Nominal Flow Rate Research Articles

Control strategies of solar heating systems coupled with seasonal thermal energy storage in self-sufficient buildings

A numerical analysis is carried out to investigate the influence of different solar collector control strategies on the performance of a solar heating system coupled with seasonal thermal energy storage. The system is used for space heating and domestic hot water production in a low-energy residential building. The performance of the controller is measured in terms of the minimum storage volume required to achieve an annual solar fraction of 100%. Three controllers were numerically investigated: (1) a high-flow controller (HFC) with a constant nominal flow rate of 40 l/h⋅m2, (2) a low-flow controller (LFC) with a constant nominal flow rate of 12.5 l/h⋅m2, and (3) a variable-flow controller (VFC) with a flow rate in the range 4 – 40 l/h⋅m2 whose objective function is given by a predefined temperature at the outlet of the collector. The performance of the investigated controllers is assessed by conducting full year simulations using an in-house, experimentally validated model. A detailed comparative analysis reveals that the reasons behind the specific performance characteristics of each controller are closely related to the thermal stratification effected in the storage and to the capability of the controller to preserve the stratification throughout the year.

Pressure Fluctuation Reduction of a Centrifugal Pump by Blade Trailing Edge Modification

The pressure fluctuation inside centrifugal pumps is one of the main causes of hydro-induced vibration, especially at the blade-passing frequency and its harmonics. This paper investigates the feature of blade-passing frequency excitation in a low-specific-speed centrifugal pump in the perspective of local Euler head distribution based on CFD analysis. Meanwhile, the relation between local Euler head distribution and pressure fluctuation amplitude is observed and used to explain the mechanism of intensive pressure fluctuation. The impeller blade with ordinary trailing edge profile, which is the prototype impeller in this study, usually induces wake shedding near the impeller outlet, making the energy distribution less uniform. Because of this, the method of reducing pressure fluctuation by means of improving Euler head distribution uniformity by modifying the impeller blade trailing edge profile is proposed. The impeller blade trailing edges are trimmed in different scales, which are marked as model A, B, and C. As a result of trailing edge trimming, the impeller outlet angles at the pressure side of the prototype of model A, B, and C are 21, 18, 15, and 12 degrees, respectively. The differences in Euler head distribution and pressure fluctuation between the model impellers at nominal flow rate are investigated and analyzed. Experimental verification is also conducted to validate the CFD results. The results show that the blade trailing edge profiling on the pressure side can help reduce pressure fluctuation. The uniformity of Euler head circumferential distribution, which is directly related to the intensity of pressure fluctuation, is improved because the impeller blade outlet angle on the pressure side decreases and thus the velocity components are adjusted when the blade trailing edge profile is modified. The results of the investigation demonstrate that blade trailing edge profiling can be used in the vibration reduction of low specific impellers and in the engineering design of centrifugal pumps.

Accuracy and Uncertainty of Gradient Based Leak Localization Procedure for Liquid Transmission Pipelines.

This paper describes issues of leakage localization in liquid transmission pipelines. It focuses on the standard leak localization procedure, which is based on the calculation of pressure gradients using pressure measurements captured along a pipeline. The procedure was verified in terms of an accuracy and uncertainty assessment of the resultant coordinate of a leak spot. An important aim of the verification was to assess the effectiveness of the procedure in the case of localization of low intensity leakages with a level of 0.25–2.00% of the nominal flow rate. An uncertainty assessment was carried out according to the GUM convention. The assessment was based on the metrological characteristics of measuring devices and measurement data obtained from the laboratory model of the pipeline.

Rapid Prototyping of Pneumatic Directional Control Valves.

The main objective of the study was to design a pneumatic directional control valve for controlling pneumatic drives and produce it using a rapid prototyping technique. As the basic design assumption was to achieve high performance through a high flow rate and a low pressure drop, it was necessary to determine two flow parameters: the sonic conductance and the critical pressure ratio. The flow rate of compressed air and the diameters of the pneumatic conduits and fittings are important as they affect the rate of travel of the pneumatic cylinder piston. The 3D solid model of the directional control valve, developed in a CAD program, was used to simulate and optimize the flow rate. The analysis was performed by means of ANSYS CFX, a computational flow dynamics program. The main elements of the valve, i.e., the spool and the body, were produced using the PolyJet Matrix technology. The prototype was tested experimentally to determine the nominal flow-rate, calculate the flow parameters in accordance with the ISO 6358-1989 standard and compare them with the CFD simulation data. The simulation results showed very good agreement with the measurement data. The CFD analysis of the 3D solid model enabled us to optimize the flow of compressed air through the valve. The rapid prototyping method was found to be suitable to produce a fully functional directional control valve, which was confirmed through measurements at a test stand. The attempt to combine rapid prototyping used to fabricate pneumatic directional control valves with CFD used to simulate their operation was successful. The study shows that it is possible to design and construct a fully functional directional control valve characterized by high efficiency, high performance and a small pressure loss in a very short time and at a very low cost, which makes rapid prototyping superior to conventional methods of prototype making.

Theoretical and Experimental Investigation of a 34 Watt Radial-Inflow Steam Turbine With Partial Admission

Abstract A microsteam turbine with a tip diameter of 15 mm was designed and experimentally characterized. At the nominal mass flow rate and total-to-total pressure ratio of 2.3 kg h−1 and 2, respectively, the turbine yields a power of 34 W and a total-to-static isentropic efficiency of 37%. The steam turbine is conceived as a radial-inflow, low-reaction (15%), and partial admission (21%) machine. Since the steam is limited in the system (solid oxide fuel cell), a low-reaction and high-power-density design is preferred. The partial-admission design allows for reduced losses: The turbine rotor and stator blades are prismatic, have a radial chord length of 1 mm and a height of 0.59 mm. Since the relative rotor blade tip clearance (0.24) is high, the blade tip leakage losses are significant. Considering a fixed steam supply, this design allows to increase the blade height, and thus reducing the losses. The steam turbine drives a fan, which operates at low Mach numbers. The rotor is supported on dynamic steam-lubricated bearings; the nominal rotational speed is 175 krpm. A numerical simulation of the steam turbine is in good agreement with the experimental results. Furthermore, a novel test rig setup, featuring extremely thin thermocouples (ø0.15 mm) is investigated for an operation with ambient and hot air at 220 °C. Conventional zero- and one-dimensional predesign models correlate well with the experimental results, despite the small size of the turbine blades.

РАЗРАБОТКА И АВТОМАТИЗАЦИЯ ИЗМЕРЕНИЯ И РЕГУЛИРОВАНИЯ РАСХОДА ТЕПЛОНОСИТЕЛЯ В ЯЧЕЙКАХ ТВЭЛ МОДЕЛЬНЫХ ТЕПЛОВЫДЕЛЯЮЩИХ СБОРОК

The article presents the results of the development of a formula for determining the flow rate in the fuel element cells, taking into account the real velocities distribution in the flow cross section (average velocity deficit); the functional diagram of the system for monitoring and controlling the flow rates in the fuel element cell and the algorithm of the program of the flow control system at the experimental stands with spills or blowdowns of bundles of heat-releasing element cell simulators. Automation of flow control is carried out on the basis of the previously obtained semiempirical relationship between the volumetric flow rate of the coolant in the fuel element cell, the maximum flow rate in the flow on the cell axis and friction pressure losses along the length of the stabilized flow section; and also on the basis of the dependence of the average speed on the maximum speed and the coefficient of friction resistance. The formula used in the program code makes it possible to determine the coolant flow rate in a tightly packed fuel element cell with an accuracy of up to 2% of the nominal flow rate. The results presented in the article are of practical value for experimenters who investigate the heat transfer (or heat transfer) coefficients of model fuel assemblies, as well as fuel bundles with a limited number of fuel rod simulators, including life tests on full-scale fuel assemblies.

A Novel Method for GreenLight MoXy Laser Fiber Irrigation System to Improve Performance and Durability: A New Standard of Care?

Introduction and Objectives: The GreenLight™ MoXy® laser fiber has been used since 2010 for benign prostatic hyperplasia procedures. We tested a novel principle to increase the saline irrigation flow rates beyond the current standard of gravity drip (∼22 cc/minutes) within the fiber-attached cooling system to potentially prevent excessive tissue adherence and to eliminate the likelihood of degradation due to abnormal overheating. The objective was to assess differences between the ordinary and active pumping methods with ≥2 times flow rate after conditioning of the laser fiber. Materials and Methods: A controllable full, tissue-contact system was utilized for conditioning in a porcine model, applying 180 W of vaporization mode of GreenLight XPS console for 30 continuous minutes. Four groups were evaluated using different saline flow rates; the nominal flow rate (control group, 22 mL/minute), digital pump set (35 mL and 50 mL/minute), and a manual pressure cuff with hand pump set using a 3-L saline bag with pressure of 300 mmHg (35-80 mL/minute). At the end of the conditioning process, a mechanical pull force test was executed on the fiber metal cap to evaluate the bonding strength. A failed event was defined as the natural detachment of the metal cap during the conditioning process or a cap pull force smaller than 22.24 N resulting in detachment. Additional physical parameters, including fiber tip temperature information and laser beam power transmission efficiency, were analyzed. Results: Detachment of the cap occurred less frequently when using the 300 mmHg pressure cuff saline bag compared to the nominal flow rate (6.67% vs 50%, respectively). The average operating fiber tip temperatures were lower in the higher flow rate groups compared to nominal, measured at 315°C and 305°C. compared to 442°C. Moreover, a significantly lower FiberLife Event count and an ∼5% increase of the average final laser transmission efficiency were observed in the higher flow rate groups. Conclusions: Our study demonstrates superior results when using active pumping or high-pressure systems to increase saline flow rates in terms of laser fiber durability without any additional cost. More specifically, use of a manual pressure cuff with starting pressure at 300 mmHg, a system that is readily available in most operating rooms, increases MoXy fiber durability. Further studies are required to assess if this technique will improve user experience, clinical outcomes, and procedure costs.

Analysis on the Inception of the Magnetohydrodynamic Flow Instability in the Annular Linear Induction Pump Channel

Abstract Flow instability is the intricate phenomenon in the annular linear induction pump (ALIP) when the pump runs at off-design working condition. A three-dimensional (3D) numerical model is built to simulate the flow in the pump channel. The pump heads at different flow rates are accurately predicted by comparing with experiment. The simulation results show the fluid velocity is circumferentially nonuniform in the pump channel even at the nominal flow rate. The flow in the middle sector continuously decelerates to nearly zero with the reducing flow rate. Reversed flow occurs in the azimuthal plane, followed by vortex flow. The reason for the heterogeneous velocity field is attributed to the mismatch between nonuniform Lorentz force and relatively even pressure gradient. It is seen that the flow in the region of small Lorentz force has to sacrifice its velocity to match with the pressure gradient. An analytic expression of the axial Lorentz force is then developed and it is clearly demonstrated the Lorentz force could be influenced by the profiles of velocity and radial magnetic flux density. The coupling between velocity and magnetic field is studied by analyzing the magnitudes of different terms in the dimensionless magnetic induction equation. It is found the dissipation term is determined by not only the magnetic Reynolds number but also the square of wave number of the disturbance in each direction. The smaller disturbing wave number weakens the dissipating effect, resulting in the larger nonuniform magnetic field and axial Lorentz force.

Multi-Objective Optimization of Multistage Pump Balance Drum System Based on BP Neural Network and Genetic Algorithm

The axial force balancing capacity of a balance drum is a key factor affecting the life of multi-stage centrifugal pumps. In this paper, a double shell segmental multistage pump is taken as the research object. The hydraulic performance and axial force performance are set as the optimization objectives, and the performance data are obtained by numerical simulation with FLUENT software. The BP neural network is used to establish the prediction model of structural parameters of the balance system, hydraulic performance and residual axial force performance, and it is used as the adaptive value evaluation model of genetic algorithm to solve the optimal value in the sample space. The results show that the radial clearance of the balance drum and the balance tube orifice flowmeter, the axial width of the balance cavity are the significant factors affecting the hydraulic performance and axial force performance of the multistage pump. When the radial clearance of the balance drum is 0.1mm, the clearance of the orifice flowmeter is 1.95mm, and the axial width of the balance cavity is 55mm, the multi-stage pump has the best hydraulic performance and the smallest residual axial force. The vortex band in the balance cavity can increase the amount of the fluid spin and enhance the axial force balancing capacity of the balance drum. The greater the area occupied by the negative high-rotation fluid in the balance cavity, the stronger the ability of the balance drum to balance the axial force. The test results show that compared with the prototype multistage pump, at nominal flow rate, the head and efficiency of the optimized model are increased by 0.71% and 1.63% respectively, and the bearing temperature and vibration speed of the multi-stage pump are significantly reduced.

Statistical analysis of fine resolution flow datasets helps characterizing flow behaviour in primary clarifiers: a decision support method

Abstract In situ measurement campaigns of primary clarifiers are rarely implemented properly because of their cost, time, and energy demand. Hydrodynamic modelling possibilities for such reactors have been intensely examined recently, but on-site factors affecting flow characteristics (e.g. flow distributors) have not received sufficient attention. This paper describes the use of ANOVA in examining fine resolution flow datasets and the related decision support method for in situ measurement campaigns and subsequent modelling processes. The characteristics of the flow and the applicability of 2D and 3D methods to investigate hydrodynamic features are discussed through the example of a rectangular primary clarifier, also considering the reproducibility of measurements ranging from typical nominal flow rates to peak loads. Based on the data, recommendations are provided on the adequate sizing of a measurement campaign, potentially reduced to a single longitudinal section (2D measurement). According to our results, performing hydrodynamic measurements with a 2D-arrangement of measuring points is sufficient in the case of such clarifiers, also with regard to the design processes. When applying the described methods, the related efforts and costs may be reduced and estimated more easily. However, care should be taken when applying this method to determine the spacing of measuring points correctly.

Effects of the hydrofoil blade on the pressure pulsation and jet‐wake flow in a centrifugal pump

AbstractA hydrofoil blade design (HBD) is proposed to suppress the unsteady pressure pulsations in a centrifugal pump. Numerical simulation is carried out using the SST k‐ω model to obtain the unsteady flow field in the pump both with HBD and the conventional blade design (CBD). The pressure pulsations with the two types of blade profiles are compared at the nominal flow rate, whereas the jet‐wake flow patterns and vortex structures are analyzed to clarify the effect of the HBD on the flow field. The pressure pulsation amplitudes at the blade frequency (fBPF) are significantly reduced with the HBD, especially near the volute tongue, with a reduction of 72%. It is evident that HBD can effectively suppress the pressure pulsation. It is for these reasons that the relative velocities in the jet region at the impeller outlet are reduced, and the velocity gradients between the pressure and suction side are decreased, which contributes to improving the flow uniformity at the impeller outlet. Besides, the vorticities at the impeller outlet are reduced, and the high energy vortices shedding from the blade trailing edge are restrained. The combined effects of the uniform flow field and low vorticities contribute to the reduction of pressure amplitude with the HBD. The findings would serve as a reference for the pump designs with low noise and vibration.

A computationally-efficient finite element method for the hydraulic analysis and design of subsurface drip irrigation subunits

A finite element model was developed for the hydraulic design of subsurface drip irrigation subunits. The governing differential equation for steady-state water flow in a multi-outlet pipeline was derived according to the energy and mass conservation equations and was discretized using the Galerkin method. An equation system containing unknown hydraulic heads was constructed and solved using direct stiffness algorithm and Gaussian elimination. The local head loss from the emitter was calculated as a fraction of the kinetic head. The emitter flow rate and its variation were evaluated using an analytical expression of positive soil water pressure and a log transformation of saturated hydraulic conductivity. The model adopted a virtual emitter concept, which allowed for rapid convergence on an ordinary computer. The finite element formulation made the model capable of analyzing both branched and looped pipe network systems. A MATLAB software script was developed, and the hydraulic performance of subsurface drip irrigation subunits was analyzed. The results indicate that a higher number of elements discretized in a pipe led to a higher accuracy of the model, with 20 elements being sufficient. The subsurface drip irrigation subunit can be recognized as an integrated water energy dissipation system. The average value and uniformity of emitter flow rate were determined by the pipe system and soil hydraulic properties. The designed maximum lateral length of a drip and a subsurface drip irrigation subunit was different. In the presented design example, that difference was determined by the emitter nominal flow rate and variation of the soil saturated hydraulic conductivity.

Effects of the staggered blades on unsteady pressure pulsations and flow structures of a centrifugal pump

Effects of the staggered blades on unsteady pressure pulsations of a centrifugal pump with a specific speed ns=147 are investigated by the numerical simulation method. The obtained results are compared with the original blades. To clarify the resulting effects, eight monitoring points are used to extract pressure signals at three typical working conditions, and component at the blade passing frequency fBPF is emphasized. Results show that the pump efficiency and head will be reduced by the staggered blades, and at the nominal flow rate, the reduction is about 1.5% from comparison with the original blades. For all the eight points, the staggered blades contribute to the reduction of pressure amplitudes at fBPF when the pump works at three flow rates. The averaged reduction is 15.5% at the nominal flow rate. However, the negative effect on the second harmonic of fBPF will be caused by the staggered blades, and the corresponding pressure amplitude will increase at 2fBPF. It means that the pressure pulsation energy will be redistributed among the discrete components in pressure spectrum by the staggered blades. From the TKE distribution, it is found that the TKE values on the blade pressure side will be significantly affected by the staggered blades.

Experimental study and analysis of hydraulic characteristics of diaphragm (chamber) gas flow meter

In the conditions of life, the most common household gas flow meters are diaphragm (chamber) flow meters. From a technical point of view, hydraulic and durability characteristics are important A basic requirement that must be met by measuring instruments used for industrial or domestic applications is to be as accurate as possible. The diaphragm flow meter type BK G2.5T was experimentally studied in the work. The hydraulic (resistance) characteristic Δp = f (Q) of this type of flow meters is obtained and it is derived the analytical dependence of this characteristic - square parabola and means pressure drop at a nominal flow rate – Δpm = 0,4 mbar. The established pulsation character of the operation of the diaphragm flow meter is analyzed by the introduced one the characteristic of the pressure pulsations δp = pmax - pmin = f (Q), as for the specific flow meter the pulsations are δp = 0,1…0,2 mbar. The original results from obtained researches will be useful for constructors for optimization of the design of the gas systems.

Effect of angled spray nozzle designs on spray distribution and droplet spectrum

ABSTRACT New technologies have been developed to promote uniform, sustainable, safe and effective application of phytosanitary products. In this scenario, spray nozzles of different designs and jet angles can optimize application. Therefore, we aimed to analyze the effect of angled flat fan spray nozzles on spray pattern uniformity and droplet spectrum formation. The spray volumetric distribution of standard flat fan, double flat fan and the new angled flat fan spray nozzle, using two spray volumes were assessed. For that, the spray pattern distribution and the coefficient of variation (CV) were determined. The droplet spectrum characterization produced by the same treatments was performed in a real-time particle size analyzer. Also the effect of adding a fungicide mixture associated with an adjuvant on droplet formation was evaluated. All spray nozzles, regardless of design and spray volumes evaluated, produced CV values below 7%, considered acceptable by international uniformity standards. There was a difference in spray pattern according to the spray nozzle design and spray volume. It was evidenced that the main differences found in droplet spectrum occurred due to spray nozzle type, spray mixture and nominal flow rate, with little influence of spray jet angled or spray volumes.

Investigation of mechanical ventilation for cooling in high-rise buildings

Cooling-related energy consumption is growing rapidly in buildings. High-rise buildings usually have high cooling loads and cooling-related energy consumptions. Reducing the cooling load of high-rise buildings is critical for decreasing cooling-related energy consumption and peak electricity demand. Due to their cold climates, ventilative cooling (VC) is available for a long time throughout the year in Canada and Northern Europe, not only during shoulder seasons, but also in summer periods. Mechanical ventilation is an option for providing VC and reducing high-rise cooling load. However, the mechanical ventilation system in high-rise buildings is typically designed and used for maintaining indoor air quality, rather than for removing indoor heat. This study aims to use the mechanical ventilation system for VC in high-rise buildings and explore the associated energy saving approaches. Energy models of components in the cooling system were developed. Based on the models developed, different energy saving approaches were proposed, including applying the optimal control method, using energy efficient fans, and increasing nominal fan flow rates. A case study was conducted on an institutional high-rise building to validate the models developed and evaluate the proposed energy saving approaches. It was found that with energy efficient fans, applying the optimal control method and increasing the nominal ventilation flow rate can achieve energy savings for cooling. Increasing the optimal nominal ventilation rate further does not significantly increase energy savings. The conclusions of this study provide vital information regarding high-rise VC for new building design and HVAC system retrofit in existing buildings.

Effect of wand-type underdrains on the hydraulic performance of pressurised sand media filters

Sand media filtration is frequently used in drip irrigation systems. Commercial filter designs may use different underdrain models but wand-type designs provide a large ratio of horizontal area covered by underdrains and are expected to provide a uniform flow of water through the medium. The complexity of these designs makes it difficult to analyse the effects of changing the position of wand and the slot open area. These underdrain effects were studied by means of a computational fluid dynamics (CFD) model assuming clean water conditions. The backwashing process was not considered. The CFD results were validated using experimental data from a commercial sand media filter with 10 wands. Unbalanced flows between underdrains were observed in the original configuration. Two new designs were proposed: (1) a design that uses the same type of wands as the original filter but distributes them so as to have an equal horizontal area served by each wand; (2) a design that uses the same spatial distribution as the original filter but with longer wands in those regions of the original filter with lower volumetric flow. CFD simulations indicate that design (1) can reduce the pressure drop through the filter at nominal volumetric flow rates by up to 5.8% with a more uniform flow inside the medium and design (2) could improve the performance of the filter by achieving an up to a 4.9% reduction of pressure drop. Thus, the spatial distribution of underdrains is a key parameter in the hydraulic performance of sand media filters.

Effect of blood flow on platelets, leukocytes, and extracellular vesicles in thrombosis of simulated neonatal extracorporeal circulation

BackgroundExtracorporeal membrane oxygenation (ECMO) has frequent and sometimes lethal thrombotic complications. The role that activated platelets, leukocytes, and small (0.3‐micron to 1‐micron) extracellular vesicles (EVs) play in ECMO thrombosis is not well understood. ObjectivesTo test the effect of blood flow rate on the generation of activated platelets, leukocytes, and EVs in a simulated neonatal ECMO circuit using heparinized human whole blood. MethodsSimulated neonatal roller pump circuits circulated whole blood at low, nominal, and high flow rates (0.3, 0.5, and 0.7 L/min) for 6 h. Coagulopathy was defined by thromboelastography (TEG), STA®‐procoagulant phospholipid clot time (STA®‐Procoag‐PPL), and calibrated automated thrombogram. High‐resolution flow cytometry measured the cellular expression of prothrombotic phospholipids and proteins on platelets, leukocytes, and EV. ResultsDespite heparinization, occlusive thrombosis halted flow in two of five circuits at 0.3 L/min and three of five circuits at 0.7 L/min. None of the five circuits at 0.5 L/min exhibited occlusive thrombosis. Phosphatidylserine (PS)‐positive platelets and EVs increased at all flow rates more than blood under static conditions (P < .0002). Tissue factor (TF)‐positive leukocytes and EVs increased only in low‐flow and high‐flow circuits (P < .0001). Tissue factor pathway inhibitor (TFPI), at 50 times more than the concentration in healthy adults, failed to suppress thrombin initiation in low‐flow and high‐flow circuits. ConclusionsThis in vitro study informs ECMO specialists to avoid low and high blood flow that increases TF expression on leukocytes and EVs, which likely initiate clot formation. Interventions to decrease TF generated by ECMO may be an effective approach to decrease thrombosis.

Dynamic flow behavior and performance of a reactor coolant pump with distorted inflow

In the operation of a nuclear plant system, a distorted inflow of a reactor coolant pump appears owing to the steam generator channel head and multi-bend, leading to the deterioration of pump performance and stability. In the present study, three-dimensional numerical calculations of three model geometries are carried out using block grid technology, with RNG k-ε and DDES model applied in the steady and transient simulation. The simulation results are validated with an experiment testing the pump with a short inlet pipe. As for the results, under the distorted inflow condition, the pump head and efficiency are reduced by 4% and 5.2% respectively at the nominal flow rate. Additionally, when the pump is coupled with upstream structures, the inlet flow becomes distorted and more chaotic, and the swirl and radial flow are produced by asymmetric pressure difference. Meanwhile, a pair of local vortices appears in the inlet section, forming re-distributed mass flow rates. As the distorted flow enters the pump, the blade inlet pressure and flow rate are unevenly distributed. Moreover, the evolution process of the vortex is accompanied with strong non-uniformity in the impeller channel, and thus asymmetric tangential force is imposed on the blades, increasing the risk of the fatigue breakdown of the impeller.

Challenges of fast sampling of volatiles for thermal desorption gas chromatography - mass spectrometry

Fast active sampling of volatile organic compounds (VOCs) under field conditions still is a great challenge especially when the exposure time to the source of emissions is a restricting factor. Hence, to identify ideal conditions for such applications, we systematically compared fast active sampling of VOCs collected on two common adsorbents under two regimes: first, very low gas volumes (from 300 mL) sampled at nominal flow rate and, second, sampling at the maximal applicable flow rate (0.5 L/min) before loss of sorbent material was experienced. For XAD-2 and Tenax TA, efficient sorbents for on-site VOC-sampling followed by thermal desorption GC–MS, significant differences in the signal response of volatile compounds were related not only to the varied experimental factors alone, but also to their interactions and to compound volatility. In the first regime, volatiles (∼0.004–3.13 mM) from Tenax TA gave the highest signal response only above 800 mL sampled gas volume while at low concentrations (∼0.004–0.12 mM), satisfactory recovery from XAD-2 required longer analyte-sorbent interaction. For the second regime, the relative recovery was severely impaired down to 73 ± 23%, n = 56 for Tenax TA and 72 ± 17%, n = 56 for XAD-2 at intermediate concentration, and 79 ± 11%, n = 84 for Tenax TA at high concentration compared to the relative recovery at standard flow rate. Neither Tenax TA nor XAD-2 provided a 100% total recovery (calculated using breakthrough values) for any of the evaluated compounds. Finally, two-way and three-way interactions identified in a multi-variable model, explained not only the dependence of the signal response on different experimental variables, but also their complex interplay affecting the recovery of the VOCs. In conclusion, we show for the first time that XAD-2, a material only recently introduced for the adsorption of volatiles from the gas phase, competes well with the standard material Tenax TA under conditions of fast sampling. Due to the similar absolute recovery with Tenax TA even at low concentration and with regard to the better detection limits, we consider XAD-2 the better choice for fast sampling of VOCs, particularly with low sample volumes at regular flow. For fast sampling with high flow rate, however, both sorbents might be selected only if the corresponding recovery loss can be accepted for the study.