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The aim of this study was to examine the drying kinetics of pears (Pyrus communis L.) with and without vacuum impregnation and under the different temperature by using tray dryer. Vacuum impregnation were applied to the the pears (15 mm thickness, 65 mm outer and 20 mm inner dimensions respectively) with the conditions of 50⁰ Brix impregnation solution concentration, 225 mbar vacuum pressure and 45 min vacuum time. Drying process was carried out at temperatures of 55, 65 and 75°C. Drying time of non-vacuum impregnated pears was determined 640, 500 and 340 min and vacuum impregnated pears was determined 700, 540 and 560 min respectively. Page, Exponential, Henderson and Pabis, Diffusion Approach were examined for testing the drying kinetics. Experimental values are in accordance with the expected values resulted Page and Difussion models of with and without vacuum impregnated pears. Effective diffusion coefficient (Deff) was varying 2.74×10-11 to 7.31×10-11 m2/s. m2/s with respect to the drying temperatures. The activation energy for the non-vacuum impregnated and vacuum impregnated pears was 32.93 kJ / mol and 24.25 kJ / mol, respectively.

Hydrogen-peroxide-based low-temperature sterilization is a new sterilization technology for temperature-dependent medical devices. The effect of the process parameters of hydrogen-peroxide-based sterilizer on the sterilization performance of process challenge devices (PCDs) needs to be investigated. Sterilant amount, operating temperature, vacuum pressure, diffusion time, and chamber loading of the sterilizer on the sterilization performance of PCDs were adjusted. Seven PCDs with various morphologies and material containing biological indicators (BI) (EZTest, Geobacillus stearothermophilus) were used to evaluate the sterilization performance. The sterilization success rates of PCDs were 86, 71, and 57% with controlled temperature and pressure, diffusion time, and sterilant volume injection, respectively. The PCD material and structure also obviously affected sterilization performance. The sterilization of PCD A is the least successful for all parameters. Meanwhile, the sterilization of PCD B was influenced by the diffusion time and the sterilant injection volume. PCD B and PCD C were successfully sterilized by controlling the temperature and pressure. The weights and volume of the sterilization loading chamber resulted in a different sterilization performance. Sterilization performances of PCD 1, PCD 2, and PCD 3 were

The use of seeders with pneumatic distribution systems is increasingly demanding for plantation of corn crop. Knowledge about the operation and adjustments of the components of agricultural machines is fundamental to increase the good distribution of plants and to ensure higher productivity. The main goal of this research was to evaluate the influence of the size of the corn seed sieve under different vacuum pressure regulations on a pneumatic distribution system, to understand the longitudinal uniformity of the plants, as well as the final and individual productivity per plant. The vSet® (Precision Planting®) pneumatic distribution system equipped with 4 corn seed sieves (C1, C4, R1, and R4) subjected to 4 different vacuum pressure adjustments (7, 12, 17 and 22 in H2O-1) was applied as treatments on corn hybrid 30F53VYH. The design used was that of randomized blocks, with subdivided plots and 4 replications. The main plot presented the vacuum pressures and the subplots presented the sieves, each composed of two sowing lines of 20 m in length. The results showed that low vacuum pressure resulted in increased unevenness between corn spacings and consequently lower yield. Smaller sieves showed less gaps and higher percentages of normal spacing. The larger sieves showed higher standard deviation and more gaps. Regular and uneven gaps provided a higher number of grains per row, higher number of grains per corn spike and a higher grain yield per corn spike.

Bu çalışmada, sıcak hava ile kurutma (50, 60, 70 °C ve 1.8 m/s), mikrodalga kurutma (180, 360, 540 W) ve dondurarak kurutma (0.2, 0.15, 0.1 mbar) olmak üzere üç farklı kuruma yöntemi deneysel olarak incelenmiş ve yağı azaltılmış beyaz peynirin (RFWC) kurutma kinetiği belirlenmiştir. Mikrodalga kurutma yönteminde işlem süresi, RFWC için sıcak havayla kurutma ve dondurarak kurutma yöntemlerinden önemli ölçüde daha kısadır. RFWC'nin kuruma kinetiğini temsil eden en yüksek R2 ve en düşük RMSE ve χ2 değerlerini hedefleyen en uygun kurutma modelini belirlemek için yarı deneysel modeller uygulanmıştır. Farklı kurutma yöntemleri için efektif difüzyon katsayısı değerleri 1.521 x 10-9 ile 4.432 x 10-8 m2/s arasında değişmiştir. Sıcaklık, mikrodalga gücü ve vakum basıncının artırılmasıyla efektif difüzyon katsayısı değerleri artmıştır. Aktivasyon enerjisi değerleri sıcak havayla kurutma için 12.421 kJ/mol ve mikrodalga kurutma için 5.599 W/ g olarak belirlenmiştir., In the current study, three different drying methods, including hot air drying (50, 60, 70 °C and 1.8 m/s), microwave drying (180, 360, 540 W) and freeze-drying (0.2, 0.15, 0.1 mbar) were experimentally studied and the drying kinetics of reduced-fat white cheese (RFWC) were determined. Microwave drying process time was significantly shorter than hot air drying and freeze-drying for RFWC. Semi-empirical models were applied to determine the most appropriate drying model targeting the highest R2 and the lowest RMSE and χ2 values representing the drying kinetics of RFWC. The effective diffusion coefficient values for different drying methods varied from 1.521 x 10-9 to 4.432 x 10-8 m2/s. Through increasing the temperature, microwave power, and vacuum pressure, effective diffusion coefficient values increased. The activation energy values were determined as 12.421 kJ/mol for hot air drying and 5.599 W/g for microwave drying.

In current work, the effects of drying temperature (60, 65, 70, and 75 °C), vacuum pressure duration (VPD; 6, 9, 12, and 15 min), and ambient pressure duration (APD; 2, 3, and 4 min) on drying kine...

This paper presents a case study on the improvement of thick marine deposits. A new method that combines vacuum pressure and surcharge load with no need for a sand cushion is proposed and evaluated...

International audience; Gas separation by adsorption processes such as pressure swing adsorption (PSA) presents an attractive alternative for upgrading biogas to biomethane. A new vacuum pressure swing adsorption (VPSA) cycle is proposed for a unit designed to purify pre-cleaned biogas (40% CO 2 and 60% CH 4) in industrial conditions (feed flow rate more than 500Nm 3 /h and large-volume equipment). The process simulations performed to optimize the VPSA unit consider the kinetic separation of the feed components by using an appropriate carbon molecular sieve (CMS) adsorbent having a high kinetic separation selectivity for CO 2 with respect to CH 4. The designed VPSA unit is composed of five columns that perform three equalization steps. Minimizing methane losses during the regeneration steps necessitates injecting part of the off-gas rich in CO 2 at the bottom of the column during the production step to push the CH 4 forward. The produced biomethane meets the specification (97% CH 4) of grid injection purity. The developed cycle allows a CH 4 recovery of 92% to be obtained with a specific energy consumption of 0.35kWh/Nm 3 , thus meeting the initial requirements for industrial exploitation of VPSA technology for biomethane purification from biogas sources.

Palladium (Pd) membranes for industrial applications have gained much interest as of late. The purification of hydrogen through Pd membranes has therefore been proposed as a viable solution to traditional separation methods. Hydrogen permeation can be enhanced when coupled with a vacuum at the permeate side. In this study, the effect of different degrees of vacuum pressures on H2 permeation through a high-permselectivity Pd membrane in different binary gas mixtures was investigated and compared to those without vacuum. Three feed gases containing H2 concentrations of 90, 70, and 50 vol% were used. Hydrogen permeation rates were studied at 320, 350, and 380 °C under vacuum pressures ranging between 0 and −60 kPa. An increase in vacuum degree intensified H2 permeation. However, best performance improvements were observed at lower H2 concentrations, lower temperatures, and also at lower vacuum pressures for all gas mixtures. The highest performance improvement of 88.83% was with the gas mixture containing 50% H2 at 320 °C with a −15 kPa vacuum pressure. Hence, from an efficiency point of view, lower temperatures and vacuum pressures were preferred for all the gas mixtures. Activation Energies were also relatively lower for conditions with a vacuum for all gas mixtures.

Thermal management of Al composites is a crucial issue to keep the promising performance and excellent reliability of the devices. We revealed a novel method to enhance the surface property of graphite flakes (GF) with Cu and Ni coatings by chemical plating way. Taking advantage of Cu and Ni co-doped GF and silicon powders, the GF@Cu@Ni/Si/Al composites were fabricated by vacuum pressure infiltration method. The GF@Cu-30@Ni-10 composites revealed about 2 times larger TC (474.4 W/m·K) and lower CTE 6.22 ppm/K than neat Al. Our strategy for highly TC offers not only the advanced process for dispersing reinforcements but also an extremely simple way for the anisotropic composites with high TC and low CTE.

Horizontal spacing of horizontal extraction gas wells can be designed to achieve a 90% pumping rate of the total generated landfill gas (LFG) from given waste properties (viz: gas permeability, landfill gas generation and non-homogeneity with depth), cover characteristics and vacuum pressure. However, cover characteristics and vacuum pressure are also important design parameters and different combinations of them result in different distributions of gas pressure in the waste, some of which would induce problematic air intrusion while others might pose threat to cover stability. This paper uses the maximum gas pressure directly below cover to distinguish these combinations, and provides the first study of the effects of the above parameters on potential outcomes. The ability of the overlying cover to resist LFG emission from the landfilled waste is suggested not to exceed a critical value, otherwise the maximum gas pressure below it would become at least 1 kPa larger than atmospheric pressure. A design formula for this critical value is proposed with respect to typical values of waste properties, vacuum pressure and the buried depth of horizontal wells in wide ranges. Together with consideration of recovery efficiency, the proposed method can be used to design a horizontal extraction gas collection system and a cover system in better working condition, and to evaluate the maximum gas pressure below cover. These applications are illustrated by a worked example.

Wood is highly regarded as the most sustainable resource that is widely used in structural applications. To extend its practicality in electrically conductive applications, it is necessary to confer electrical conductivity to the insulating wood. The most common strategy is to derive carbonized wood powder via an annealing process. Even though these carbonized wood powders are electrically conductive, they lost the ancestry characteristic of wood, that is, excellent mechanical properties. As such, it is of great importance to realize the concept of conductive wood while at the same time maintaining or even enhancing its mechanical properties further. By leveraging on the naturally formed transportation channels found in trees, conductive particles can be aligned along these ordered channels. To substitute active transport in living plants, a vacuum pressure impregnation process was used to infiltrate these conductive particles into the transportation channels. As a result, Cu/wood composite, denoted as Cu-SW, exhibited a minimum volume resistivity of 1.366 × 10

This paper demonstrates the application of a graphene–ferric oxide (hollow mesoporous α-Fe2O3 microspheres) nanocomposite for the measurement of vacuum pressure. Numerous research and industrial sy...

A process to upgrade a biogas product to biomethane has been investigated. Recycling of an absorbent is important for low-cost upgrading of biogas by chemical absorption. This study investigated the alkaline recovery of absorbent solution by thermal decomposition at various temperatures (75, 85 and 95 °C) and various vacuum levels (0.2, 0.4 and 0.6 bar). During heating, CO2 and H2S were released from the absorbent solution, which increased the pH. The highest pH 10.58 was reached for NaHCO3 solution from initial pH 8.86 when treated at 95 °C and 0.6 bar vacuum level (gauge pressure). The mass fraction of CO32− in the solution increased from 0.06 to 0.78. Experiments on H2S removal from NaHS solution gave the highest pH 10.38 at 95 °C and 0.6 bar vacuum pressure. Moreover, the performance of the recovered alkaline solution was tested in biogas absorption. The results show that CO2 and H2S removal efficiencies of alkaline solution before and after recovery were similar, at 80 and 99 % respectively. This study demonstrated that thermal decomposition has high potential for recovering the alkaline used absorbent, for recirculation back into the absorption process.

A central solenoid model coil (CSMC) is to verify the large-scalar superconducting coil manufacture technology for China Fusion Engineering Test Reactor (CFETR) in Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The CSMC composed of Nb3Sn and NbTi hybrid superconducting magnet can reach to 12 T maximum magnetic field. The main manufacturing processes of the coil are developed and verified by R&Ds and mockup coil fabrication. For now, all the five coils winding and 2/3 of terminals fabricating are finished, and the heat treatment for the Nb3Sn inner coil is completed. The turn releasing and insulation wrapping process and station for the heat treated Nb3Sn coil has been developed. The major remaining processes for the five coils are ground insulation wrapping and vacuum pressure impregnation (VPI). The mockup coil VPI will be performed firstly to validate the process. This article introduces the main manufacturing progress of the CFETR CSMC.

Conventional landslide drainage methods always seem to lack a long-term and efficient drainage capacity. Thus, it is necessary to develop a new drainage method that does not have these disadvantage...

This study was conducted to enhance the physical, mechanical and thermal properties of the short cycle coconut wood (SC-CTL) by impregnating with the kraft black liquor (BL) and black liquor/phenol formaldehyde (BL/PF) resin. The SC-CTL was impregnated with different kraft BL and BL/PF resin concentrations (i.e., 10, 15, 20 and 25% w/w) using the vacuum pressure method. Dimensional stability, mechanical and thermal properties of the impregnated SC-CTL were analyzed according to the standards. The results showed that the impregnation of BL/PF resin into SC-CTL have improved the coconut wood’s dimensional stability, mechanical and thermal properties. The morphology of coconut wood’s cells loaded with BL/PF resin clearly showed a full penetration. The results also suggested that the addition of 20% BL/PF resin was sufficient to enhance the dimensional stability, mechanical and thermal properties of SC-CTL. Thus, it is evident that the BL has the potentiality to be used as impregnant in SC-CTL through impregnation with vacuum-pressure method.

The performance of vertical pumping wells in municipal solid waste (MSW) landfills can be effectively enhanced if vacuum pressure is applied to the well. In this study, a dual-porosity model for coupled leachate and gas flow to vertical wells in MSW landfills has been established. The proposed model divides waste into fracture and matrix domains; the leachate and gas in these two domains flow horizontally and vertically into a vertical well together, and mass exchange occurs between them. The hydraulic conductivity of the fracture domain is much higher than that of the matrix domain. The model is solved using the finite-difference method to obtain numerical solutions of the leachate pumping rate Qw and leachate level drawdown S. Numerical simulations indicate that Qw and S decrease with the increasing hydraulic conductivity ratio of the fracture and matrix domains, kirf/kirm. As the proportion of the fracture domain in the total domain wf increases, additional large pores are available for leachate flow, and Qw and S gradually increase. Qw and S estimated by the single-porosity model are 1·5–3·0 times as large as those obtained using the dual-porosity model. Qw and S increase with the increasing vacuum pressure applied at the pumping well. A field vacuum well pumping test was carried out at Tianziling landfill to verify the proposed model. When the vacuum pressure at the well increased from 0 kPa to −30 kPa, Qw increased from 33 m3/day to 45 m3/day at t = 36 h and S increased from 2·7 m to 5·6 m at a radial distance from the pumping well r = 10 m. The dual-porosity model performed better than the single-porosity model when simulating the pumping test.

In this paper, we assess the performance of vacuum pressure swing adsorption (VPSA) for co-purification of H2 and CO2 through modelling and process optimization. VPSA allows for the integration of ...

Using the theory of oscillations of theoretical mechanics, a method has been developed for calculating the parameters of a selected massager cage. The resulting equations allow one to select the main operating parameters of the massager, to calculate their effective values.

In this study, a novel osmotic membrane was developed by polyamide (PA) coating on the tubular electrospun nanofiber (TuEN) support membrane. Water and reverse salt flux properties of the obtained membrane were investigated by applying pressure in addition to the osmotic forces. Surface characterization of the membrane was carried out by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analyses and flux performance tests were performed in both cross flow and submerged membrane setups. Applying pressure from the feed to the concentrate side had significant effects on the water and salt fluxes. Higher pressure differences between the feed and concentrate sides resulted in unexpected high water fluxes up to 500 Lm(-2)h(-1) (LMH). Besides, the pressure helps to transfer the salt content of feed water into the concentrate side, differently from the osmotic process preventing the salinity build-up at the feed side. PA coated TuEN membrane operated under pressure will exhibit a favorable solution in water/wastewater treatment applications, especially for membrane bioreactors (MBR) in terms of preventing salt accumulation in the bioreactor, decreasing the membrane fouling, increasing the volume of product water, and enabling the concentrate management.

A series of modified triaxial tests was conducted to investigate the deformation characteristics of mini-prefabricated vertical drain (PVD) unit cells. The factors considered are the (1) magnitudes of surcharge load (ps) and vacuum pressure (pvac); (2) pre-vacuum consolidation period (tva) before applying surcharge load; (3) surcharge loading rate (SLR); and (4) initial effective stress state in the specimens. Based on the test results, relationships between the coefficient of earth pressure (Kes) at the end of surcharge load application and the normalized horizontal and vertical specimen strains are established. Further, a method is proposed for estimating the value of Kes, and therefore the horizontal and vertical strains of the PVD improved soil layer subjected to combined vacuum pressure and surcharge load using loading conditions and basic soil properties. Finally, the proposed method was applied to a case history reported in the literature and good agreement between the field-measured and calculated lateral displacement and settlement was obtained, which suggesting that the proposed method can be a useful tool for designing preloading projects involving combined vacuum and surcharge loads.

Annotation Purpose. Substantiation of design parameters of two-chamber collector of milking apparatus by stabilization of vacuum mode of milkline of milking apparatus. Methods. An analysis of the results of experimental studies was used, which were carried out in laboratory conditions using methods of planning multi-factor experiments and statistical processing of experimental data using appropriate software. Results. Based on the results of theoretical substantiation, a prototype of a two-chamber milking collector of a milking machine was made and experimental studies were carried out on with varying structural factors according to the intensity of milk breeding. The analysis of the results of the experimental studies indicates that the rational diameter of the milk hose is 12 mm, with a throttle hole of 2 mm. The use of the proposed two-chamber collector with a portion inlet of air in the milking machine allows us to stabilize the vacuum pressure in the sucking phase, as a result of which milk with low content of somatic cells is of the highest quality. Conclusions. It has been found that the stable operation of the milking machine provides a constant vacuum pressure in the sucking phase and a sufficient drop in the vacuum pressure in the compression phase. The appropriate pressure level will be maintained by combining the diameters of the milk hose 12 mm and the throttle opening 2 mm. Keywords: milking machine, vacuum pressure, milk-shaped hose, throttle hole, two-chamber collector.

Composite scaffolds are made by various methods, such as copolymerization, freeze gelation, and thermally induced phase separation, which can compound materials with different properties using solvents and heat. However, it is difficult to compound solvents and heat-sensitive materials such as natural polymers. In this study, we investigated a vacuum pressure impregnation (VPI) method for creating a composite of natural polymers. A collagen solution could not be introduced into a poly (l-lactide) (PLA) porous material using an immersing treatment, but it is possible using the VPI method. The resulting PLA-collagen composite scaffold had greater water adsorption and degradation than a PLA scaffold. These results indicate that VPI may be a promising method for creating composites of natural materials. Impact Statement This is the development of a method for introducing cells into a completed porous material in a short time. This technology is expected to be applied to tissue regeneration and 3D culture.

The deformation characteristics of soil among prefabricated vertical drains (PVDs) subjected to vacuum pressure are investigated using a model test conducted on dredged slurry. Red iron particles are used to indirectly indicate the lateral displacement of soil under vacuum preloading. Test results showed that, in addition to the settlement of soil between two PVDs, there was also lateral displacement that varied with consolidation time and lateral distance from the PVD because of lateral vacuum suction. The lateral displacement arose successively with the increasing lateral distance. And it increased from zero on the PVD surface and dropped back to zero again at the midpoint between the two PVDs. There should have been a maximum value of the lateral displacement at a point near the PVD. The combined vertical and lateral displacement formed a soil pile around the PVD and showed a ‘V’ shaped soil surface.

In this paper, a feasibility study was carried out to evaluate cyclic adsorption processes for capturing CO2 from either shifted synthesis gas or H2 PSA tail gas of an industrial-scale SMR-based hydrogen plant. It is expected that hydrogen is to be widely used in place of natural gas in various industrial sectors where electrification would be rather challenging. A SMR-based hydrogen plant is currently dominant in the market, as it can produce hydrogen at scale in the most economical way. Its CO2 emission must be curtailed significantly by its integration with CCUS. Two Vacuum Pressure Swing Adsorption (VPSA) systems including a rinse step were designed to capture CO2 from an industrial-scale SMR-based hydrogen plant: one for the shifted synthesis gas and the other for the H2 PSA tail gas. Given the shapes of adsorption isotherms, zeolite 13X and activated carbon were selected for tail gas and syngas capture options, respectively. A simple Equilibrium Theory model developed for the limiting case of complete regeneration was taken to analyse the VPSA systems in this feasibility study. The process performances were compared to each other with respect to product recovery, bed productivity and power consumption. It was found that CO2 could be captured more cost-effectively from the syngas than the tail gas, unless the desorption pressure was too low. The energy consumption of the VPSA was comparable to those of the conventional MDEA processes.

Cross laminated timber (CLT) is known as a composite material that possesses high-performance properties. As an engineered timber product, it has been proven that CLT has better properties in terms of its strength compared to solid sawn timber. However, the strength of this product is influenced by its bonding integrity. To date, the production and performance of CLT from tropical hardwood is still less known. A lot more studies need to be explored especially on bonding integrity that contributes to CLT’s strength efficiency. High temperature and humidity as well as the uniqueness of the tropical anatomical structure of hardwood significantly affected this bonding integrity. Therefore, preliminary study is conducted under laboratory scale before the manufacturing is executed in industrial scale. In this study, the bonding integrity of the CLT panels from tropical hardwood namely, Light Red Meranti and Keruing are assessed. The CLT panels are manufactured via semi-scale of vacuum press for three and five layers with dimensions of 1.3 m length × 1 m width in accordance with EN16351. Block shear are carried out in this bonding integrity study. A total number of 189 test samples were taken at various locations from these panels to represent the entire CLT panel. Four type of treatments are provided to simulate various service conditions, which are dry, wet, wet + re-dry, and delamination (induced pressure) environments. All designed tests are conducted in accordance with EN16351 and EN14374. The characteristic value of shear strength and wood failure percentage (WFP) were measured. From this study, the bonding performance of Light Red Meranti shows the good bonding performance compared to Keruing.

Well resistance depends on discharge capacity of prefabricated vertical drains (PVDs), which affects the consolidation rate of soil at high water content importantly. Due to the lack of an axisymmetric large-strain consolidation model considering well resistance under vacuum pressure, the effect of well resistance on the degree of consolidation of ultra-soft soil is not clear. An axisymmetric large-strain consolidation model under vacuum pressure accounts for well resistance, self-weight stress, and vacuum attenuation along depth; both vertical and radial flow are proposed. Existing models established by Cao et al. and Nguyen et al. are special cases of the proposed model. The model and calculation method in this study are verified by the reported laboratory tests. The change laws of degree of consolidation defined by stress affected by key parameters of well resistance factor are discussed. It is found that the development of degree of consolidation will be delayed by the decreases of discharge capacity of PVDs and initial water content, as well as the increases of spacing ratio and time parameter of well resistance. The minimum demands of discharge capacity of PVDs with negligible well resistance increase exponentially with the increase of length of PVDs. The attenuation of vacuum pressure along the depth has greater influence on the degree of consolidation of soil than the attenuation of discharge capacity along the depth.

Operative delivery requires the use of a vacuum extractor, obstetricians can choose the appropriate vacuum extractor to make the delivery process smoother and safer. However, there is no biomechanical literature focused on the imposed effects of a vacuum extractor prepared with different materials and vacuum pressure on the fetal head during the process of delivery. Therefore, we first established and performed the finite element analytical model to explore the influences of vacuum extractors manufactured from different materials on the fetal head under various extractive pressures. The model of the vacuum extractor was designed as a hemispherical shape, and the material of the vacuum extractor was composed of silicone rubber and stainless steel for comparison. Four different vacuum pressures (500 cm H2O, 600 cm H2O, 700 cm H2O, and 800 cm H2O) were applied as the factors for investigation. The reaction force on the fetal head, von Mises stress of vacuum extractor, and von Mises stress on the skull of fetal head were measured and analyzed to evaluate the effects. The results revealed that subtle divergent influences of different vacuum pressures were observed, and the stainless-steel vacuum extractor induced a larger reaction force (358.04–361.37 N), accompanied with stress (13.547–13.675 MPa), on the fetal head than non-metallic or relatively softer materials. The results provide a reliable basis for selecting proper vacuum extractor during operative delivery to avoid obstetrical complications, such as scalp scratch, cephalohematoma and even intracerebral hemorrhage.

Air valves operate as protection devices in pipelines during drainage processes in order to mitigate vacuum pressures and control the transient flows. Currently, different authors have proposed one-dimensional models to predict the behaviour of orifices during filling and draining events, which offer good numerical results. However, the three-dimensional dynamic behaviour of air-admission orifices during drainage processes has not been studied in depth in the literature. In this research, the effects of air inflow on an orifice installed in a single pipe during drainage events are analysed using a three-dimensional computational fluid dynamics model by testing orifices with diameters of 1.5 and 3.0 mm. This model was validated with different experimental measurements associated to the vacuum pressure, obtaining good fits. The three-dimensional model predicts additional information associated to the aerodynamic effects that occur during the air-admission processes, which is studied. Subsonic flows are observed in different orifices with Mach numbers between 0.18 and 0.30. In addition, it is shown that the larger-diameter orifice ensures a more effective airflow control compared to the smaller-diameter orifice.