Secondary Pump Research Articles

Study on the Internal Flow Characteristics of High Flowrate Emergency Drainage Series-parallel Pump

Abstract Floods have become the main natural disaster threatening the safety of peoples lives and property. It is of great significance to develop high flow emergency drainage equipment. An innovative structure of pumps with high flow rate and multiple operating conditions is proposed in this paper to achieve series and parallel operation. It established an automatic optimization platform that integrates functions such as 3D modeling, mesh generation, computational fluid dynamics, and scheme optimization, and developed an efficient hydraulic model for a volute mixed flow pump combining flow field diagnostic techniques. The research results indicate that the inlet distortion of the secondary stage pump is the main cause of pump performance loss for both series and parallel operation condition. The third-generation vortex identification method was used to diagnose the internal flow of the pump under two operating conditions and control strategies were proposed. The final optimization scheme show that the pump can reach 1800 m3/h with a head of 9.6m and efficiency of 80% in parallel operation condition. In series operation condition, the pump can reach 900 m3/h with a head of 18.3m and an efficiency of 75.3%.

A new approach to predict pump transient phenomena in Molten salt reactor Experiment (MSRE) by missing data identification and regeneration

Molten Salt Reactor Experiment (MSRE) is being extensively used for validating the computational tools for Molten Salt Reactors (MSRs). The pump transient tests were performed during the operation of MSRE to obtain the reactivity response to flow perturbation. The transient flow rate during this set of tests is required as input to predict the reactivity response. Since the primary loop of MSRE was not equipped with a flow rate meter, the transient flow rate, which is the crucial factor for the reactivity change in MSRE, is missing. Achieving an accurate simulation of the reactivity response to the MSRE pump transient tests necessitates a precise estimation of the transient flow rate.This paper endeavors to reconstruct the missing flow rate with the aim of offering a valuable input for simulating reactivity responses in the pump transient test series. In order to obtain an accurate transient flow rate, we employed a centrifugal pump transient model based on the affinity laws and solved the model for the MSRE secondary pump to validate the underlying assumptions of the model. In addition, we constructed the homologous pump head curves based on the water test data for the same purpose. The affinity law approximation is proved to be adequate in predicting the MSRE pump startup transient with the root-mean-square error (RMSE) in the normalized flow rate to be 0.03. On the other hand, for the MSRE pump coastdown transient, the preliminary results indicate that neither the affinity law approximation nor the homologous head curve is sufficient to provide acceptable predictions. To overcome this noticeable modeling deficit, we propose an innovative approach based on a straightforward data mining technique to regenerate the MSRE pump coastdown homologous relations using the measured data of the secondary pump. These relations are transferred to the primary pump and used to simultaneously solve for the impeller speed and the flow rate of the pump in the primary pump coastdown. With the new approach, the estimated RMSE in the normalized pump speed for the primary pump coastdown is reduced 0.0052. This excellent agreement validates the accurate calculations for the flow rate during the pump coastdown transient. We also performed an uncertainty analysis to quantify the confidence interval of the predicted quantities, which further justifies the robustness of the proposed approach.

Liftoff of a soft-actuated micro-aerial-robot powered by triboelectric nanogenerators

Aerial insects can nimbly navigate in cluttered natural environments while they interact with delicate objects such as flowers and leaves. To achieve insect-like agility and robustness, power dense dielectric elastomer actuators (DEAs) have been developed for driving sub-gram micro-aerial-vehicles (MAVs). However, despite exhibiting muscle-like bandwidth and resilience, DEAs require a high driving voltage in the range of 1 – 2 kilovolts. This requirement poses substantial challenges for developing compact boost electronics and energy sources, which prohibit power autonomous operations of soft-actuated sub-gram MAVs. Here, we develop a compact and high power triboelectric nanogenerator (TENG) that can effectively charge a high-voltage DEA and enable the liftoff of a soft-actuated MAV. We propose an In-plane Charge Pump (ICP) design that can deliver over 1500 V and 110 mW without requiring a secondary charge pump or magnetic circuit components such as inductors or transformers. Compared to conventional free-standing mode TENGs, our ICP design shows a 280 % and 920 % increase in voltage and energy generation, respectively. When this TENG powers a DEA-driven MAV, the 160 mg robot achieves liftoff with a lift-to-weight ratio of 1.75. This result highlights the potential of powering high-voltage microrobots with energy-harvesting devices.

The Application of Laser-Scanning 3D Model Reconstruction Technology for Visualizing a Decommissioning Model of the Heavy Water Research Reactor

Currently, over 100 nuclear power units globally have been in operation for more than 40 years. Hindered by the limitations of computer technology at the time, these nuclear facilities lack detailed electronic drawings. Activities such as equipment replacement and process circuit system modifications during operation result in discrepancies between paper drawings and actual conditions. Given the complexity and irreversibility of nuclear facility decommissioning activities, virtual simulation technology is often employed before the decommissioning process begins to assist in designing and validating decommissioning plans. Consequently, the creation of high-precision 3D models is crucial for subsequent decommissioning designs. Through innovatively utilizing laser-scanning 3D model reconstruction technology in the reconstruction of the model of China’s first heavy water research reactor undergoing decommissioning, this paper provides an overview of the process of laser-scanning 3D model reconstruction and its application in reconstructing the heavy water research reactor model. Using a 3D laser scanner, four decommissioning areas of the heavy water research reactor, including the reactor building, secondary water pump room, ventilation center, and low-level radioactive wastewater storage tank area, were subjected to 3D laser scanning. The acquired point cloud data from 572 scanning stations were processed using point cloud processing software for denoising, stitching, and triangulation. The triangulated model was then imported into modeling software for 3D reconstruction, ultimately establishing a digitalized model of the heavy water research reactor suitable for subsequent decommissioning simulation and design.

Wall-embedded micro heat pump for radiant heating in buildings: Evaluation of energy and thermal comfort performance

This paper presents a novel radiant heating system with a wall-embedded micro heat pump (WEMHP) for residential buildings. The interior surface temperature of the exterior wall-section empowered by the micro heat pump is independently controlled, enabling distributed thermal comfort delivery. The micro heat pump consists of a miniature compressor along with an aluminum roll-bond condenser and evaporator. In contrast to conventional hydronic radiant systems and heat pumps with separate indoor and outdoor units (i.e., split systems), the WEMHP is a “packaged” system that would not require on-site installation and charging of a secondary water loop and circulation pump or refrigerant piping. This could ultimately lead to reduced installation and maintenance costs. In this study, a detailed system model is presented and integrated with a single-zone building model to assess the energy performance of the WEMHP in heating mode. For a designed living room scenario with an external wall WEMHP-to-wall ratio (HPWR) of 0.6 and window-to-wall ratio (WWR) of 0.2, the simulation results show that up to 23 % energy savings compared with a baseline air-to-air heat pump are possible. The results also indicate the HPWR needs to be higher than 0.4 to achieve performance comparable to the baseline. Additionally, experiments were conducted in a laboratory environment in which surface temperatures were controlled to emulate different scenarios for integration of WEMHP technology and to evaluate thermal comfort conditions. The experimental results show that the median operative temperature differences in the indoor environment were within 0.5 °C for various locations while the largest radiant asymmetry was 2.2 °C for the designed room configuration. Moreover, simulations were conducted to evaluate thermal comfort conditions in applications having a smaller HPWR of 0.4 with various values of WWR. Overall, the combined simulation and experimental study shows that the WEMHP has potential to reduce energy use while maintaining thermal comfort at acceptable levels where the HPWR is higher than 0.4.

Experimental study on optimal heating cycle characteristics of CO2 secondary throttling heat pump system for electric vehicles

Experimental study on optimal heating cycle characteristics of CO2 secondary throttling heat pump system for electric vehicles

Experimental performance evaluation of water source heat pumps in different circumstances and comparison to air source heat pumps

This study aims to present a novel experimental method for studying the performance of wa-ter source heat pumps which have not received sufficient attention, although this is particu-larly important for hot regions with great potential of hot water sources. The experimental model has special characteristics as it allows to investigate the performance of heat pumps under different operating conditions and allows a comparison between different types of heat pumps without the need to install a ground heat exchanger. The ground heat exchanger is known to be the most expensive part of any experimental model. In addition to that, it only allows to study the performance under specific conditions. The ground heat exchanger was replaced by a secondary heat pump that allows to provide an environment that simulates the different operating conditions of different types of heat pumps. It was found that water source heat pumps are more efficient than air source heat pumps with efficiency that increases with increasing water source temperature. It was found that increasing the water source tempera-ture from 5 to 20 oC, improved the rate of heat extracted from the water source by 11.3% and the coefficient of performance by 2.8% for each degree. Another important feature of water source heat pumps is the stability of the energy flow rates, which is a guarantee of higher sea-sonal performance coefficients. It can be concluded that hot regions with high potential of hot water sources has valuable opportunities to invest in the field of water source heat pumps with the consequent significant energy savings.

Transient three-dimensional numerical simulation on asymmetrical flow and thermal characteristics of CEFR sodium pool under one secondary pump shaft stuck accident

The China Experimental Fast Reactor (CEFR) primary circuit adopts a pool-type structure. The sticking of the main circulating pump shaft in the secondary circuit is an important design-based accident for CEFR, and it is necessary to investigate the three-dimensional thermal-hydraulic phenomena in the sodium pool under the accident. However, conducting relevant experiments directly is almost impossible due to the large dimensions and intricate flow paths within the reactor. In the present work, the “modular modeling and integrated coupling calculation” method is used to build the detailed model and calculate the primary circuit of CEFR in a 1:1 scale. The three-dimensional thermal-hydraulic phenomena inside the sodium pool under the accident condition of one secondary circuit pump shaft stuck are simulated. According to the calculation results, the backflow phenomenon of the fault loop pressure pipe and the intermediate heat exchanger (IHX) begins to appear around 50 s. An obvious thermal stratification phenomenon occurs in the hot pool at the beginning of the accident. As the accident progresses, the temperature difference between the hot and cold pools decreases gradually, and the thermal stratification of the hot pool gradually diminishes. The temperature difference between the inlet and outlet of the same IHX decreases from a maximum of 170 °Cto 2 °C. During the course of the accident, the peak temperatures calculated for the fuel assembly cladding and fuel pellet are 541.78 °C and 1040.17 °C, respectively, which is far below the designed temperature limit of 800 °C and 2800 °C, respectively. Moreover, comparative analysis is conducted on the simulation results of pump shaft stuck in the primary and secondary circuits. The results suggest that when the shaft of one secondary circuit pump is stuck, the average temperature of the sodium at the outlet of the core is higher and the temperature difference between the inlet of different loop pumps is greater, which places more substantial demands on the reactor component structure. It provides significant numerical reference for the safety design and assessment of CEFR.

Stack cooling system coupled with secondary heat pump in fuel cell electric vehicles

Fuel cell electric vehicles (FCEVs) requires proper thermal management of a proton-exchange membrane fuel cell (PEMFC) stack, but conventional thermal management systems (TMSs) cannot manage the thermal requirements of PEMFCs under high-power density at high ambient temperatures. In this study, a stack cooling system coupled with a secondary heat pump in an FCEV is suggested. The enhanced thermal flexibility of the secondary heat pump system enabled extensive cooling with various TMS configurations. The cooling performance with different TMS configurations was evaluated, considering the thermal and electrical coupling of the heat pump system and the PEMFC stack. The results show that the stack temperature was lowered up to 2.6 °C when the excessive cooling load of the stack radiator was distributed to the cabin radiator under a relatively low-power output condition. To dissipate a large amount of waste heat from the stack, TMS requires a temporary shutdown of the cabin cooling system. In this case, utilizing the inactive outdoor heat exchanger as an additional radiator decreased the temperature up to 18.4 °C by extending the heat transfer area for stack cooling. This study proposes a cooling scheme for an FCEV and suggests appropriate cooling methods and configurations under various operating conditions.

Fault detection and isolation for a secondary loop refrigeration system

Secondary loop refrigeration systems offer advantages over conventional system architectures: refrigerant charge reduction, maintenance simplification, and reduced safety hazards. Currently, no model-based fault detection for a secondary loop system has been reported. This article presents a fault detection and isolation scheme for a secondary loop refrigeration system where parametric faults (dirt/ice-buildup and secondary loop pump failure) and sensor faults (four temperature sensors in the secondary loop) are detected and isolated. The fault detection and isolation system is based on unknown input observers and on extended Kalman filters. The models are obtained through physical relations combined with experimental parameter determination (gray-box model) and are cross-validated against measurement data. The complete fault detection and isolation architecture is experimentally validated on a secondary loop refrigeration system mounted on a cooling box inside a climate chamber. Experimental results show that important parametric faults can be reliably detected and isolated, and the fault detection and isolation of sensor faults are effective.

Battery thermal management strategy utilizing a secondary heat pump in electric vehicle under cold-start conditions

When an energy storage system (ESS) operates in cold conditions, the power and capacity of the battery critically fade. Therefore, an appropriate battery thermal management strategy (BTMS) is essential to prevent severe driving range loss at low ambient temperatures. However, none of existing studies considered the effect of BTMS on the driving range from a systematic perspective. Thus, we evaluated the trade-off between the performance enhancement by ESS heating and the additional energy consumption for ESS heating. We suggested and analyzed three BTMSs combined with a secondary heat pump: self-heating, active heating, and heat recovery. Active heating of the battery augmented the driving range of the EV by up to 18.8% over the self-heating strategy when the battery was used to full depletion, whereas the heat recovery strategy reduced the state-of-charge (SOC) decrease and thus increased EV driving range in nondepleted conditions. Furthermore, battery preheating with the heat pump achieved a temperature rise of 20 °C within an hour, consuming 38.4% less battery power than with conventional electric heater preheating. We expect this study contributes to the range extension of EV by suggesting the optimal BTMS depending on the driving conditions.

Preclinical evaluation of the fluid dynamics and hemocompatibility of the Corheart 6 left ventricular assist device.

Corheart 6 (Corheart) is a newly developed magnetically levitated continuous-flow left ventricular assist device currently undergoing multicenter clinical trials in China. Featuring a small size, minimal weight, and low power consumption, the Corheart aims to improve pump hemocompatibility, reduce adverse events, and enhance the quality of life of heart failure patients. Computational simulations assessed flow field, shear stress, and washout, while in vitro and in vivo experiments were performed to further demonstrate hemocompatibility. Numerical results show that the flow path in the Corheart blood pump is well designed. There is no significantly high shear stress in the majority of the flow domain. Short secondary flow paths and small pump size (small priming volume) provide good washing (0.049 and 0.165 s to remove 55% and 95% old blood, respectively), allowing low hemolysis levels both in computational and in vitro hemolysis tests (in vitro hemolysis index ranges from 0.00092 ± 0.00006 g/100 L to 0.00134 ± 0.00019 g/100 L). Good hemocompatibility was further evidenced by ten 60-day sheep implants tested with relatively low flow rates of 2.0 ± 0.2L/min; the results showed no hemolysis or thrombosis. Numerical and experimental results shed light on the fluid dynamics characteristics and hemocompatibility of the Corheart. It is believed that the Corheart will provide more promising possibilities for minimally invasive implantation techniques and for those patients with a small body surface area.

Weibull model for RUL estimation at RSG-GAS reactor implemented on PA01-AP01 secondary pump

Abstract Remaining Useful Life (RUL) estimation has been extensively explored in recent years. RUL could be used in deciding the maintenance timeline or inspection interval for the Reaktor Serba Guna – G. A. Siwabessy (RSG-GAS reactor). RSG-GAS reactor is a pool-type research reactor (built by the Interatom Internationale of Germany) and has been operating for more than 30 years to date. This study aimed to propose a Weibull model to find the RUL estimation value of the distribution parameters of the mean time to failure (MTTF). Therefore, the RSG-GAS reactor would be higher safety, longer lifetime and higher reliability with a smaller failure rate including for the PA01-AP01 secondary pump. The research methodology is processing data collection and estimating the parameters of the Weibull model to determine maintenance timeline or inspection intervals based on the MTTF value in case the reliability has reached the targeted percentage. Results show that the RUL estimation has been obtained for the RSG-GAS reactor. In the implemented study, a maintenance timeline has been stipulated for the PA01-AP01 secondary pump (with the model of KSB and type of CPK-S350-400) for the reliability of 90% and RUL estimation of circa 29 days.

Potential assessment of transcritical CO2 secondary loop heat pump for electric vehicles

The excellent heating performance and environmental advantages of the transcritical CO2 heat pump system make it a great fit for the electric vehicles (EVs). However, the high operating pressure leads to the possibility of excessive CO2 concentration in the cabin. To ensure the safety of passengers, a secondary loop (SL) system is proposed. In this study, we make a comparison between the traditional direct (TD) system and the SL system for an EV. The results show that the optimal coolant flow rate, with a range of 0.56 to 1.36 L/min in heating mode and 5.60 to 8.80 L/min in cooling mode, can increase the COP of the SL system in all working situations. In the heating mode, the COP of the SL system is 13.98% to 21.96% lower than that of the TD system, and the cruising range of the EV is reduced by 1.4 km ∼ 10.0 km. In cooling mode, the COP of the SL system is 16.95% to 22.45% lower than that of the TD system, and the cruising range has a reduction of 7.7 km ∼ 20.9 km. Results demonstrate that running the SL system in cooling mode rather than heating mode is more detrimental to EVs.

Performance evaluation of plasma nitrided 316L stainless steel during long term high temperature sodium exposure

Enhancement of wear resistance of components used in fast reactors is necessary for long service life of the components. Plasma nitriding is a promising surface modification technology to impart high hardness and improved wear resistance of various steel components. This study discusses the characterization of chrome nitrided SS316L casing ring used in secondary sodium pump of fast breeder reactor and its stability under long term sodium exposure. Microstructural and hardness analysis showed that stress relieved component could be chrome nitrided successfully to a thickness of about 100 μm. Assessment of in-sodium performance of the chrome nitrided casing ring subjected to long term exposure up to 5000h at 550°C, showed retention of chrome nitrided layer with a case depth almost similar to that before sodium exposure. A slight decrease in the hardness was observed due to prolonged high temperature sodium exposure. Tribological studies indicate very low coefficient of friction indicating the retention of good wear resistance of the coating even after long term sodium exposure.

Post-Implant Phosphodiesterase-5 Inhibitors in Patients with Left Ventricular Assist Device: A Systematic Review and Meta-Analysis.

Background: Despite the improvement in left ventricular assist device (LVAD) technology and the advent of third-generation LVADs, hemocompatibility-related events remain a significant issue. Therefore, new pharmacological treatments are necessary to optimize patient management and to further reduce hemocompatibility-related events. The purpose of the present systematic review and meta-analysis was to summarize the existing data regarding the safety and efficacy of post-implant phosphodiesterase-5 inhibitors (PDE-5i) on hemocompatibility-related events. Methods: Among the 258 articles in Pubmed, Scopus, and CENTRAL that were retrieved (1990–2022), 15 studies were included in the qualitative synthesis, and 9 studies were included in the quantitative synthesis. The fixed-effects model was used because it is statistically sound for combining a very small number of studies. The primary endpoint of the study was all-cause mortality, whereas the secondary endpoints were ischemic stroke, pump thrombosis, and gastrointestinal bleeding. Results: Mortality was significantly lower in the PDE-5i group vs. the control group (OR: 0.92 [95% CI: 0.85, 0.98]; p = 0.02). The secondary endpoints ischemic stroke (OR: 0.87 [95% CI: 0.78, 0.98]; p = 0.02) and pump thrombosis (OR: 0.90 [95% CI: 0.82, 0.99]; p = 0.04) were also lower in the PDE-5i group. The incidence of gastrointestinal bleeding was significantly higher in patients with LVAD receiving PDE-5i (OR: 1.26 [95% CI: 1.11, 1.44]; p < 0.01). In the overall analysis, the heterogeneity of outcomes was low, except for pump thrombosis. Conclusions: The use of PDE-5i post-implant was associated with lower mortality and thrombotic events but with a higher risk of gastrointestinal bleeding.

Observation and biomedical application of plasmon-enhanced fluorescence induced multiple stimulated Stokes Raman scattering in FITC-conjugated gold nanoparticles solution

This work describes the observation of multi-wavelengths due to stimulated Raman scattering from deep red to near-infrared (NIR) induced by plasmon-enhanced fluorescence (PEF) of fluorescein isothiocyanate (FITC) conjugated gold nanoparticles (F-AuNP) excited by 488 nm diode laser. Coupling between the near-field of localized surface plasmons of AuNP with molecules amplifies the fluorescence signal i.e. brightness hence the quantum yield by several orders of magnitude. Resonance Rayleigh scattering and PEF conditions are satisfied due to the overlapping of 488 nm of the laser beam with the maximum absorbance of FITC, and the SPR of AuNP with FITC emission spectrum at ≈525 nm. PEF acts as Stoke sand secondary pump beam for further optical excitation. Surface-enhanced Raman scattering (SERS) showed FITC molecular bonds at 600, 1680, and a weak deviation at 1280 cm−1, respectively. Longer wavelengths with higher output power were observed between 180° and 270°, and shorter wavelengths with lower power between 90° and 0° respectively. F-AuNPs were incubated and up taken by the oyster mushroom (OM) grown in the lab for bioimaging purposes and studied by phase-contrast microscope (PCM), and fluorescence microscope (FM). The FM results revealed visible colours, which can be utilized for in vitro and in vivo biosensing applications.

Development of Flow-Based Heating Supply Water Temperature Control for Apartment Building Using District Heating System

In the heating supply systems in apartment buildings utilizing district heating, the supply water temperature setting is a critical control for providing sufficient heating and effective usage of the heating energy. Conventional water temperature control methods such as fixed temperature (FT) control can result in energy wastage and outdoor air temperature reset (OTR) control cannot reflect the variation in the heating demands of households because it only considers the outdoor air temperature. Therefore, this study proposes an advanced control method called flow-based residential energy demand (f-RED) control, which sets the supply water temperature based on the outdoor air temperature and household heating demands (i.e., the changes in the circulated heating water flow). To determine the performance of the proposed method compared to the conventional one, this study utilizes building energy simulation. The simulation analysis results confirm that the f-RED control method appropriately sets the supply water temperature based on a combination of the two factors, supplies heat according to heating demands, and reduces the energy consumption of the circulation pump by approximately 1.6% and that of the secondary pump by 4.2%. Thus, the f-RED control method is able to utilize heat energy more effectively and efficiently than the conventional control method.

Pressure-Enhanced Liquid Chromatography, a Proof of Concept: Tuning Selectivity with Pressure Changes and Gradients.

Many chromatographers have observed that the operating pressure can dramatically change the chromatographic retention of solutes. Small molecules show observables changes, yet even more sizable effects are encountered with large biomolecules. With this work, we have explored the use of pressure as a method development parameter to alter the reversed-phase selectivity of peptide and protein separations. An apparatus for the facile manipulation of column pressure was assembled through a two-pump system and postcolumn flow restriction. The primary pump provided an eluent flow through the column, while the secondary pump provided a pressure-modulating flow at a tee junction after the column but ahead of a flow restrictor. Using this setup, we were able to quickly program various constant pressure changes and even pressure gradients. It was reconfirmed that pressure changes impact the retention of large molecules to a much greater degree than small molecules, making it especially interesting to consider the use of pressure to selectively separate solutes of different sizes. The addition of pressure to bring the column operating pressure beyond 500 bar was enough to change the elution order of insulin (a peptide hormone) and cytochrome C (a small serum protein). Moreover, with the proposed setup, it was possible to combine eluent and pressure gradients in the same analytical run. This advanced technique was applied to improve the separation of insulin from one of its forced degradation impurities. We have referred to this method as pressure-enhanced liquid chromatography and believe that it can offer unseen selectivity, starting with peptide and protein reversed-phase separations.

Mechanism Study of Hydrocarbon Differential Distribution Controlled by the Activity of Growing Faults in Faulted Basins: Case Study of Paleogene in the Wang Guantun Area, Bohai Bay Basin, China

Abstract Mechanisms that lead to different quantities of hydrocarbon accumulation in complex fault blocks are a major subject that impacts further development plans of oil and gas fields. To better understand such mechanisms, fault activity has been interpreted along with existing electron micrographs from the fault zone, petrophysical data, and the occurrence of the seismic pump. This enabled us to investigate the controlling mechanisms of the growth faults and other associated faults with the main growth fault in the Wang Guantun area that could have impacted hydrocarbon distribution. The results showed that the activity of Kongdong growth fault is periodic and intermittent, which produced strong seismic pumping action. Furthermore, a series of secondary faults were generated in adjacent strata due to the fault activity, which could have led to the formation of a secondary seismic pump source. A combination of these two incidents is believed to influence the differential distribution of hydrocarbons in the area, in fault-associated reservoirs. Ultimately, we correlated the activity of the growth fault to the strength of the pumping force causing the distribution of hydrocarbons in the active parts of the faults (pump source position) on the horizontal plane and vertically located reservoirs to be more dominant.