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The influence of vacuum pressure applied on H2 separation from a palladium membrane is explored in this study. Three factors with three levels are considered, including the membrane chamber temperature with levels 320 °C, 350 °C, and 380 °C; the retentate-side total pressure with levels 1, 2, and 3 atm; and the permeation-side vacuum pressure with levels 0, 25, and 50 kPa. The Taguchi, response surface methodology (RSM), and multivariate adaptive regression splines (MARS) methods are employed to analyze the effects of the three parameters on hydrogen separation and predict their optimal combination. The retentate-side total pressure exhibits the highest impact on H2 permeation, following the permeation-side vacuum pressure and then the membrane chamber temperature. The maximum H2 flux is 0.226 mol∙s−1∙m−2, with H2 recovery of 91 % obtained at the optimal conditions with a temperature of 380 °C, a total pressure of 3 atm, and a vacuum pressure of 50 kPa. The improvement in H2 flux reaches 21.6 % compared with the case without the imposed vacuum pressure at the same temperature and total pressure. This result shows the imposed vacuum pressure is an efficient way to enhance H2 permeation. The maximum relative errors between the experimental data and the predictions from the Taguchi, RSM, and MARS methods are 6.74 %, 3.37 %, and 8.08 %, respectively. The RSM method presents higher accuracy than Taguchi and MARS, perhaps due to a more precise analysis of the interaction terms. The smaller amount of input data and ignoring the temperature effect in MARS could be the reason for the lower accuracy. Nevertheless, the MARS method still demonstrates acceptable results. The cost of the Taguchi method is lower than that of the RSM method since it requires fewer experimental cases. In a word, the choice of the prediction method depends on the desired accuracy and the experimental cost.

Vacuum-soaked biomass gasification is a method being developed to replace fossil fuels in a safe, simple, and reliable manner. The biomass gasification process demands high temperatures in the region of 800–1000 °C, yet even when applying vacuum pressure and soaking the biomass, the experimental results of the gasification temperature can be maintained properly. Cyclone and heat exchanger system, the reactor's syngas exit temperature, which is typically 600 °C, and may be lowered to under 50 °C. The heat exchanger's temperature profile indicates that 8 m are the most practical/ideal length. The heat exchanger's effectiveness is almost perfect (0.99) and higher than in earlier experiments (0.43–0.55). The use of an open-water jacket improves the performance of the heat exchanger by lowering the LMTD by 33.60% and lowering the heat transfer rate by 24.55%. Open-water life jackets do not significantly improve effectiveness.

This paper addresses a retrofitting vacuum membrane distillation (VMD) setup to reduce the accumulated pressure inside the permeated side. This modification is necessary to extend the operation of the VMD to extreme operation conditions of higher hot water temperatures. This modification, denoted as a hybrid configuration, proposes the injection of a cold water stream into the VMD cell without mixing it with the permeate. Energy and exergy efficiency analyses were performed to assess the effectiveness of the hybrid configuration. The performance of the modified system indicated an improvement in terms of permeate flux (J), the gain output ratio (GOR), and the utilitarian exergetic efficiency (ηex,u), which reach up to two and three times that of the base configuration of the VMD system. However, the exergetic efficiency (ηex) of the hybrid system showed marginal improvement compared to the base case over the tested range of hot water temperatures. This is because the enhanced vapor production is penalized by excess energy consumption. Moreover, the highest exergy destruction percentages occurred in the operational components (e.g., heater and chillers) which fall in the range of 19.0–68.9%. The exergy destruction percentage in the original components (e.g., the VMD cell and condenser) did not exceed 8.3%. Furthermore, this study indicated that the hybrid configuration requires additional tuning and optimization to perform efficiently over wide operating conditions.

ObjectiveAspiration thrombectomy is used to treat endovascular stroke treatment by clot removal through vacuum and suction forces. We aimed to investigate the pressures and suction forces generated by different pump systems for aspiration.MethodsVacuum pressure was measured using a vacuum gauge with a closed tip for a 60cc syringe and aspiration pumps. Using an artificial thrombus made from polyvinyl alcohol hydrogel and latex membrane, we assessed the catheter tip force generated on an artificial thrombus using 5Fr Sofia and 6Fr Sofia PLUS intermediate catheters combined with Penumbra Jet Engine or Stryker Medela AXS Universal Aspiration Set. Subsequently, we calculated the catheter tip forces based on the pressure [catheter tip size (force = area × pressure)], and compared with the measured catheter tip force.ResultsThe 60cc syringe generated the highest vacuum pressure. Among the automatic pumps, the Penumbra jet engine generated the highest vacuum pressure. The catheter tip forces on the artificial thrombus and latex membrane were 18.5 ± 1.70 and 8.0 ± 1.23 gf, respectively, and 13.9 ± 1.37 and 5.6 ± 0.83 gf, respectively using the 5 Fr Sofia with the Penumbra Jet Engine and the Stryker Medela AXS Universal Aspiration Set, respectively. The corresponding values for the 6 Fr Sofia PLUS with the Penumbra Jet Engine and Stryker Medela AXS Universal Aspiration Set were 39.7 ± 3.88 and 20.7 ± 0.92 gf and 25.4 ± 4.96 and 18.0 ± 0.84 gf. For a constant catheter diameter and the automatic pump, the catheter tip force was significantly larger in the artificial thrombus than latex membrane (p < 0.001, ANOVA).ConclusionThe catheter diameter, vacuum pressure, and clot softness are positively correlated with the catheter tip force.

In this study, a new design of photovoltaic thermal (PV/T) collector is proposed. This design uses a vacuum layer above the silicon wafer and not exists in the traditional PV/T collector. This layer is used to decrease the heat loss from the top surface of the PV/T collector. The analysis is conducted using a 3D thermal modeling. The new collector design with the vacuum layer achieved a 26.6% increase in the thermal power while keeping the electrical the same at Reynolds number of 50 and solar radiation of 1000 W/m2. In addition, the degradation of the vacuum pressure slightly influence the thermal performance while increasing the vacuum pressure from 0.01 Pa to 10 Pa. While further increase in the vacuum pressure from 10 Pa to 1.013×105 Pa substantially decreases the gained thermal power with insignificant increase in the electrical power.

This article demonstrates the results of experimental research one of the pulsators. Its main difference from others is a pneumatic electromagnetic pulsator in combination with a collector. Therefore, this article describes in detail the process of studying the pulsator. The planned experiment was carried out on by Factorial experiments with multiple factors. The influence of factors (the ripple frequency n, the milk ejection q and the ratio between strokes t/T) on the vacuum pressure in the inter wall chamber of teat cups was studied. The regression equation of the dependence response criterion on factors is modeled. This dependence is demonstrated graphically. Also there is a contour graph which is for more detailed information. Article in English. Pneumatinio elektromagnetinio pulsatoriaus su kolektoriumi tyrimo rezultatai Santrauka Šiame straipsnyje yra pateikti vieno iš pulsatoriaus eksperimentinio tyrimo rezultatai. Esminis išskirtinis šio pulsatoriaus bruožas – kolektoriaus buvimas. Buvo atliktas išsamus faktorinis eksperimentas. Tiriamas tokių faktorių, kaip pulsacijų dažnio n, pieno išskyrimo q ir taktų santykio t/T, poveikis vakuuminiam spaudimui vidinėje melžimo mašinos kameros sienelėje. Buvo suformuluota regresinė lygtis, vaizduojanti faktorių priklausomybės atsako kriterijų. Ši priklausomybė pavaizduota grafiškai. Taip pat yra pridėtas kontūrinis grafikas detalesnei informacijai pademonstruoti. Reikšminiai žodžiai: melžimo mašina, pulsatorius, elektromagnetinis pulsatorius, kolektorius, vakuuminis spaudimas, pulsacijos dažnis, išmesta pieno masė, faktoriai.

To improve the problem of low seeding efficiency facing the single-row planting mode traditionally used in China, this study aimed to design a novel three-row pneumatic precision metering device. The working principle and main structure were introduced in the paper. The three main factors affecting the seeding performance comprised of vacuum pressure, angular velocity of the metering tray, and taper angle of the sucking hole. A Box-Behnken experiment design having the qualified index and missed seeding index as the experimental index was used, and the results indicated that optimal performance of the metering device was achieved when the vacuum pressure was 2.16 kPa, the angular velocity of the metering tray was 29.43 rpm, and the taper angle of the sucking hole was 61.51°. The qualified index of the inner, middle, and outer ring was 95.12%, 94.68% and 94.24% respectively, while the missed seeding index of the inner, middle, and outer ring was 3.67%, 3.12% and 2.58% respectively under the optimal combination of parameters. The bench test results were basically consistent with the optimized results. This paper can provide support for the design of a three-row pneumatic precision metering device for Brassica chinensis.

The study assessed the effect of jatropha, linseed, eucalyptus, neem and jojoba oils on protection of three wood species (Acacia nilotica, Dalbergia sissoo and Pinus wallichiana) against termite attack by Odontotermes obesus. Conditioned and pre-weighed blocks of each wood species were vacuum-pressure impregnated with a 15% concentration of the oil-ethanol solutions.. Resistance of treated and untreated wood against termites was tested under laboratory as well as field conditions using choice and no-choice tests. Oil treated wood showed significant reductions in weight loss compared to control treatments. Complete termite mortality was recorded for all oil treatments except eucalyptus oil. Linseed oil showed good results in each treatment in terms of feeding resistance as well as mortality of termites followed by neem, jatropha, jojoba and eucalyptus oil. The lower weight losses were found in both choice and no-choice field tests for linseed oil treated Dalbergia sissoo while untreated Pinus wallichiana sapwood had the greater weight loss. It was observed that the oil retention was significantly more in sapwood than in heartwoods. The retention of oils justified that wood with high oil retention showed more resistance against the termite except eucalyptus oil treatment of Pinus wallichiana.

Experiments were carried out to optimize the parameters of cell tray vegetable seeder with the aim of adopting it to a specific working conditions. Two major factors, the vacuum pressure in the seeding drum and suck hole diameter were tested on cabbage seeds (Valentina cultivar) and plastic tray with 64 cells at three levels (–1, 0, +1) for each factor using the orthogonal central composite design (CCD) regression experiment. The effects of these factors on the single-seed rate (seed singulation), double-seed rate and empty-seed rate were investigated. The experimental results showed that major factor affecting single-seed rate, empty-seed rate and multi-seed rate was vacuum pressure, while suction hole diameter do not affect double-seed rate. It has been established that the round holes of the seeding drum conform to the round-shaped cabbage seeds to ensure high-quality seeding within the required agrotechnical indices — up to 96.0 % of single-seed sowing, and up to 4 % seeding of cells with double and emptyseed rate. The study determined the optimal parameters of vacuum pressure to be 2,9 kPa and 1,0 mm for suction hole diameter at a constant speed of conveyor belt 2,4 m/min. These parameters provided the basis for design and performance improvement of the tray vegetable seeding mechanism.

Sowing is affected by numerous factors, and thus high‑quality sowing is a very important task for agricultural engineers and managers of profitable agricultural production. The primary purpose of sowing is placing seeds at proper depths and in‑row spacings in well‑prepared soil. Plant population particularly gives prominence to sowing as it directly affects the uniformity of plant growth and development. Soybean planting is especially dependent on the quality of planting for yield formation due to the significant vicinity of seeds. Provided all external factors of high‑quality sowing are met, i.e. sowing conditions, the quality of sowing depends upon the planting mechanism. The following features of the planting mechanism are the most important: RPM of the seed disc, the travel speed of a seeder, and the values of gauge and vacuum pressure. This paper presents the results of sowing three different fractions of soybean seeds under laboratory conditions. The quality measurement of sowing was performed at different values of vacuum pressure and RPM of the seed disc. On balance, an increase in vacuum pressure results in improved sowing quality due to a stronger adherence of seeds to the seed disc. Lower values of vacuum pressure do not exert significant effects on the quality of sowing, regardless of the seed fraction. However, higher RPM of the seed disc entail an increase in the coefficient of variation. On the basis of the results obtained, a mathematical model for predicting changes in the coefficient of variation of sowing quality was developed using different operating parameters.

Specific gas permeability of beech wood was determined and compared with values obtained after nanosilver-impregnation and heat-treatment in three mediums of air, water, and water steam at 150 °C for four durations of 1, 2, 3, and 4 h. Separate sets of specimens for each group were prepared and impregnated with a 400 ppm aqueous nanosilver suspension. The results revealed that the effect of heat treatment in hot-air depended on the duration of treatment. Hydrothermal treatment generally increased gas permeability, this was attributed to the dissolving of extractives in the hot water medium, although lower duration of one hour did not significantly change permeability. Hygrothermal treatment increased gas permeability at all four durations, revealing its effectiveness as a pre-treatment to improve penetration of preservatives and fire-retardants into wood texture in wood preservation industry. High thermal conductivity of silver nanoparticles intensified the effects of heat treatment in all mediums.

Long-term durability of the vacuum edge seal plays a significant part in retrofitting triple vacuum glazing (TVG) to existing buildings in achieving progress towards a zero-energy building (ZEB) target. Vacuum pressure decrement with respect to time between panes affects the thermal efficiency of TVG. This study reports a 3D finite element model, with validated mathematical methods and comparison, for the assessment of the influence of vacuum pressure diminution on the thermal transmittance (U value) of TVG. The centre-of-pane and total U values of TVG are calculated to be 0.28 Wm−2 K−1 and 0.94 Wm−2 K−1 at the cavity vacuum pressure of 0.001 Pa. The results suggest that a rise in cavity pressure from 0.001 Pa to 100 kPa increases the centre-of-pane and total U values from 0.28 Wm−2 K−1 and 0.94 Wm−2 K−1 to 2.4 Wm−2 K−1 and 2.58 Wm−2 K−1, respectively. The temperature descent on the surfaces of TVG between hot and cold sides increases by decreasing the cavity vacuum pressure from 50 kPa to 0.001 Pa. Nonevaporable getters will maintain the cavity vacuum pressure of 0.001 Pa for over 20 years of life span in the cavity of 10-mm wide edge-sealed triple vacuum glazing, and enable the long-term durability of TVG.

In memoriam of Dr. H. Peter STEINHAGEN In this work we present a mathematical model to predict the red oak wood vacuum drying kinetics. The mathematical model considers molecular diffusion and two-dimensional flow of humidity. The experimental work was carried out in controlled conditions of temperature and relative humidity to estimate the effective diffusion coefficient and moisture content in the wood. An “Arrhenius” type expression was employed for temperature dependence of diffusion coefficient.

The defects can be reduced, compared to that of traditional drying, by vacuum drying of red oak. In this work we present a mathematical model to predict the red oak wood drying kinetics. The mathematical model considers molecular diffusion and two-dimensional flow of humidity. The experimental work was carried out in controlled conditions of temperature and relative humidity to estimate the effective diffusion coefficient and moisture content in the wood. An "Arrhenius" type expression was employed for temperature dependence of diffusion coefficient

Computer modeling of water distribution systems has proven to be an effective and reliable technology for simulating and analyzing system behavior under a wide range of hydraulic conditions. This article describes the identification of the hydraulic conditions in an existing pressure wastewater pipeline from the “X” pumping station to the pressure slope camera. Frequent pipe failures were observed in the pipeline after it has been renovated. Pressure variations in the characteristic points of the pipeline were analyzed applying the model and simulation tools. The critical operational modes of the pipeline were identified and their impact on the pipe failure discussed. Article in Lithuanian. Hidraulinis slėginės nuotekų linijos modeliavimas Anotacija. Vandens paskirstymo sistemų modeliavimas naudojant kompiuterį yra patikima, efektyvi ir saugi technologija, padedanti imituoti ir analizuoti sistemos veikimą esant plačiam hidraulinių sąlygų diapazonui. Straipsnyje aprašomas hidraulinių sąlygų identifikavimas realioje slėginėje nuotekų linijoje nuo siurblinės „X“ iki slėgio slopinimo kameros. Renovavus slėginę nuotekų liniją buvo pastebėtas avarijų dažnėjimas. Taikant modelį atlikti skaičiavimai ir identifikuotos hidraulinės sąlygos būdinguosiuose slėginės linijos taškuose. Identifikuotas ir aptartas hidraulinių smūgių poveikis vamzdynui. Reikšminiai žodžiai: nuotekų linija, hidraulinis smūgis, modeliavimas, vakuuminis slėgis, siurblinė.

Simulated column performance curves were constructed for existing paraffin separation vacuum distillation column in LAB plant (Arab Detergent Company/Baiji- Iraq). The variables considered in this study are the thermodynamic model option, top vacuum pressure, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates composition were constructed. Four different thermodynamic model options (SRK, TSRK, PR, and ESSO) were used, affecting the results within 1-25% variation for the most cases. The simulated results show that about 2% to 8 % of paraffin (C10, C11, C12, & C13) present at the bottom stream which may cause a problem in the LAB plant. The major variations were noticed for the top temperature & the paraffin weight fractions at bottom section with top vacuum pressure. The bottom temperature above 240 oC is not recommended because the total bottom flow rate decreases sharply, where as the weight fraction of paraffins decrease slightly. The study gives evidence about a successful simulation with CHEMCAD