Performance Characteristics Of Pump Research Articles

Experimental investigation on heating performance of a gas engine-driven heat pump system with R410A

• A novel energy-efficient GHP experimental platform is designed based on scroll compressors with R410A. • The effects of five factors on heating performances of the GHP system are systematically investigated. • The mode-4, which only recovers waste heat using the heating water, can improve the heating performance of the GHP system. • In mode-4, the PER is between 0.981 and 2.155, and the rate of waste heat recovery is between 49.12 % and 77.70 %. In this study, the performance characteristics of a gas engine-driven heat pump (GHP) system for heating applications were experimentally investigated. A novel energy-efficient air-source GHP experimental platform was designed based on scroll compressors with R410A. The changes in heating capacity ( Q h ), gas consumption power ( P gas ), compressor power ( P comp ), primary energy ratio ( PER ), and coefficient of performance ( COP ) were obtained under varying conditions of condenser water flow rate G w (6.10–15.25 m 3 /h), water inlet temperature t w,in (24.0–44.2 ℃), engine speed N eng (1200–2400 r/min), and ambient air temperature T amb (−15–7 ℃). The performances of the four heating modes (mode-1 to mode-4) were compared at an ambient air temperature of −20 ℃. The results showed that t w,in , N eng , and T amb had significant influences on heating performance, whereas G w had a slight impact. Compared with other heating modes, mode-4, wherein the recovered waste heat was only transferred to the heating water, could improve the heating performance of the GHP system. In the mode-4 heating experiments, PER was between 0.981 and 2.155, the rate of waste heat recovery was between 49.12 % and 77.70 %, and the engine thermal efficiency was between 27.02 % and 33.24 %.

Effects of a Detached Eddy Simulation-Curvature Correction (DES-CC) Turbulence Model on the Unsteady Flows of Side Channel Pumps

A side channel pump is a pump with a high head and a small flow that is widely used in various industrial fields. Many scientists have studied the hydraulic performance, pressure fluctuation characteristics, and gas-liquid mixed transport characteristics of this type of pump. However, these studies mainly focused on the single-stage impeller of the side channel pump, without considering the inter-stage connection channel and the multistage timing effect. These characteristics affect the hydraulic performance and pressure-pulsation characteristics of the side channel pump. Therefore, we carried out a numerical simulation and an experimental comparison on the multistage side channel pump to explore its flow characteristics during the stages. This study focused on the influence of different turbulence models on the numerical simulation of multistage side channel pumps. Shear stress transport (SST), detached eddy simulation (DES), and detached eddy simulation-curvature correction (DES-CC) turbulence models were selected for consideration. By studying the pressure and velocity streamline distribution, the turbulent kinetic energy, and the shape and volume of the vortex core area simulated by the three models, we concluded that the DES-CC model, when compared to the other models, can more fully reflect the vortex characteristics and the simulation results that are closer to the experimental data. The results of this study can be used as the basis for future research on multistage side channel pumps.

Optimal compressor discharge pressure and performance characteristics of transcritical CO2 heat pump for crude oil heating

The compressor discharge pressure is an important parameter for optimizing the performance of a transcritical CO2 heat pump system. In this study, the factors influencing the optimal compressor discharge pressure of an air source transcritical CO2 heat pump system were examined experimentally. The results showed that the optimal compressor discharge pressure is affected by the gas cooler water inlet temperature and gas cooler CO2 outlet temperature. Consequently, a correlation formula for the optimal compressor discharge pressure appropriate for a more comprehensive temperature range and higher prediction accuracy was determined based on the experimental data. Compared with the experimental results, the maximum error was less than 10%, which is minor considering the lower gas cooler CO2 outlet temperature. In addition, a control strategy for the optimal compressor discharge pressure based on the degree of superheat correction was proposed. Subsequently, under variable operating conditions, the air source transcritical CO2 heat pump crude oil heating system was continuously operated based on this control strategy. The results showed that the compressor discharge pressure agreed with the optimal compressor discharge pressure calculated using the new correlation formula. Compared with the control strategy of constant opening under a variable frequency mode, the results showed that the system could operate under the control strategy proposed in this paper, the thermodynamic perfection of the system being higher.

Optimization Design for the Centrifugal Pump under Non-Uniform Elbow Inflow Based on Orthogonal Test and GA_PSO

The non-uniform inflow caused by the elbow inlet is one of the main reasons for the low actual operation performance of a centrifugal pump. Orthogonal experiment and GA_PSO algorithm are used to improve the head and efficiency of a centrifugal pump with an elbow inlet based on the method combining numerical simulation and prototype experiment in this paper. The effects of the design parameters, including elbow inlet radius ratio, blade inlet angle, blade number, blade wrap angle, blade outlet angle, impeller outlet diameter, blade outlet width and flow area ratio, on the pump head and efficiency are studied in the orthogonal experiment. The blade inlet angle is the major factor to match the non-uniform inflow and reduce the flow loss in the impeller inlet to contribute to enhancing the pump performance and cavitation characteristics. The particle swarm optimization (PSO) algorithm is optimized by integrating the genetic algorithm (GA), which ensures that the PSO-calculation result avoids falling into the local optimization and the global optimal solution is obtained as quickly as possible. The centrifugal pump with an elbow inlet is optimally designed by the GA_PSO algorithm. According to the performance test results, the efficiency of the optimized pump is 4.7% higher than that of the original pump.

Energy performance and flow characteristics of a slanted axial-flow pump under cavitation conditions

Cavitation is a complex flow phenomenon that hinders the efficient, safe, and stable operation of hydraulic machinery. To investigate the effect of cavitation on energy performance and flow characteristics of hydraulic machinery, cavitating flow in a slanted axial-flow pump based on entropy production theory and vortex dynamics is studied. The results show that the impeller chamber is a primary region of cavitation and energy loss generation under different cavitation conditions, including the incipient, growing, and wedge-shaped cavitation stages. In the incipient cavitation stage, as degree of cavitation strengthens, the flow at the impeller blade is smooth with little cavitation, and the variation in entropy production is constant, resulting in a stable energy performance. As it evolves into the wedge-shaped stage, the cavitation grows from the tip region near the impeller blade to the hub. At this time, the entropy production increases in the impeller chamber, resulting in a drop in energy performance. Meanwhile, flow separation appears at the impeller blade, and a secondary tip leakage vortex is promoted. The region with high vorticity basically matches the region with the high local entropy production rate. According to the relative vorticity transport equation, compressibility of cavitation strongly affects the relative vorticity in the impeller chamber, indicating that cavitation indirectly increases entropy production and energy loss by affecting the vorticity distribution, resulting in the drop in energy performance.

Study on fluid dynamic characteristics of a low specific speed centrifugal pump with emphasis on trimming operations

In the present investigation, the fluid dynamic characteristics of a narrow channel centrifugal pump are studied using numerical simulations with special emphasis on pump trimming operations. The trimming operations at optimized rate, reduce the pressure fluctuations and hydraulic noise in pumps, but at the cost of pump performance characteristics. This has been extensively studied by the researchers in the past; however, the efficacy of trimming operations on industrial pumps with narrow channel passage impellers is to be explored. A low specific speed pump with narrow channel impeller passage and radial discharge volute (M1) with specific speed of 14.7 is considered for the present investigation. Detached Eddy Simulation (DES) is used in transient simulations and Fast Fourier Transform (FFT) is used to understand the pressure fluctuations and hydraulic noise at the Blade Pass Frequency (BPF) and its harmonics. The pressure fluctuation behavior along the impeller periphery is monitored at 30 equidistant probes and 7 probes covering the volute tongue. These results are compared with the similar study for impeller with oblique trimming of 30° (M2) and impeller oblique trimming along with volute trimming (M3). The flow behavior in M1 is dominated by a Jet-wake flow in the impeller passage which acts as a primary source of flow non-uniformity. The resulting non-uniform flow on the impeller periphery interacting with the volute tongue causes vortex shedding behind the volute tongue, subsequently leading to discharge recirculation in the impeller. The coefficient of pressure fluctuations near volute tongue at BPF is reduced by 10.3% in M2, whereas it is enhanced by 24% in M3 relative to M1. The enhanced vortex shedding behind the volute tongue in addition to the vortex train along the impeller periphery causes rise of the pressure fluctuations in M3.

Investigation on performance in water jet pump under turning conditions

Turning has a significant effect on the performance of water-jet pump. Here, the axial flow water-jet pump was used as the research object, the performance and inner flow characteristics of water-jet pump under different turning angle were simulated through numerical simulation. The thrust, vorticity, bubbles in impeller, vapor volume fraction and surface load of blade were analyzed in detail when the turning angles were ±10°, ±20°, and ±30°, respectively. The results demonstrate that the thrust of the water-jet pump decreases linearly with the increase of the turning angle. At the same angle, the thrust of the water-jet pump when turning right is larger than that when turning left, and the maximum thrust difference is 9.14% of that without the turning angle. As the turning angle increases, the overall pressure of the water-jet pump decreases and the streamline distribution gets turbulent gradually. The vortex direction is the same as the turning direction basically. And the vortex distribution range is smaller when turning right under the same turning angle. The cavitation bubbles in the impeller occur firstly at the rim of the blade inlet and develop to the middle of the blade as the turning angle increases. The cavitation area is concentrated on the blade at turning side and the cavitation area when turning right is smaller than that when turning left.

Theoretical performance characteristics of a travelling-wave phase-change thermoacoustic heat pump

Thermoacoustic technology is a promising approach for environmentally-benign, low-cost heat pumping. Herein, we present a theoretical investigation on phase-change thermoacoustic heat pumping employing both an ideal model (a short heat pump in a pure travelling-wave field), as well as a full-size, looped-tube thermoacoustic heat pump. In the analysis of the short heat pump, we identified and assessed the main factors and their influence on the performance of an ideal phase-change travelling-wave heat pump. The results show that, ideally, the cooling power can be significantly increased by up to one order of magnitude, and the COP (coefficient of performance) can also be improved by the incorporation of phase change into the thermoacoustic cycle. Meanwhile, the analysis of the full system provides a more practical view of the enhancement due to phase change. A significant increase of cooling power is observed in the phase-change system with a high concentration of the reactive component, but increased of the COP only occurs under small temperature differences (below 10 K). The main reason for the gap in observed performance between the ideal model and the full system is the deviation, under a large temperature difference, of the acoustic field from the requirements for effective enhancement, as revealed in the ideal model. Our results demonstrate the potential of the phase-change travelling-wave thermoacoustic heat pump for efficient and low-cost heat pumping, especially for small temperature difference applications.

Investigation on the Effect of Impeller Design Parameters on Performance of a Low Specific Speed Centrifugal Pump Using Taguchi Optimization Method

In order to investigate the effect of blade design on pump performance, a CFD analysis was carried out, and the results were compared with experimental performance data of a low specific speed radial pump, which presents a good agreement. After model verification, the effect of impeller geometrical parameters includes blade outlet angle, wrap angle, and width at the exit, was investigated on the pump’s performance. Moreover, these parameters were chosen on three levels using an L9 orthogonal standard array of the Taguchi optimization method. The efficient levels of variables were calculated using the analysis of variance (ANOVA) method. The results revealed that impeller width at exit and blade outlet angle is the most effective pump shaft power and efficiency parameters. To minimize power, the optimal levels are the outlet angle of 27∘∘, wrap angle of 150∘∘, and width at the exit of 9 mm. Further, an outlet angle of 23∘∘, a wrap angle of 155∘∘, and a width at the exit of 9 mm lead to maximum pump efficiency. According to the validation simulations, an increase of 2.4% inefficiency and a minimum power of 3.9KW were achieved. The Overall Evaluation Criteria (OEC) technique revealed that considering 23∘∘, 160∘∘, and 9 mm for outlet angle, wrap angle, and width at the exit, minimum shaft power, and maximum pump efficiency will be achieved. ANOVA introduced width at the exit as the most governing parameter of pump performance characteristics.

Experimentally determined effect of swirl on the performance of a rotodynamic pump

Pre-swirl in the approach flow towards a pump leads to a decreased efficiency or even to malfunctioning of a pump. Especially for pumping stations with large rotodynamic pumps, the risk of malfunctioning should be minimized. For this reason, hydraulic investigations are performed prior to the construction of pumping stations to assess the amount of pre-swirl in the approach flow and if needed, to design local measures to decrease it. This article presents a test set-up of a simplified pump sump in which the pump performance characteristics are measured at a real pump for a wide range of predefined corotating and counterrotating swirl angles. The swirl angles are measured in a transparent model pump at scale 1:1 with a swirl meter at four bell diameters above the bell-mouth. The findings discussed in this paper provide insight in the relation between pre-swirl in the approach flow and pump performance.

Two-Way Coupling Simulation of Solid-Liquid Two-Phase Flow and Wear Experiments in a Slurry Pump

The slurry pump is one of the most important pieces of equipment in mineral transportation and separation systems, and it has complex two-phase flow characteristics and wear mechanisms. By employing numerical and experimental methods, the solid–liquid two-phase flow characteristics and wear patterns were investigated in this study. A two-way coupling discrete phase model (DPM) method was used to predict the flow pattern and the wear location and shows good agreement with the experimental observations. The pump performance characteristics of numerical results under pure water conditions were consistent with the experimental results. The effects of particle parameters and operating conditions on the internal flow field and wear were compared and discussed. The results show that the wear degree increased with the increase in volume flow rate and solid volume fraction. With the increase in particle size, the wear range at the impeller inlet became significantly smaller, but the wear degree became obviously larger. This study provides a basis for reducing the wear and improving the hydraulic performance of slurry pumps.

Study of the influence of the design of a centrifugal wheel on the pressure characteristics of a multistage pump

The article presents the results of an experimental study of the influence of the number of blades on the pressure-energy characteristics of a multistage centrifugal pump. A vertical submersible multistage centrifugal pump was tested, in which impellers with a different number of blades (6, 7 and 8 blades) were varied. The wheels were manufactured using the latest rapid prototyping technology through SLA printing on high strength polymer resin. The operating speed of the pump was varied at 1450, 2050 and 2850 revolutions per minute (rpm). The effect of different numbers of impeller blades on the performance of a centrifugal pump was investigated on three parameters: pump head (H), hydraulic power and efficiency (η). As a result of the experiments, the dominant influence of the speed on the performance of the centrifugal pump was revealed. It was also found that all pump performance characteristics are generally sensitive to changes in rotational speed, and not to changes in the number of blades. As a result of the research, it was revealed that the flow rate during pump operation plays a key role in head, power and efficiency indicators. The conducted research allowed to conclude that the number of blades does not have a significant impact on the performance of a centrifugal pump.

Multiphase numerical analysis of the vortex formation near the suction of the vertically mounted axial-flow pump with influence of the free water level

Presented paper deals with the numerical investigation of a flow in a complete hydraulic system of a pump station. The station uses a recently developed high-efficiency axial-flow pump with the specific speed ns=680 min-1. The pump is vertically mounted in the suction object with the free water level and equipped with the suction bell and the suction cone with one rib. For the numerical simulations, the lowest possible water level is considered. Such scenario is the most limiting for the pump station design and need to be analysed properly. The unsteady multiphase numerical simulations were focused on the creation of the complex vortical structures at the suction part of the mentioned axial-flow pump. This phenomenon strongly influences the pump performance (hydraulic efficiency, delivery and suction head, etc.) and operation (especially the vibrations and noise) characteristics. The unsteady flows inside the investigated domains are simulated using Ansys Fluent with appropriate solver settings. The Scale Resolving Simulations (SRS) are used to model large vortices and the interaction between stationary and rotating parts.

Performance characteristics of centrifugal pump using central composite design

The influence of five major impeller parameters: the outer diameter, inletand outlet blade angles, number of blades and blade thickness on the performance was analysed using central composite design. In this work, design of experiments technique was used to develop second order regression model for assessing the pump performance characteristics. The results suggest that outer diameter, the number of blades and the blade thickness have strongly influenced the performance of the pump. Based on the requirements of head, efficiency, and power input, modification in dimension of these three parameters could yield a superior performance.

Effects of the Rates on the Performance and Pressure Pulsations of a High-Speed Pump with Straight Blade

Along with the crucial requirement for efficiency improvement in the cutting-edge petrochemical technology, the evaluation of the dynamic performance characteristics of high-speed pump is becoming increasingly important. It has become a main topic in the research of high-speed pump to minimize the pressure pulsation induced by the fluid in the pump body, so as to reduce the mechanical vibration. Although the research on the transient flow characteristic and pressure fluctuation of a high-speed pump with straight blades is of great significance, it has been seldom explored. In this work, the flow instability of a 16 straight-blade high-speed centrifugal pump is studied numerically at a rotational speed of 8500 rpm and flow rate of 3 m3/h. Results show that with the influence of rotor-stator interaction, time-domain pressure signals at the tongue show double peak characteristic, whereas a single peak characteristic exists at the diffuser wall. The pressure fluctuation near the tongue is reduced to approximately half of that at the volute wall by the water ring effect accompanied with the high-pressure factor. At the tongue region, the amplitude of the blade passing frequency is reduced by the unsteady flow, whereas the harmonic wave was increased at 2–4 times of the blade passing frequency.

Performance characteristics of a cascade multi-functional heat pump in the winter season

Cascade multi-functional heat pumps are becoming popular due to their ability to simultaneously provide cooling, heating, and hot water. In this study, the performance characteristics of a water-to-water cascade multi-functional heat pump designed to provide heating, hot water, and simultaneous heating and hot water during the winter season are analyzed according to variation in secondary fluid temperature. The simultaneous heating and hot water cycle was optimized to meet the design heating and hot water capacities by increasing the compressor speeds of the low stage and high stage cycles above those in the heating and hot water cycles. An increase in the outdoor heat exchanger entering water temperature increased the performance of the cascade multi-functional heat pump in all operating modes, while an increase in the indoor heat exchanger entering water temperature resulted in a decrease in the performance of the cascade multi-functional heat pump in all operating modes except the capacity of the hot water cycle in heating-hot water mode. Furthermore, an increase in the hot water entering water temperature resulted in a decrease in the performance of the cascade multi-functional heat pump. The cascade multi-functional heat pump in heating-hot water mode showed similar performance trends as individual heat pumps for space heating and hot water generation and provided much stable hot water capacity at varying outdoor entering water temperature conditions. Cascade multi-functional heat pumps have the potential to provide better energy efficiency at higher heating and hot water loads, and can, therefore, be used for simultaneous space heating and hot water generation in winter seasons.

Investigation of energy performance, internal flow and noise characteristics of miniature drainage pump under water–air multiphase flow: design and part load conditions

Investigation of energy performance, internal flow and noise characteristics of miniature drainage pump under water–air multiphase flow: design and part load conditions

Performance Characteristics and Energy Loss Analyses of a High-Speed Centrifugal Pump with Straight Blades

Along with the rapid growth of cutting-edge petrochemical technology and the pressing demand for efficiency improvement, evaluation of the performance characteristics of high-speed pump is becoming increasingly important. In this paper, numerical simulation is presented on the flow instability of a 16 straight-blade high-speed centrifugal pump with flow rate of 3 m3/h and rotating speed of 8500 rpm. Combined with the analysis of flow stability, the entropy production method is introduced to evaluate regions of high mechanical energy loss and its distribution at different flow rates. Results show that approximately 96% of the energy loss of the pump is produced in the volute, gap, and front and back chambers. Large energy loss is observed near the trailing edge of the blade and volute tongue, which are caused by the small region including both the high and low pressure gradients and large momentum exchange by the flow separation, respectively. Moreover, the rotor–stator interaction causes much energy loss at the wall of the volute and front and back chambers. Owing to the circumferential pressure gradient and the 90° leading edge of the straight blade, the fluid tends to form counter-rotating recirculation vortices. The large number of blades narrows the passage and limits the formation of large vortices in flow channels, thus the backflow phenomenon seems not to worsen with the rise of flow rates. Hence, the entropy production in most of the flow parts are insensitive to flow rates.

Multi-Objective Optimization of Efficiency and Pressure Fluctuation for Vertical Inline Pump

Vertical inline pump is a single-stage single-suction centrifugal pump. In order to save the installation space, there is a bent pipe before the impeller. In this paper, to achieve efficient and stable operation of the pump, a multi-objective optimization of efficiency and pressure fluctuation on the inlet pipe of vertical inline pump was proposed based on Latin Hypercube Sampling. The geometric shape of an inlet pipe is controlled by the mid curve and the shape of cross section. The fifth-order Bezier curve was adopted to fit the mid curve and a round cross section was set. Totally 7 design parameters of the inlet pipe were selected as design variables, and the pump efficiency and the pressure fluctuation amplitude at the tongue were set as the optimization objectives. 36 groups of sample points were obtained from Latin hypercube sampling (LHS). The results showed that at design flow rate, the efficiency increased from 77.60% to 79.33%. Comparing with prototype, the pressure fluctuation amplitudes of main frequency at two monitoring points were decreased by 0.89% and 9.15%. It was observed that the profile of inlet pipe has an obvious influence on the pump performance and unsteady flow characteristics. Therefore, the profile of inlet pipe will be the key component for the optimization of vertical inline pump, and this study can provide theoretical guidance for researching the hydraulic efficiency and unsteady pressure fluctuation.

Influence of engine torque fluctuations on performance characteristics of pumps mounted on vehicles

A fire pump mounted on the fire engine is driven by a car engine. The engine has plurality of combustion chambers and converts the reciprocating motion of the pistons into rotational motion while shifting the combustion timing of each combustion chambers. When the force generated by the combustion is converted into torque, periodic torque fluctuation is generated. Torque fluctuation finally generates the rotation fluctuation. We analyzed pump performance by the rotation with the sinusoidal fluctuation for the impeller. From the viewpoint of torque and total head, each variable fluctuated in the same phase, but it was confirmed that there was a difference in fluctuation range. With engine rotation fluctuation given to the pump, we verify the pressure characteristics and efficiency on the outlet side change by CFD. In this paper, therefore, we report the results of CFD on pump output characteristics when periodic rotational fluctuations occur due to unsteady torque characteristics of the engine.