Spray Flow Research Articles

Effect of bubble cutting on spray characteristics and dust control performance in the effervescent atomization

Effervescent atomization performance depends on the bubble size inside the mixing chamber, consequently influencing the spray dust control performance. This paper proposes an optimization of atomization quality and dust control performance by incorporating a bubble cutter in the atomizer mixing chamber. The effects of the bubble cutter aperture on spray characteristics and flow characteristics were experimentally investigated under different operating conditions. Experimental results showed that Sauter means diameter (SMD) decreases with increasing injection pressure and gas-liquid mass flow ratio (GLR). Furthermore, SMD initially increased and then decreased by reducing the aperture of the bubble cutter from 500 µm to 80 µm. In particular, high injection pressure (Pi =0.6 MPa) and low gas-liquid mass flow ratio (GLR=0.09) strengthened the effects of the bubble cutter aperture on SMD. Moreover, bubble cutter causes a contiguous concentrated droplet size distribution, but it has little effect on droplet velocity. Ultimately, the optimal bubble cutter aperture on the efficiency of respirable dust control efficiencies was theoretically calculated. The dust control efficiency is a maximum at the bubble cutter with an aperture of 230 µm for the effervescent atomizer in this paper. Spray dust control efficiency reaches 93.15 %, which effectively solves the problem of high dust concentration pollution in the mechanized working environment.

Numerical simulation on shell-side flow pattern transition and heat transfer of non-azeotropic refrigerant mixture

The non-azeotropic hydrocarbon refrigerant mixture flowing across shell-side of spiral wound heat exchanger is widely used in liquefied natural gas production industry. However, the phase-change heat transfer mechanism is still lack of thorough understanding. A numerical model is presented for simulating evaporation heat transfer of non-azeotropic hydrocarbon refrigerant mixture, CH4/C2H6, across multiple spiral wound tubes. Volume of Fluid model (VOF) was used to obtain liquid–vapor interface. The heat and mass transfer rates for each component were given as source terms. Thermophysical properties of the mixture were given using mixing laws in the literature. A flow pattern map was developed based on simulation results. The flow pattern transition and heat transfer were analyzed for the mixture with several component mixing ratios. With increasing vapor quality, pure ethane and methane-ethane mixture appear different flow patterns. The pure ethane has smoother liquid film on the tube wall than the methane-ethane mixture. The increasing of methane promotes the flow pattern transition. With vapor quality of 0.2–0.3, falling film flow transfers to shear flow. Shear flow transfers to spray flow for vapor quality of 0.7–0.8, where the heat transfer coefficient starts to decrease for methane-ethane mixture. For falling film flow, the heat transfer coefficient of pure ethane is higher than the methane-ethane mixture. The outcomes may help spiral wound heat exchanger design and evaluation for liquefied natural gas production.

Fractional Order Modeling of PWR Pressurizer Dynamics and Fractional Order Nonlinear H∞ Controllers Design in LabVIEW

The novel fractional order intelligent transient dynamics and advanced fractional order nonlinear robust control synthesis scheme of the Pressurized Water Reactor (PWR) pressurizer are addressed in this research work. The Graphical User Interface (GUI) is designed for closed-loop model-based PWR pressurizer dynamical studies in LabVIEW. Based on the demand for power, the reactor power and turbine power are predicted using a fractional order backpropagation algorithm in an open loop configuration. Using turbine power and heater power as input variables, pressurizer level, pressurizer pressure and coolant average temperature as output variables, the open loop multi-input multi-output (MIMO) dynamic model of pressurizer is estimated using fractional order artificial intelligence in LabVIEW. Four fractional order robust nonlinear H∞ sub-controllers are designed for charging flow, spray flow, proportional heaters power and backup heaters power. All the dynamic controller models are in fractional order nonlinear H∞ framework and are designed in LabVIEW. The performance of the proposed design work is evaluated in closed loop configuration at 100 %, 75 % and 15 % in steady state conditions. Dynamic transient analysis is performed from 100% to 90% power reduction scenario and found satisfactory and within design limits and robust bounds.

Effects of microgravity on cryogenic spray quenching of a simulated propellant storage tank with enhancement by surface coating and flow pulsing

In-space cryogenic propulsion will play a vital role in space exploration mission to the Moon and future mission to the Mars. The enabling of in-space cryogenic rocket engines and the Lower-Earth-Orbit (LEO) cryogenic fuel depots for these future manned and robotic space exploration missions begins with the technology development of advanced cryogenic thermal-fluid management systems for the propellant transfer line and storage tank system.One of the key thermal-fluid management operations is the chilldown of the propellant storage tank. As a result, highly energy efficient, breakthrough concepts for quenching heat transfer to conserve and minimize the cryogen consumption during chilldown have become the focus of engineering research and development, especially for the deep-space mission to Mars. In this paper, we introduce such thermal transport concepts and demonstrate their feasibility in space for cryogenic propellant storage tank chilldown in a simulated space microgravity condition on board an aircraft flying a parabolic trajectory. In order to maximize the storage tank chilldown thermal efficiency for the least amount of required cryogen consumption, the breakthrough quenching heat transfer concepts developed include the combination of cryogenic spray quenching cooling, Teflon thin-film coating on the simulated tank surface, and spray flow pulsing. The boiling heat transfer physics that supports the concepts is clearly explained. The completed flight experiments successfully demonstrated the feasibility of the concepts and discovered that spray cooling is the most efficient cooling method for the tank chilldown in microgravity. In microgravity, the data shows that the chilldown thermal efficiency can reach 30% with Teflon coating alone. However, Teflon coating together with flow pulsing was found to substantially enhance the chilldown efficiency further to reach the 50% goal.

Phase Doppler Anemometer - The Shift From Simulation To The Real World

A Monte Carlo type simulation program has been developed to model phase Doppler systems. The work was divided into four main sections, the development of a launch strategy of a known range of droplet sizes and trajectories, the determination of the scattered light fields using Mie theory, the generation of the photomultiplier signals, and then their processing to generate drop size estimates followed by the comparison of these data with the launched data. The signal processing portion of the simulation measured the Doppler frequency in each signal to estimate the droplet velocity. Rather than using measurements of the phase differences between the multiple Doppler-shifted signals, the time shift between the arrival times of each signal was used to estimate the dropsize. This provided a linear relationship between the dropsize and the signal time shift. The missing link in the simulation is the ability to guide the experimentalist as to the best way to acquire the signal bursts and determine how accurate the measurements would be when using a PDA system to determine the droplet size distributions in real spray flows. Thus, the only way to determine measurement accuracy is to include that in the signal processing of an actual PDA system and spray. In an assessment of the capabilities of the signal processing technique, a sequence of Doppler bursts from an actual spray characterization were recorded and used as input to the software signal processor. The Time Shift Technique was based on the use of Weighted Average calculations to determine the exact middle of each of the three photomultiplier signal bursts. However, it was found that good quality signal bursts are required. Since cycle measurement techniques are less effected by noise, a cycle technique based on the samples captured by the AD converter was added to the software. Whereas this technique did show an improvement in measurement accuracy it led to the development of a cycle technique based on the signal burst frequency. This involved a reconstruction of the original captured bursts. The measurement errors were found to be in the micron range.

Modeling and Characteristics of Airless Spray Film Formation

Based on the computational fluid dynamics (CFD) theory, this paper proposes a film formation model and a numerical simulation method that can be used in thickness prediction of airless spraying robots. The spraying flow field and the film formation process in the airless spraying process were simulated by the Eulerian–Eulerian approach, and the airless spraying film formation model including the paint expansion model and the wall hitting model was established. To verify the correctness of the model, numerical simulations of static spraying and dynamic spraying were carried out on the plane and arc surfaces. The simulation results showed that the width of the spraying flow field on the far wall increased linearly with the longitudinal distance in the major-axis direction. The busbar spraying on the outer surface of the arc surface showed the similar characteristics to the plane in the major-axis direction. Besides, the annular spraying was similar to the plane spraying in the minor-axis direction, but the inner surface spraying was completely opposite. When spraying the outer surface, the film thickness increased with the increase of the inner diameter but was smaller than that of the plane spraying, while the inner surface spraying was completely opposite. In the spraying experiment, the plane dynamic spraying and the arc plane inner and outer surface translation spraying were selected for verification. The experimental results were in good agreement with the simulation results, indicating that the film formation model of airless spraying established in this paper is basically correct. As a result, this model can be used for thickness prediction of spraying robots.

Nanostructured Coating for Aluminum Alloys Used in Aerospace Applications

A thin industrial corrosion-protection nanostructured coating for the Al alloy AA2024-T3 is demonstrated. The coating is prepared in a two-step process utilizing hard anodizing as a pre-treatment, followed by sealing and coating by atomic layer deposition (ALD). In the first step, anodizing in sulfuric acid at a low temperature converts the alloy surface into a low-porosity anodic oxide. In the second step, the pores are sealed and coated by low-temperature ALD using different metal oxides. The resulting nanostructured ceramic coatings are thoroughly characterized by cross-sectioning using a focused ion beam, followed by scanning electron microscopy, transmission electron microscopy, X-ray microanalysis, and nanoindentation and are tested via linear sweep voltammetry, electrochemical impedance spectroscopy, salt spray, and energetic atomic oxygen flow. The best thin corrosion protection coating, made by anodizing at 20 V, 1 °C and sealing and coating with amorphous Al2O3/TiO2 nanolaminate, exhibits no signs of corrosion after a 1000 h ISO 9227 salt spray test and demonstrates a maximum surface hardness of 5.5 GPa. The same coating also suffers negligible damage in an atomic oxygen test, which is comparable to 1 year of exposure to space in low Earth orbit.

A laser-induced breakdown spectroscopy method to assess the stochasticity of plasma-flame transition in sprays

An experimental approach is presented to evaluate the impact of plasma composition arising from pulse-to-pulse energy and mixture fluctuations on the non-resonant laser-induced ignition of sprays. This allows for spark events to be conditioned on the successful or failed establishment of a flame kernel, a phase dominated by plasma decomposition and recombination reactions and the on-set of combustion reactions, that is, independent of the subsequent flame growth phase controlled by propagation phenomena only, such as fuel availability and turbulent strain. For that, laser-induced breakdown spectroscopy of the spark-generated plasma is carried out, followed by OH high-speed imaging of the kernel. Exploratory experiments in spatially uniform and polydisperse kerosene droplet distributions in a jet suggest that the hydrogen concentration in the plasma deriving from the fuel dissociated by the spark is closely related to the generated OH radicals levels and, in turn, with the success of establishing a flame kernel. This suggests that the ignition process is heavily controlled by mixture fluctuations at the spark, inherent of spray flows. The instantaneous mixture at the spark is estimated with a stochastic model, with the probability density function of the equivalence ratio exhibiting values higher than twice the mean value, while the highest probability occurs at lean conditions between the gaseous equivalence ratio and the overall equivalence ratio. The findings corroborate insights on the early-phase ignition obtained from direct numerical simulations, and the framework paves the way for the development of smart online engine-health tools to assess relight capability in future aeroengines.

A new robust modeling strategy for multi-component droplet heat and mass transfer in general ambient conditions

Liquid fuels used for spray combustion processes are predominantly composed of several mixed components. The atomization of a liquid jet forms multi-component liquid droplets. These droplets are subject to heat and mass transfers in a vast range of atmosphere configurations, resulting in complex interactions. This example of spray combustion summarizes the diversity of scenarios that a droplet may experience in a spray flow. Unfortunately, available models in the literature exhibit limitations for characterizing such complex interactions. This work proposes a novel modeling strategy to account for such interactions in diverse scenarios grounded in a consistent computational approach. We derive a new formulation from general transport equations of the gas phase. We validate the resulting model by comparing numerical results with available experimental data and consider binary mixtures of liquids evaporating in different ambient conditions. Compared to other reference approaches, the proposed model proves to be efficient in all tested scenarios, including severe atmosphere compositions and states. Additional differential diffusion effects among participating species are observed, not only for mass but also for heat transfer.

Impact of Multi-Component Surrogates on the Performances, Pollutants, and Exergy of IC Engines.

Even though there is a pressing interest in clean energy sources, compression ignition (CI) engines, also called diesel engines, will remain of great importance for transportation sectors as well as for power generation in stationary applications in the foreseeable future. In order to promote applications dealing with complex diesel alternative fuels by facilitating their integration in numerical simulation, this paper targets three objectives. First, generate novel diesel fuel surrogates with more than one component. Here, five surrogates are generated using an advanced chemistry solver and are compared against three mechanisms from the literature. Second, validate the suggested reaction mechanisms (RMs) with experimental data. For this purpose, an engine configuration, which features a reacting spray flow evolving in a direct-injection (DI), single-cylinder, and four-stroke motor, is used. The RNG k-Epsilon coupled to power-law combustion models is applied to describe the complex in-cylinder turbulent reacting flow, while the hybrid Eulerian-Lagrangian Kelvin Helmholtz-Rayleigh Taylor (KH-RT) spray model is employed to capture the spray breakup. Third, highlight the impact of these surrogate fuels on the combustion properties along with the exergy of the engine. The results include distribution of temperature, pressure, heat release rate (HRR), vapor penetration length, and exergy efficiency. The effect of the surrogates on pollutant formation (, , ) is also highlighted. The fifth surrogate showed 47% exergy efficiency. The fourth surrogate agreed well with the maximum experimental pressure, which equaled 85 Mpa. The first, second, and third surrogates registered 400, 316, and 276 g/kg fuel, respectively, of the total CO mass fraction at the outlet. These quantities were relatively higher compared to the fourth and fifth RMs.

Cylinder-to-cylinder variation of knock and effects of mixture formation on knock tendency for a heavy-duty spark ignition methanol engine

The knock characteristics of a high-pressure port fuel injection heavy-duty SI engine fueled with pure methanol were investigated experimentally and numerically. This paper aims to provide the optimization direction of the injection strategy from the perspective of knock suppression and thermal efficiency improvement. Both experiment and simulation prove that injection during the intake stroke with high injection pressure can mitigate knock because the strong interaction between spray and intake flow helps to form the more homogeneous and lower temperature mixture which prolongs the ignition delay of end-gas. As the injection timing (αinj) varies from 320°CA to 480°CA, the combustion speed and thermal efficiency increase first and then decrease, while the knock tendency is the opposite. Take the combustion at αinj of 320°CA as a baseline, the faster combustion speed at αinj of 380°CA caused by the homogeneous mixture contributes to the higher thermal efficiency, while that of 480°CA caused by the higher temperature further enhances the knock tendency. There is a significant cylinder-to-cylinder variation of the knock tendency. The knock tendency of the cylinder with the less fresh air charge is lower because of the lower in-cylinder temperature and pressure.

Identification of slurry fuel components in a spray flow

The paper presents the experimental research findings for the spraying characteristics of promising composite fuels. Slurries were produced from typical coal processing waste (filter cake), a liquid bio-additive (rapeseed oil), biomass (sawdust) and a liquid noncombustible binder (water). The most important spraying characteristic is the distribution of fuel components in a jet. Optical recording techniques (Laser Induced Fluorescence, Interferometric Particle Imaging and Shadow Photography) were used to study it. A fluorophore (Rhodamine B) was used in the experiments. A group of light filters was also employed for wavelengths 580–680 nm. The research made it possible to identify zones, containing individual components and/or their mixtures, in a sprayed fuel jet. The average concentrations of coal processing waste in individual droplets and in an overall aerosol flow were recorded. The proportion of droplets containing wood biomass in a spray flow was determined. A method was proposed to reliably determine the structure of fuel jets with different component compositions. The method involves combining three optical techniques. The experimental data obtained make it possible to predict the conditions for efficient ignition and combustion of slurry fuel components in combustion chambers, taking into account their separation and atomization when they are sprayed by nozzles.

Detection of N-phenylpropanamide vapor from fentanyl materials by secondary electrospray ionization-ion mobility spectrometry (SESI-IMS)

Opioids pose a serious health risk to abusers and law enforcement officials responsible for detecting and handling these classes of drugs. Given the dangers posed by this class of drugs, fentanyl in particular, non-contact detection methods are highly desired. Determination of fentanyl vapor signature enables the identification of target analytes for the indirect detection of the parent opioid without direct sample handling. Diluted N-phenylpropanamide (NPPA), a degradant of fentanyl, was injected into a bench-top ion mobility spectrometer (IMS) to develop a method to detect NPPA in solution. The same parameters were used to assist in developing a method for gas phase NPPA detection. By varying the source voltage and direct spray and mass flow rates, the effects of system impurities were minimized. Weak and strong acids were then added to the electrospray solvent and gas phase NPPA was detected from the headspace of masses of 5 mg or greater of pure fentanyl.

Particle Engineering by Nano Spray Drying: Optimization of Process Parameters with Hydroethanolic versus Aqueous Solutions.

Nano spray drying has emerged as an outstanding platform for engineering micro- and nanoparticles, with growing applications in various areas of drug delivery. As a new technology involving distinct technical design, parameters of the nano spray drying process are not fully elucidated. In a quality-by-design approach, the aim of the current study was to gain thorough understanding of critical determinants of product characteristics in the Büchi Nano Spray Dryer B-90. Following a factorial experimental design, a series of spray drying experiments were conducted to gain new insights into the influences of the inlet temperature, the spray solvent, and the solute concentration in the spray solution on the yield, the moisture content, and the particle size of the nano spray-dried powder material. Special consideration was given to the potential of using hydroethanolic in comparison with aqueous solvent systems and to particle engineering for pulmonary drug delivery. Lactose and mannitol, widely used as excipients in dry powder inhalation formulations, were used as model materials. Lactose and mannitol are known to spray dry in amorphous and crystalline forms, respectively. The yields of spray drying of lactose and mannitol amounted generally to 71.1 ± 6.6% w/w and 66.1 ± 3.5% w/w, respectively. The spray-dried materials exhibited generally a number-weighted median particle diameter of 1.6 ± 0.2 μm and a volume-weighted median particle diameter of 5.1 ± 1.0 μm. A detailed analysis of the results improved understanding of the interplay between process parameters in the Nano Spray Dryer. The results demonstrate that optimization of spray generation is the key to yield optimization. On the other hand, particle size is determined by the spray mesh pore size and the spray solution degree of saturation. Selection of an appropriate spray solvent and using spray solution additives could optimize spray flow. In parallel, the spray solvent and the solute concentration in the spray solution determine the degree of saturation. Guidance on optimization of particle engineering by nano spray drying is provided.

Cryogenic spray quenching of simulated propellant tank wall using coating and flow pulsing in microgravity

In-space cryogenic propulsion will play a vital role in NASA’s return to the Moon mission and future mission to Mars. The enabling of in-space cryogenic engines and cryogenic fuel depots for these future manned and robotic space exploration missions begins with the technology development of advanced cryogenic thermal-fluid management systems for the propellant transfer lines and storage system. Before single-phase liquid can flow to the engine or spacecraft receiver tank, the connecting transfer line and storage tank must first be chilled down to cryogenic temperatures. The most direct and simplest method to quench the line and the tank is to use the cold propellant itself that results in the requirement of minimizing propellant consumption during chilldown. In view of the needs stated above, a highly efficient thermal-fluid management technology must be developed to consume the minimum amount of cryogen during chilldown of a transfer line and a storage tank. In this paper, we suggest the use of the cryogenic spray for storage tank chilldown. We have successfully demonstrated its feasibility and high efficiency in a simulated space microgravity condition. In order to maximize the storage tank chilldown efficiency for the least amount of cryogen consumption, the technology adopted included cryogenic spray cooling, Teflon thin-film coating of the simulated tank surface, and spray flow pulsing. The completed flight experiments successfully demonstrated that spray cooling is the most efficient cooling method for the tank chilldown in microgravity. In microgravity, Teflon coating alone can improve the efficiency up to 72% and the efficiency can be improved up to 59% by flow pulsing alone. However, Teflon coating together with flow pulsing was found to substantially enhance the chilldown efficiency in microgravity for up to 113%.

Machine learning with knowledge constraints for process optimization of open-air perovskite solar cell manufacturing

Machine learning with knowledge constraints for process optimization of open-air perovskite solar cell manufacturing

Three dimensional MHD nanoluid stagnation point low withhigher order chemical reaction

In hot and dry climates, evaporative cooling of the air by water spray can be applied in several requirements, such as evaporative condensers which the airflow is precooled by the water spray before it reaches the condenser. The interaction between water droplets and the air is a complicated two-phase flow that is affected by the several parameters. Here, an Eulerian-Lagrangian 3D model was developed to investigate the influence of important parameters on spray cooling performance in a rectangular duct. The evaluated parameters include the number of nozzles, inlet air flow rate, and spray water flow rate. The results represented that growth in the number of nozzles causes a reduction in the spray cooling efficiency. Thi s is due to decrease of droplets retention time within the duct by increasing the number of nozzles at a constant total spray flow rate in the cases. The maximum and minimum spray cooling efficiency belong to the cases with one nozzle at water flow rate of 20 l/h and four nozzle at water flow rate of 5 l/h, respectively. The difference between spray cooling efficiency at 3 and 4 number of nozzles is less than 1.8%. Moreover, increasing the air flow rate from 0.5 l/h to 2 l/h (by 300%) makes a decrease in the spray cooling efficiency up to 58.6%.

Simulation Analysis on the Jet Flow Field of a Single Nozzle Spraying for a Large Ship Outer Panel Coating Robot

A mathematical model of the cavity flow of the fan nozzle, a mathematical model of jet atomisation, and a simplified physical model of the equivalent entity are established. A simulation of the spraying flow at different spraying pressures is carried out using a 0.48 calibre nozzle as a case study, and compared with experimental data; error results between 4.3% and 7.5% indicate the simulation means used are reliable and the simulation model is valid. The simulation means include using the effective simulation model to further explore the evaluation index of atomisation characteristics; in the critical Weber number on the impact of atomised particles, analysis of the impact of the critical Weber number on the diameter of atomised particles and the speed of movement, and determining the critical Weber number; atomisation spraying effect, for atomisation pressure on atomised particle diameter, speed of movement, impact kinetic energy, deposition rate, and liquid film growth, etc. The results show that, in the existing high-pressure airless spraying equipment within the range of permissible pressure 6~16 MPa, with the increase in atomisation pressure, the better the atomisation effect of the paint, the better the atomised particle spraying adhesion deposition rate of the paint, and the better the overall spraying effect.

Experimental investigation of CsI aerosol removal in containment spray system test facility of 700 MWe IPHWR

Post-accident management of the radionuclide in a nuclear reactor is always a focus point from the nuclear power plant safety point of view. A number of systems using different radionuclide scrubbing mechanisms are already deployed in the Indian nuclear reactors to safeguard the public during and post-accident scenario. However, it is always desirable to achieve “As Low As Reasonably Achievable” (ALARA) philosophy. In the same lines, to further strengthen the safety of Indian nuclear reactors, Containment Spray System (CSS) is introduced in 700 MWe Indian pressurized heavy water reactors to cater/mitigate the aftermath of the Design Basis Accidents (DBA) i.e., Loss Of Coolant Accident (LOCA) and Main Steam Line Break (MSLB). It provides the fast vapour suppression and radionuclide removal from containment during/post design basis accidents. In the present work the experimental investigation of the effect of water spray on the CsI aerosol scrubbing/CsI aerosol removal is studied in a scaled down facility. Experiments are also carried out for the CsI aerosol removal when spray is not operating. In order to encompass the containment pressures during DBA, 1.0 bar(g) initial vessel pressure is used to simulate the accident conditions. For simulation of aerosols after accident CsI nano particles (spherical) suspended in the air and CsI dry aerosols are used. The spray flow rate for all the experiment is kept constant approximately 11.3 lpm. However different Sauter Mean Diameter (SMD) (D32 = 590 µm, 745 µm, 1000 µm) are used to study the effect of droplet diameter on CsI aerosol removal. The temporal variation of the vessel relative pressure gas mean temperature and wall temperature is measured. Vessel depressurization rate with time is recorded. CsI aerosol removal/ CsI aerosol concentration variation with time is measured using two diverse measurements system namely scrubber method and Optical Particle Counter (OPC). Global decontamination factor and global collection efficiency is deduced based on the studies. Few tests without spray are also carried out to estimate the plate out effect on CsI aerosol removal.

Generation of Ions from Aqueous Taylor Cones near the Minimum Flow Rate: "True Nanoelectrospray" without Narrow Capillary.

Generating ultrafine charged droplets using electrospray is crucial for attaining high ionization efficiency for mass spectrometry. The size of the precursor charged droplets depends on the spray flow rate, and conventional wisdom holds that an electrospray of a nL/min flow rate (nanoelectrospray) is only possible using narrow capillaries with an inner diameter of ∼1 μm or smaller. Here, the electrospray of aqueous solutions with high electric conductivities generated from a large off-line capillary of 0.4 mm i.d. has been performed using a high-pressure ion source. The electric discharge is avoided by operating the ion source at 2.5 bar gauge pressure. The highly stable Taylor cone can be tuned to a near-hydrostatic state that exhibits the "true nanoelectrospray" properties, i.e., high salt tolerance and minimal ion suppression. The Q1/2 scaling law describing the electrospray current I and flow rate Q is found to be valid down to the nanoflow regime under a condition that is free of electric discharge. For a given solution, the flow rate and the size of the initial droplets and ionization species can be controlled with the spray current as the indicator for the instantaneous flow rate without changing the emitter capillary of different sizes. In regard to the application, the nanoelectrospray with a large micropipette tip is easy to use, free of clogging when dealing with viscous and high-salt buffer solutions, and with reduced surface interaction with the emitter inner surface. An acquisition of very clean mass spectra of proteins from concentrated solutions of nonvolatile salts such as phosphate-buffered saline is demonstrated.