Pump Model Research Articles

Study of unsteady flow-induced vibration of centrifugal pump volute casing using fluid-solid coupling

The paper studies the flow-induced vibration of the volute of a centrifugal pump using the coupled approach of computational fluid dynamics (CFD) and finite element method (FEM). In the present paper, a numerical model of the centrifugal pump for fluid-solid coupling solution was established, and the unsteady flow of the centrifugal pump under different working conditions was simulated by unsteady CFD calculations. Then, the fluctuation pressure on the volute inner surface was extracted and used as the fluid load that induces the volute vibration. The volute vibration response including displacement, and acceleration was discussed based on the results of fluid-solid coupling solutions. The results show that the non-uniform distribution of fluctuation pressure along the volute, and the dominant vibration frequencies of the pump volute are blade frequency and its harmonics, and the minimum vibration and stress of the volute appear at the design condition. Overall, this research gives insight into the flow-induced vibration of centrifugal pump volute casing.

Research on rheological behavior of fresh concrete single-cylinder pumping based on SPH-DEM

In contrast to traditional approaches to simulating fresh concrete, the model applied here allows issues such as liquid phase and the motion of sub-scale particles to be considered. The rheological behavior of fresh concrete materials was investigated, and the slump test and pumping process of fresh concrete were simulated by combining the smooth particle hydrodynamics coupled with discrete element method. Based on Bi-viscosity model and Bingham model, linear and nonlinear fitting of rheometer data and the derivation equations were educing. Bi-viscosity model and the Bingham model were compared in slump test. The results show that the Bi-viscosity model is more accurate in simulation, and the error percentage is less than 10%. The Bi-viscosity model was used to simulate and predict the results of slump experiment, and the influence of rheological parameters on the slump velocity and shape was obtained. The simulation analysis model of concrete single-cylinder pumping is established, and the experimental and simulation analysis models are compared. The results show that the SPH-DEM pumping pressure prediction is very close to the experimental results.

Simplified water-source heat pump models for predicting heat extraction and rejection

Simplified heat pump models are needed for the design of ground heat exchangers used with ground-source heat pump systems. Design engineers commonly have only manufacturer's data with which to construct a heat pump model that can predict heat extraction and heat rejection given building heating and cooling loads and take account of the entering fluid temperatures to the heat pump. Earlier work has used simple polynomials to predict the ratio of heat extraction to heating and heat rejection to cooling. Unfortunately, manufacturers' catalog data do not always provide sufficient support to calculate the polynomial coefficients. Therefore, in the absence of experimental data, simplified and acceptably accurate models are needed to exploit a limited number of operating points.This paper presents a review of available manufacturers' data in North American and European markets. The available data vary from country to country, depending on the standards in use in each country. In particular, data availability is poorer for the European heat pumps compared to North American heat pumps.Then, a range of models is investigated, characterizing the results by the required inputs and the root mean square error and recommendations are provided. Models are validated against catalog and experimental data.

New ex vivo method to objectively assess insulin spatial subcutaneous dispersion through time during pump basal-rate based administration

Glycemic variability remains frequent in patients with type 1 diabetes treated with insulin pumps. Heterogeneous spreads of insulin infused by pump in the subcutaneous (SC) tissue are suspected but were barely studied. We propose a new real-time ex-vivo method built by combining high-precision imaging with simultaneous pressure measurements, to obtain a real-time follow-up of insulin subcutaneous propagation. Human skin explants from post-bariatric surgery are imaged in a micro-computed tomography scanner, with optimised parameters to reach one 3D image every 5 min during 3 h of 1UI/h infusion. Pressure inside the tubing is recorded. A new index of dispersion (IoD) is introduced and computed upon the segmented 3D insulin depot per time-step. Infusions were hypodermal in 58.3% among 24 assays, others being intradermal or extradermal. Several minor bubbles and one occlusion were observed. IoD increases with time for all injections. Inter-assay variability is the smallest for hypodermal infusions. Pressure elevations were observed, synchronised with air bubbles arrivals in the tissue. Results encourage the use of this method to compare infusion parameters such as pump model, basal rate, catheter characteristics, infusion site characteristics or patient phenotype.

Selection of relevant features to detect and diagnose single and multiple simultaneous soft faults in air-source heat pumps

Soft faults in air-source heat pump systems can cause various issues, such as decreased performance, increased energy consumption, and long-term damage. This paper presents a comprehensive modeling approach of air-source heat pumps that considers individual and simultaneous soft faults validated against empirical experiments from the literature, a perspective limited in previous research. The methodology is based on the simulation of fault-free and faulty system performance utilizing heat pump modeling software. The results are a selection of variables and their trends to select the appropriate features to detect and diagnose single and double soft faults. The model also computes the impacts of these combined faults on COP, revealing significant reductions. Specifically, combinations of overcharge with condenser fouling and undercharge with compressor valve leakages induce COP reductions ranging from 17% to 38%, depending on operating conditions. The model can be used to develop faulty heat pump data, which can be adapted to other system typologies and conditions and used as input for data-driven Fault Detection and Diagnosis (FDD) methodologies.

Variable refrigerant flow heat pump model with estimated parameters and emulated controller based on manufacturer data

A new physics-based and modular variable refrigerant flow (VRF) heat pump model aimed toward multi-year simulations is presented. The model allows the simulation of any number of indoor units (IU), outdoor units (OU) and compressors. A parameter-estimation procedure and a control strategy both using available manufacturer data is proposed. The model is validated against data collected from a VRF system that services the first floor of the former ASHRAE Headquarters Building in Atlanta (USA), comprised of 22 IU, 2 OU, and 8 compressors. Results show that the model accurately predicts the total energy consumption over a two-month cooling period, with a relative error, normalized mean bias error, and coefficient of variation of the root mean square error of 1%, 1.6%, and 16.7%, respectively.

Numerical investigation on operational performance of seawater-source heat pump system coupled with capillary-box heat exchangers

In view of the energy-saving potential of the seawater-source heat pump system (SWHPs) coupled with capillary-box heat exchangers (CBHEs), the operational performances of this system were investigated on various temporal scales, including annually, monthly, and daily. An overall system numerical model was developed by integrating the CBHEs, heat pump and dynamic building loads model. The results indicated that the annual COPh was 3.4. In the coldest month, the monthly COPh was 3.3, and the daily COPh was mainly determined by the daily heating demand. The corresponding annual COPc was 4.8. In the hottest month, the monthly COPc was up to 5.0, and the daily COPc was more sensitive to seawater temperature fluctuations. On a typical summer day, the operating time of the heat pump with an hourly capacity ratio above 50 % was about 2.7 times that of a typical winter day. Due to the effective removal of the heat discharged from the CBHEs in the seabed, the impact of heat accumulation on the performance of this system can be neglected in the long-term operation. This study provided practical implications for the design and application of the CBHEs-coupled SWHPs.

A New Approach to Study the Effect of Complexity on an External Gear Pump Model to Generate Data Source for AI-Based Condition Monitoring Application

The external gear pump, like any other hydraulic component, is vulnerable to failure, which may lead to downtime as well as the failure of other components linked to it, thereby causing production loss. Therefore, establishing a condition monitoring system is crucial in identifying failure at an early stage. Traditional condition monitoring approaches rely on experimental data that are collected by means of sensors. However, the sensors utilized in the experiments may have calibration issues, which lead to inaccurate measurements. The availability of experimental data is also limited as it is difficult and expensive to create and detect a fault in a component. Hence, it is essential to develop a simulation model that mimics the performance of the actual system. The data generated from the model can be utilized to create the data source required for automated condition monitoring. A new methodology based on a detailed geometric model for simulating the External Gear Pump is described and compared to two models analyzed in the authors’ previous work, namely Schlosser’s loss model and simple geometric model. In this paper, the three models are compared with experimental data and the method utilized for fault injection. Schlosser’s loss model, as well as the detailed geometric model, are found to be suitable in terms of validation; however, the latter is a better candidate in terms of fault injection. Hence, the detailed geometric model can be implemented as a tool to generate the data source for condition monitoring applications.

Compressor Heat Pump Model Based on Refrigerant Enthalpy and Flow Rate

Compressor Heat Pump Model Based on Refrigerant Enthalpy and Flow Rate

Fluid-induced vibration analysis of centrifugal pump including rotor system based on Computational Fluid Dynamics and Computational Structural Dynamics coupling approach

The flow-induced vibration of centrifugal pump under the effect of stator-rotor interaction are studied by Computational Fluid Dynamics method and Computational Structural Dynamics method based on the principle of one-way decomposition fluid-structure interaction. Firstly, the unsteady flow characteristics in centrifugal pump are studied by adopting the Computational Fluid Dynamics method, the numerical model of the whole flow field of the centrifugal pump is established, and the pulsating pressure characteristics of volute and impeller in the centrifugal pump are analyzed. The accuracy of the flow field modeling method and calculation method in this paper is verified by external characteristic test. Secondly, the vibration characteristic test of centrifugal pump is carried out, and the structural dynamic model and boundary conditions of centrifugal pump are verified and corrected in the modal test. Finally, the flow-induced excitation calculated by the flow field is simultaneously applied to the structural dynamics model of the centrifugal pump according to different transmission ways, and the flow-induced vibration of the whole centrifugal pump including the rotor system is calculated and analyzed by the Computational Structural Dynamics method in conjunction with rotor dynamics. Compared with the vibration test results, the validity of the flow-induced vibration calculation method of centrifugal pump in this paper is verified. The results show that under the influence of stator-rotor interaction effect, the blade passing frequency and shaft frequency are the main characteristic frequencies of pressure pulsation and dynamic response in the centrifugal pump.

A selection method of variable speed centrifugal pumps for maximum hydraulic efficiency

Variable speed pumps (VSPs) are more energy efficient compared to other flow control methods such as throttling control valves. However, their selection process is not straightforward because the pump characteristics should be optimised against the load profile of the flow system for maximum hydraulic efficiency. This paper presents a VSPs selection method based on generic mathematical models of centrifugal pumps efficiency, characteristics and similitude, which enables the extension of this method to other types of turbomachines. This selection method results in a nonlinear algebraic equation that is solved numerically to obtain a reference flow rate that maximises the pumping system hydraulic efficiency. This reference flow rate is subsequently used to obtain the pump characteristic curves at all operating pump speeds. The results show that this method is fast, accurate and reliable. Because the developed method uses generic pump models rather than specific models from manufacturers’ databases, it enables the integration of VSP selection process in early engineering design phases of pumping systems.

Designing a Model of Solar Photovoltaic Water Pumping System for Off-Grid Localities in Tanzania

Modeling of photovoltaic (PV) water pumping system for rural water localities is vital especially in these modern days, in Tanzania. This is due to the rise of high number of solar-powered rural water projects constructed lacking appropriate design. The fate result into poor and substandard projects delivering below expectations. Kikombo Solar Water Project situated in Dodoma; Tanzania is one among poorly designed solar project chosen as a case study to validate proposed model. The main problem of Kikombo project is unsatisfactory amount of water from domestic points to satisfy population demand. This matter has been raised by pumping-station attendants and the Kikombo village community. The Kikombo water project can only deliver 14.21 m3/day while required demand is 50 m3/day. In order to solve the existing problem, solar water pumping model was developed. It consists of PV array, a motor-pump (AC), inverters (DC–AC converter), maximum power point tracker (MPPT) integrated with a controller and a storage water tank. Analysis was done in MATLAB to estimate which parameters should be upgraded to meet the water requirements. Moreover, the input and output variable for each model component were identified and simulated in MATLAB software. Finally, PV model was validated and system capacity improvement to rectify designs limitation for Kikombo is proposed. The model results were validated through real measurement data at Kikombo water pumping station. The differential error of 0.04062 was observed as a system error. PV model displayed an error of 0.0509 for power output, 0.0383 for current and 0.0131 for voltage; inverter displayed error of 0.0686 and 0.0406 for motor pump. In order to acquire sufficient water demand of 50 m3 /day, the PV panel and pump capacities should be increased to 8.82 kW and 7.35 kW respectively from the existing PV panel’s power of 2.5 kW and motor-pump of 4 kW.

Chemical heat pumps beyond the Carnot limit

Based on the working mechanisms of heat pumps and chemical pumps, a model of the chemical heat pump operating between the two thermal material reservoirs with different temperatures and chemical potentials is established. The general expression of the coefficient of performance (i.e. generalized Carnot coefficient of performance) is derived, and a series of meaningful results are obtained. The different characteristics of the chemical heat pump operating under different conditions are revealed. It is found that the coefficient of performance of the chemical heat pump can be larger than that of the Carnot heat pump operating under the same temperature span or the reversible coefficient of performance of the chemical pump operating under the same chemical potential span. The reason is that the chemical heat pump operating between two thermal material reservoirs is driven by the temperature field and the chemical potential field at the same time. Moreover, it is expounded that these results accord with the second law of thermodynamics.

Superhydrophobic Microchannel Heat Exchanger for Electric Vehicle Heat Pump Performance Enhancement

Battery-powered electric vehicles (EVs) have emerged as an environmentally friendly and efficient alternative to traditional internal combustion engine vehicles, while their single-charge driving distances under cold conditions are significantly limited due to the high energy consumption of their heating systems. Heat pumps can provide an effective heating solution for EVs, but their coefficient of performance (COP) is hampered by heat transfer deterioration due to frost accumulation. This study proposes a solution to this issue by introducing a microchannel heat exchanger (MHE) with superhydrophobic surface treatment (SHST) as a heat pump evaporator. A computational fluid dynamics MHE model and a dynamic heat pump model are developed and rigorously validated to examine the detrimental impact of frost accumulation on heat transfer, airflow resistance, and heat pump performance. When the frost layer thickness is 0.8 mm at a given air-side velocity of 1.0 m/s, the air-side heat transfer coefficient can be reduced by about 75%, and the air-side pressure drop sharply increases by 28.4 times. As frost thickness increases from 0 to 0.8 mm, the heating capacity drops from 3.97 to 1.82 kW, and the system COP declines from 3.17 to 2.30. Experimental results show that the frost thickness of the MHE with SHST reaches approximately 0.4 mm after 30 min, compared to that of 0.8 mm of the MHE without SHST, illustrating the defrosting capability of the superhydrophobic coating. The study concludes by comparing the performance of various heating methods in EVs to highlight the advantages of SHST technology. As compared to traditional heat pumps, the heating power consumption of the proposed system is reduced by 48.7% due to the defrosting effect of the SHST. Moreover, the single-charge driving distance is extended to 327.27 km, an improvement of 8.99% over the heat pump without SHST.

Acausal Modelling of Advanced-Stage Heart Failure and the Istanbul Heart Ventricular Assist Device Support with Patient Data.

In object-oriented or acausal modelling, components of the model can be connected topologically, following the inherent structure of the physical system, and system equations can be formulated automatically. This technique allows individuals without a mathematics background to develop knowledge-based models and facilitates collaboration in multidisciplinary fields like biomedical engineering. This study conducts a preclinical evaluation of a ventricular assist device (VAD) in assisting advanced-stage heart failure patients in an acausal modelling environment. A comprehensive object-oriented model of the cardiovascular system with a VAD is developed in MATLAB/SIMSCAPE, and its hemodynamic behaviour is studied. An analytically derived pump model is calibrated for the experimental prototype of the Istanbul Heart VAD. Hemodynamics are produced under healthy, diseased, and assisted conditions. The study features a comprehensive collection of advanced-stage heart failure patients' data from the literature to identify parameters for disease modelling and tovalidate the resulting hemodynamics. Regurgitation, suction, and optimal speeds are identified, and trends in different hemodynamic parameters are observed for the simulated pathophysiological conditions. Using pertinent parameters in disease modelling allows for more accurate results compared to the traditional approach of arbitrary reduction in left ventricular contractility to model dilated cardiomyopathy. The current research provides a comprehensive and validated framework for the preclinical evaluation of cardiac assist devices. Due to its object-oriented nature, the featured model is readily modifiable for other cardiovascular diseases for studying the effect of pump operating conditions on hemodynamics and vice versa in silico and hybrid mock circulatory loops. The work also provides a potential teaching tool for understanding the pathophysiology of heart failure, diagnosis rationale, and degree of assist requirements.

Dynamical Modelling of a Centrifugal Fan Driven by an Induction Motor and Experimental Validation

The application of electrical drives in the control of centrifugal fans and pumps is a well-established area that leads to substantial energy savings. It requires electrical and automation engineers to have some knowledge relevant to drives about fan and pump modelling since ignoring or oversimplifying fan/pump modelling for the intended drive design compromises the required control quality. This paper improves the existing dynamical models of fans and pumps integrated with induction motors via neural network estimation of overall fan/pump efficiency; this estimation is based on the voltage frequency of the driving induction motor, pressure, and flow rate, followed by the separation of the fan’s or pump’s own efficiency for the motor load torque computation, enhancing the accuracy due to the correct reflection of the power balance. The model is developed with a view to being convenient for control design applications. For the first time for dynamical models, it is verified experimentally, justifying the necessity of the first-order nonlinear differential equation for the flow rate. The validation includes a direct approach based on analysis of transient behaviour caused by a small-step perturbation of the frequency of the motor voltages and an indirect approach based on the introduced concept of the dynamical flow rate and pressure estimators.

Dehumidification load ratio: influence mechanism on air conditioning and energy saving potential analysis for building cooling

The construction energy consumption (EC) makes up around 35% of the total energy used. Half of this energy is used for air-conditioning to cool spaces. The effectiveness of cooling relates to various factors, particularly the dynamic thermal performance of air-conditioners (AC) in different conditions. Studying heat pumps in diverse hot and humid climates, especially where dehumidification matters in summer AC, reveals efficiency. Examining the connection between coefficient of performance (COP) and heat removal aids in lowering building energy usage and improving cooling systems. To achieve this, a validated thermodynamic model of heat pumps and a specific transient building heat transfer model were combined. The study focused on three distinct hot and humid climate zones: Guangzhou, Wuhan, and Jiuquan. Simulations of heat pump performance were conducted throughout the year to analyze variations in COP, relative humidity (RH), and latent heat load (LHL).Key findings indicate that the COP of heat pumps is notably influenced by the practical amount of dehumidification required. A positive correlation (correlation coefficient: 0.52151) exists between COP and LHL, emphasizing the importance of addressing dehumidification needs. The research highlights that the COP remains consistently high when the heat pump manages between 45% to 80% of the LHL. Practically, these findings have crucial implications for heat pump applications and building EC reduction, particularly in regions with pronounced dehumidification requirements during the cooling season. By understanding the interplay between heat pump efficiency, humidity, and heat load, practitioners can optimize heat pump performance to achieve energy savings. This research provides a valuable reference for designing and implementing cooling systems in various hot and humid climates, facilitating energy-efficient practices and environmentally friendly building operations.

Characterization of flux pump-charging of high-temperature superconducting coils using coupled numerical models

Flux pumps provide a promising solution for contactless charging of high-temperature superconducting (HTS) coils, eliminating the need for bulk current leads and reducing the heat burden for the cryogenic system. Characterizing the nonlinear effects of an HTS coil charged by a flux pump and understanding the dynamics of the charging process is essential for promoting the practical application of flux pumps. Numerical models provide a fast and cost-effective way of achieving this. In this study, we propose a methodology for coupling HTS coil and flux pump models using an electrical circuit, resulting in reduced computation costs. We validate the effectiveness of our approach against the experimental results of an HTS coil charged by a dynamo-type flux pump. Specifically, we obtain the voltage produced by the HTS dynamo using a 3D model based on the minimum electromagnetic entropy production method and apply this voltage to the load HTS coil using a formulation finite-element method model coupled via an electrical circuit. The simulated charging current shows good agreement with experimental observations, validating our modeling strategy. The results demonstrate that the flux flow state in the HTS coil is the primary factor limiting the charging performance of the HTS dynamo as the charging current approaches the coil’s critical current. Furthermore, based on the simulation, we demonstrate that, when using flux pumps, it is advisable to leave a margin between the operating current and the critical current of the coil. Overall, our approach has the potential to be applied to HTS coils charged by any device.

Simulation Analysis of Working Circuit Performance of Mountain Pepper Harvester Based on Improved Load-Sensitive System

China’s Guizhou is a typical karst landscape province with high production of chili pepper, but it is mostly planted in mountainous areas, while manual harvesting of chili pepper has the deficiencies of high labor intensity, low efficiency, and high labor cost; in addition, there is no harvesting machinery applicable to the dense planting pattern of the chili pepper in mountainous areas in China. The fully hydraulic mountain track-based self-propelled pepper harvester 4JZ-1.0A is designed to solve the above problems. The pepper harvester spiral comb picking head is an important part of the whole machine design, the design of the hydraulic system of the working circuit of the picking head is the key to realizing the hydraulic control part of the whole system. In this paper, the working principle diagram of the improved load-sensitive hydraulic system is designed and analyzed for the study of whether the working circuit of the pepper picking head of the pepper machine can meet the requirements of mountain operation, taking the working circuit of the mountain pepper harvester as the research object. In addition, the load-sensitive pump model and the simulation model of the whole working circuit are established by the AMESim platform 2019.2 (Siemens simcenter amesim). The operating performance of the system under variable flow conditions, variable load conditions, and an improved sensitive system is analyzed. The simulation results show that the improved load-sensitive system can effectively reduce the oscillation and cavitation during cylinder operation and improve the system efficiency and the performance and service life of the components. The performance of the hydraulic system of the working circuit of the mountain pepper harvester was verified in the test, meeting the requirements of working use. This provides a theoretical basis for the improvement and optimal design of a mountain pepper harvester hydraulic system.

Study of the Optimization of Rail Pressure Characteristics in the High-Pressure Common Rail Injection System for Diesel Engines Based on the Response Surface Methodology

This paper establishes a mathematical model of the high-pressure common rail injection system used in diesel engines according to the parameters of its key components, and AMESim 2020 software was used to establish a simulation model of the common rail injection system used in diesel engines. The simulation model mainly includes a high-pressure oil pump model, a common rail pipe model, and a model of four injectors. This paper also describes an experimental analysis of the accuracy of the established simulation model. Through a simulation analysis of the system rail’s pressure fluctuation and pressure characteristics, it was concluded that the length of the common rail pipe, the diameter of the common rail pipe, and the inner diameter of the high-pressure fuel pipes are important influencing parameters for the rail pressure characteristics of the system. In this study, according to the original common rail pipe and high-pressure fuel pipe model, a response surface methodology was used to optimize and analyze the parameters of the common rail pipe and high-pressure fuel pipes, and the optimal size parameters for the common rail pipe and high-pressure fuel pipes were obtained with the minimum rail pressure fluctuations and the average rail pressure setpoint. After the optimization, the pressure for the common rail pipe of the high-pressure common rail system was increased by 0.82%, the pressure fluctuation was reduced by 21.66%, the injection pressure was increased by 1.15%, the single injection volume was increased by 0.86%, and its fuel injection characteristics were significantly improved.