Abstract

Industrial lubrication involves the use of significant amounts of lubricants. How lubricants are manufactured, used, applied and disposed of, has a direct impact on the efficient use of energy in the relevant industry sector. The primary drivers for the use of lubricants are reduction of friction and minimisation of wear. Any new developments that can contribute to these, are critical for survival in a highly competitive environment and should be an ongoing activity. In industrial operations different lubrication requirements will depend on whether the equipment is stationary with or without moving contacts (transformers, gearboxes, mills, turbines, cutting operations, etc.). The selection and use of high-performance lubricants will depend on the origin and type of the base oil, (mineral-oil based, synthetic or plant-oil). The quantities of lubricants used in various operations are affected by the design of the system, (enclosed, once-through or alternative application techniques). Manufacturing, use, disposal and re-processing of lubricants can all have a significant impact on the environment and the extent of this needs to be considered throughout. Before a lubricant can be put to use, its quantitative friction and wear characteristics need to be determined. Determination of these characteristics can seldom be performed in the application environment, since the ideal, lubricated, operating environment is designed for minimal (ideally zero) wear, while a laboratory-based performance test needs to produce quantitative results within a short time. For this reason, laboratory test configurations and operating conditions can often end up to be extreme and far removed from reality. Validating laboratory test results and relating these to the application environment is therefore an important step towards the quantification of friction and wear behaviour. In this presentation an inclusive methodology is proposed whereby the optimal lubricant to use in a given application can be evaluated, compared and selected from an energy-efficiency and environmentallyconscious perspective using available information, supplemented by appropriate in-line process measurements and representative models, similar to their use in model-based control systems.

Abstract

In this study, the energetic performance of a slightly modified R134a domestic refrigerator using a limited mass charge (30g) of R600a refrigerant and various concentrations (0, 0.2, 0.4 and 0.6 g/L) of Al2O3-Mineral oil lubricants was evaluated. Performance evaluated include: cabinet temperature, refrigeration capacity, power consumption and coefficient of performance. Results showed that the application of the Al2O3 based nanolubricants gave lower steady state cabinet temperature, coefficient of performance and refrigeration capacity in comparison to the baseline (0 g/L) lubricant. The energy consumption of the system decreased by 0.7 % for 0.6 g/L concentration and increased by 15-24 % for 0.2 and 0.4 g/L nanolubricant concentrations in comparison to the baseline system. In conclusion, 0.6g/L concentration of Al2O3 based nanolubricants could be used as a substitute within the system.

Abstract

This paper documents the conceptual design and performance assessment of the cooled turbine of the Allam cycle. A conceptual fluid-dynamic design model is combined with a blade cooling model capable of dealing with unconventional fluids and implementing several cooling technologies. Preliminary results for a 600 MW turbine with 6 stages indicate that 5 stages need to be cooled and the film cooling effectiveness is severely limited by the high Reynolds number of the main stream.

Abstract

In-cylinder air flow structures are known to strongly impact on the performance and combustion of internal combustion engines (ICE). Therefore, the main objective of this study is to analyze the in-cylinder flow field characteristics of a single-cylinder small engine to see the effect of intake port inclination at equivalent rated engine speed using simulation model under various intake valve lift conditions. The variation of intake port inclination is -15˚, 0˚, 11.5˚, 15˚, 30˚ and 45˚. The engine geometry was created using SolidWorks, then exported and analyzed using commercial CFD method, CONVERGE. The result shows that the change of intake port inclination give effect to swirl ratio to be irregular shape. The bigger the inclination of intake port the smaller the irregular shape of swirl ratio. The change of intake port inclination also give effect to tumble ratio where the maximum tumble ratio occurs at -15˚. The bigger the inclination of intake port the smaller of the tumble ratio. The result shows that the in-cylinder flow structure is greatly influenced by the intake port inclinations irrespective of intake valve lift. Maximum Turbulent Kinetic Energy (TKE) was highest at full intake valve lift irrespective of the inclination. Also, the maximum TKE was the highest for -15˚ intake port inclination compared to other inclinations irrespective of the intake valve lift at equivalent rated engine speed. Based on the visualization of air flow in-cylinder engine, the air flow has the same tendency where vortices formation occurs below the intake valve. However, the change in the intake port inclination give effect to the change of the velocity magnitude. The bigger the inclination of the intake port the smaller the velocity flow at the in-cylinder engine will be. The maximum velocity occurs at the middle of in-cylinder engine. Finally, it is concluding that the analysis carried in this work is useful in predicting the flow and in-turn optimizing combustion chamber of modern internal combustion engines.

Abstract

This paper studies the experimental results of perovskite-based chemical looping combustion (CLC). Chemical looping combustion is a kind of combustion that can separate the fuel from air and avoid the mix of carbon oxide and air. This concept can realize the carbon oxide separation and storage without penalty. That key of CLC is focused on the oxygen carrier, e.g., metal oxide and perovskite. The study aims to assess the performance of a novel perovskite-type oxide as the oxygen carrier. We synthesized a series of La1- yCayCu0.1Ni0.9O3 (x=0, 0.1, 0.5, 0.9) by combustion method. These materials were characterized by using SEM, XRD, BET for unveiling the morphology, structure, and particle properties. Experiments were executed to investigate the reactivity of the redox materials in the thermogravimetric analyzer (TGA) in the respects of oxygen capacity, stability, and regenerability. Isothermal reaction and redox cycles are demanded to evaluate the performance. Hydrogen and methane as the fuel are both considered in this study. Besides, the effect of the temperature from 400 to 800 oC and the redox cycles were evaluated. The La1-yCayCu0.1Ni0.9O3 showed favorable reactivity in the CLC and achieved stable properties in the reaction cycles. The experimental results for CLC indicate that the La1-yCayCu0.1Ni0.9O3 has the potential to be used as the oxygen carriers for CLC system.

Abstract

Solid oxide fuel cell (SOFC) technology has the advantages of high efficiency, low emission and fuel flexibility, but high cost and short lifetime are still the bottlenecks hindering its large-scale commercial application. The performance of SOFC systems will gradually evolve into faults in the long run, leading to variation of the dynamic and static characteristics of the system. The control system designed according to the original system characteristic would face with problems such as parameter mismatch, inaccurate control and even wrong control laws. In this paper, based on a 1kW steam-reforming SOFC system multi-mode model, the dynamic and static characteristics of SOFC systems under the condition of performance degradation and fault evolution are investigated, and a complete health evaluation system is developed for the first time in the SOFC field to optimize the system control and identify early faults for the pre-treatment. The simulation results show that with the improved system controller higher system efficiency and longer lifetime of the SOFC system could be achieved, dealing with the performance degradation and fault evolution mechanisms in reality.

Abstract

The distributions and transients of temperature are practical indicators of the state and the properties of Solid Oxide Fuel Cells (SOFCs), yet few methods are available to interpret the temperatures in-situ for the internal states of the stack. A heat balance model was developed to estimate the distribution of heat sources in a Solid Oxide Fuel Cell short stack. The model is based on the temperatures measured with 6 thermocouples in the stack and treats the stack as 6 elements, taking into account the heat transfer among the elements and the test bench. A significant change in heat source distribution before and after tests with carboncontaining gases was revealed with the model, indicating possible cell damage near the fuel inlet. The model will be further calibrated for better accuracy and spatial resolution.

Abstract

This work stems from the idea of demonstrating the feasibility of using micro combined plants for the simultaneous generation of electrical and thermal energy, by external combustion of low quality fuels. In particular, this study is aimed at acquiring the knowledge necessary for the development of a small power plant consisting of a micro gas turbine and an innovative steam microturbine. The topping cycle is carried out with a micro gas turbine coupled with a heat exchanger and an external combustor, in which biomass is burned. For the bottoming cycle an impulse turbine has been adopted, characterized by a variable section nozzle, capable of expanding widely variable steam flow rates, with small efficiency losses.

Abstract

Wind tower is well-known traditional Arabic architectural element that creates passive ventilation in buildings for human comfort in hot and arid regions. Meanwhile, greenhouse agriculture has been a profitable technology despite the large energy and water need. Integrating these technologies can result in substantial energy and water saving. Still, sensible cooling proved to be unsustainable operation with depletion in relatively short time period. This suggests utilization of very high specific heat materials or integration of trans-evaporative cooling. The latter is simulated by developing a high-fidelity 3-D computational fluid dynamics (CFD) model governed by the non-isothermal Navier-Stokes flow in conjugated heat and turbulent flow regime. Effect of mist flow rate, and seasonal ambient conditions on the greenhouse parameters, i.e. temperature, relative humidity and vapor pressure deficit, are assessed and compared. Results are favorable and show to bring the needed ideal cooling for typical greenhouse crops. It is estimated however on the average 2,102 L/m2 /year of water is needed to bring the temperature, relative humidity and vapor pressure deficit to their optimum ranges in the summer weathering of Abu Dhabi city.

Abstract

The generation of electricity demand profiles is a fundamental task to determine the potential flexibility that could be introduced to an electrical system when applying demand side management. In this study we compare the results of two approaches, classical time series analysis and unsupervised clustering, to generate synthetic and anonymized electricity demand profiles. The objective is to retain the statically characteristics and descriptive value of real profiles without compromising company confidentiality. In this case the methods are applied to data obtained from a Chilean paper industry. The results reflect the complexity of the task and show the advantages and disadvantages of both methods.