Pump Model Research Articles

Assessment of the regional heating system combined with geothermal source, air source and energy storage

Regional integrated heating using renewable energy is an efficient way to achieve the target of carbon emission reduction. Based on geothermal sources, air source heat pumps, and inter-seasonal energy storage technologies, a multi-source integrated regional heating system is proposed, which can meet the requirement of heating in buildings. With a residential community with an area of 35700 m2 as the study case, the models of geothermal source heat pump and air source heat pumps are constructed. Next, the energy performance and environmental performance of the integrated district heating system are analyzed. The study manifests that the multi-source central heating system reduces the energy consumption by 45.73% in comparison with the tranditional boiler solution, and the CO2 emission is reduced by 787.83 tCO2. The multi-source heat pump system can achieve social benefits, with the help of reasonable dispatching between the source and load sides, and the contribution of renewable energy. The long-term stable operation of the energy system can be achieved. The study provides a theoretical reference for the application of the conventional energy systems combined with geothermal energy.

Simple Learning-Based Robust Nonlinear Control of an Electric Pump for Liquid-Propellant Rocket Engines

This paper presents a robust nonlinear control strategy for an electric pump for liquid-propellant rocket engines. In order to compensate for model uncertainties and disturbances, a gradient-descent-based simple learning control strategy is employed that minimizes the cost function defined on the error dynamics of the nonlinear system. Detailed stability analysis for the nonlinear system is provided. Computer simulation results are included to demonstrate the effectiveness of the nonlinear control method using an electric pump model consisting of a brushless permanent-magnet direct current (DC) motor and a centrifugal pump. In particular, it is shown that by employing the developed nonlinear controller, the mass flow rate can be successfully kept at a certain level, can be changed instantly from one level to another (immediate decrease or increase), or can be changed linearly/nonlinearly, gradually, and continually for a certain period.

Study the Effect of Operating Temperature on Performance in Dry Scroll Vacuum Pump

The dry scroll vacuum pump is a kind of variable capacity dry vacuum pump that is applied in chemical, pharmaceutical, semiconductor, and scientific instruments. Analyzing the thermodynamic characteristics of the scroll vacuum pump and studying the impact of operating temperature on its consistent performance are necessary for the design and application of the cooling system of the scroll vacuum pump. Based on the dynamics mesh method, the computational fluid dynamics (CFD) simulation model of a multi-stage dry scroll vacuum pump is established in this study. Under the suction pressure of 1000 Pa, the simulation calculation is carried out at different operating temperatures of fixed scrolls (25 °C, 45 °C, and 65 °C). The results show that the pumping speed, the gas compression power, and the energy efficiency ratio are significantly affected by different temperatures. The operating temperature of the pump has been reduced from 65 °C to 25 °C, the pumping speed is increased by approximately 5.97%, the gas compression power is increased by approximately 4.32%, and the energy efficiency ratio is increased by approximately 1.745%. This research provides a transient simulation method using dynamic mesh technology for the study of the dry scroll vacuum pump, and the results can provide a theoretical basis for the design and application of the cooling system of the dry scroll vacuum pump.

Thermodynamic modeling of a residential heat pump for combined space and water heating using binary CO2-based mixtures

The residential sector answers for a considerable share of the energy consumption worldwide. An alternative to meet technical and environmental requirements of space heating and hot water demanded by this sector uses CO2 mixtures as a refrigerant in compression-based cycles. However, while CO2 is nonflammable and has low GWP and ODP, it performs poorly due to its low specific refrigerating effect and large throttling losses. Differently, mixtures with a low-GWP refrigerant and CO2 could enhance the performance of these cycles while attending the environmental requirements. Therefore, this study considered the use of a combined heat pump for space and water heating using binary mixtures of CO2 and several refrigerants. Through a computational model, three configurations were tested, along with different ratios of space heating to hot water demands, and different CO2 mass fractions on the mixture. The heat pump configuration with the best performance range was the one with three gas coolers, where the low temperature gas cooler preheats the water, the intermediate equipment heats the space, and the high temperature gas cooler heats the already preheated water to the operating temperature. For this arrangement, heat pumps primarily dedicated to space heating benefit from mixtures with low mass fractions of CO2, approximately 10%. In contrast, heat pumps primarily attending water heating perform better for high mass fractions of CO2 (∼ 90%). Furthermore, in this combined configuration, about 87% of the mixtures analyzed could have higher coefficient of performance than pure fluids, indicating an improvement of CO2 heat pumps.

Effects of unstable flow structures on energy transfer mechanism in a centrifugal pump

To reveal the energy loss mechanism of the centrifugal pump, numerical simulation and experimental investigation are conducted to obtain the complex flow field of a single-stage centrifugal pump under various flow conditions. Particular emphasis is focused on the qualitative and quantitative analysis of the distribution and variation characteristics of irreversible loss in the pump model. The results show that the energy loss in the centrifugal pump mainly originates from the entropy generation caused by the turbulent dissipation and wall friction, which are typically generated in the volute and impeller domains. It is worth noticing that the energy loss in the volute is closely associated with non-uniform velocity distribution and the evolution of the shedding vortices from the impeller exit whilst the energy loss in the impeller are greatly affected by unstable flow phenomena such as flow separation, backflow, and jet-wake pattern. At the overload operating conditions, the wall entropy generation possesses a substantial influence on energy loss, which is mainly related to the wall shear stress. Meanwhile, the influence of the rotor-stator interaction and inflow impacting on the energy loss is enhanced with increasing flows. Finally, the omega method captured the vorticity structures near the tongue at partial flow conditions, thereby, revealing the relationship between the high magnitude of flow loss and the evolution of different scales of strong vorticity sheets.

Ecological function performance analysis and multi-objective optimization for an endoreversible four-reservoir chemical pump

Ecological function (E1) based on energy analysis is introduced into endoreversible four-reservoir chemical pump model. Optimization relationship between E1 and coefficient of performance (χ) is obtained. Effects of energy distribution ratio (a) of working fluid, chemical potential ratios (μH/μM and μO/μL) of material reservoirs and mass transfer coefficient ratios (b1, b2 and b3) on the optimal E1 performance are analyzed. Using NSGA-Ⅱ, taking intermediate parameter k (k=1−μ1/μH, where μ1 is chemical potentials of working fluid corresponding to reservoir μH) as optimization variable, and taking χ, dimensionless rate of energy pumping (Σ*), dimensionless E1 (E1*) and dimensionless entropy generation rate (σ*) as objective functions, multi-objective optimization (MOO) is performed, and Pareto frontiers under different optimization schemes are obtained. Deviation indices (D s) are introduced to compare the results of different MOO combinations with three decision-making methods. Trend of E1*−χ is parabolic-like one, there is an optimal χ (χE1*) to maximize E1* (E1max*); When a and μH/μM increase or μO/μL decreases, χE1* increases and E1max* decreases; When b1, b2 and b3 increase, E1max* decreases; When two-objective (σ* and E1*) optimization is carried out, the smallest D (0.3214) is obtained by TOPSIS. MOO can better balance the contradictory relationship of cycle performance parameters and improve the comprehensive performance of chemical pump.

Design and Implementation of a Three-Dimensional CAD Graphics Support Platform for Pumps Based on Open CASCADE

In the pump industry, designers commonly utilize mainstream three-dimensional computer-aided design (CAD) software (Unigraphics NX 12.0 and SolidWorks 2023). However, these CAD packages are generic and not optimized for the specific requirements of the pump industry. This leads to a lack of flexibility and increased complexity in their usage, as well as higher computational demands, resulting in elevated learning and operational costs. Additionally, there are concerns about potential information leaks and software restrictions. In this paper, we studied the organization architecture of commercial three-dimensional CAD software, and compared and analyzed the geometric kernels and rendering engines of mainstream three-dimensional software. Using the Open CASCADE geometric kernel and OpenSceneGraph rendering engine, together with the Visual Studio 2021 development environment and Qt interface library, we developed an autonomous copyright three-dimensional CAD graphics support platform for pumps. Based on the three-dimensional platform, we tested the commonly used graphics elements and basic algorithms required for pump modeling, and successfully designed and modeled the impeller and volute casing of a centrifugal pump. Through computational simulations and experimental verifications, we demonstrated that the accuracy and precision of the pump model designed on this platform meets the design requirements, indicating that this platform has practical pump design and modeling capabilities. Compared to commercial three-dimensional CAD software, this platform exhibits superior flexibility and interactivity in three-dimensional modeling that is specifically tailored for pump products. Consequently, it fully satisfies the needs for three-dimensional parameterized modeling and visualization of pumps.

Calculation of transportation resistance of different soils in Dredging Engineering

Pipeline transportation is a process of continuous balance between pumping pressure and pipeline resistance. Therefore, accurate calculation of pipeline transportation resistance can optimize the accuracy of the pump model and working parameters. The slurry transported in the dredging project is complicated, and the dredged soil in different regions is quite different resulting in different motion states in the transportation process. Different types of flow patterns are suitable for different resistance calculation models. In this paper, according to the actual dredger filling project, the real transmission resistance of the project is obtained by means of pipeline pressure monitoring data analysis. Three different transmission resistance calculation formulas of Wang Shaozhou formula, Durand formula and DHLLDV model are used to compare the clay, fine sand and medium coarse sand. The calculation results show that the Durand formula is the best for calculating the transmission resistance of medium coarse sand; the DHLLDV model is better for calculating the transport resistance of fine silt; the error between the DHLLDV model of clay transport resistance and Wang Shaozhou formula is small. In this paper, the calculation error analysis of three different kinds of soil is carried out, and the best calculation formula for three types of soil is obtained. The accurate calculation method of theoretical formula in dredging and filling projects is obtained, and the reference table of three kinds of soil for transportation resistance is proposed, which provides a reference for dredging project transportation.

Effects of Volute Structure on Energy Performance and Rotor Operational Stability of Molten Salt Pumps

A double-volute molten salt pump with two outlet pipes is proposed based on the original pump model. A numerical approach coupling finite element analysis and computational fluid dynamics (CFD) is implemented to investigate the operational stability and energy performance of two molten salt centrifugal pumps for high-temperature molten salt. The entropy production of the single-volute and double-volute molten salt pumps is investigated. The effects of the volute structures on the mechanical behavior of the impeller and shaft are considered. According to the findings, the local entropy production in the molten salt pump is dominated by the local pulsating entropy production (Spro-T), with the double-volute scheme achieving reduced energy loss. A visualization of the flow field and the local entropy production rate (LEPR) distributions indicate that the LEPR is positively correlated with the complexity of the flow, and higher levels of turbulence intensity lead to greater LEPR. The double-volute scheme enhances the complexity of the flow in the impeller, resulting in an increase in the LEPR compared with the single-volute design. However, the LEPR in the whole double-volute molten salt pump is reduced compared with the single-volute design. It is discovered that the double-volute molten salt pump experiences a less radial hydraulic force. Although the double-volute design has a slightly higher maximum equivalent stress on the impeller than the single-volute scheme, the rotor deformation is significantly less. In general, the double-volute scheme reduces energy loss and ensures better structural stability.

Design and fluid analysis of the microsegment gear tooth profile for pump operating at high speed and high pressure

In order to solve the problem of oil trapping in involute gear pumps, a new tooth profile based on the microsegment tooth profile and incorporating the circular arc tooth profile theory has been designed in this study. Firstly, the tooth profile equation of the microsegment gear profile for the pump has been derived. Then, the spatial tooth surface equation of the helical microsegment gear for the pump has been derived, and the feasibility of the new tooth profile has been verified using the contact spot experiment. The characteristics of the new gear profile without oil trapping and the closed “8” type mesh line have been analyzed, from which the output flow rate of the microsegment gear pump has been verified to be constant. A conclusion has been drawn on the applicability of the microsegment gear tooth profile for the pumps. Further, the fluid analysis model of the microsegment gear pump has been proposed to analyze the oil pressure distribution and state of fluid motion at high pressures in the microsegment gear pump. A comparison of the performances of the involute and the microsegment gear pumps shows that the output pressure and maximum pressures of the microsegment gear pump are smoother than that of the involute gear pump. Analysis of the effect of the high rotational speed on the output oil pressure and the maximum pressure shows that the former increases, whereas the latter varies very little with the rotational speed.

Multi-Objective Parameter Optimization of Submersible Well Pumps Based on RBF Neural Network and Particle Swarm Optimization

In order to improve the hydraulic performance of a submersible well pump, steady and transient simulations were carried out based on ANSYS CFX software. The head and efficiency of the submersible well pump under standard operating conditions were taken as the optimization objectives, and the impeller outlet placement angle, outlet width, and vane wrap angle were selected as the optimization variables using the Plackett-Burman experimental design method. The RBF neural network training samples were constructed using the uniform experimental design method to build a hydraulic performance prediction model for the submersible well pump, and a multi-objective particle swarm optimization was used to solve the model and obtain the Pareto optimal solution set. Using the head and efficiency of the initial model as the boundary, the Pareto optimal solution and the corresponding structural parameters are sought. After the optimization, the head of the individual with the better head is increased by about 2.65 m, and the efficiency of the individual with the better efficiency is increased by about 2.3 percentage points compared with that of the initial model. The pressure gradient in the impeller flow channel is more obvious, the work capacity is significantly improved, the vortex area of the spatial guide vane is smaller, the flow line is more regular, and the pressure pulsation amplitude at the inlet and outlet of the impeller and the spatial guide vane is significantly reduced.

Digital Control Method and Performance Analysis of the Double-Compound Axial Piston Pump.

The flow control range of the double-compound axial piston pump with the traditional mechanical-hydraulic feedback servo control is limited and the accuracy is poor. Accordingly, this paper proposes a digital control scheme and its control strategy using a linear stepper motor direct drive servo valve for the precise control and double pumps cooperation of the double-compound axial piston pump. A numerical model of the digital control double-compound axial piston pump is established, and the validity of the model is verified by experimental tests. The performance advantages of the digital control method relative to the mechanical-hydraulic feedback servo control method are analyzed, as is the performance of the control strategy for double pumps. The results show that the digital control method can achieve a wider range of flow control than the traditional mechanical-hydraulic feedback servo control method and avoid the torque impact on the prime mover caused by the active control. The combination of the flow control and the power control including four control modes can meet the performance requirements of the double-compound axial piston pump. The highest priority is given to the energy-saving control, which can reduce the displacement of the main pump in the nonworking state to reduce the additional power loss. The study provides a basis for the accurate matching and optimization of power to load and flow to operating speed of the double-compound axial piston pump.

Transient modeling of a chemisorption heat pump using ammonia with expanded graphite – NaBr

Numerical and experimental studies of a chemisorption heat pump driven by a low-temperature heat source were conducted. A transient model of a heat exchanger and reactor was developed. Equations of mass, momentum, energy and chemical reaction were considered and modeled. One of the important parameters related to the chemical reaction is the non-equilibrium curve of the working fluid and adsorbent pair. An experiment was conducted to obtain the non-equilibrium curve for NH3 and expanded graphite – NaBr under a low-temperature condition. The correlation for the non-equilibrium curve was suggested and applied to the transient model. A transient analysis of the reactor was then carried out. By comparing the simulation results to the experimental results, it was confirmed that the model of the reactor is valid. An experiment and simulation of the entire system were conducted. The transient features of the chemisorption heat pump when operated three times in an alternating manner were analyzed based on the simulation and experimental results. The simulation and experimental results showed similar values and tendencies of the temperature and pressure. Hence, the simulation model for the entire system was validated. Based on the proposed model, performance analysis according to the reactor fin tube design conditions was performed. Depending on the fin tube design, the average cooling capacity differed 2.13 times from 70.2 to 149.2 W. Depending on the fin tube design, the COP differed 2.2 times from 0.15 to 0.33. Based on the results of this study, the design condition of fin tube to achieve the optimal cooling capacity or COP was confirmed.

Strategies employed in the design and optimization of pump as turbine runner

The low hydraulic efficiency of the pump as turbine (PAT) poses a major challenge to the runner design. This paper introduces a new strategy for designing and optimizing the performance of PAT runner. The strategy process is mainly divided into four steps, namely blade parametric design, significance evaluation of parameters, construction of optimizing surrogate model and optimization of improved PSO algorithm. Compared with the current design methodologies, not only does this optimization strategy propose the system design and optimization process, but also it breaks down the process into well-defined steps and simplifies them. The hydraulic efficiency of PAT optimized by this optimization strategy reaches 84.76%, which improves 3.93%. A test bench has been built to test the optimizing strategy. The maximum difference of experimental data is 1.5%, which meets the requirements of practical engineering application, and verifies the reliability of the optimization strategy process. The optimizing strategy process can be extended to apply to pump, fan, conventional turbine and other blade fluid models, and it can be further extended to apply to the optimization design of 3D blades with a high specific speed.

Improved order of magnitude estimate of rotational effects on HAWTs

This work proposes an improved order of magnitude estimate methodology of rotational effects on wind turbines, by applying the partial pressure field concept to the case of rotating wind turbine blades, which allows isolating acceleration that rises as a result of the rotation of the blades; then an order of magnitude scaling is performed to estimate the partial pressure due to rotation for both fully attached flow and massively separated flow. In the case of fully attached flow, it was found that rotational effects are negligible; while in the case of massively separated flow, rotational effects were found to be important. The pressure reduction was found to scale linearly with the aspect ratio inside the separated boundary layer, while it scales quadratically with the aspect ratio in the outer inviscid flow. A new estimate of the Rossby number is proposed, which is found to be the inverse of the pressure reduction coefficient estimate in the outer inviscid flow. Then, a semi-empirical model of the pressure reduction is proposed based on the order of magnitude estimate in the outer inviscid flow. The proposed semi-empirical model is then compared against the reference data of three wind turbines, namely, MEXICO, NREL phase VI, and AVATAR 10 MW rotors; along with the already known centrifugal pumping model. The results showed that the centrifugal pumping alone, inside the separated boundary layer, is not sufficient to produce the large force augmentation observed in experimental data. In contrast, the improved semi-empirical model provided a good agreement with experimental data, thanks to the quadratic scaling of the aspect ratio. And, the new estimate of the Rossby number proved to be advantageous over the existing Rossby number estimate in terms of the dependency on the angle of attack. Furthermore, the tangential and drag force coefficients were found to be strongly dependent on the airfoil type and its corresponding pressure shape. In contrast, the normal and lift force coefficients were found to be less dependent on the airfoil type. The proposed semi-empirical model is still strongly empirical, future work needs to account for the complex effect of airfoil type and its consequent interaction with the outer inviscid flow through the boundary layer.

Experimental and numerical analysis of a CO2 dual-source heat pump with PVT evaporators for residential heating applications

Multi-source energy systems are a promising solution to lower the environmental impact of the heating and cooling sector and enhance the exploitation of renewable energy sources. In this context, dual-source solar-assisted heat pumps exploit solar energy and air as the low-temperature heat sources. However, the efficiency of solar-based systems is strictly related to weather conditions, location, and time. Therefore, there is a need for accurate models to be used in dynamic simulations of these systems and perform detailed performance analyses and study the involved energy flows.This paper presents an experimental and numerical investigation of a direct-expansion solar-assisted heat pump (DX-SAHP) operating with CO2 as the refrigerant. The heat pump prototype can work with an air-finned coil heat exchanger or photovoltaic-thermal (PVT) solar collectors as the evaporator. The solar-mode configuration allows the exploitation of the heat from solar radiation to evaporate the refrigerant and to improve the photovoltaic electricity production due to the cooling of the cells up to 8%.A numerical heat pump model, integrated with novel gas-cooler and PVT collectors models, has been developed and implemented as a TRNSYS type for dynamic simulations of the system. The model has been validated with continuous measurements during the heat pump operation in solar and air modes. The proposed model can be used for performing seasonal simulations of a heat pump operating with a transcritical CO2 cycle. Moreover, the outcomes of the analysis show how the configuration of a CO2 heat pump with a direct-expansion air-finned coil heat exchanger or PVT can be used to enhance the performance of the heat pump and increase the electrical efficiency of the photovoltaic cells.

Novel photothermal response intelligent polyurethane sponge with switching wettability for oil/water separation

Intelligent oil–water separation materials with stimulating response have received extensive attention. In this paper, a novel, cost-effective, and simple approach is developed to produce a photothermal-responsive smart sponge with switchable wettability. The polydopamine (PDA) and photothermal agent copper sulfide (CuS) were grafted PU sponge surface. Thermal-responsive polymers P(VTMS-co-NIPAm) and 1-octadecanethiol (ODT) are then decorated on the PDA/CuS@PU surface through free radical polymerization and Michael addition reaction. The obtained PCPO@PU exhibits rapidly switchable wettability between hydrophobicity and hydrophilicity depending on the temperature response of P(VTMS-co-NIPAm) induced by photothermal effect of CuS. The PCPO@PU showed excellent separation performance with oil absorption ratio 8–33 g·g−1 and average self-desorption efficiency of more than 70%, but also has a remarkable recycling effect. Specifically, the photothermal response of PCPO@PU does not require additional chemical initiation and both address the limitations of materials that respond to specific light species and heat. More importantly, the PCPO@PU is able to realize the fluorescent lamp-peristaltic pump model, which can be a significant step toward its widespread application for oil–water separation in nature marine environment.

A fault prognosis strategy for an external gear pump using Machine Learning algorithms and synthetic data generation methods

Fault prognosis is an important area of research that aims to predict and diagnose faults in complex systems. The sudden failure of industrial components can have adverse consequences for an organisation in terms of time, cost and workflow. It is, therefore, critical to ensure the maintenance of equipment components in optimal condition in order to avoid downtime that may cause significant disruption. Due to this reason, in recent years, there has been an increasing interest in creating innovative methods for fault prognosis that can increase system reliability and reduce maintenance costs. Gear pumps are widely utilised in a variety of industrial applications, and their reliability and effectiveness are crucial for achieving optimal system performance. Gear pumps, on the other hand, are prone to malfunctions and failures, which can result in substantial downtime and maintenance costs. The challenge is to develop a fault prognosis approach that is reliable and accurate enough to detect and diagnose defects in a gear pump before they cause system failures. This paper proposes a novel computational strategy for the fault prognosis of an external gear pump using Machine Learning (ML) approaches. Due to the unavailability of sufficient experimental data in the vicinity of failure mechanisms, a novel approach to generating a high-fidelity in-silico dataset via a Computational Fluid Dynamic (CFD) model of the gear pump in healthy and faulty working conditions is presented. However, considering the computational demand for rerunning the same CFD simulations, novel synthetic data generation techniques are implemented by perturbing the frequency content of the time series to recreate other working conditions and constructing degradation behaviour using linear and cubic interpolation methods for run-to-failure scenarios. The synthetically created datasets are used to train the underlying ML metamodel for fault prognosis. Two types of ML algorithms are employed for fault prognosis: Multilayer Perceptron (MLP) and Support Vector Machine (SVM) algorithms. A series of numerical examples are shown, allowing us to infer that the proposed modelling technique is feasible in an industrial setting and that employing the MLP algorithm delivers superior fault prognosis results when compared to SVM. Furthermore, datasets generated using the cubic interpolation method have lower prediction errors than datasets generated using the linear interpolation method due to the smoother degradation behaviour in the data.

Potential Energy Recovery and Direct Reuse System of Hydraulic Hybrid Excavators Based on the Digital Pump

The potential energy recovery of hydraulic excavators is very significant for improving energy efficiency and reducing pollutant emissions. However, the more common solutions for potential energy recovery require more energy conversion processes before these potential energies can be reused, which adds to the complexity and high cost of the system. To tackle the above challenges, we proposed a novel energy recovery system for hydraulic hybrid excavators based on the digital pump with an energy recovery function. The new system could operate in three different modes: pump, energy recovery, and direct reuse. Based on the descriptions of the working principle of the digital pump and the whole energy recovery system, the mathematical models of the digital pump, the excavator arm cylinder, and the accumulator were established and the AMESim simulation model (combining mechanics, hydraulics, and electrics) was developed. The dynamic characteristics of the energy recovery system were studied under no-load and full-load conditions. The simulation results showed that this scheme could achieve 86% energy recovery when the boom was lowered and reused the recovered energy directly when raised, which could decrease the system input energy by 78.1%. This paper can provide an optimized solution for construction machinery or off-road vehicles and presents a reference for the research on digital hydraulics.

Modeling and Simulation of High-Temperature Heat Pump Combined with Solar Energy

Heat pumps can utilize various sources of heat to increase the temperature of a room or water. This study uses solar energy as a heat source for high-temperature heat pumps. The type of heat pump used is a vapor compression heat pump and is used to produce steam. The study created a model and simulation of a heat pump combined with solar energy. System modeling is divided into three subsystems: solar collector, thermal storage, and a heat pump—the WinDali program used in heat pump simulation. The Simulation results show a close relationship between solar intensity and system performance. The maximum COP obtained is 1.32. The heat pump can generate steam for 7.25 hours, and the lifted temperature obtained is 28°C.