In natural gas-steam combined cycle power plants, the connection section between the gas turbine and the waste heat boiler is characterized by a sharply expanded channel confined by plates with large inclination angles, which often results in unsatisfactory flow pattern and consequently leads to a reduction in deNO_x efficiency in the downstream. Installation of triple layers of deflectors is proposed to improve the flue gas flow uniformity. Computational fluid dynamics modeling approach is adopted to investigate the influences of the deflector parameters including installation arrangements, installation angle and density on the flue gas flow characteristics in the flue duct. A large vortex is clearly observed in the connection section with a vorticity up to 20 m^–1, when no deflector is installed. Installing a single layer of deflector with varying installation angles is able to decrease the size of the vortex, while installation of double layers of similar deflectors leads to a satisfactory flow pattern in the connection section. A more preferable flue gas flow pattern in the whole boiler channel is obtained by a setup of triple layers of deflectors. The optimal lengths projected horizontally are 2.25 m, 1.36 m and 0.70 m for the three-layer deflector plates, and the distances between two plates are 1.20 m, 1.40 m and 1.00 m separately. The installation angle is between 15° and 30° with uniform incrementation for the first deflector, and between 15° and 60° with uniform incrementation for the second deflector. A relative velocity standard deviation of 2.1% is obtained at outlet cross-section with the triple deflectors. The research results can provide theoretical guidance for the design of flue gas flow equalization devices

With the rapid development of artificial intelligence, virtual reality and augmented reality technology, it is possible to realize real-time monitoring of operation state of air cooling island of direct air cooling unit by using digital virtual technology. Firstly, a three-dimensional model of the air-cooled island is established, and the operating state parameters of the air-cooled island are obtained by numerical calculation. The air-cooled island operating state database and display and query software are developed. Secondly, based on the concept of digital twin, a meteorological station is set up in the power plant to obtain real-time change data of ambient temperature, wind speed and wind direction, and the operating conditions of the unit are used as software input parameters. Finally, the operation state of the air-cooled island is calculated and displayed in three dimensions. The real-time display technology for air operation state of air cooling system based on digital twin avoids the investment and maintenance of a large number of measuring points on site, which lays a foundation for the development of intelligent power stations.

In order to improve the flow field structure of rain area in cooling tower and further increase the ventilation, on the basis of the existing flat plate type wind guide plate, this paper proposes a streamline wind guide plate with low wind resistance that can be arranged in the rain area. Under the design condition, by taking the conventional cooling tower and the reformed tower with flat plate-type air guide plate arranged at each height as the reference objects, the influences of the low wind resistance streamline air guide plate on ventilation, flow field structure and temperature distribution of the whole tower are analyzed, at five different arrangement heights (1/6, 1/3, 1/2, 2/3, 5/6 air intake height). The results show that, with the rise of the height of the air guide plate arrangement, the air distribution in each region of the tower has changed, which has a significant effect on the packing heat exchange in inner zone, so that the cooling performance of the whole tower improves at first and then declines. When arranging the streamlined wind guide plate at 2/3 height of the air inlet, the ventilation increment and the average temperature reduction at the bottom of the filler area reaches the optimal value, and the improvement effect of the cooling tower performance is the best. Compared with the conventional cooling tower, the circulating water temperature drop and the ventilation increases by 2.65% and 2.78%, respectively. In addition, the circulating water temperature drop increases by 1.2% after the tower is retrofitted with a low wind resistance streamlined air guide, compared with the flat plate with an optimal arrangement height.

To investigate the potential of carbon emission monitoring technology in optimizing thermal power unit operations beyond the “double control” of emissions in thermal power enterprises, an F-class gas-steam combined cycle unit where a CO₂ monitoring system is installed at the tail chimney is selected to be discussed. Research is conducted using online fuel monitoring data from the front pressure regulating station and flue gas monitoring data from the rear chimney environmental protection measurement point. The results reveal that, in the high-load section, the flue gas monitoring carbon emission rate is consistently higher than the fuel monitoring rate, although both curves exhibit similar trends, indicating comparable yet offsetting data. For units operating at medium loads, atmospheric conditions are crucial. Elevated temperatures may increase heat loss, while reduced air pressure can minimize compressor energy consumption, thereby decreasing the unit’s instantaneous carbon emission intensity. Among various parameters, adjusting the turbine expansion ratio, compressor pressure ratio, and steam fuel power ratio could be effective strategies to minimize carbon emissions without altering the unit load.

To accurately assess the overall performance of integrated energy systems, with a focus on their key characteristics of low carbon emissions and high efficiency, and to facilitate the safe integration of renewable energy, this study proposes a weighted energy utilization efficiency index. The integrated energy system in industrial parks is identified as a typical scenario for the application of comprehensive energy. Considering the relatively low energy conversion efficiency of renewable sources in these systems, the study evaluates the performance of the renewable and fossil fuel energy systems using energy efficiency ratios and primary energy utilization rates. Moreover, the proportion of supplied energy is utilized as a weighting factor to indicate the system’s relative significance within the total energy framework, leading to the calculation of the weighted energy utilization efficiency for the park’s integrated energy system. Through comparative analysis with conventional metrics such as primary energy utilization rate and exergy efficiency, the results indicate that the proposed index can effectively reflect the level of renewable energy integration, showcasing the system’s core features of low carbon and high efficiency. This is crucial for directing strategies towards energy saving and consumption reduction.

Geothermal power generation, as one of the main ways to develop and utilize geothermal resources, is of great significance to promote the low-carbon and clean energy structure and the realization of the “dual carbon”. Firstly, the development history of geothermal resources in the world is analyzed. Then, main geothermal power generation technologies such as dry steam power generation, flash steam power generation, binary cycle power generation and wellhead power generation technology are overviewed. On this basis, the hot dry rock power generation, thermovoltaic power generation, supercritical CO₂ cycle power generation, combined power generation technology and multi-energy eomplementary power generation technologies such as geothermal-solar, geothermal-wind, geothermal-biomass, and geothermal-ocean energy, are elaborated in detail. Finally, combining with the current situation and existing problems of geothermal power generation in China, some suggestions for the development of geothermal power generation are put forward, to provide reference for the future development of geothermal power generation.

To study the effect of dust on performance of photovoltaic power generation, a laboratory bench was built to collect daily power generation data of clean and polluted photovoltaic strings while monitoring meteorological data to analyze the influence of dust accumulation and weather on power generation performance of photovoltaic modules. The results indicate that, the increase in PM_2.5 mass concentration in winter and the frequent occurrence of sandstorms in spring lead to a significant accumulation of dust on surface of the photovoltaic modules, resulting in a rapid increase in cumulative power generation losses. However, in summer, due to increased precipitation, dust is difficult to accumulate on photovoltaic modules, resulting in a slow increase in cumulative power generation losses. In addition, the DTW algorithm is employed to find similar days. Firstly, the entropy method is used to calculate the weights of each meteorological parameter. Then, the DTW values corresponding to each meteorological parameter on each historical day are calculated in reverse chronological order, multiplied by their weights, and added together to obtain the comprehensive DTW value for each historical day. By comparing the comprehensive DTW values of each historical day, the meteorological similar day that is closest to the current day is selected. In order to avoid extreme weather conditions, a portion of the dataset is selected as the validation set, and the criteria for finding similar days are optimized. The data from 9:00 to 15:00 each day is divided into three time periods for analysis, and the condition that the average solar irradiance is not less than 600 W/m² is set. After optimization, the evaluation index determination coefficient of the prediction model is 0.83, and the root mean square error is 0.22, indicating a significant improvement in prediction performance. Finally, the algorithm is used to develop a cleaning strategy for the photovoltaic power plant. After comparing the cumulative power generation loss with the cleaning cost, it is determined that the power plant should be cleaned every 28 days under long-term non rainfall conditions.

Renewable energy suffers some drawbacks such as instantaneity, instability, and the mismatch between supply and demand during the utilization. Thermochemical heat storage exhibits distinct advantages, including high heat storage density, elevated heat storage temperature, and negligible heat loss during the long-term storage. It has the capability to convert intermittent energy sources into stable moderate and high temperature heat energy to fulfill the needs of fluctuating output. The classification, basic mechanisms and characteristics of thermochemical heat storage within reaction temperature range of 400~1 100 ℃ are reviewed. Subsequently, the thermal storage performance of typical thermochemical heat storage materials, such as carbonates, hydroxides, oxides, metal hydrides, ammonia and methane are analyzed, and the structural targeted regulation and modification methods are investigated, alongside the introduction of typical demonstration projects. Following this, the reactor design and system integration of solid-gas and gas-gas reaction systems are discussed. In the last, the future research interests are deliberated and proposed in the development and industrial application of thermochemical energy storage materials.

The microwave attenuation method is one of the common methods for online measurement of carbon content in fly ash in recent years. However, due to the differences in sampling locations and sampling devices of the fly ash, there is a large uncertainty in particle size of the fly ash, which results in a large error in the measurement of carbon content in fly ash. The existing carbon content fitting models are all based on the relationship between the attenuation of the characteristic frequency signal by fly ash and the carbon content of fly ash, which has problems such as large error and poor adaptability. In order to solve these problems, this paper proposes to use the time-domain main peak attenuation of the signal instead of the attenuation of the signal at the eigenfrequency as a method for online fitting of the carbon content in fly ash. To correct the error caused by the uncertainty of fly ash particle size, the effects of fly ash with different particle size ranges on the measurement of ash level and fly ash carbon content are compared on the basis of the study on ash level and carbon content measurement. The results show that, the peak attenuation of the signal in the time domain is used to calculate the carbon content, and the results are in good agreement with the actual values. For the same mass of ash samples in the waveguide, the particle size of the fly ash does not have any significant effect on the measurement accuracy of the ash level. When the microwave method is applied to measure the carbon content in the fly ash in the waveguide, for the same mass of ash samples, the attenuation of the fly ash on the microwave signal inside the waveguide decreases gradually with the particle size of the fly ash. Thus, the measured value of carbon content increases as the particle size of the fly ash decreases.

The P-U characteristic curve of a photovoltaic array exhibits multi-peak characteristics in partially shaded environments, leading to the inefficiency of conventional maximum power point tracking (MPPT) algorithm in tracking the maximum power. To address this issue, this paper proposes a two-layer control model for photovoltaic MPPT based on an improved tuned swarm optimization (TSO) algorithm. In the upper layer, the Levy flight strategy and polynomial mutation strategy are embedded into tuna algorithm, creating the Levy-polynomial mutation tuna swam optimization (LPTSO) to search for the global maximum power point. In the lower layer, the perturbation observation method is employed to locally track the global maximum power point, thereby reducing power oscillations in local shading environments. The two-layer control model is applied to the photovoltaic MPPT simulation system, and the simulation experimental results show that, for multi-peak MPPT control, the proposed model achieves significant improvements in convergence speed, tracking efficiency, power oscillations, etc. In conclusion, the proposed two-layer control model for photovoltaic MPPT effectively addresses the issue of maximum power tracking failure in partially shaded environments.