep 21-25..
-
Konferensbidrag (refereegranskat)abstract
- This paper describes an investigation into the off-design performance comparison of single and two-shaft gas turbine engines. A question that has been asked for a long time in which gas turbine delivers a better thermal efficiency at part load. The authors, notwithstanding their intensive searches, were unable to find a comprehensive answer to this question. A detailed investigation was carried out using a state of the art performance evaluation method and the answer was found to be: It depends! In this work, the performance of two engine configurations is assessed. In the first one, the single shaft gas turbine operates at constant shaft rotational speed. Thus, the shape of the rotational speed line will have an important influence on the performance of the engine. To explore the implications of the shape of the speed line, two single shaft cases are examined. The first case is when the speed line is curved and as the compressor pressure ratio falls, the non-dimensional mass flow increases. The second case is when the speed line is vertical and as the compressor pressure ratio falls, the non-dimensional mass flow remains constant. In the second configuration, one shaft couples a compressor and a turbine (often called the gas generator shaft). The second shaft couples the power turbine to the driven equipment. The two shafts can be controlled to operate at different rotational speeds and also varying relationships between the rotational speeds. The part-load operation is characterised by a reduction in the gas generator rotational speed.The tool, which was used in this study, is a 0-D whole engine simulation tool, named Turbomatch. It was developed at Cranfield and it is based on mass and energy balance, carried out through an iterative method, which is based on component maps. These generic, experimentally derived maps are scaled to match the design point of a particular engine before an off-design calculation is performed. The code has been validated against experimental data, it has been used extensively for academic purposes and the research activities taken place at Cranfield University.For an ideal cycle, the single shaft engine was found to be a clear winner in terms of part-load thermal efficiency. However, this picture changed when realistic component maps were utilised. The basic cycle and the shape of component maps had a profound influence on the outcome.The authors explored the influence of speed line shapes, levels of component efficiencies and the variation of these component efficiencies within the operating range. This paper describes how each one of these factors, individually, influences the outcome.
|
|
| 5. |
- Nikolaidis, Theoklis, et al.
(författare)
-
Off-Design Performance Comparison Between Single and Two-Shaft Engines Part 1-Fixed Geometry
- 2022
-
Ingår i: Journal of engineering for gas turbines and power. - : ASME. - 0742-4795 .- 1528-8919. ; 144:8
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes an investigation into the off-design performance comparison of single and two-shaft gas turbine engines. A question that has been asked for a long time is which gas turbine delivers a better thermal efficiency at part load. The authors, notwithstanding their intensive searches, were unable to find a comprehensive answer to this question. A detailed investigation was carried out using a state-of-the-art performance evaluation method and the answer was found to be: It depends! In this work, the performance of two engine configurations is assessed. In the first one, the single-shaft gas turbine operates at constant shaft rotational speed. Thus, the shape of the compressor map rotational speed line will have an important influence on the performance of the engine. To explore the implications of the shape of the speed line, two single-shaft cases are examined. The first case is when the speed line is curved and as the compressor pressure ratio falls, the nondimensional mass flow increases. The second case is when the speed line is vertical and as the compressor pressure ratio falls, the nondimensional mass flow remains constant. In the second configuration, the two-shaft engine, the two shafts can be controlled to operate at different rotational speeds and also varying relationships between the rotational speeds. The part-load operation is characterized by a reduction in the gas generator rotational speed. The tool, which was used in this study, is a 0-D whole engine simulation tool, named Turbomatch. It was developed at Cranfield and it is based on mass and energy balance, carried out through an iterative method, which is based on component maps. These generic, experimentally derived maps are scaled to match the design point of a particular engine before an off-design calculation is performed. The code has been validated against experimental data elsewhere, it has been used extensively for academic purposes and the research activities that have taken place at Cranfield University. For an ideal cycle, the single-shaft engine was found to be a clear winner in terms of part-load thermal efficiency. However, this picture changed when realistic component maps were utilized. The basic cycle and the shape of component maps had a profound influence on the outcome. The authors explored the influence of speed line shapes, levels of component efficiencies, and the variation of these component efficiencies within the operating range. This paper describes how each one of these factors, individually, influences the outcome.
|
|
| 6. |
- Xu, Tianhao, et al.
(författare)
-
Performance evaluation of three latent heat storage designs for cogeneration applications
- 2021
-
Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 225, s. 444-462
-
Tidskriftsartikel (refereegranskat)abstract
- Well-integrated thermal energy storage units can enhance flexibility and profitability for a cogeneration system by enabling its decoupling of electricity and heat production. In the present study, novel latent heat thermal energy storage technologies are numerically investigated on their thermal and economic performance to evaluate their implementation at an existing combined cycle power plant. Three commercially available storage designs are analyzed: one shell-and-tube heat exchanger design based on planar spiral coils, and two types of advanced macro-encapsulated designs with capsules resembling ellipsoid and slab in shape, respectively. For the spiral coil design, three-dimensional flow velocity and temperature fields are simulated with finite volume method to predict the transient storage heat transfer process, including the effect of secondary flow induced by centrifugal forces. For the macro-encapsulated designs, effective heat transfer coefficients between heat transfer fluid (HTF) and phase change material (PCM) are inferred from scaled-down storage prototyping and testing. A onedimensional two-phase packed bed model was developed based on the apparent heat capacity-based enthalpy method to numerically study the heat transfer in macro-encapsulated PCM. With an operating temperature range of 46-72 degrees C and a HTF supplying flowrate range of 4.2-8.4 m3/h defined by the cogeneration strategy, thermal power and accumulated storage capacity are calculated and compared for the first three hours of charge and the first hour of discharge for the three designs. The effect from increasing the HTF flowrate to accelerate charging/ discharging processes is indicated by the simulation results. Performance comparison among the three designs shows that the slab capsule design exhibits the highest accumulated storage capacity (710 kWh) and state of charge (40%) after three hours of charge, though it has a lower theoretical total storage capacity (1760 kWh) than the spiral coil design (1830 kWh). The ellipsoid capsule design shows a slightly lower accumulated storage capacity (700 kWh) than the slab design for 3-hr charge and an equivalent accumulated storage capacity/depth of discharge (250 kWh/14%) as the latter. Furthermore, the storage power cost of the slab capsule design is the lowest, by 6-12% lower than the spiral coil design and by 2-3% lower than the ellipsoid capsule design. However, with the highest design flowrate of 8.4 m3/h, the low state of charge (below 40%) after three hours and the low depth of discharge (below 14%) after one hour indicate that redesigning the heat transfer boundary conditions and the configurations of the three units are necessary to meet desirable storage performance in cogeneration applications.
|
|
