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The coal reserves overlain by buildings, water bodies and railways are estimated to be about 14 billion tons in China. Based on the concept of green mining, in order to save the unit energy, Double pumps in parallel forms of pumping are adopted in 0the paste filling of the pumping system. The optimal solution of the objective function could be obtained by taking the unit flow power of the pumping system as the objective function, using the quadratic polynomial by the least square method curve fitting and by the application of MATLAB. Thereby it is possible to reduce power consumption and increase the efficiency of the operating economy in the paste filling station.

This paper analyzes the characteristics of paste filling material and the parallel output of double pump. By combining the equipment layout of the paste filling station, using the uncertainty fluid topology optimization method based on SIMP to optimize parallel connection structure, we designed the engineering model optimized connection. The optimized connection improves the capacity of the paste filling pump, reduces the filling energy consumption and the load pressure of the pump, and can achieve good economic and social benefits.

This paper aims to optimize the weighing control system and compensate weighing error for weighing control system of coal mine paste-filling weighing control system.

The process of the paste-filling weighing control system is analyzed and the mathematical model of the paste-filling material weight is established. Then, the back-propagation (BP) neural network is used to optimize the control system and compensate the weighing error.

Without the BP neural network, the weighing error of the paste-filling control system is more than 3 per cent, whereas after optimization with the BP neural network, the weighing error is less than 1 per cent. With the simulation results, it is seen that the weighing error of the paste-filling control system decreases and the accuracy of the weighing control system improves and optimizes.

The method can be further used to improve the control precision of the coal mine paste-filling system.

Flow measurement plays an important role in modern industrial production. Flow measurement methods based on optical fiber systems have become a main research focus.

Applying flow measurement theory and the structural characteristics of optical fiber, flow measurement of paste can be achieved through a combined laser Doppler and optical fiber sensing system based on the principle of optical fiber grating sensors and flow sensors. The system is developed to include light selection, photoelectric detection, a voltage amplifier circuit and a signal filtering circuit.

The system is shown, through a comparative experiment, to be of higher accuracy than the traditional ultrasonic method.

A new method for measuring the paste flow is presented, which is based on the principle of optical fiber Doppler. The method has the advantages of convenient installation, high accuracy and low cost. Experiments show that the method is feasible.

A range of small self‐contained hydraulic machine test sets are now available which permit small groups of students to obtain the usual performance characteristics of pumps and turbines with some ease‐though at the expense of efficiency due to scale effects. As most lecture courses include the application of pumps to systems as well as the basic considerations affecting pump performance, it was felt that a layout that allowed the student to combine two pumps in series and then in parallel would introduce him to the hydraulic considerations involved as well as give a more flexible piece of equipment that would permit these tests and a performance test to be conducted (for the basic performance curves would have to be produced first). The apparatus evolved is described, and skeleton laboratory instructions are attached as an appendix. When two similar pumps are connected in series, the fluid passes through each in turn, and the total head produced is approximately double that of one pump as illustrated in figure 1. When two similar pumps are connected in parallel, the total head produced is that of one pump, but the flow is approximately doubled, as shown in figure 2. Figure 3 is a diagrammatic layout of the hydraulic system. The apparatus consists basically of two similar pumps A and B which can be run as single units, connected and operated in series, or connected and run in parallel as will be seen from figure 3, the valves 2 and 4 are closed when series operation is desired, and flow controlled by valve 6; when operation in parallel is required valve 3 is closed, all others being open. A single sump tank is provided, flow measurement is achieved by simple volumetric means and pressure is measured by bourdon‐type gauges, a, b, c and d. The pumps are supplied by Stuart Turner with a duty of 50 feet at approximately 1300 gpm at 2900 rpm, they may operate at 1450 rpm or 2900 rpm, are provided with swinging stators for torque measurement and with a revolution counter for average speed determination. As will be seen from the appendix, the sequence of tests to be performed requires the student to obtain the basic performance characteristics of each pump at the two rotational speeds possible, and to compare them using the Similarity laws; then to test the pumps connected in series and parallel and to compare the performance obtained with that predicted. Figures 4 and 6 give some typical curves and show that the actual performances in series and parallel do not quite fulfil those predicted ignoring losses‐the student is required to consider the contributory factors in his discussion. The writer is grateful to Plint and Partners Limited for their co‐operation.

This paper aims to study a modular method for designing a paste filling station (PFS) for a coal mine (CM) to reduce the PFS’s input cost and achieve reutilization.

Modular design criteria for the PFS are proposed and a modular division (MDiv) model and an evaluation method are established. The correlation-strength matrix of the PFS parts expressed in the form of rough numbers is transformed into a fuzzy equivalent matrix. The theory of rough sets and the fuzzy clustering method are introduced for PFS MDiv. The evaluating method is established for the PFS MDiv scheme based on the principle of fuzzy comprehensive evaluation.

Taking a particular CM PFS as an example, the above method is used to modularize the PFS, and the optimal division of the PFS is finally determined via the above evaluation system. Applying this method solves the problem of high cost investment in the initial stage of PFS construction.

The theory of rough sets and the fuzzy clustering method are introduced for PFS MDiv. An evaluating method is established for the PFS MDiv scheme based on the principle of fuzzy comprehensive evaluation, thereby providing new ideas for PFS transformation and reutilization.

This study aims to solve the premature failure of the rubber stator due to wear, reduce the frictional resistance moment of the screw pump to solve the problem of a model of Daqing oilfield screw pump oil recovery system shutdown after the difficult start.

For the first time, the rotor surface of a screw pump was treated with dot-matrix texture to study the effect of dot matrix texture on the tribological performance of the stator-rotor friction subsets of screw pump. Reciprocating friction tests with different texture morphologies (S-shape, double tongue) and angular parameters (0°, 45° and 90°) were conducted at 10% of the texture area and pump silicone grease.

When point texture was added to the surface of the rotor sample, the friction coefficient and wear quantity of the sample were lower than those of the surface without texture treatment, and the double tongue 0° combination showed the best tribological properties. At this time, the average coefficient of friction and wear is reduced by 22.8% and 62%, 28.6% and 64.8%.

The introduction of texture can effectively improve the tribological performance of progressive screw pumps, and this paper provides important theoretical and experimental support for the design of progressive screw pumps in practical applications.

Currently heating and cooling in buildings is responsible for over 30% of the primary energy consumption in the United Kingdom with a similar amount in China. We analyze heat pumps and district thermal energy network for efficient buildings. Their advantages are examined (i.e., flexibility in choosing heat sources, reduction of fuel consumption and increased environmental quality, enhanced community energy management, reduced costs for end users) together with their drawbacks, when they are intended as means for efficient building heating and cooling.

A literature review observed a range of operating conditions and challenges associated with the efficient operation of district heating and cooling networks, comparing primarily the UK’s and China’s experiences, but also acknowledging the areas of expertise of European, the United States, and Japan. It was noted that the efficiency of cooling networks is still in its infancy but heating networks could benefit from lower distribution temperatures to reduce thermal losses. Such temperatures are suitable for space heating methods provided by, for example, underfloor heating, enhanced area hydronic radiators, or fan-assisted hydronic radiators. However, to use existing higher temperature hydronic radiator systems (typically at a temperatures of >70°C) a modified heat pump was proposed, tested, and evaluated in an administrative building. The results appears to be very successful.

District heating is a proven energy-efficient mechanism for delivering space heating. They can also be adaptable for space cooling applications with either parallel heating and cooling circuits or in regions of well-defined seasons, on flow and return circuit with a defined change-over period from heating to cooling. Renewable energy sources can provide either heating or cooling through, for example, biomass boilers, photovoltaics, solar thermal, etc. However, for lower loss district heating systems, lower distribution temperatures are required. Advanced heat pumps can efficiently bridge the gap between lower temperature distribution systems and buildings with higher temperature hydronic heating systems

This chapter presents a case for district heating (and cooling). It demonstrates the benefits of reduced temperatures in district heating networks to reduce losses but also illustrates the need for temperature upgrading where building heating systems require higher temperatures. Thus, a novel heat pump was developed and successfully tested.

This paper aims to present a numerical study on the natural convection, which operates either as an evaporator or condenser unit of the heat pump system to pre-cool and pre-heat the ambient fresh air.

This study focuses on natural air cooling or heating within the air channel considering the double skin configuration. Particular focus is given to the analysis of airflow and the heat transfer processes in an air channel to cool or heat the ambient fresh air. In this study, the physical model consists of one wall, either heated uniformly or cooled uniformly, whereas the other wall is adiabatic.

The results show that the variation of both velocity and temperature is observed as the flow transition occurs at the evaporator or condenser wall. In either case, the temperature rises in the range of 6.3–8.4°C with an increase in mass flow rate from 0.07–0.08 kg/s in the photovoltaic thermal condenser part, while in the photovoltaic thermal evaporator part, the change in mass flow rate from 0.048–0.061 kg/s causes a decrease in temperature from 7.1–4.5°C.

The solar-assisted photovoltaic thermal heat pump system, in building façade having an air layer application, is feasible for pre-heating and pre-cooling the ambient fresh air and also reduces the energy needed to treat the fresh air.

The influence of condensing and evaporating temperature under natural convection mode in double skin conformation is considered for pre-heating and pre-cooling of ambient fresh air.

This paper aims to provide a comprehensive literature review on modelling electro-osmotic flow in porous media.

Modelling electro-osmosis in fluid systems without solid particles has been first introduced. Then, after a brief description of the existing approaches for porous media modelling, electro-osmotic flow in porous media has been considered by analysing the main contributions to the development of this topic.

The analysis of literature has highlighted the absence of a universal model to analyse electro-osmosis in porous media, whereas many different methods and assumptions are used.

For the first time, the existing approaches for modelling electro-osmotic flow in porous have been collected and analysed to provide detailed indications for future works concerning this topic.