Behavior Of Pump Research Articles

Experimental evaluation of a heat pump for the water-supplyheating of a public swimming pool

In this work the analysis of the thermodynamic behavior of heat pumps (HP) which supply the energy needed in the public pool at the Aquatic Center of Azcapotzalco was performed. There are 18 installed HP’s but only those needed to provide the energy required are alternately activated. The evaluation was conducted during May and June of 2015. We selected one of the HP to implement temperature and pressure gauges at the inlet and outlet of the compressor. The measurements were made every day at three times, 6:30, 13:00 and 18:00 hours. In a period of 24 hours, 1 000 L evaporated, there was no variation registered overnight, since the pool was covered with plastic to avoid loss of the fluid. The heat pump provided 150 kW to maintain the water temperature at the right level of operation, namely 28 °C. The coefficients of performance (COP) of the HP were 6.39 at 6:30, 7.42 at 13:00 and 7:32 at 18:00 hrs., values which are very close to the one provided by the manufacturer.

Studies on pumping behavior of a test cryopumping facility

Since more than a decade cryopumps are used as one of the reliable vacuum pump to get clean ultra-high vacuum. The pumping performance of a cryopump is always depends on the type of sorbent used, operating temperature of pumping surface and the type of gases. There is always a variation of the reported pumping speed towards the actual experimental pumping speed. Hence the actual pumping speeds were measured as per the American Vacuum Society (AVS) standard for the different gases and compared with the reported values for the test cryopump Marathon® CP-12. Experiments were performed for the operating pressure range of 5E-7 mbar to 1E-4 mbar with a calibrated throughput varying from 1mbar-ltr/s to 1E-3 mbar-ltr/s. It was observed that the pumping speed for a particular gas always depends on the working pressure and the operating temperature. Measured pumping speed values are in good agreement with the catalogue value for the operating pressure range of 3E-5 mbar to 4E-5 mbar.

Experimental investigation on a 3 kW organic Rankine cycle for low-grade waste heat under different operation parameters

The experimental study of a 3kW organic Rankine cycle (ORC) system using an open-drive scroll type expander and R245fa has been investigated. The expander is originally hermetic-type refrigerant scroll compressor with built-in volume ratio of 3.24. The effects of pressure drop, degree of superheating and condenser temperature on system overall performance are examined. Moreover, the detailed behavior of pump and expander are explored. The experimental results show that the pressure drop exhibits a relatively higher sensitivity on system performance. The condenser temperature exhibits a negative effect on electrical power, thermal efficiency and system generating efficiency. The maximum expander shaft power, electrical power, thermal efficiency and system generating efficiency are 2.64kW, 1.89kW, 5.92% and 3.93%, respectively. The highest thermal efficiency does not represent the highest expander shaft power.

Operation characteristic of a R123-based organic Rankine cycle depending on working fluid mass flow rates and heat source temperatures

The test and operation characteristic of an organic Rankine cycle using R123 and a scroll expander have been investigated. The steady-state operation characteristic is addressed with the varying working fluid mass flow rates ranging of 0.124–0.222kg/s and heat source temperatures ranging of 383.15–413.15K. The behaviors and detailed discussion for those four major components (pump, evaporator, expander and condenser) are examined. The experimental results show that the environmental temperature presents a higher influence on the pump behaviors. The range of pump power consumption, isentropic efficiency and back work ratio are 0.21–0.32kW, 26.76–53.96%, and 14–32%, respectively. The expander isentropic efficiency presents a slight decrease first and then a sharp increase with mass flow rate, while a degree of superheating more than 3K is necessary to avoid expander cavitation. The expander isentropic and generator efficiencies are in range of 69.10–85.17% and 60–73%, respectively, while the respective heat transfer coefficients for evaporator and condenser are ranging of 200–400 and 450–2000W/m2K. The maximum expander shaft power and electrical power are 2.78kW and 2.01kW, respectively, while the maximum system generating efficiency is 3.25%. Moreover, the tested thermal efficiency presents a slight decrease trend with mass flow rate.

Long term behavior of a geothermal heat pump with oversized horizontal collector

This study presents the results of a 3year experiment concerning the behavior of a geothermal ground-water heat pump used for heating a small residential house. The study is focused on the one side on the ground temperature variation around the horizontal collector oversized by ≈50%, mounted at 1.7m depth and on the other side on the working conditions and performances of the heat pump itself. It was highlighted that due to the oversizing of the geothermal collector, the ground temperature did not drop below 2°C and ground freezing was avoided. The ground temperature recovered each year during the non-heating season. The heat pump coefficient of performance was determined in the range of (3.18–8.59) in different operating periods.

Longitudinal Spin Relaxation of Optically Pumped Rubidium Atoms in Solid Parahydrogen

We have grown crystals of solid parahydrogen using a single closed-cycle cryostat. We have doped the crystals with rubidium atoms at densities on the order of 10^{17} cm^{-3} and used optical pumping to polarize the spin state of the implanted atoms. The optical spectrum of the rubidium atoms shows larger broadening than previous work in which the rubidium was implanted in solid argon or neon. However, the optical pumping behavior is significantly improved, with both a larger optical pumping signal and a longer longitudinal relaxation time. The spin relaxation time shows a strong dependence on orthohydrogen impurity levels in the crystal, as well as the applied magnetic field. Current performance is comparable to state-of-the-art solid state systems at comparable spin densities, with potential for improvement at higher parahydrogen purities.

Improving Groundwater Management for Indian Agriculture: Assessing Tradeoffs Across Policy Instruments

Despite efforts to reform management of water resources, groundwater levels have continued to decline steadily in key aquifers across India, leading to serious environmental concerns and impacts. While policy makers have looked to efforts aimed at improving the efficiency of field-level irrigation and strengthening ownership and property rights in local resource management, hydrologists have asserted that more direct control of consumptive use patterns of water is needed. In this paper, we illustrate the divergence between current groundwater usage patterns and an optimal path, in which the groundwater levels are stabilized with better demand-side management. The paper assesses the tradeoffs embedded in alternative policy instruments that are aimed at modifying the groundwater pumping behavior of agricultural water users. The challenges of regulating smallholder agricultural water users are shown to be relevant in determining which instrument might have the best chance of slowing the depletion of groundwater resources in the hard-rock aquifers of India, and promoting the long-run sustainability of this critical natural resource.

Theoretical and experimental study of a synchronal rotary multiphase pump at very high inlet gas volume fractions

Theoretical and experimental analyses are performed to investigate the pumping behaviour of a synchronal rotary multiphase pump (SRMP) at very high inlet gas volume fractions (GVFs). A comprehensive SRMP model is developed to predict the pump performance at very high inlet GVFs, including the steady-state behaviours and the transient distributions of interesting variables during pump operation. The experimental work is implemented using N32 oil and air as the working fluids to measure the global performance parameters of the SRMP at the inlet GVFs of 91–98% and different differential pressures. The SRMP model is validated by comparison of the simulated and experimental results. The results show that the inlet GVF has a significant effect on the pump behaviour. At a given differential pressure, the leakage loss increases dramatically with the inlet GVF, which results in a significant decrease in the volumetric flow rate of the SRMP. Because of the large proportion of shaft power wasted by the high-pressure back flow, the SRMP exhibits lower pump efficiency at the higher inlet GVFs.

Dynamic modeling and simulation of a double-effect absorption heat pump

This paper presents a new dynamic model to study the transient thermochemical behavior of a double-effect absorption heat pump (DEAHP). It has been designed according to the experience with an experimental DEAHP totally integrated into a solar-assisted multi-effect distillation (MED) plant set up at CIEMAT – Plataforma Solar de Almería (PSA). The non-linear first-principles model was implemented using the equation-based object-oriented Modelica modeling language and is based on a mathematical formulation that describes the main heat and mass transfer phenomena in this kind of facilities. A modular and hierarchical modeling methodology has allowed a graphical modeling development. Submodels that wrap the different physical phenomena are interconnected between them, thus making a three level deep hierarchy. All the submodels have been calibrated and validated with experimental data. The numerical predictions show a good agreement with measured data.

Adherence to Insulin Pump Behaviors in Young Children With Type 1 Diabetes Mellitus.

Parents of young children are responsible for daily type 1 diabetes (T1DM) cares including insulin bolusing. For optimal insulin pump management, parents should enter a blood glucose result (SMBG) and a carbohydrate estimate (if food will be consumed) into the bolus advisor in their child's pump to assist in delivering the recommended insulin bolus. Previously, pump adherence behaviors were described in adolescents; we describe these behaviors in a sample of young children. Pump data covering between 14-30 consecutive days were obtained for 116 children. Assessed adherence to essential pump adherence behaviors (eg, SMBG, carbohydrate entry, and insulin use) and adherence to 3 Wizard/Bolus Advisor steps: SMBG-carbohydrate entry-insulin bolus delivered. Parents completed SMBG ≥4 times on 99% of days, bolused insulin ≥3 times on 95% of days, and entered carbohydrates ≥3 times on 93% of days, but they corrected for hyperglycemia (≥250 mg/dl or 13.9 mmol/l) only 63% of the time. Parents completed Wizard/Bolus Advisor steps (SMBG, carbohydrate entry, insulin bolus) within 30 minutes for 43% of boluses. Inverse correlations were found between children's mean daily glucose and the percentage of days with ≥4 SMBG and ≥3 carbohydrate entries as well as the percentage of boluses where all Wizard/Bolus Advisor steps were completed. Parents of young children adhered to individual pump behaviors, but showed some variability in their adherence to Wizard/Bolus Advisor steps. Parents showed low adherence to recommendations to correct for hyperglycemia. Like adolescents, targeting pump behaviors in young children may have the potential to optimize glycemic control.

Viscoelastic Properties of Fresh Cement Paste to Study the Flow Behavior

During concrete pumping, the migration and redistribution of particles occur in a pipe and the lubrication layer that forms between the bulk concrete and the pipe wall is the governing factor determining the flow behavior. In order to identify flow behavior of pumping, in this study, the viscoelastic properties related to the microstructural behavior of a flocculated suspension were examined by using dynamic oscillatory measurements. Cement paste is assumed to be a constituent material of the lubrication layer and ten cases of mixing design are employed by changing the proportions of mineral admixtures. The relationship between the yield stress obtained from the steady shear test and the dynamic modulus resulted from the oscillatory shear measurement was derived and the implications of the correlation are discussed. Moreover, based on the investigation of the viscoelastic properties with oscillatory measurements, the initial behavior of pumped concrete was analyzed systematically.

Single-Stage Pumping of Concrete up to 2.432 km (1.51 miles): Admixture, Mixture, and Full-Scale Trials

AbstractThis paper reports a systematic study conducted during application of pumping concrete for distances up to 2.432 km at an actual construction site. Admixture design for maintaining flowable concretes through 12 h, while setting within 20 h and developing stripping strength in 30 h was critical. Full-scale field trials for checking field behavior of concrete, pump, their interactions and manpower training are synergistic; weather plays a critical role. The mixes are to be adjusted in response to change in ambient temperatures and differences between production and placement temperatures. A distance-dependent mixture design approach was used for optimizations that lead to the development of a distance-paste-binder curve.

Nonreciprocal behavior of the spin pumping in ultra-thin film of CoFeB

The processional magnetization induced spin current at the interface between CoFeB and Ta has been studied experimentally using spin pumping and inverse spin Hall effect for different thicknesses of CoFeB film down to 1.6 nm. It is found that upon decreasing the thickness of the CoFeB, the frequency of the peak position of the spin pumping signal reduces and dispersion relation of the ferromagnetic resonance changes from a quadratic to a linear behavior indicating the presence of an interfacial perpendicular anisotropy. Furthermore, a nonreciprocal behavior between the spin pumping signal amplitude at positive and negative fields is observed which could be as large as 100%. Our experimental results suggest reduction of the effective demagnetization field and possibly the spin waves nonreciprocal behavior mediated by the Dzyaloshinskii-Moriya interaction at the Ta/CoFeB interface are responsible for the large nonreciprocity of the spin pumping signal.

Transient behavior of a centrifugal pump during starting period

A theoretical analysis on transient flow inside a centrifugal pump was carried out, building on unsteady and incompressible fluid equations applied to the impeller during the starting periods. The transient flow behavior is governed by two hyperbolic partial differential equations; namely continuity and motion equations. The characteristics method of the specified time intervals was used to analyze the dynamic characteristic of the pump. To follow the dynamic behavior of the pump during startup periods, a numerical study was performed on the pump impeller with different openings of the discharge valve. The comparison between the numerical and experimental results of the pump characteristic curve has shown a good concordance. The results have also revealed that the pressure increase is important in the case of a short starting period of the pump and a large mass of water in the pipelines. In this study, the effect of the impeller diameter and number of blades on the pressure evolution was also analyzed.

The influence of the biological pump on ocean chemistry: implications for long-term trends in marine redox chemistry, the global carbon cycle, and marine animal ecosystems.

The net export of organic matter from the surface ocean and its respiration at depth create vertical gradients in nutrient and oxygen availability that play a primary role in structuring marine ecosystems. Changes in the properties of this ‘biological pump’ have been hypothesized to account for important shifts in marine ecosystem structure, including the Cambrian explosion. However, the influence of variation in the behavior of the biological pump on ocean biogeochemistry remains poorly quantified, preventing any detailed exploration of how changes in the biological pump over geological time may have shaped long‐term shifts in ocean chemistry, biogeochemical cycling, and ecosystem structure. Here, we use a 3‐dimensional Earth system model of intermediate complexity to quantitatively explore the effects of the biological pump on marine chemistry. We find that when respiration of sinking organic matter is efficient, due to slower sinking or higher respiration rates, anoxia tends to be more prevalent and to occur in shallower waters. Consequently, the Phanerozoic trend toward less bottom‐water anoxia in continental shelf settings can potentially be explained by a change in the spatial dynamics of nutrient cycling rather than by any change in the ocean phosphate inventory. The model results further suggest that the Phanerozoic decline in the prevalence ocean anoxia is, in part, a consequence of the evolution of larger phytoplankton, many of which produce mineralized tests. We hypothesize that the Phanerozoic trend toward greater animal abundance and metabolic demand was driven more by increased oxygen concentrations in shelf environments than by greater food (nutrient) availability. In fact, a lower‐than‐modern ocean phosphate inventory in our closed system model is unable to account for the Paleozoic prevalence of bottom‐water anoxia. Overall, these model simulations suggest that the changing spatial distribution of photosynthesis and respiration in the oceans has exerted a first‐order control on Earth system evolution across Phanerozoic time.

A method for variable pressure load estimation in spur and helical gear pumps

A systematic procedure is proposed to determine variable excitation loads coming from pressure evolution inside tooth spaces in external gear pumps. Pressure force and torque are estimated with respect to the angular position of the gears, taking into account the phenomena that occur during the meshing course. In particular, the paper proposes a general methodology aiming at determining pressure force and torque components along the three coordinate axes and suitable to be applied on both spur and helical gear configuration. Firstly, the method to calculate pressure loads acting on a single tooth space during a complete revolution is given, then the total pressure force and torque loading each gear is obtained. Particular attention is addressed on the description of the helical gear scenario. As an example, the method is applied to a tandem gear pump, characterized by the presence of two stages, one with spur gears and one with helical gears. An experimentally assessed model to calculate the pressure ripple inside the tandem pump is described and the proposed procedure for pressure load estimation is applied. Eventually, the pressure loads estimated with the present procedure are compared with other estimation methods already described in the literature. The comparison shows that the present methodology is able to describe a wider range of phenomena involved in the meshing evolution and to determine all the pressure force and torque components applied to helical gears. The method gives suitable results to study the balancing and the dynamic behavior of gear pumps.

Convective flow reversal in self-powered enzyme micropumps

Surface-bound enzymes can act as pumps that drive large-scale fluid flows in the presence of their substrates or promoters. Thus, enzymatic catalysis can be harnessed for “on demand” pumping in nano- and microfluidic devices powered by an intrinsic energy source. The mechanisms controlling the pumping have not, however, been completely elucidated. Herein, we combine theory and experiments to demonstrate a previously unreported spatiotemporal variation in pumping behavior in urease-based pumps and uncover the mechanisms behind these dynamics. We developed a theoretical model for the transduction of chemical energy into mechanical fluid flow in these systems, capturing buoyancy effects due to the solution containing nonuniform concentrations of substrate and product. We find that the qualitative features of the flow depend on the ratios of diffusivities δ=D(P)/D(S) and expansion coefficients β=β(P)/β(S) of the reaction substrate (S) and product (P). If δ>1 and δ>β (or if δ<1 and δ<β ), an unexpected phenomenon arises: the flow direction reverses with time and distance from the pump. Our experimental results are in qualitative agreement with the model and show that both the speed and direction of fluid pumping (i) depend on the enzyme activity and coverage, (ii) vary with the distance from the pump, and (iii) evolve with time. These findings permit the rational design of enzymatic pumps that accurately control the direction and speed of fluid flow without external power sources, enabling effective, self-powered fluidic devices.

Flow dynamical behavior and performance of a micro viscous pump with unequal inlet and outlet areas

ABSTRACTThe micro viscous pump is an important type of fluidic device. Optimizing the working performance of the pump is crucial for its wider application. A micro viscous pump design with unequal inlet and outlet areas is proposed in this paper. The flow field of the viscous pump is investigated using 2D laminar simulations. The mass flow rate and driving power are studied with different opening angles. The effects of the Reynolds number and the pressure load on the working performance are discussed in detail. Flow structures and vortex evolution are analyzed. With larger inlet and outlet areas, a higher mass flow rate is obtained and less driving power is achieved. A high pressure load results in a reduction in mass flow rate and an increase in driving power. Pumps with large opening angles are more susceptive to the Reynolds number and the pressure load. The adverse impact of the pressure load can be reduced by increasing the rotor speed. The vortex structure is affected by the geometric and operating parameters in the flow field. The flow dynamical behavior of the viscous pump exerts significant influence on its pumping ability. The present work gives rise to performance improvements for the micro viscous pump.

A Study on the Dynamics and Vibration Behavior of an Axial Piston Pump Using Combined MBD/FE Approach

In the present work a combined multibody dynamics(MBD) and finite element(FE) approach is developed for modeling the dynamics and vibration behaviour of an axial piston type hydraulic pump. A MBD model of the pumping mechanism is developed to predict the dynamic excitation forces at the bearings and control piston locations. The dynamic excitation forces in the frequency domain are obtained using fast fourier transform (FFT) with a rectangular type windowing function. A detailed FE model of the pump is developed consisting of the internal components, housing, and end cover. The dominant mode shapes and natural frequencies of the pump assembly are studied. The forced vibration behaviour of the pump is predicted by using the dynamic excitation forces from the MBD model. The numerical results are compared with the experimental results and a good agreement is found. Further, numerical studies are carried out to study the influence of component mass and stiffness on the vibration response.

Solar Assisted Ground Source Heat Pump in Cold Climates

The geothermal heat pump (or ground source heat pump) uses the ground as heat source or sink for heating and cooling respectively. The design of the borehole field is the key element of these systems since the wrong evaluation of the boreholes’ length affects the initial costs and/or the energy performance of the heat pump. The geothermal heat pumps are considered as renewable energy technologies, consequently can help the community to reduce the primary energy uses and also the CO2 emissions. However the sustainability and efficiency are ensured in the long period only when the heat balance through the ground is guaranteed.This work evaluates the thermal behavior of ground source heat pumps in cold climates, where the thermal load profile of buildings is not balanced between heating and cooling, especially in residential sector characterized by low internal loads. In these contexts, the heat pump mainly works in heating mode, extracting continuously heat from the ground. As a result, the ground temperature decreases gradually during the years affecting the energy performance of the heat pump. A possible solution to this problem is to use solar thermal collectors to stabilize or gradually increase the mean ground temperature (these systems are called Solar Assisted Ground Source Heat Pump – SAGSHP).In this work a multi floors residential building with 12 flats (88 m2 each) is analyzed in three climate zones, making use of the simulation tool TRNSYS. Different configurations of the plant system have been investigated and the case without the solar thermal collectors has been considered as reference.