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With the rapid development of horizontal drilling technology, the drilling fluid shale shaker (DFSS) features high capacity and high efficiency. Hence, a vibrating mechanism of a three co-rotating rotor system coupled with springs is proposed for designing large-sized and heavy-duty vibrating screens in petroleum drilling engineering. To master synchronization of the vibrating system, the dynamic equations of three corotating rotors coupled with springs are first developed based on Lagrange’s equations. Second, synchronous conditions of the system are derived based on the average method, and its stability criterion is obtained by adopting Hamilton’s principle. Furthermore, the influences of various factors, including positional parameters of three motors, stiffness coefficient of the springs and frequency ratio on synchronization behaviour, are numerically analysed in the steady state. Additionally, the Runge–Kutta algorithm with adaptive control is employed to build an electromagnetic coupling model, and the relationships between the synchronization state of the system and its mechanical-electrical coupling characteristics are investigated. Finally, an experimental prototype is designed to validate the theory and numerical analysis. The research result shows that the in-phase synchronization of three co-rotating rotors coupled with springs is easy to implement with the selection of a sufficiently large stiffness.

The scale of structure element is especially important to obtain good filtering results in multiscale morphological filtering (MMF) method. In general, the optimal scale of structure element is set to be a fixed value in traditional morphological filter, therefore it is difficult to extract the fault feature from rolling bearing vibration signal effectively. A novel multiscale morphological filtering algorithm is proposed based on information-entropy threshold (IET-MMF) for early fault detection of rolling bearing. Compared with traditional MMF method, several optimal scales of structure elements are achieved according to the energy distribution characteristic of different vibration signals. The information entropy theory is applied to quantify the analyzed signals, and the optimal threshold of information entropy is obtained by iterative algorithm to ensure integrity of useful information. The simulation and rolling bearing experimental analysis results show that the IET-MMF method can extract fault features of vibration signals effectively.

As a crucial part of Ultra High Voltage Direct Current (UHVDC) transmission line, the security of the valve hall is stressed much importance. Therefore, it is vital to figure the insulator and shielding apparatus properly and further to obtain the applicable grading ring design, or corona discharge is possibly to take place, thus to risk the safety of the whole substation. In this paper, the model of a new-style suspension insulator in front of the valve tower with triple ones in cone conformation was established using finite-element method (FEM) software ANSYS. The surface field distribution was calculated and was compared to the critical field. In addition, several types of optimization schemes for grading ring were put forward to reduce the maximum field. The results indicated that the triple grading ring design could help reduce the maximum field.

A dual-source powered mixed effect AC (absorption chiller) is applied in a CCHP (combined cooling heating and power) system. This CCHP system integrates both fossil fuel energy and solar energy together. Refrigeration performance of this mixed effect AC under both waste heat mode and solar mode are tested and compared. In waste heat mode, the AC is simultaneously powered by exhaust gas waste heat and hot water waste heat from an ICE (internal combustion engine). And five working conditions under different electric output of ICE are tested to study the refrigeration performance. In solar mode, the AC is powered by hot water from a solar thermal collector matrix, and its refrigeration performance is tested in a selected day to study the operation characteristics. Test results show that, the mixed effect AC can reach a COP (coefficient of performance) of 0.91 in waste heat mode. But its COP is only about 0.6 in solar mode for there is only hot water heating source. Comparison results show that, waste heat mode is not necessarily better than solar mode and vice versa. In terms of primary energy consumption, waste heat mode is worse than solar mode when the part load ratio of ICE is below 0.62.

CCHP (combined cooling heating and power) system based on ICE (internal combustion engine) has been widely used. A key issue is to efficiently recover the jacket water and exhaust gas waste heat for refrigeration. In this work, a mixed effect absorption chiller (AC), which couples single effect and double effect processes together, is investigated to recover these two kinds of waste heat simultaneously. The high pressure generator is powered by exhaust gas while one low pressure generator is powered by jacket water waste heat. Thermodynamic characteristics and off-design performance are simulated. Considering thermodynamic constraints, the start point temperature in low pressure generator should be 77°Cor lower. For a 16 kW ICE, the cooling output can reach 34.4 kW with COP of 0.96 and exergy efficiency of 0.186. Comparing with double effect or single effect AC, it can make a better use of different waste heat in CCHP system.

Tri-generation system is efficient in supplying thermal energy and electricity. But it is very difficult to satisfy multiple load demands simultaneously in real applications. Therefore, the benefit of tri-generation system is not so easy to realize. If the electric load is separated from the thermal load, difficulty of control would be avoided. In this work, combined cooling and heating (CCH) mode of tri-generation system is proposed. The generated electricity is only used to power the HVAC device, which converts all the electricity into thermal energy. Namely, there is only thermal output in this kind of mode. As for the rest electric load of user, it can be ensured by the public grid. Considering 20% of total energy consumption and 50% of building energy consumption may come from the HVAC system in developed countries. The CCH mode of tri-generation system would be potential in energy saving. The influences of system capacity, HVAC performance, public grid efficiency, and energy prices on system performances are analyzed. Results show that the CCH mode of tri-generation system can be much better than an independent HVAC system. For a system with generator capacity over 100 kW, the payback period could be less than 4 years.

A micro-CCHP (micro combined cooling, heating and power) system is proposed and investigated. It mainly consists of an internal combustion engine (ICE), an adsorption chiller (AD), a thermal management controller (TMC) and some other devices. The waste heat of ICE is collected and managed by the TMC. So the waste heat can be automatically assigned to different water cycles for heating, cooling, or to be released. Considering the complexity of micro-CCHP system, both experiment and simulation are conducted. Firstly, the experimental system and methodologies are described in detail. Then, simulation models of ICE and AD are proposed in order to simulate the system performance. Based on results of experiment and simulation, system characteristics for heating and cooling are investigated. Some influence factors are taken into account, such as the part load ratio of ICE, buffer tank set point temperature, hot water tank set point temperature, chilled water temperature and cooling water temperature of AD. Results show that the system can realize 17.7 kW heating output, 6.5 kW cooling output and 16 kW electric output simultaneously. The experimental primary energy ratio reaches 0.765 in heating mode and 0.56 in cooling mode.

As the practical load conditions vary with time, the performance of micro combined cooling heating and power (micro-CCHP) system depends a lot on the operation strategy. So, it is significant to study the system performance and find the optimal operation strategies for various load conditions. There are many devices can be considered in micro-CCHP system. In this study, a comprehensive micro-CCHP system is built, basing on gas engine and adsorption chiller. Auxiliary devices, such as gas boiler, heat pump and electric chiller, are also considered in the study of operational optimization. In order to find the optimal operation strategies and discuss why they are the optimal ones, a mixed-integer non-linear programming model is developed. Energy saving ratio and cost saving ratio are chosen as the objectives and they are calculated hierarchically. Operation strategies under various load conditions are analyzed in detail and two dimensional distributions of system performance are presented. Results show that, optimal operation strategy changes with load conditions for energy saving optimization while it also changes with energy prices for cost saving optimization. For energy saving optimization, micro-CCHP system is always superior to conventional separated system when the heating load is over 12 kW in CHP (combined heating and power) mode or over 21 kW in CCHP mode. For cost saving optimization, micro-CCHP system can be superior to conventional separated system when the dimensionless energy price ratio is less than 0.45.

Converter valve possesses the function of AC-DC voltage conversion and power transmission. It is an important device in the valve hall of UHVDC converter station. Since the corona discharge has a serious impact on the safe and stable operation of converter valve, it is necessary to analyze its surface electric field (E-field) distribution. In this paper, the structure characteristics of three typical double valve designs have been analyzed, which were respectively used in three high voltage (400-800kV) valve halls of one ±800kV UHVDC transmission project in China. Based on the project drawings, the equivalent model of each type of double valve with shielding structure was built with three-dimensional (3D) finite-element method (FEM) software ANSYS. Considering the interaction of double valves in actual valve hall, three double valve FEM models of same type in one hall, which formed the upper 6-pulse bridge in the 12-pulse converter unit, were built for the analysis of E-field distribution. Due to the hybrid AC-DC operating voltage, the transient E-field analysis with discrete loading voltage waveforms was adopted in these models. After calculation, the E-field distribution characteristic of different double valve types were summarized and compared under the normal operating condition. The results showed that the surface E-field strength on the shielding structure of all the double valves was lower than the critical value of corona inception and could meet the project requirements. This research could provide valuable references for shielding structure design and optimization of converter valve in the UHVDC transmission project.