Pump Performance Curve Research Articles

Simulation and optimisation of vacuum (pressure) swing adsorption with simultaneous consideration of real vacuum pump data and bed fluidisation

Pressure swing adsorption (PSA) is a promising technology for gas separation and purification, receiving considerable attention in the past decades. Existing studies on simulating PSA involving a vacuum pump, the vacuum (pressure) swing adsorption [V(P)SA] process, typically estimate vacuum pump energy consumption using an approximate constant energy efficiency or an empirical energy efficiency correlation, leading to inaccurate representation of realistic vacuum pump performance. In this work, we propose an enhanced computational approach for simulation and optimisation of V(P)SA processes through simultaneous incorporation of realistic vacuum pump performance prediction models and adsorption bed fluidisation limits. The vacuum pump prediction models are developed using data-driven modelling techniques with realistic vacuum pump performance data. The enhanced computational approach more accurately accounts for the V(P)SA performance, without relying on an estimated vacuum pump efficiency and assumed pressure/flow rate boundary conditions at the vacuum pump end of the adsorption bed. Furthermore, this approach prevents the bed fluidisation. The computational results show that the developed prediction models accurately represent the actual performance curves of the vacuum pump. It is also demonstrated that incorporating the vacuum pump prediction models and fluidisation constraints in PSA optimisation leads to significantly different optimal solutions compared to when these factors are not considered.

Numerical and Experimental Analysis of Vortex Pump with Various Axial Clearances

Axial clearance is a critical parameter affecting the performance of vortex pumps. In this study, numerical simulation and experimental validation methods are employed to establish four different clearance schemes. The analysis focuses on multiple aspects, including the internal flow field, clearance flow field, leakage flow, and recirculation flow, to investigate the impact of axial clearance on the internal flow field and the external characteristics of the vortex pump. The results indicate that under the pressure difference between the inlet and outlet, the main flow leaks from the high-pressure region at the outlet to the clearance flow channel, and the clearance flow returns to the main flow channel at the low-pressure region of the inlet. As the axial clearance increases, the intensity of the vortices inside the pump gradually decreases. This leads to a reduction in intensity of the momentum exchange between the fluid inside and outside the impeller, causing a decline in the pump performance curve. Simultaneously, the increase in clearance reduces the flow resistance in the clearance region, and the clearance flow gradually stabilizes. The interaction between the clearance flow and the main flow intensifies, causing the leakage flow and recirculation flow to increase rapidly, which results in significant energy loss.

Design and Realization of Fully Automatic Pump Performance Test System

With the development of automation technology, it gradually replaces manual labor in various fields. Pumps are widely used in various production processes in the industrial field. To enhance the automation level of the pump production and testing process will significantly reduce production costs. This paper aims to design and realize a set of fully automatic, high-precision pump performance testing system. The fully automated operation of the performance test is designed according to the flow rate automatic sampling method, to achieve the accurate measurement of the pump operating conditions. Utilizing the PID algorithm, the valve is automatically adjusted through PLC control to realize the accurate positioning of the flow measurement point. With the help of the software program to carry out the calculation and analysis of test data, to achieve the visualization of the test process of the whole performance test data management. At the same time, SQL Server database is used to realize rapid query and management of test data. After the test verification, the system realizes the full-automatic measurement of the pump performance curve, and the measurement accuracy conforms to the standard of ISO 9906:2012.

Numerical and experimental analysis of the cavitation and flow characteristics in liquid nitrogen submersible pump

In this paper, the cavitation and flow characteristics of the unsteady liquid nitrogen (LN2) cavitating flow in a submersible pump are investigated through both experimental and numerical approaches. The performance curve of the LN2 submersible pump is obtained via experimental measurement. Numerical simulations are performed using a modified shear stress transport k–ω turbulence model, incorporating corrections for rotation and thermal effects as per the Schnerr–Sauer cavitation model. The numerical framework is verified by comparing the cavitation morphology features with previously reported visual data of the LN2 inducer and aligning pump performance data with those obtained from experimental tests of the LN2 submersible pump. The results indicate that cavitation at the designed flow rate predominantly manifests as tip clearance vortex cavitation in the inducer. Increased flow rates exacerbate cavitation, potentially obstructing the flow passage of the impeller. The vortex identification method and the vorticity transport equation are employed to identify the vortex structures and analyze the interaction between cavitation and vortices in the unsteady LN2 cavitating flow. The vortex structures primarily concentrate at the outlet of the impeller flow passage, largely attributed to the vortex dilation term and baroclinic torque. The influence of thermal effects on the cavitation flow of submersible pumps is analyzed. An entropy production analysis model, comprehensively involving various contributing factors, is proposed and utilized to accurately predict the entropy production rate within the pump. This study not only offers an effective numerical approach but also provides valuable insight into the cavitation flow characteristics of the LN2 submersible pump.

A Graphical Approach to Visualize and Interpret Biochemically Coupled Biomechanical Models.

The last decade has seen the emergence of progressively more complex mechanobiological models, often coupling biochemical and biomechanical components. The complexity of these models makes interpretation difficult, and although computational tools can solve model equations, there is considerable potential value in a simple method to explore the interplay between different model components. Pump and system performance curves, long utilized in centrifugal pump selection and design, inspire the development of a graphical technique to depict visually the performance of biochemically-coupled mechanical models. Our approach is based on a biochemical performance curve (analogous to the classical pump curve) and a biomechanical performance curve (analogous to the system curve). Upon construction of the two curves, their intersection, or lack thereof, describes the coupled model's equilibrium state(s). One can also observe graphically how an applied perturbation shifts one or both curves, and thus how the other component will respond, without rerunning the full model. While the upfront cost of generating the performance curve graphic varies with the efficiency of the model components, the easily interpretable visual depiction of what would otherwise be nonintuitive model behavior is valuable. Herein, we outline how performance curves can be constructed and interpreted for biochemically-coupled biomechanical models and apply the technique to two independent models in the cardiovascular space. The performance curve approach can illustrate and help identify weaknesses in model construction, inform user-applied perturbations and fitting procedures to generate intended behaviors, and improve the efficiency of the model generation and application process.

Evolution mechanism of unsteady internal flow of an ultra-high head pump-turbine in pump mode

In this study, the unsteady flow of an ultra-high-head model pump turbine in pump mode is numerically investigated, revealing the evolution mechanism of unsteady flow diffusion and propagation. Under high-flow-rate and high-efficiency conditions, stable flow separation occurs in the channel of the stay vanes. As the flow rate decreases, the flow separation gradually spreads in the radial direction and expands from the stay vanes to the guide vanes. This causes a partial blockage in the channel of the guide vanes. Meanwhile, the flow separation gradually switches from stable to unstable with a low-frequency rotation (about 4.8 % of the impeller rotational frequency) in the circumferential direction. In addition, the correlation between the hump characteristics and unsteady flow is discussed. For an ultra-high-head pump turbine, the unstable flow initiates at static operating conditions from the pump performance curve with negative slope, which is significantly different from medium and low-head pump turbines.

Design and Optimization of Slurry Conveying System for Small-sized Cutter Suction Dredger

Aiming at the production capacity of a newly-built small-sized dredger, the slurry conveying system is optimized. Based on the performance test of the model pump, the water performance curve of the dredge pump is obtained through similarity conversion; By comparing the resistance of the two pipe diameters, the diameters of the suction and discharge pipes on the dredger are optimized, and the resistance consumption of the slurry conveying pipeline on the dredger is reduced. The proportion of the resistance of the pipe on the dredger to the head of the dredge pump is reduced from 11.7% and 28.7% to 4.8% and 13.5% respectively at the flow of 900 m3/h and 1,200 m3/h; After optimizing the pipe diameter, the NPSHa of the device is increased, the risk of cavitation of the dredge pump is reduced, and the slurry transportation capacity of the dredger is improved; The operating points of slurry transportation with conveying distance of 500 m to 3,000 m are calculated and analyzed respectively, and the production prediction curve is obtained to meet the design capacity of the dredger. The optimization of the slurry conveying system improves the matching of the dredge pump and pipeline to the dredger, and provides equipment support for the environmental protection dredging project of rivers, lakes and reservoirs.

Design and operation investigation for the fifth-generation heating and cooling system based on load forecasting in business districts

The fifth-generation heating and cooling system (5GDHC) is a bidirectional low temperature network, which is a good solution for decarbonization and energy-saving in building cooling and heating. Because of its complex configurations, 5GDHC requires specific advanced control strategies for different scenarios. This paper aims to investigate 5GDHC with multiple sources in the business district in hot-summer and cold-winter zone through modelica simulation. The analysis and forecasting of district loads were used to study the design and operation strategies of 5GDHC. A suitable heat pump performance curve was presented for 5GDHC after comparing several heat pumps. And the larger the total flow in the network, the more beneficial it is for users. In this study, 5GDHC for the business district performed best when it adopted the strategy of continuous operation of the ground heat exchanger, nighttime operation of the surface-water coil, and supplemental cooling of the cooling tower upon it is needed, resulting in a 16.6% reduction in CO2 emissions compared to the strategy that all sources operated continuously. Besides, carbon emission analysis showed the importance of balancing operational cost with carbon emission. This study will help optimize the design and operation of 5GDHC in business district scenarios.

Condition Indicator Developed for All-Metal Progressing Cavity Pumps

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 209763, “Development of an All-Metal Progressing-Cavity-Pump Condition Indicator,” by John W. Sheldon, SPE, C-FER Technologies; Justin MacDonald, SPE, Athabasca Oil; and Evan Noble, SPE, Technical Consultant, et al. The paper has not been peer reviewed. _ All-metal progressing cavity pumps (AMPCPs) are frequently used in oil and gas applications to produce high temperature fluids to surface but can exhibit accelerated wear during operation that results in decreasing volumetric efficiency over the pump’s life. In the complete paper, the authors present a proposed condition indicator that estimates the wear experienced by an AMPCP at any point in operation and takes into consideration the potential effects of downhole operating conditions. The proposed condition indicator also can be extrapolated into the future and used to estimate the potential remaining useful life (RUL) of an AMPCP. Introduction AMPCPs are composed of a metal stator and rotor, which enables them to operate in much higher temperature fluids compared with standard elastomeric PCPs. Because of metal-on-metal contact between the stator and rotor, AMPCPs typically experience more accelerated wear than elastomeric PCPs, resulting in reduced pump efficiency and shorter overall pump life. While decreasing pump efficiency can be a result of pump wear, it also can be caused by changes in operating conditions, such as increasing pump differential pressure or decreasing pump speed. For this reason, when estimating the state or condition of an AMPCP, pump efficiency alone may be a misleading or imperfect indicator. This paper expands on previous work in the literature by developing a condition indicator that can be used over the course of pump operation to diagnose pump-upset events or estimate the RUL of the AMPCP. Estimating Pump Wear Currently, no method exists of directly measuring the wear on the stator and rotor during operation. Earlier researchers proposed an indirect means of measuring stator and rotor wear based on the degradation of the pump-performance curve over time. The following calculation process is used to estimate the degradation in pump performance relative to a comparatively higher performing reference pump at any point in production. The estimate of pump performance is provided in the form of a pump-wear index (PWI). 1. A reference pump-performance curve is first selected and plotted. This pump-performance curve should correspond to a substantially more efficient pump and allow comparison of the performance of different actual operating pumps. The reference pump-performance curve selected by the authors in the complete paper reflects an operating speed of 200 rev/min. 2. The reference pump-performance curve then is shifted using an equation provided in the complete paper to be the performance curve for the reference pump running at the speed of the actual operating pump. The equation is derived using the assumption that pump slippage is independent of pump speed. The newly shifted reference pump-performance curve is calculated using a corresponding pump speed of 150 rev/min. 3. The volumetric efficiency of the actual operating pump is then plotted based on the pump’s actual operating differential pressure. 4. The degradation in pump performance, also referred to as the PWI, is then calculated as the ratio of the final reference pump speed to the actual operating pump speed. Thereafter, this procedure is then conducted for each production data point over the course of a pump’s time in operation.

Improved Prediction Model and Utilization of Pump as Turbine for Excess Power Saving from Large Pumping System in Saudi Arabia

The throttling process is frequently encountered in many industrial practices utilizing Pressure Reducing Valves (PRVs). This process is typically used to control pressure and flow in pipeline networks. The practice of utilizing PRVs is considered simple and cheap in terms of installation cost and control. It dissipates the excess fluid energy that can be used for other purposes. This paper studies the feasibility of utilizing the Pump as Turbine (PAT) concept to partially recover the excess power dissipated from PRVs located at the discharge lines of refined product shipping pumps at one of the hydrocarbon distribution facilities in Saudi Arabia. Multiple PAT installation layouts have been studied to achieve this goal, selecting the optimum option to maximize the power recovery. The final selection of PAT was conducted to achieve a reasonable payback period. A new method for predicting the pump performance in reverse mode was developed depending on the manufacturer’s pump performance curves. The comparison of the proposed model with experimental data and previous models for three modes of operation reveals that the proposed model in this paper’s results either have the minimum deviation or the second minimum deviation out of all models. In the case of flow ratio prediction, the predicted deviation is merely 3.83%, −1.14%, and 1.35% in three modes of operation. For power prediction, the proposed model is the best and the only reliable model out of all with the least deviation of −7.48%, 0.07%, and −3.16% in three modes of operation. The economic analysis reveals the Capital Payback Time (CPP) for five optimum PATs is around 5 years. The new method was also validated against previous models showing more precise performance prediction of multistage centrifugal pumps running in turbine mode.

Numerical and experimental study of mixed flow pump as turbine for remote rural micro hydro power plant application

The use of a pump as opposed to a turbine/pump as turbine (PAT) for off-grid electrification applications is one of the important ways to be considered in efforts to equalize electrical energy in Indonesia. The main problem in PAT applications is how to predict pump performance if applied as a turbine to find out its best characteristics and efficiency points. This study discusses a method to find pump performance specifications when using a pump with a mixed flow type as a turbine for Micro Hydro Power Plants. The numerical method by utilizing computational Fluid Dynamics (CFD) based software simulations that have been proven to be accurate according to previous studies was selected for use in obtaining predictions of the pump characteristics as turbines. Then the PAT characteristics of the CFD simulation results are validated by conducting direct testing. The results of the CFD numerical simulation using ANSYS Fluent software show the performance curve of a mixed flow pump operated as a turbine at various rotating speeds. The highest efficiency for each rotating speed ranges from 35-40%. The test results directly show the PAT characteristics, that the performance range is close to the numerical simulation results with a difference of 10%.

Active Optimization of Chilled Water Pump Running Number: Engineering Practice Validation

To realize building energy conservation, appropriate operation of building energy systems is necessary. A chilled water pump, an essential component for chilled water transportation in building cooling systems, consumes substantial energy. Hence, its operation should be optimized. Previous studies on optimal pump control mostly focused on pump speed/frequency control, while the control of pump running number is usually too passive to realize energy-saving objectives. Moreover, existing relevant studies have some disadvantages, such as (1) too complex a workflow for maintenance; (2) dependence on accurate system performance models that take substantial data and labor to establish; and (3) high requirements on monitoring and sensors. To tackle those problems, this article proposes a simple, feasible approach to optimize the running number (on/off status) of chilled water pumps for building energy conservation. The proposed method is merely based on similarity/affinity laws and pump performance curves feasible for engineering practices. It has been implemented on a real cooling system in a battery factory. Our results suggest that: (1) based on similarity/affinity laws and pump performance curves, the estimation of potential targeted pump working points is accurate enough for optimal control (the flow rate estimation error is less than 2%, the frequency estimation error is less than 1 Hz); (2) the energy-saving effect of this control method is evident (20% of pump energy is saved by the proposed method compared to the former control logic); (3) the water grid operation condition is maintained well: cooling supply is not sacrificed by the control intervention (compared to the working condition before the intervention, grid pressure difference changed by 1.4%, flow rate changed by 2.6%). Regarding the low preconditions, simple workflow, and acceptable energy-saving performance of the proposed method, it is suitable for energy conservation in building cooling systems.

Homologous curve generation for reactor coolant pump of small modular reactor by testing and CFD analysis

Nuclear-reactor safety verification in the design stage requires knowledge of the homologous curves (dimensionless performance curves) of the reactor-coolant pump. In this study, homologous curves for the pump of a small modular reactor were generated first experimentally and then via computational fluid dynamics (CFD). Most of the simulated homologous curves agreed closely with experiment. Moreover, the effect of increasing the working fluid temperature or reducing the flow rate and rotation speed were insignificant. Thus, in most cases, CFD can replace physical testing for the measurement of homologous curves; when tests are still needed, they can be conducted at low temperature and at flow rates and rotation speeds below the rated values.

Transient Characteristic Analysis of Variable Frequency Speed Regulation of Axial Flow Pump

In order to explore the influence of different rotational acceleration on the transient internal and external flow characteristics of the axial flow pump and improve the performance of the pump, numerical simulations and experiments were used to analyze the variable frequency speed regulation characteristics of the axial flow pump. Taking three-dimensional turbulent numerical simulation as the main research method and CFX as the calculation platform, three variable frequency speed regulation methods were used to conduct transient numerical simulation; keep the acceleration constant, increased and decreased; and obtain the real-time pump performance curve and pressure characteristic curve. Uniform acceleration and deceleration with constant acceleration maintained the stable change and good stability of head and shaft power, and the pressure change was the most stable in the process. The acceleration and deceleration with decreasing acceleration ran most smoothly at high speed, and the frequency conversion effect was the best. At the same time, the transition to steady-state operation was also the most stable. The research in this paper can provide reference for the stable operation of variable frequency speed regulation of the axial flow pump.

An Indirect Approach for Flow Pattern Transition Identification Inside a Low-Specific-Speed Centrifugal Pump with Experimental Verification and Theoretical Modeling

Summary Of significant importance to the multiphase flow, the gas/liquid two-phase flow patterns and the transition boundaries between them are extremely difficult to be characterized inside the centrifugal pumps because the steel-made nontransparent casing shrouds the impeller’s flow passages. How to visualize the internal flow patterns within the rotating impeller has drawn considerable attention. In this study, an indirect approach proposed by Gamboa and Prado (2011) to recognize the gas/liquid flow patterns in the centrifugal impeller via inflection characteristics of H-Q performance curves is used and verified by both experimental tests and numerical simulations. To further validate the indirect flow pattern recognition approach to a low-specific-speed centrifugal pump, the acrylic-made transparent impeller was adopted to conduct experimental testing, in which the internal two-phase flow pattern can be visualized by a high-speed camera. The 3D numerical simulation was performed and compared with corresponding visualization experiments to illustrate the two-phase flow structures. The preliminary results reveal that the inflection characteristics on the H-Q performance curves of the centrifugal pump can be regarded as the flow pattern transition boundaries under various flow conditions. The experiments and simulations conducted for this paper further validated an existing mechanistic model to predict flow pattern transitions.

Design and execution of a verification, validation, and uncertainty quantification plan for a numerical model of left ventricular flow after LVAD implantation.

Left ventricular assist devices (LVADs) are implantable pumps that act as a life support therapy for patients with severe heart failure. Despite improving the survival rate, LVAD therapy can carry major complications. Particularly, the flow distortion introduced by the LVAD in the left ventricle (LV) may induce thrombus formation. While previous works have used numerical models to study the impact of multiple variables in the intra-LV stagnation regions, a comprehensive validation analysis has never been executed. The main goal of this work is to present a model of the LV-LVAD system and to design and follow a verification, validation and uncertainty quantification (VVUQ) plan based on the ASME V&V40 and V&V20 standards to ensure credible predictions. The experiment used to validate the simulation is the SDSU cardiac simulator, a bench mock-up of the cardiovascular system that allows mimicking multiple operation conditions for the heart-LVAD system. The numerical model is based on Alya, the BSC's in-house platform for numerical modelling. Alya solves the Navier-Stokes equation with an Arbitrary Lagrangian-Eulerian (ALE) formulation in a deformable ventricle and includes pressure-driven valves, a 0D Windkessel model for the arterial output and a LVAD boundary condition modeled through a dynamic pressure-flow performance curve. The designed VVUQ plan involves: (a) a risk analysis and the associated credibility goals; (b) a verification stage to ensure correctness in the numerical solution procedure; (c) a sensitivity analysis to quantify the impact of the inputs on the four quantities of interest (QoIs) (average aortic root flow [Formula: see text], maximum aortic root flow [Formula: see text], average LVAD flow [Formula: see text], and maximum LVAD flow [Formula: see text]); (d) an uncertainty quantification using six validation experiments that include extreme operating conditions. Numerical code verification tests ensured correctness of the solution procedure and numerical calculation verification showed a grid convergence index (GCI)95% <3.3%. The total Sobol indices obtained during the sensitivity analysis demonstrated that the ejection fraction, the heart rate, and the pump performance curve coefficients are the most impactful inputs for the analysed QoIs. The Minkowski norm is used as validation metric for the uncertainty quantification. It shows that the midpoint cases have more accurate results when compared to the extreme cases. The total computational cost of the simulations was above 100 [core-years] executed in around three weeks time span in Marenostrum IV supercomputer. This work details a novel numerical model for the LV-LVAD system, that is supported by the design and execution of a VVUQ plan created following recognised international standards. We present a methodology demonstrating that stringent VVUQ according to ASME standards is feasible but computationally expensive.

Long-term performance investigation of a GSHP with actual size energy pile with PCM

• Long term Performance investigation of ground source heat pump system. • Energy pile coupled with phase change materials under an actual building load. • Optimization of Phase change materials’ location inside the energy pile concrete shell. • Effect of utilizing multiple PCM melting temperature inside a single energy pile. The use of geothermal energy has increased significantly (90 time) since 1995. Among these increases, Ground Source Heat Pumps (GSHP) has contributed by 40 times in an effort to reduce the burning of fossil fuels and contribute to the reduction of green house gas emissions. The space requirements and high initial cost of borehole fields hinder the widespread use of GSHPs. The use of foundation piles, used as a ground heat exchanger, has been proposed to overcome these limitations. Research has shown that foundation piles have a lower depth and smaller spacing compared to boreholes. Phase Change Materials (PCMs) have been proposed as a potential solution to increase the storage capacity and decrease the thermal radius of energy piles. In the current study, a 3-D finite element model was developed to study the effects of PCMs on the performance of energy piles against a real building load for a complete year, while integrating an actual heat pump (HP) performance curve into the numerical model. The effects of the PCM location and melting range were also investigated. The study revealed a 5.2% enhancement in the Coefficient of Performance (COP) during the melting of the PCM, and a negative effect of up to 1.8% during the completely solid-state. Locating the PCM cylinders inside of the concrete shell led to better performance compared to when the PCM cylinders were located outside of the concrete shell. The best locations were found to be between the center of he pile and the U-loop. The PCM melting range of (4–6)°C was better than the melting range of (1–3)°C for the current study load. Lastly, the use of multiple PCM melting temperatures for a given design was investigated. The results revealed that the use of multiple PCM melting temperatures led to a performance enhancement of up to 26%.

Numerical simulation of complex flow structures and pressure fluctuation at rotating stall conditions within a centrifugal pump

AbstractRotating stall contributes to global oscillation vibration problems, accompanied by noise and possible turbomachinery damage. This study with special emphasis on the vaned diffuser investigates the unsteady pressure interaction with the stall within the pump. A low specific speed centrifugal pump (ns = 69), fitted with a vaned diffuser is modeled and studied. The model pump performance curve shows the characteristic positive slope at 30% of the best efficiency point flow rate; 1.0 ΦΝ which is attributed to the stall phenomena. A finite volume method is employed with unsteady computations initialized utilizing shear stress transport k‐ω before proceeding with DDES. Pressure fluctuation and velocity magnitude normalized values are used to investigate the evolution of stall cell generation. The root mean square (RMS) values and normalized pressure (Cp) values are elicited to gain insight into pressure pulsation within the flow domain. The distinguished “starfish” shape is observed for monitor points md1 to md20, with the RMS trend decreasing with increasing flow rate from the pump shut off. Although in the vaned diffuser flow channel, an increase in pressure fluctuation along the flow channel toward the trailing edge is observed, the vaned diffuser channel shows a similar trend. The stall cell propagates at a speed of ΩRS = 0.078 at 0.2 ΦΝ, while at 0.1 ΦΝ propagates at a speed of ΩRS = 0.087; the stall speed tends to increase approaching pump shut off. Three distinguishable stall channels are observed from the flow structure for a five vaned diffuser; entering the stall, stalled, and stall recovery stages, within the flow channels.

Analysis of the Effect of Fan-Type Inducer Blade Angle on Pump Suction Performance

Industrial centrifugal pumps that require low NPSHR over a wide flow range, such as when pumping liquefied natural gas from storage tanks, are equipped with low solidity fan type inducers. Further improvement of pump suction performance is industrially expected because the lowest liquid level height that can be pumped directly affects the economic efficiency. In this study, several inducers made by a 3D printer were attached to an industrial centrifugal pump and investigated experimentally and using computational fluid dynamics to analyze the effect of the blade angle of the fan-type inducer on pump suction performance. The experimental results showed that the blade angle has no significant effect on the pump performance curve but has a clear influence on the pump suction performance, and CFD was used to investigate the cause of this for a flow rate with φ = 0.099, the design flow coefficient of the attached centrifugal pump. From the calculation results, the vapor volume was visualized and flow blockage due to cavitation in the internal flow path of the pump was analyzed. It was confirmed that the tendency of cavitation generation differs depending on the inducer vane angle even at the same cavitation number. Further analysis of the CFD results revealed that the influence of the swirling flow generated by the inducer on the flow field at the impeller inlet changed the occurrence of cavitation at the impeller inlet, leading to the occurrence of cavitation at the impeller inlet. As a result, the authors considered that there is a clear influence on the breakdown performance of the centrifugal pump.

Analysis of energy-saving effect of fresh air heat recovery system for residential buildings in severe cold area

In recent years, the tightness of residential buildings has been continuously enhanced, causing the problem of indoor air quality degradation. Therefore, it is necessary to introduce fresh air that meets the air quality requirements from the outside, and the outdoor air temperature in the severe cold area is low, which increases the fresh air load of the building. To save energy consumption, regularly use air heat recovery equipment to recover heat energy. In order to verify the energy-saving effect of the fresh air heat recovery system in residential buildings in severe cold areas, taking an experimental building in Shenyang as an example, the operating performance curve of an air source heat pump equipped with a fresh air heat recovery system was measured, and TRANSYS software was used to simulate and compare two kinds of heat recovery mode, namely the exhaust mixture of outdoor air and pure out door air low temperature heat source. The results show that when the exhaust air is mixed with outdoor air as the low-temperature side heat source, the average COP value reaches 3.24 and increases by 17%, which can save 7.6% of the energy consumption of the air source heat pump throughout the entire heating season.