To address the large temperature difference in the air heater (AH) inlet of a traditional exhaust heat utilization system and energy grade mismatch problems during the heat and mass transfer processes, this study proposed a new multi-level waste heat cascade utilization system. Based on a principle of “temperature-to-port and cascade utilization”, this system uses the boiler side high-temperature flue gas and low-temperature air, and the turbine side high-temperature feed water and low-temperature condensate water, to conduct cross heat exchange according to the energy grade matching principle. Combined with a typical 1000 MW coal-fired unit, the heat transfer characteristics and energy-saving benefits of the new system were analyzed. The results showed that the new system has excellent performance: the heat rate decreased by 91 kJ/kWh, coal consumption decreased by 3.3 g/kWh, and power generation efficiency increased to 49.39%.
The ultra-supercritical double reheat thermal system, featuring the back-pressure extraction steam turbine (BEST) system, effectively addresses the challenge of excessive extraction steam superheat. This solution significantly enhances power generation efficiency, contributing to practical advancements in energy conservation, emission reduction, and sustainable development. Focused on a 1000 MW ultra-supercritical double reheat unit with the BEST reheating system, this study examined thermal system performance and equipment energy consumption. Computational analyses under variable conditions explored the impact of reheat steam temperature and main steam pressure on unit thermal economy. Results revealed that higher steam temperatures increased main steam turbine power output while reducing the BEST output. The feedwater pump motor exhibited the highest energy consumption, consistently exceeding 50%. Additionally, increasing reheat steam temperature initially improved thermal system efficiency, but diminishing returns were observed at higher temperatures. Furthermore, maintaining reheat steam temperature and increasing main steam pressure further enhanced the thermal economy of the ultra-supercritical double reheat unit.
In response to the growing significance of hydrogen as a clean energy carrier, this study investigates the advanced rectifier technologies employed in electrolytic hydrogen production. First, the topologies of three rectifiers typically employed in industry—24-pulse thyristor rectifiers, insulated gate bipolar transistor (IGBT) rectifiers, and 24-pulse diode rectifiers with multi-phase choppers—are described in detail. Subsequently, at a constant 5 MW power level, the three rectifiers are compared in terms of rectifier efficiency, grid-side power quality, power factor, and overall investment cost. The results indicate that in comparison to the other two rectifiers, the thyristor rectifier provides superior efficiency and cost advantages, thereby maintaining a dominant market share. Additionally, case studies of rectifier power supplies from three real-world industrial projects are presented, along with actual grid-side power quality data. Finally, the challenges, potential applications, and future prospects of rectifiers in renewable energy-based hydrogen production are discussed and summarized.
A series of Mn/Ce-based bimetal-organic frameworks, recorded as MCDx (x = 1, 2, 4, 6), were prepared by a solvothermal synthesis method to explore their effects and performance in the synergistic catalysis of toluene under the irradiation of non-thermal plasma. The catalytic properties of different manganese loadings in MCDx for degradation of toluene were investigated. The microphysical structures of the material were analyzed by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The results showed that a MCDx coupling with non-thermal plasma can greatly improve the degradation efficiency, the energy efficiency and the CO2 selectivity, and could also significantly reduce the generation of O3 in the by-products. Among the test samples, MCD6 with Mn:Ce = 6:1 (molar ratio) showed the best catalytic performance and stability, exhibited toluene catalytic efficiency 95.2%, CO2 selectivity 84.2% and energy efficiency 5.99 g/kWh, and reduced O3 emission concentration 81.6%. This research provides a reference for the development and application of synergistic catalysis based on bimetal-organic frameworks and non-thermal plasma in the reduction of industrial volatile organic compounds.
Abstract Carbon emissions from fossil energy not only cause a lot of extreme weathers, but also global warming. Accurately forecasting of electricity demand can promote the development of the renewable energy, which is vital to achieving the goal of carbon peak and carbon neutrality. In this paper, a nonlinear interval grey model based on genetic algorithm and BP neural network optimization (BPGA-IGM (1,1)) is proposed to predict electricity consumption. Firstly, based on the forecast of China's energy consumption and China's coal consumption, the reliability and superiority of the BPGA-IGM (1,1) model have been verified. Then, the model and other competing models are applied to forecast Shanghai's electricity consumption. The empirical results show that the model designed in this paper could obtain more accurate and reliable prediction results. According to the empirical results, Shanghai's electricity consumption continues to rise to a higher level of no less than 1978.19 million kWh by 2025. On the basis of this issue, several suggestions have been offered.
In conventional heat pipe based battery thermal management systems the thermal contact between the battery and the heat pipe is enhanced by means of heat conductive elements. These additional elements introduce multiple layers of thermal resistance and contribute to increased weight. This paper aims to address this issue by minimizing the contact thermal resistance and potentially reduce this additional weight. The proposed solution relies on capillary-driven evaporative cooling (CDEC), wherein a wick structure is directly integrated onto the battery's surface to enable direct cooling. To demonstrate this concept, an experimental study was conducted by affixing a Copper foam ton an emulated battery block, and using ethanol and Novec 7000 as cooling media. The CDEC system's thermal performance was assessed under three heating conditions, and different operating conditions. The results indicated that the copper foam with higher pore density outperformed the other due to its greater wetting height. The maximum cell surface temperature was maintained at around 40 °C for a continuous 50W heat input. Furthermore, the thermal resistance of the system was lowered by a factor of 6 compared to an air-cooled system. The thermal resistance ranged from a minimum of 0.32 to a maximum of 1.5K/W, which were comparatively low compared to some existing battery thermal management system designs. This paper introduces an innovative battery cooling concept, presents experimental evidence of its feasibility, and demonstrates its ability to effectively regulate battery temperature within acceptable limits even under high heat loads, while minimizing overall thermal resistance.
The heat balance algorithm can evaluate the influence of a individual factor alone, and overall economic influence can be calculated through simulation. Therefore, the heat balance algorithm can be the basis of our weighting algorithm research, helping us to find the relationship between data. Calculating the effect of a individual factor on the economics of the unit also grasps the level of influence of a certain factor change on the overall unit. The purpose of studying the weighting algorithm is to analyse the effect of the above factors economically and analyse the association among them. With the three and four transformation measures, by validating the data, it is found that based on the heat consumption income of individual transformation measures: back pressure optimization < cylinder efficiency improvement < waste heat utilization < low pressure cylinder efficiency improvement < medium pressure cylinder efficiency improvement < High pressure cylinder efficiency improvement < external steaming cooler. The heat consumption benefit value of the above-mentioned transformation technical scheme can be calculated based on the maximum benefit (back pressure optimization transformation).
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