Capas finas de ZrO2 para mejorar la resistencia química de los vidriados mates de calcio

La resistencia al ataque químico de vidriados cerámicos susceptibles al mismo, concretamente formulados a partir de una frita mate de calcio, se ha mejorado depositando en la superficie una capa delgada de óxido de circonio. Un sol de circonio estabilizado es el precursor de la capa, el cual se deposita mediante aerografía sobre el vidriado cocido y con un tratamiento térmico suave (Tmax ≈ 400 ºC), es transformado en ZrO2 y anclado a la superficie. Los ensayos de resistencia química demuestran que el vidriado protegido no sufre un ataque apreciable visualmente por parte del ácido clorhídrico concentrado, condiciones en las que el mismo vidriado sin el recubrimiento resulta gravemente dañado. El precursor utilizado genera una capa de óxido de circonio que protege el vidriado subyacente, de modo que el ataque químico por parte del ácido clorhídrico queda confinado al entorno de las grietas y discontinuidades de la capa depositadaPeer reviewe

Part-load performance modelling of a reheated humid air turbine power cycle

Humid air turbines have previously demonstrated the potential to deliver high efficiency and power output combined with low emissions. This paper investigates the part-load performance of a 40 MW class advanced humid air turbine for power generation applications across a range of operating conditions. The paper investigates the impact of the main burner and reheater burner on the system’s part-load power output and thermal efficiency and provides insights into the behavior of the key modules across the power spectrum of operation including the saturator tower which was never reported previously. The impact of the ambient air and sea water temperature on the cycle’s performance are also investigated. The outcome of the research shows that the thermal efficiency if the system is less than 0.26% penalized when operating down to 50% of the design power output. Sea water temperature was found to have a more notable impact than ambient air temperature on both power output and thermal efficiency Overall, this work constitutes a step ahead in understanding the potential benefits of an advanced humid air turbine system for power generation applications across a range of operating conditions which is not previously shown

The impact of heat exchanger degradation on the performance of a humid air turbine system for power generation

This paper aims to analyse the impact of air-water heat exchanger’s degradation on the performance of a reheated humid air turbine system for power generation applications. A number of thermal models to simulate the performance of the various sub-systems was put together and validated against experimental data. The performance degradation of the heat exchangers is characterised by means of a degradation coefficient, which is used to drive the cycle into off-design and part-load conditions when degradation is accounted for. Three heat exchanger design scenarioswere investigated, namely a low, a medium and a high effectiveness in order for the impact of the degradation penalties on cycle thermal efficiency to be determined. The performance deterioration of the heat exchangers is also analysed from an exergetic point of view in order to identify the key sources that penalise the thermal efficiency of the humid air turbine system. The degradation analysis shows that typical levels of intercooler deterioration cause notable penalties in the cycle performance, reducing its thermal efficiency and power output by 1.8 percentage points and 28% respectively compared to the un-degraded operation. The exergy analysis showed that the deterioration of the intercooler also penalises the efficiency of the low pressure compressor and reheater, which contribute to the performance penalty of the cycle too. It is also found that the degradation of the intercooler can also lead to operability penalties at the low pressure compressor by reducing its surge margin. The effects of the deterioration of the aftercooler and economiser were found to only have a weak effect on the system’s performance. The outcome of the work constitutes a step forward in understanding of the performance behaviour of an advanced cycle when heat exchanger degradation is present

Techno-economic analysis of a reheated humid air turbine

The purpose of this paper is to identify the economic potential of a reheated humid air turbine system for power generation applications. A parametric analysis is performed to correlate the technology level of the system with the required cost of the electricity for economic viability. The effect of fluctuations of the main cost drivers is evaluated via an uncertainty analysis. The performance of the studied reheated humid air turbine is compared against previously studied humid configurations and well established gas-steam combined cycles. The fuel cost is found to be driving the cost of electricity. The uncertainty analysis also shows the dependency of the optimum cycle design parameters upon the market prices. The analysis reveals the capability of the reheated humid air turbine to be an economically viable option for the power generation sector featuring an estimated cost of electricity 2.2% lower than simpler humid cycles, and 28% lower than established combined cycles currently in service. The outcome of the work constitutes a step forward in the understanding of the economic performance of advanced complex cycles and proves the potential of such systems for applications where high efficiency and economic performance is jointly required

Design point performance and optimization of humid air turbine power plants

With the recent drive towards higher thermal efficiencies and lower emission levels in the power generation market, advanced cycle power plants have become an increasingly appealing option. Among these systems, humid air turbines have been previously identified as promising candidates to deliver high efficiency and power output with notably low overall system volume, weight and emissions footprint. This paper investigates the performance of an advanced humid air turbine power cycle and aims to identify the dependencies between key cycle design variables, thermal performance, weight and cost by means of a parametric design optimization approach. Designs of the main heat exchangers are generated, aiming to ascertain the relationship between their technology level and the total weight and acquisition cost of them. The research outcomes show that the recuperator and the intercooler are the two components with the largest influence on the thermal efficiency and the total cost. The total weight of the power system is driven by the technology level of the recuperator and the economizer. Finally, the effectiveness of the aftercooler seems to have the greatest impact in reducing the total acquisition cost of the system with minimum penalty on its thermal efficiency

Small Wind Turbine Emulator Based on Lambda-Cp Curves Obtained under Real Operating Conditions

[EN] This paper proposes a new on-site technique for the experimental characterization of small wind systems by emulating the behavior of a wind tunnel facility. Due to the high cost and complexity of these facilities, many manufacturers of small wind systems do not have a well knowledge of the characteristic lambda-Cp curve of their turbines. Therefore, power electronics converters connected to the wind generator are usually programmed with speed/power control curves that do not optimize the power generation. The characteristic lambda-Cp curves obtained through the proposed method will help manufacturers to obtain optimized speed/power control curves. In addition, a low cost small wind emulator has been designed. Programmed with the experimental lambda-Cp curve, it can validate, improve, and develop new control algorithms to maximize the energy generation. The emulator is completed with a new graphic user interface that monitors in real time both the value of the lambda-Cp coordinate and the operating point on the 3D working surface generated with the characteristic lambda-Cp curve obtained from the real small wind system. The proposed method has been applied to a small wind turbine commercial model. The experimental results demonstrate that the point of operation obtained with the emulator is always located on the 3D surface, at the same coordinates (rotor speed/wind speed/power) as the ones obtained experimentally, validating the designed emulator.Martínez-Márquez, CI.; Twizere-Bakunda, JD.; Lundbäck-Mompó, D.; Orts-Grau, S.; Gimeno Sales, FJ.; Segui-Chilet, S. (2019). Small Wind Turbine Emulator Based on Lambda-Cp Curves Obtained under Real Operating Conditions. Energies. 12(13):1-17. https://doi.org/10.3390/en12132456S1171213Nichita, C., Luca, D., Dakyo, B., & Ceanga, E. (2002). Large band simulation of the wind speed for real time wind turbine simulators. IEEE Transactions on Energy Conversion, 17(4), 523-529. doi:10.1109/tec.2002.805216Pillay, P., & Krishnan, R. (1988). Modeling of permanent magnet motor drives. IEEE Transactions on Industrial Electronics, 35(4), 537-541. doi:10.1109/41.9176Tanvir, A., Merabet, A., & Beguenane, R. (2015). Real-Time Control of Active and Reactive Power for Doubly Fed Induction Generator (DFIG)-Based Wind Energy Conversion System. Energies, 8(9), 10389-10408. doi:10.3390/en80910389Martinez, F., Herrero, L. C., & de Pablo, S. (2014). Open loop wind turbine emulator. Renewable Energy, 63, 212-221. doi:10.1016/j.renene.2013.09.019Castelló, J., Espí, J. M., & García-Gil, R. (2016). Development details and performance assessment of a Wind Turbine Emulator. Renewable Energy, 86, 848-857. doi:10.1016/j.renene.2015.09.010Kojabadi, H. M., Chang, L., & Boutot, T. (2004). Development of a Novel Wind Turbine Simulator for Wind Energy Conversion Systems Using an Inverter-Controlled Induction Motor. IEEE Transactions on Energy Conversion, 19(3), 547-552. doi:10.1109/tec.2004.832070Choy, Y.-D., Han, B.-M., Lee, J.-Y., & Jang, G.-S. (2011). Real-Time Hardware Simulator for Grid-Tied PMSG Wind Power System. Journal of Electrical Engineering and Technology, 6(3), 375-383. doi:10.5370/jeet.2011.6.3.375Wasynczuk, O., Man, D. T., & Sullivan, J. P. (1981). Dynamic Behavior of a Class of Wind Turbine Generators during Random Wind Fluctuations. IEEE Power Engineering Review, PER-1(6), 47-48. doi:10.1109/mper.1981.5511593Dai, J., Liu, D., Wen, L., & Long, X. (2016). Research on power coefficient of wind turbines based on SCADA data. Renewable Energy, 86, 206-215. doi:10.1016/j.renene.2015.08.02