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An integrated electric–gas system (IEGS) is the manifestation and development direction of a modern smart power system. This paper employs the cloud-edge computing method to research IEGS’s optimal dispatch to satisfy data protection requirements between power systems and natural gas systems and reduce data transmission pressure. Based on cloud-edge computing architecture, this paper constructs a cloud-edge computing method based on the Multi-agent Deep Deterministic Policy Gradient (MADDPG) algorithm to solve optimal dispatch problems. Then, this paper proposes an IEGS dispatch strategy based on cloud-edge computing, which conducts distributed computing independently at the edge of power and natural gas, and the cloud implements global dispatch based on boundary information and edge learning parameters. This method does not require the exchange of all information between the power system and natural gas system, effectively protecting data privacy. This paper takes the improved IEGS of the IEEE 9 node and Gas 8 node as an example to analyze. The equipment output of this dispatch method is within a reasonable range, and the cost is reduced by 0.21% to 1.03% compared with other methods, which verifies the effectiveness of the cloud-edge computing method in solving dispatch problems.

Gasification is a promising technology for the conversion of mixed solid waste like refuse-derived fuel (RDF) and municipal solid waste (MSW) into a valuable gas consisting of H2, CO, CH4 and CO2. This work aims to identify the basic challenges of a single-stage batch gasification system related to tar and wax content in the producer gas. RDF was first gasified in a simple semi-batch laboratory-scale gasification reactor. A significant yield of tars and waxes was received in the produced gas. Waxes were analyzed using gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectrometry. These analyses indicated the presence of polyethylene and polypropylene chains. The maximum content of H2 and CO was measured 500 sec after the start of the process. In a second series of experiments, a secondary catalytic stage with an Ni-doped clay catalyst was installed. In the two-stage catalytic process, no waxes were captured in isopropanol and the total tar content decreased by approximately 90 %. A single one-stage semi-batch gasification system is not suitable for RDF gasification; a large fraction of tar and waxes can be generated which can cause fouling in downstream processes. A secondary catalytic stage can significantly reduce the tar content in gas.

The optimization of the production process of metal mines has been traditionally driven only by economic benefits while ignoring resource efficiency. However, it has become increasingly aware of the importance of resource efficiency since mineral resource reserves continue to decrease while the demand continues to grow. To better utilize the mineral resources for sustainable development, this paper proposes a multi-objective optimization model of the production process of metal mines considering both economic benefits and resource efficiency. Specifically, the goals of the proposed model are to maximize the profit and resource utilization rate. Then, the fast and elitist Non-Dominated Sorting Genetic Algorithm (NSGA-II) is used to optimize the multi-objective optimization model. The proposed model has been applied to the optimization of the production process of a stage in the Huogeqi Copper Mine. The optimization results provide a set of Pareto-optimal solutions that can meet varying needs of decision makers. Moreover, compared with those of the current production indicators, the profit and resource utilization rate of some points in the optimization results can increase respectively by 2.99% and 2.64%. Additionally, the effects of the decision variables (geological cut-off grade, minimum industrial grade and loss ratio) on objective functions (profit and resource utilization rate) were discussed using variance analysis. The sensitivities of the Pareto-optimal solutions to the unit copper concentrate price were studied. The results show that the Pareto-optimal solutions at higher profits (with lower resource utilization rates) are more sensitive to the unit copper concentrate prices than those obtained in regions with lower profits.

In order to explore technically feasible options for improving the performance of the H2 shaft furnace (HSF), a previously built and validated computational fluid dynamics (CFD) model was employed in the current work to assess the potential of the operation based on a center gas distributor (CGD). A set of simulations was performed to mimic scenarios where different amounts of feed gas (0–30% of 1400 Nm3/t-pellet) are injected via the CGD located at the bottom of the HSF. The results showed that a relatively large stagnant zone (approximately 8.0-m in height and 0.3-m in diameter) exists in the furnace center where the gas flows are weak owing to an overly shortened penetration depth of the H2 stream solely injected from the circumferentially installed bustle-pipe. When adopting the CGD operation, however, the center gas flows can be effectively enhanced, consequently squeezing the stagnant zone and thus leading to a better overall performance of the HSF. In particular, the uniformity of the final reduction degree (mean values ranging from 0.8846 to 0.8896) of the solid phase (i.e., pellets) is well improved under the investigated condition where the total gas feed rate is fixed at 1400 Nm3/t-pellet. As for the final mean reduction degree of solid and top gas utilization degree, the two performance indicators rise to maximal values when the CGD feed ratio is increased to 20% and then slightly drop with a further increase in the ratio.

In order to enhance the hydraulic performance of the volute pump, the Kriging model and genetic algorithm (GA) were used to optimize the 3D diffuser of the volute pump, and the hydraulic performance of the optimized model was compared and analyzed with the original model. The volute pump diffuser model was parameterized by BladeGen software. A total of 14 parameters such as the distance between the leading and trailing edges and the central axis, and the inlet and outlet vane angle were selected as design variables, and the efficiency under the design condition was taken as the optimization objective. A total of 70 sets of sample data were randomly selected in the design space to train and test the Kriging model. The optimal solution was obtained by GA. The shape and inner flow of the optimized diffuser were compared with those of the original diffuser. The research results showed that the Kriging model can effectively establish the high-precision mathematical function between the design variables and the optimization objective, and the R2 value is 0.95356, which meets the engineering needs. The optimized geometry model demonstrated a significant change, the vane leading edge became thinner, and the wrap angle increased. After optimization, the hydraulic performance of the volute pump under design and part-load conditions were greatly improved, the efficiency under design conditions increased by 2.65%, and the head increased by 0.83 m. Furthermore, the inner flow condition improved, the large area of low-speed and vortex disappeared, the pressure distribution in the diffuser was more reasonable, and the pressure gradient variation decreased.

Poultry litter is one type of biomass and waste generated from the farming process. This study performed a performance and process analysis of poultry litter to energy using the lab-scale shell and tube heat exchanger (STHE) system along with a Stirling engine and a swirling fluidized bed combustor (SFBC). The effects of tube shape, flow direction, and water flow rates on water and trailer temperature changes were investigated during the poultry litter co-combustion process. Energy flow analysis and emissions were also studied. Results showed that the water outlet temperature of 62.8 ° C in the twisted tube was higher than the straight tube case (58.3 ° C ) after 130 min of the co-combustion process. It was found that the counter-current direction had higher water temperature changes, higher logarithmic mean temperature difference (LMTD), and higher trailer temperature changes than the co-current direction. A water flow rate of 4.54 L/min showed adequate heat absorption in the lab-scale STHE system and heat rejection in the trailer. Results indicated that the lab-scale STHE system has a conversion efficiency of 42.3% and produces hot water (at about 63.9 ° C ) along with lower emissions. This research study confirmed that poultry litter can be used to generate energy (e.g., hot water and electricity) by using a lab-scale biomass conversion system for space heating applications.

The scope of this paper is to perform a detailed experimental investigation of the shape error effect on the turbulence evolution behind NACA 64-618 airfoil. This airfoil is 3D-printed with predefined typical shape inaccuracies. A high-precision optical 3D scanner was used to assess the shape and surface quality of the manufactured models. The turbulent flow was studied using hot-wire anemometry. The developed force balance device was provided to measure the aerodynamic characteristics of the airfoil. Experimental studies were carried out for three angles of attack, +10∘, 0∘, −10∘, and different chord-based Reynolds numbers from 5.3×104 to 2.1×105. The obtained results show that the blunt trailing edge and rough surface decline the aerodynamic performance of the blades. In addition, the experimental results revealed a strong sensitivity of the Taylor microscale Reynolds number to the type of shape inaccuracy, especially at Re≈1.7×105. We also discuss the evolution of the Reynolds stress components, the degree of flow anisotropy, and the power spectrum distributions depending on the airfoil inaccuracies.

In order to effectively control high temperatures inside coal gangue hills, gravity heat pipes with specific spacings are vertically installed in coal gangue hills. Heat extracted from these heat pipes can be utilized for power generation through energy conversion. In this study, an equivalent model of gravity heat pipes in coal gangue hills was established and, in a laboratory setting, experimental research and optimization were conducted on power generation per unit area using the temperature difference of gravity heat pipes for electricity generation. To facilitate real-time testing of different heat pipe parameters and to display the experimental results, a multi-parameter measurement system was designed and constructed. This study systematically investigated the effects of various structural parameters such as inclination angle, heating temperature, initial absolute pressure, and working fluid height. Through single-factor experiments, it was determined that the inclination angle had no significant impact. The range of values for heating temperature, initial absolute pressure, and working fluid height were confirmed based on six sets of experiments. To maximize the performance of the thermoelectric generator, a response surface analysis experiment was conducted using the Design-Expert software. The optimal conditions were determined to be a working fluid height of 200.001 mm, an initial absolute pressure of 0.002 MPa, and a heating temperature of 413.15 K. Under these conditions, the power generation per unit area of the thermoelectric generator reached 0.122981 W/(m2·K). The accuracy of the theoretical experiments was verified through on-site industrial experiments. By calculations, it was determined that the maximum temperature difference power generation capacity per gravity heat pipe was 42.39 W. This provides a new solution for the management of coal mine gangue hills and the secondary utilization of waste energy.