Efficient and reliable utilization of renewable energy at the user's end is the key to achieving a low-carbon life. This paper proposed a new distributed energy system around the comprehensive utilization of solar energy by integrating solid oxide fuel cell (SOFC), energy storage equipment, photovoltaic thermal (PVT) collector, and heat pump. By integrating the use of SOFC and PVT, we can further minimize reliance on fossil fuels, while employing the coupling of PVT and heat pump effectively mitigates the inherent challenges of solar energy's variability and intermittency, all while enhancing overall system efficiency. On this basis, we apply the heat current method to construct a cross-scale heat current model of the components and the system by considering the energy transfer, conversion, and storage characteristics of the system. By employing this model, we simulate the system's operation throughout an entire typical day, assess the COP enhancement of the PVT-coupled heat pump system, analyze the influence of diverse operating conditions on daily system performance, and evaluate the economy of the energy storage devices in the system.

Optimal characteristic parameters and control strategies in the operation of urban heating systems are significant for carbon reduction and high efficiency. Considering load fluctuations and real-time outdoor temperature changes, this research constructs steady-state and dynamic heat current models of the heating system based on the standard thermal resistance model. Combined with genetic algorithms, an optimal setting method is proposed for the operating characteristic parameters of the heating system under variable operating conditions. To achieve the control of the optimal characteristic parameters, the dynamic heat current model is applied to derive the system energy state space equations and obtain the state space parameter matrix. Moreover, a holistic control strategy for the heating system based on the optimal node parameters is proposed. The control simulation results show that the proposed holistic control strategy based on the optimal node temperature can save energy by 25.4 % compared with the fixed node temperature. Meanwhile, the exergy efficiency of the heating system increases by 2.3 %. That is, the proposed asynchronous time-scale holistic control method is significant for the day-ahead optimal regulation strategy of the district heating system.

Distributed power sources and diversified loads flexibly and controllably interact in the active distribution network with symmetrical characteristics, and their spatial-temporal characteristics are significant in optimizing the grid configuration and enhancing the active regulation capability of the distribution network. This contribution proposes an active distribution network architecture that considers symmetrical source and load access and constructs an active distribution network optimization scheduling model by considering the constraints of photovoltaic, energy storage, electric heat pumps, fuel cells, micro-gas turbines, and other equipment. On this basis, the overall energy balance and heterogeneous energy transfer constraints are considered with the goal of minimizing the operation cost of the system. By introducing the IEEE-33 node model, including influences distribution power source and energy storage location, dynamic characteristic of heat pump, operational performance of fuel cell, and heat load variation on the active power and reactive power of active distribution network are analyzed. When the COP increases by 0.4, the day operating cost of the system equipment decreases by 14.5%. The simulation results show that considering the temporal and spatial distribution characteristics of the equipment can improve the active distribution network operation and scheduling, promote renewable energy accommodation, and enhance the economy and flexibility of the system.

Deep exploration and effective coordination of customer-side electrical and thermal loads significantly promote renewable energy consumption. This paper proposes a distributed integrated energy system (DIES) by coupling a power distribution grid, heat supply network, wind power, photovoltaic, and combined heat and power generation. Based on the standardized thermal resistance method, the dynamic thermal power flow model of the heating network and the overall power flow model of the DIES are constructed. On this basis, the flexible heating load under the user-following resilient heating scheme is obtained by considering users' behavior and physical comfort. Based on the resilient heating scheme, a dual-layer dispatching model of the DIES is constructed, and a multi-scenario day-ahead dispatching is conducted to maximize renewable energy consumption. Compard with traditional heating schemes, the dispatch results show savings in heating demand of 7.8 % and 6.2 % with the basic resilient heating scheme and ultimate resilient heating scheme, respectively, and an increase in regional PV power consumption of 27.5 % and 35.8 %, respectively. Overall, improving heating schemes in DIES can bring comprehensive benefits to the energy saving and enhance the flexibility of system dispatching.

Thermal barrier coatings are an effective technology for improving the high-temperature performance of hot section components in gas turbine engine. Due to their excellent properties, high-entropy oxides are considered to be promising materials for thermal barrier coatings. Laser cladding is a coating preparation technology and the top coat prepared by laser cladding technology has an important application value for thermal barrier coatings. In this work, to improve the thermal cycling behavior of the La2(Ti0.2Zr0.2Sn0.2Ce0.2Hf0.2)2O7 high-entropy oxide coating, a bi-layer coating with the La2(Ti0.2Zr0.2Sn0.2Ce0.2Hf0.2)2O7 high-entropy oxide layer and the YSZ layer was designed and fabricated by laser cladding on the NiCoCrAlY alloy surface. The microstructure, phase and mechanical properties of the coating were analyzed by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and micro-hardness and nanoindentation tests, respectively. The results show that a bi-layer La2(Ti0.2Zr0.2Sn0.2Ce0.2Hf0.2)2O7/YSZ coating was successfully prepared by the laser cladding method, and shows good bonding at the interface between the layers. The high-entropy oxide layer maintains a relatively stable defective fluorite structure and its microstructure exists in the stable cellular and dendrite crystalline state after laser cladding. The high-entropy oxide layer prepared by laser cladding showed an average elastic modulus of 167 GPa and an average hardness of 1022.8HV in nanoindentation tests. Thermal cycling of the coating was carried out at 1050 degrees C. Failure of the bi-layer coating occurred after 60 thermal cycles at 1050 degrees C. Thermal stresses between different layers are calculated during thermal cycling. Due to its excellent mechanical prop-erties, the bi-layer coating with the La2(Ti0.2Zr0.2Sn0.2Ce0.2Hf0.2)2O7 high-entropy oxide and YSZ layers is ex-pected to become an effective high-entropy oxide thermal barrier coating.

Thermal barrier coating (TBC) is applied to protect the hot-section components of a gas turbine engine. In the present work, a La 2 (Zr 0.2 Ti 0.2 Y 0.2 YB 0.2 Nb 0.2 ) 2 O 7 high entropy oxide was designed, fabricated by a solid-phase reaction at 1400 °C, and subjected to an investigation of its properties. The results indicate that the La 2 (Zr 0.2 Ti 0.2 Yb 0.2 Y 0.2 Nb 0.2 ) 2 O 7 high entropy oxide had a pyrochlore structure. During synthesis, a small amount of La 2 TiO 5 was produced. The thermal conductivity of the La 2 (Zr 0.2 Ti 0.2 Yb 0.2 Y 0.2 Nb 0.2 ) 2 O 7 high entropy oxide was approximately 0.8855 W·m -1 ·K -1 at room temperature. The coefficient of thermal expansion of the La 2 (Zr 0.2 Ti 0.2 Yb 0.2 Y 0.2 Nb 0.2 ) 2 O 7 high entropy oxide was approximately 9.374 × 10 −6 K −1 at 1000 °C. To improve the service life of the TBC composed of the La 2 (Zr 0.2 Ti 0.2 Yb 0.2 Y 0.2 Nb 0.2 ) 2 O 7 , a double-layer structural coating composed of La 2 (Zr 0.2 Ti 0.2 Y 0.2 YB 0.2 Nb 0.2 ) 2 O 7 and yttria-stabilized zirconia (YSZ) layers was designed and produced on a NiCoCrAlY alloy by laser cladding. The thermal cycling behavior of the double-layer coating was studied at 1050 °C. The results indicate that a La 2 (Zr 0.2 Ti 0.2 Yb 0.2 Y 0.2 Nb 0.2 ) 2 O 7 single-phase defective-fluorite high entropy oxide was produced after preparation and thermal cycling. The spallation of the double-layer coating composed of La 2 (Zr 0.2 Ti 0.2 Yb 0.2 Y 0.2 Nb 0.2 ) 2 O 7 /YSZ occurred after 70 thermal cycles at 1050 °C. The double-layer coating composed of La 2 (Zr 0.2 Ti 0.2 Yb 0.2 Y 0.2 Nb 0.2 ) 2 O 7 /YSZ can increase the thermal cycling lifetime of TBCs containing high entropy oxides.

Thermal barrier coating (TBC) is applied to protect the hot-section components of a gas turbine engine. In the present work, a La2(Zr0.2Ti0.2Y0.2YB0.2Nb0.2)2O7 high entropy oxide was designed, fabricated by a solid-phase reaction at 1400 °C, and subjected to an investigation of its properties. The results indicate that the La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7 high entropy oxide had a pyrochlore structure. During synthesis, a small amount of La2TiO5 was produced. The thermal conductivity of the La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7 high entropy oxide was approximately 0.8855 W·m-1·K-1 at room temperature. The coefficient of thermal expansion of the La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7 high entropy oxide was approximately 9.374 × 10−6 K−1 at 1000 °C. To improve the service life of the TBC composed of the La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7, a double-layer structural coating composed of La2(Zr0.2Ti0.2Y0.2YB0.2Nb0.2)2O7 and yttria-stabilized zirconia (YSZ) layers was designed and produced on a NiCoCrAlY alloy by laser cladding. The thermal cycling behavior of the double-layer coating was studied at 1050 °C. The results indicate that a La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7 single-phase defective-fluorite high entropy oxide was produced after preparation and thermal cycling. The spallation of the double-layer coating composed of La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7/YSZ occurred after 70 thermal cycles at 1050 °C. The double-layer coating composed of La2(Zr0.2Ti0.2Yb0.2Y0.2Nb0.2)2O7/YSZ can increase the thermal cycling lifetime of TBCs containing high entropy oxides.

A pyrochlore-structured La-2(Zr0.2Ce0.2Hf0.2Sn0.2Ti0.2)(2)O-7 high-entropy oxide was designed and synthesized, and its properties were tested. Traditional two-layer structured thermal barrier coatings (TBCs) with a La-2(Z-r(0.2)Ce(0.2)Hf(0.2)Sn(0.2)Ti(0.2))(2)O-7 top-coat were prepared by plasma spraying. A phase-pure defective-fluorite high entropy-oxide top coat was thus obtained. The results confirmed the possibility of synthesizing pyrochlorestructured La-2(Zr0.2Ce0.2Hf0.2Sn0.2Ti0.2)(2)O-7. The material exhibited a low thermal conductivity, which increased with increasing temperature. The coefficient of thermal expansion (CTE) of La-2(Z-r(0.2)Ce(0.2)Sn(0.2)Hf(0.2)Ti(0.2))(2)O-7 ranged from 7.55 x 10(-6) degrees C- 1 to 8.63 x 10(-6) degrees C-1 for the corresponding range of room temperature to 1000 degrees C. After 10 thermal cycles at 1050 degrees C, the La-2(Zr0.2Ce0.2Hf0.2Sn0.2Ti0.2)(2)O-7 top coat spalled in the TBC. Spallation did not occur at the interface between the bond coat and the thermally grown oxide layer, while it is in the top coat near the bond coat. Owing to the low fracture toughness and low CTE, the thermal cycling lifetime of TBCs with the La-2(Zr0.2Ce0.2Hf0.2Sn0.2Ti0.2)(2)O-7 top coat was short.

Our understanding of structure-function relationships in biological systems demands new and more sophisticated methods for examining molecular structure. This thesis presents an effort of methodolo ...