High Pump Research Articles

Degradation Identification of an EHA Piston Pump by Analysis of Load-Holding States

In pursuit of advancing the development of more electric aircraft, the present research explores the forefront capabilities of electro-hydrostatic actuators (EHAs) as potential replacements for conventional hydraulic flight control systems. EHAs are currently used primarily as backup options due to their limited durability. As of now, the high dynamic axial piston pump is the main cause of the limited longevity of the EHA, due to strong tribological wear. The primary objective of this investigation is the identification of parameters and pump behavior to determine the current wear of the pump, as well as providing valuable insights into run-ins, temperature dependencies, and wear-related efficiency losses for future pump improvements. In the scope of this paper, the design of EHAs is explained in detail and the impact of challenging working conditions on the health status of the pump by comprehensive analysis of load-holding modes is examined. The experimental data for analysis is conducted on a longevity test bench with test profiles specifically designed to simulate real-world operational scenarios.

High efficiency LD end surface pumping quasi continuous 355nm laser

High efficiency LD end surface pumping quasi continuous 355nm laser

Mud infiltration and travel paths during mud loss experiments on horizontal borehole stability

Excessive mud pressure may endanger stability of horizontal boreholes and the success of drilling and reaming processes during Horizontal Directional Drilling (HDD). However, no laboratory studies have been undertaken to investigate the relationship between horizontal borehole instability (resulting in mud loss rather than borehole collapse) and mud infiltration and travel paths from the borehole to the ground surface. In this paper, exhumations after a series of mud loss experiments in a medium-scale test pit are used to explore mud infiltration into the sand surrounding the borehole, and the paths used to travel from the borehole to the ground. Different factors are investigated including burial depths, pump rates and the effect of multi-layered soil systems (dense sand covered by different thicknesses of loose sand or dense sandy gravel). Details of the mud travel paths from the experiments are presented. Water contents and average radial extent of mud infiltration around the boreholes are summarized. It is concluded that shear failure of the sand has a dominant role in defining the mud transport through coarse-grained soil. A primary crack appearing on the ground surface approximately above and parallel to the borehole, and secondary cracks transverse to the primary cracks then developed, linking the volumetric expansion of the sand due to mud intrusion and uplift at the ground surface. Ground movements are more dramatic in experiments involving high pump rate but the movements were reduced in experiments involving multi-layered soil systems.

Out-of-equilibrium dynamics of a grid-like Fe(ii) spin crossover dimer triggered by a two-photon excitation.

The application of two-photon excitation (TPE) in the study of light-responsive materials holds immense potential due to its deeper penetration and reduced photodamage. Despite these benefits, TPE has been underutilised in the investigation of the photoinduced spin crossover (SCO) phenomenon. Here, we employ TPE to delve into the out-of-equilibrium dynamics of a SCO FeII dimer of the form [FeII(HL)2]2(BF4)4·2MeCN (HL = 3,5-bis{6-(2,2'-bipyridyl)}pyrazole). Optical transient absorption (OTA) spectroscopy in solution proves that the same dynamics take place under both one-photon excitation (OPE) and TPE. The results show the emergence of the photoinduced high spin state in less than 2 ps and with a lifetime of 147 ns. Time-resolved photocrystallography (TRXRD) reveals a single molecular reorganisation within the first 500 ps following TPE. Additionally, variable temperature single crystal X-ray diffraction (VTSCXRD) and magnetic susceptibility measurements confirm that the thermal transition is silenced by the solvent. While the results of the OTA and TRXRD utilising TPE are intriguing, the high pump fluencies required to excite enough metal centres to the high spin state may impair its practical application. Nonetheless, this study sheds light on the potential of TPE for the investigation of the out-of-equilibrium dynamics of SCO complexes.

Spatio-temporal study of single and multi-wavelength quasi-continuous-wave generation regimes in an all-normal dispersion ring cavity

In this paper, we report a comprehensive experimental study of quasi-continuous-wave operation in an all-normal-dispersion ring cavity laser with nonlinear polarization rotation based saturable absorber action. Using the temporal mapping technique, we analyze in real time spiking dynamics, characterized by the existence of ephemeral spikes that continually emerge and decay amidst the background radiation. In particular, the effects of the pumping level and its direction of variation on the laser emission dynamics were analyzed. The overall behavior, in particular the well-defined pattern of spike evolution between their emergence until their vanishing, is found to be qualitatively invariant over a broad range of pump power, from 70 mW to 550 mW, albeit the values of spiking parameters vary widely over this range. The spiking phenomenon appears from low pumping powers, just above the laser threshold. A phenomenon of hysteresis was also discovered, as some emission parameters, in particular the optical spectrum, depend on whether pump power is being raised or decreased. 2D autocorrelation analysis also proved insightful, showing that each spike appears at random, having no connection with other spikes. Finally, high pump power settings and birefringence adjustments enabled the discovery of more complex spiking dynamics where emission at various wavelengths occur, some of the lines presenting additional slow dynamics at the millisecond scale. These results indicate that deterministic complexity is, together with stochasticity, an essential ingredient to take into account for a better understanding of the operational modes in fiber lasers far from the pulsed regime.

OPTIMIZATION OF OPERATION MODES OF THE PLUNGER PUMP OF THE FORMATION PRESSURE MAINTENANCE SYSTEM

The efficiency of pumping equipment in the context of continuous growth in electricity prices is a priority for any oil and gas production department (OGPD). The pumping stations of the reservoir pressure maintenance system are the main consumers of electricity in the OGPD. The efficiency of pumping units, as a rule, is reduced primarily to the value of their efficiency, and the criterion for the efficiency of the injection system is usually the consumption of electrical energy per unit volume of pumped liquid. At the same time, they often focus only on maintaining high pump efficiency, which optimizes pump operation, but does not take into account the impact of collectors on electricity costs.Typically, the PPD pump station will inject service water into several directions. The purpose of the studies is to find optimal modes of pumping by pumps of a pump station in several directions, which ensure minimum electric power consumption for injection. The presented article presents the calculation of the cost of pumping by one plunger (volume) pump into two directions during laminar movement of liquid in the pipeline. Injection volumes for each area are specified. Three options are considered: separate injection in each direction (1), parallel injection in both directions simultaneously until the ordered volume is injected in one of the directions, after which this direction is blocked and injection in the other direction (2), and parallel injection in both directions simultaneously with «pressed» one direction, so that the injection of the ordered volumes is completed simultaneously (3).The performed calculations showed that the useful operation of the pump performed during simultaneous pumping of some volumes of liquid (modes 2 and 3) in two different directions of the same system is the same and significantly less compared to the operation of the pump performed to fill one of these directions during separate pumping (mode 1). The maximum effect is achieved with equal injection volumes in each direction and the same reservoirs. In this case, the useful operation of the pump for simultaneous injection (mode 2 and 3) is half as much as for separate injection (mode 1).

Electrostatic-hydraulic coupled soft actuator for micropump application

The development of a soft actuator with high displacement is crucial for the effective operation of micropumps, ensuring a high fluid pump rate. This study introduces an innovative approach by presenting the design and fabrication of a novel electrostatic-hydraulic coupled soft actuator for a micropump within a microfluidic system. This pioneering soft actuator, leveraging electrostatic-hydraulic coupling, showcases a unique solution to enhance the performance of micropumps. The versatility of such a soft actuator makes it particularly promising for biomedical applications. The actuator comprises dielectric fluid in an elastomeric shell and electrodes to form the out-of-plane fluid-amplified displacement. This displacement amplification was used to generate a pumping actuation in the micropump. The actuator was characterized in terms of dielectric fluid volume, electrode size, temporal response, and amplification displacement. The soft actuator showed a maximum amplified displacement of 0.51 mm at 10 kV of the applied voltage, but a higher voltage caused a dielectric breakdown. Moreover, the actuator demonstrated the ability to operate at frequencies of 0.25 Hz and 0.1 Hz. The results of the study indicate that the fabricated electrostatic-hydraulic coupled soft actuator is a dependable and effective method of actuation for a micropump in a microfluidic system. The experimental characterization of the micropump revealed a maximum flow rate of 2304 μl min−1.

Fluidic laser beam shaper based on thermal lens effect in MoS2 and its application in optical trapping

In this work, we develop a fluidic laser beam shaper based on the thermal lens effect in MoS2 suspensions. It is demonstrated that another weak unfocused Gaussian beam (probe beam) is transformed into an annular beam due to the thermal lens effect resulting from a strong focused Gaussian beam (pump beam). The time evolution of the generated annular beam is studied, and the result shows that the annular beam exhibits asymmetric caused by heat convection with the high pump beam power. In addition, the tunability of the generated annular beam is investigated. Furthermore, the optical trapping of micro-sized particles in air using the annular beam is researched. It is found that this method exhibits stable performance capture for 3 h. The advantages of adjustable size, flexible setup and low cost of annular beam generated method are significant for lots of laser applications, such as optical trapping, optical imaging and laser machining.

Techno-economic assessment and grid impact of Thermally-Integrated Pumped Thermal Energy Storage (TI-PTES) systems coupled with photovoltaic plants for small-scale applications

The growing share of Renewable Energy Sources (RES) is rising the amount of curtailed energy to preserve grid security. With the aim of evaluating a complementary storage solution to electric batteries for both new and revamping RES power plants, this study investigates the performance of a Thermally Integrated Pumped Thermal Energy Storage (TI-PTES) system integrated with a Photovoltaic (PV) power plant aimed to enhance the energy self-sufficiency of small-scale users. The assessment is carried out for a case study characterized by a demand of electricity, heating and cooling that vary throughout the year. The studied PTES system is based on the integration of a High Temperature Heat Pump (HTHP), two Thermal Energy Storage (TES) sections and an Organic Rankine Cycle (ORC) power plant. Results show the influence of the main design parameters, such as PV size, HTHP size and TES capacities on the overall system performance, evaluated by means of the energy self-sufficiency, energy self-consumption, round-trip efficiency, Levelized Cost of Storage and the Grid Impact indicator, which quantifies the energy exchanges with the grid (feed-ins and withdrawals) to the overall user demand. The influence of seasonality on the energy performance indicators was studied as well. For the case study considered, the best combination of design parameters for the PV-PTES system is identified with reference to a PV plant whose yearly energy production equals the energy demand and for a 55 kWe High Temperature Heat Pump, a 10 kW ORC and a storage volume of 48 m3 for each of the two TES units. The PTES system is characterized by a LCOS of 0.72 $/kWh, a round-trip efficiency of 28.2 % and its integration offers several advantages over the use of a PV plant without any storage section. In particular, the PTES unit leads to a substantial increase in the self-sufficiency, within the range 1–14 %, and a considerable decrease of the grid impact indicator, within the range 2–28 %.

Low-threshold lasing from bound states in the continuum with dielectric metasurfaces

Bound states in the continuum (BICs) with extremely large quality factors (Q factors) can enhance the light–matter interaction and thus achieve low-threshold lasing. Here, we theoretically propose and experimentally demonstrate the low-threshold lasing at room temperature based on BICs. A threshold of approximately 306.7 W/cm2 (peak intensity) under a 7.5 ns-pulsed optical excitation is presented in an all-dielectric metasurface system consisting of titanium dioxide (TiO2) nanopillars with a dye film. Also, the multimode lasing can be excited by the higher pumping. Our results may find exciting applications in on-chip coherent light sources, filtering, and sensing.

A preliminary analysis of the potential reduction of CO2 emissions by using high temperature heat pumps in residential buildings in Italy

The present research aims to provide an innovative contribution to the reduction of fossil fuels and the consequent reduction of CO2eq emissions for each Italian region. Simulations have been carried out to replace space heating boilers supplied with fossil fuels with air to water heat pumps, when the environmental conditions (external temperature, temperature of the water in the emission systems, etc. ) allow it. In order to estimate the potential covering of high temperature heat pumps in Italy energy profiles of buildings have been considered together with the potential COP of heat pumps working with variable climatic control supply temperature. The potential electrification for buildings’ space heating has been estimated subdividing Italy into 21 territorial units. The work has shown that 83% of heating energy which can be covered by the heat pumps in Milan and almost 100% in Lecce. Overall, in Italy 146 TWh of current energy consumed by fossil fuels could be covered by heat pumps; at the same time 45 TWh of electric energy has to be generated to drive the heat pumps.

Cherenkov-type terahertz generation by optical rectification in KD2PO4 (DKDP) crystal

The potential of KD2PO4 (or DKDP) crystal as a terahertz generator is demonstrated, despite its extremely strong terahertz absorption. By combining the Cherenkov radiation scheme and surface-emitting geometry, femtosecond Ti:sapphire laser pulses of ∼200−300 μJ energy were converted to broadband (∼4 THz bandwidth) terahertz transients with the efficiency of ∼8×10−6. The transients produced electro-optic signals of a ∼0.15 modulation depth and ∼103 dynamic range in a 1-mm thick ZnTe detector crystal. This suggests DKDP as a potential generator crystal for terahertz time-domain spectroscopy. From our measurements, we estimated the nonlinear coefficient d36≈3 pm/V of DKDP for optical rectification, which is an order of magnitude larger than the value known from second-harmonic-generation experiments. At the same time, the obtained value of d36 is an order of magnitude smaller than the value calculated from the clamped electro-optic coefficient r63 for the MHz frequency range. At high pump intensities, we observed multiple filamentation of the pump beam and white light generation, spatially separated from terahertz generation.

Techno-economic and environmental analysis of high temperature heat pumps integration into industrial processes: the ammonia plant and pulp mill cases

Heat pumps will play an important role in improving the performance of the industrial processes aiming to decarbonize their heating requirements. Yet, defining the best operating conditions of those devices may be a challenging task, as they are embedded in larger energy conversion systems and in direct competition with fired and electric heaters and other waste heat recovery systems. The costs of the energy inputs also influence the selection of either a heat pump or a gas boiler, which affects the overall efficiency and the incremental cost of the final solution. Thus, a systematic analysis must be applied in order to determine the best option to supply the heating requirement, without considerably impacting the operational feasibility of the overall plant. In this work, the base-case performance of two industrial applications with intensive heating demand, namely, the solvent regeneration process of a carbon capture unit and the black liquor concentration process of a kraft pulp mill, are compared to that of the scenarios in which a high temperature heat pump or a mechanical vapor recompression unit are integrated, aiming to reduce the energy consumption and the environmental impact. The benefits of the integration of a heat pump or a mechanical vapor recompression unit over a conventional reboiler and a multiple effect evaporation system are discussed in the light of thermodynamic, economic and environmental indicators. As a result, the alternative approaches remain competitive vis-à-vis the conventional solutions in terms of energy consumption and operating costs. In addition, the emissions associated to the heating applications could be reduced by 45% if a high temperature heat pump is integrated. The optimized solution using a heat pump has an overall exergy efficiency 9% higher compared to the typical configuration of the ammonia plant. In pulp mills, the integration of mechanical vapor recompression systems slightly affects the performance compared to the conventional scenario with a multiple effect evaporation system.

High Performance Rotating Triboelectric Nanogenerator with Coaxial Rolling Charge Pump Strategy.

With the development of society and the advancement of technology, the emergence of the Internet of Things (IoT) has changed people's lifestyles and raised the demand for energy to a new level. However, there are some drawbacks in terms of energy supply for IoT sensors, such as limited battery capacity and limitations in replacement and maintenance. Therefore, it has become urgent to develop a sustainable green energy source (wind energy) using the surrounding environment. Meanwhile, triboelectric nanogenerators (TENGs) with advantages such as flexible structure, low manufacturing cost, and environmental friendliness provide enormous potential for constructing self-powered sensing systems. In this work, we present a novel coaxial rolling charge pump TENG (CR-TENG) based on wind energy to enhance the output performance and durability. The rolling friction charge pump TENG directly injects positive and negative charges into the main TENG, which is more wear-resistant compared to sliding friction, and greatly increases the charge density and output power. In addition, the charge pumping part and the main TENG adopt the coaxial design, reducing the complexity of the structural design. On comparing the output performance of the CR-TENG under the initial state, rectifier bridge supplemental charge strategy, and charge pump supplemental charge strategy, results shown that the output voltage performance of the CR-TENG can be improved by 5800% under the charge pump supplemental charge strategy. Moreover, the output performance of the CR-TENG remains stable after 72,000 cycles. The output power of the CR-TENG can reach 1.21 mW with a load resistance of 3 × 107 Ω. And the CR-TENG can charge a 0.1 μF capacitor to 5 V in just 1.6 s. This work provides new insights for the rotary durable high output charge pump compensating a triboelectric nanogenerator and demonstrates the important potential of harvesting environmental energy to supply intelligent IoT nodes.

Analysis and optimization of injection characteristics and comprehensive performance of low GWP refrigerant HP-1 in high temperature heat pump systems

In the context of low-GWP refrigerants becoming a research hotspot, the environmentally friendly refrigerant HP-1 with independent intellectual property rights in China has demonstrated significant advantages in fields such as data centers and 5G base stations. However, there are few applied studies in the field of high-temperature heat pumps (HTHPs), therefore, in this study, HP-1 was utilized in HTHP system and this process was combined with the injection technology. It has been proven to be an effective approach for performance improvement. The injection characteristics of HP-1-based HTHP were analyzed and optimized with a focus on safety, stability, and efficient operation. The application advantages of HP-1 were compared and analyzed in terms of thermodynamic performance and Total Equivalent Warming Impact. The results indicated that there were three types of characteristic injection pressures based on system performance, corresponding to the maximum coefficient of performance (COP), the lowest electronic expansion valve inlet refrigerant temperature, and the lowest exhaust temperature of the compressor. Further, the corresponding control equations for injection pressure were obtained. Based on the safety injection pressure, the optimal COP under injection pressure could effectively improve the COP of the system by 2.1–5.2 %, and the exhaust temperature also increased by 6.1–10.1 %. When the temperature of the heat source was 50 °C and the target heating temperature was 120 °C, the heating capacity of HP-1 increased by 10.8 % compared with that of R245fa, the COP of the system increased by 2.7 %, and the volume heating capacity increased by 10.3 %. Moreover, the emission reduction effect of HP-1 was significant, and the carbon dioxide emissions were reduced by 15.4–39.1 %. The analysis shows that HP-1 exhibits better performance and environmental characteristics than HFC-245fa. This study is of guiding significance to improve the thermodynamic performance of HTHP, for the safe and efficient operation and energy saving and emission reduction in the industrial field.

Thermodynamic analysis of high temperature cascade heat pump with R718 (high stage) and six different low-GWP refrigerants (low stage)

Decarbonizing industrial heating globally is a significant challenge, driving the integration of high-temperature heat pumps for heat recovery and electrification in the industrial sector. However, current high-temperature heat pumps with low global warming potential refrigerants face limitations in delivering high-temperature heat due to their restricted compressor discharge temperature or require several compressors/intercoolers. To address these issues, a novel high-temperature cascade heat pump system is proposed, utilizing water (R718) in the high stage, while selecting one among six low GWP refrigerants (R1234ze(Z), R1233zd(E), R1336mzz(Z), R600, R600a, R601) in the low stage, with single compressor at each stage. To manage high discharge temperatures of high stage, liquid water injection is applied during high stage compression, modeled for both wet and dry steam. The model is validated against available experimental data with maximum error less than 5 %. Further, the effectiveness of the internal heat exchanger in low stage cycle is assessed for all investigated low stage refrigerants. Results reveal that R718 + R600 offers the optimal refrigerant working pair, achieving a maximum COP × VHC of 2895.1 kJ m−3 for delivering high temperature heat at water condensation temperature of 190 °C and recovering heat from low temperature waste energy of 50 °C.

Integration of large-scale heat pumps to assist sustainable water desalination and district cooling

Climate change intensifies stress on global potable water supply. Over 2 billion people still lack access to safe potable water, hindering social and economic development in arid regions. As a result, cost-effective desalination is important. The two main desalination technologies are thermal-based and membrane processes. The membrane-based desalination process Reverse Osmosis is gaining more and more popularity. The reason is that thermal-based processes often rely on non-renewable heat sources, while high temperature heat pumps offer a sustainable alternative for heat supply. Thus, this study investigates the integration of a transcritical CO2 heat pump into thermal-based desalination processes. The CO2 process operates at up to 180 °C, with an eco-friendly working fluid. The heat pump provides both potable water and potentially cooling energy. Six configurations were considered, showing comparable energy demands to RO. Moreover, considering cooling duty, the integrated system outperforms RO. A commercially available 19 MWel transcritical CO2-based heat pump system can produce up to 64.000 m3/d of potable water and 75 MW of cooling energy. This highlights the potential of heat pumps as sustainable solutions for addressing water scarcity and providing cooling.

Two-phase flow and heat transfer on a cylinder via low-velocity jet impact

Combining the benefits of jet impact and phase-transition heat transfer, jet impact boiling has been widely adopted in industrial scenarios. Notably, owing to limitations of high-velocity jets, such as high impact stress and pumping pressure in liquid circuits, low-velocity jet impacting deserves more attention and explorations. In this paper, under an atmospheric environment with wall heating temperatures ranging from 36 °C to 128 °C, the two-phase flow and heat transfer characteristics (local surface temperature, boiling curves and liquid loss rate) of low-velocity jet impacting on a cylindrical surface are investigated by experiment, followed by the analysis on the effects of jet outlet velocity and impact height. The findings reveal that, with the increase of heat transfer rate, the heat transfer regimes in sequence are non-phase transition (single-phase convection and air-liquid two-phase convection) and nucleate boiling. The influences of jet impact height and outlet velocity on local surface temperatures are pronounced at non-phase transition stage. In impact region, along with average superheat, the growth rates of heat transfer rate and liquid loss rate increase significantly from non-phase transition to nucleate boiling stage, and slow down at anaphase of nucleate boiling stage. Interestingly, the increase in outlet velocity delays the onset of slowdown in growth of liquid loss rate to some extent. Overall, the heat transfer rate and liquid loss rate are significantly enhanced at higher jet outlet velocity of 0.60 m/s, but not affected significantly by impact height.

Multidisciplinary Optimization of Thermodynamic Cycles for Large-Scale Heat Pumps With Simultaneous Component Design

Abstract The performance of high temperature heat pumps (HTHPs) is highly dependent on the efficiency of its main components, which need to be optimally matched especially in closed cycles. The design process is therefore a challenging task as many disciplines and varying modeling depths need to be considered. Consequently, this is usually a sequential procedure beginning with cycle definition and raising the fidelity for component design. Fundamental design decisions are made based on assumptions for component performance. Mistakes in the phase of cycle definition are hard to reverse in later design stages. Therefore, this work introduces holistic approaches to the multidisciplinary design of closed Brayton cycles. Aerodynamic compressor design with two-dimensional throughflow analysis and geometry-based heat exchanger sizing are simultaneously optimized with thermodynamic cycle parameters. The presented methodologies make use of highly sophisticated design tools drawing on many years of experience in gas turbine design. The results demonstrate that holistic heat pump optimization can be successfully performed with reasonable computational effort. The advantages compared to conventional sequential design are elaborated. A comparison of two optimization concepts indicates that splitting up the design vectors of cycle and components shows the tendency to improve robustness. Finally, the tradeoff between system compactness and performance is demonstrated with a multi-objective optimization study.

Data-based, high spatiotemporal resolution heat pump demand for power system planning

Decarbonizing the residential building sector by replacing gas boilers with electric heat pumps will dramatically increase electricity demand. Existing models of future heat pump demand either use daily heating demand profiles that do not capture heat pump use or do not represent sub-national heating demand variation. This work presents a novel method to generate high spatiotemporal resolution residential heat pump demand profiles based on heat pump field trial data. These spatially varied demand profiles are integrated into a generation, storage, and transmission expansion planning model to assess the impact of spatiotemporal variations in heat pump demand. This method is demonstrated and validated using the British power system in the United Kingdom (UK), and the results are compared with those obtained using spatially uniform demand profiles. The results show that while spatially uniform heating demand can be used to estimate peak and total annual heating demand and grid-wide systems cost, high spatiotemporal resolution heating demand data is crucial for spatial power system planning. Using spatially uniform heating demand profiles leads to 15.1 GW of misplaced generation and storage capacity for a 90% carbon emission reduction from 2019. For a 99% reduction in carbon emissions, the misallocated capacity increases to 16.9-23.9 GW. Meeting spatially varied heating load with the system planned for uniform national heating demand leads to 5% higher operational costs for a 90% carbon emission reduction. These results suggest that high spatiotemporal resolution heating demand data is especially important for planning bulk power systems with high shares of renewable generation.