Gas In Tube Research Articles

INCREASING THE CONVERSION ACCURACY OF MODEL GAS (Ar) CONSUMPTION INTO XENON CONSUMPTION WHEN USING CAPILLARY TUBES IN THE WORKING SUBSTANCE FEED SYSTEMS OF ELECTRIC PROPULSION

The article discusses the possibility of improving the method of converting the mass flow rate of the model gas (Ar) to the mass flow rate of the working gas (Xe) in capillary tubes. The well-known method of such conversion, which is used in electric propul- sion systems, is based on Poiseuille’s law for laminar flow. The results of the experimental verification of the method showed the accuracy from 21 % to 30 %. On the basis of the conducted experimental studies, it was proposed to enter a correction factor depending on the inner diameter of the capillary into the existing methodology of mass flow recalculation, which made it pos- sible to significantly reduce the error of recalculation of Ar mass flow rate into Xe mass flow rate to ±4 %. Increasing the accuracy of the calculation allows the wide use of argon model gas in the selection of capillary flow restrictors for feed systems of low- and medium-power electric propulsion systems and during testing of assembled systems at various stages of development and testing.

Inhalation anesthesia in the cat: Development of cuff pressure when using nitrous oxide

During inhalation anesthesia with nitrous oxide in oxygen the pressure in the cuff of the endotracheal tube may increase due to diffusion of nitrous oxide into the cuff. The aim of the study was to investigate the development of cuff pressure during nitrous oxide anesthesia under clinical conditions in feline patients and to identify possible influencing factors such as tube size and gas flow rate. The prospective study included cats scheduled for inhalation anesthesia with nitrous oxide for a minimum duration of 60 minutes at the Department for Small Animals of the University of Leipzig. Cuff pressure was adjusted with a cuff manometer and its development was recorded. In total, the cuff pressure values of 24 cats were recorded. Animals were allocated into groups by tube size (ID 4.0 mm and ID 4.5 mm) and by fresh gas flow rate: low flow rate (0.6 l/min) and high flow rate (3 l/min). During anesthesia, cuff pressure increased over time, with statistical significance occurring from 45 minutes onwards in comparison to the initial cuff pressure (p=0.005). After 60 minutes, there was a mean cuff pressure increase of 3 cmH2O. Despite this moderate mean increase, highly variable pressure values up to 48 cmH2O in individual animals were recorded. No cat reached the termination criterion of 60 cmH2O cuff pressure. Effects of tube size (p=0.63) and flow rate (p=0.334) on the cuff pressure were not evident. After a period of 45 minutes of nitrous oxide administration, a significant increase in cuff pressure occurs in the cat. However, tube size and total gas flow rate do not seem to influence the cuff pressure development. When using nitrous oxide during inhalation anesthesia, regular cuff pressure evaluation and correction are necessary and hence recommended in feline patients. As individual pressure changes may be highly variable, no fixed recommendations for optimal management are possible.

Thermal-hydraulic characteristics analysis of steam–air condensation in vertical porous-wall corrugated tubes

In the passive containment cooling systems (PCCS) of Generation III nuclear power plants, the condensation performance of steam containing non-condensable gas (NCG) in condensate tubes is critical for removing heat from the nuclear power plant containment. By applying a novel porous-wall corrugated structure in the condenser tubes of this system, it was found that under certain conditions, a double vortex is formed inside and outside the porous layer, which is conductive to the transportation and condensation of steam to the condensing wall. The VOF multiphase relation and Brinkman–Forchheimerextended Darcy model in combination of local heat balance, condensation and species transport equations are employed to describe the heat and mass transfer in the porous-wall corrugated tube during condensation. The numerical analysis are conducted to investigate the effects of waveform channel, porous layer and its thicknesses, subcooling of cooling wall and inlet air mass fractions on flow and condensation under different inlet velocities, in which simulations agree with the experimental data. The results show that the condensation heat transfer is greatly influenced by the vortex distribution and air accumulation. At inflowing velocity of 1 m/s, the waveform with amplitude of 1 mm and wavelength of 18 mm can achieve the highest performance evaluation factor, φ (about 67.5 % enhancement than the smooth tubes). The ratio of waveform amplitude to wavelength needs to be chosen properly in consideration of convection between solid matrix and steam–air mixture in porous layer, and non-condensation gas distribution near cooling wall of condensation tube.

CFD investigation on the radial heat transfer in a two stage co-axial pulse tube cooler working at liquid hydrogen temperature

Co-axial pulse tube coolers are very popular in practical applications due to their compactness, while radial heat transfer between regenerator and pulse tube due to temperature mismatch at the same axial location affects the cooling performance. Two stage pulse tube coolers are commonly used at liquid hydrogen temperature, and multiple radial heat transfer occurs in gas-coupled co-axial pulse tube cooler system due to the first stage annular pulse tube. CFD simulation models with and without radial heat transfer based on an actual gas-coupled two stage co-axial pulse tube cooler have been conducted to analyze the mechanism and effect. The heat transfer processes between the gas and pulse tube wall are analyzed and compared. Simulation results indicate that after introducing radial heat transfer, expansion efficiency of the second stage pulse tube is improved from 74% to 90.9% with radial heat flow from it to the regenerator and the first stage pulse tube. The cooling power at the second stage is notably increased compared to the model without radial heat transfer, while minor performance reduction at the first stage. This study may provide a valuable reference for the design of multi-stage pulse tube coolers.

Oxygen atom and ozone kinetics in the afterglow of a pulse-modulated DC discharge in pure O2: an experimental and modelling study of surface mechanisms and ozone vibrational kinetics

The chemical kinetics of oxygen atoms and ozone molecules were investigated in a fully-modulated DC discharge in pure oxygen gas in a borosilicate glass tube, using cavity ringdown spectroscopy (CRDS) of the optically forbidden O(3P2)→O(1D2) absorption at 630 nm. Measurements were made over a range of tube temperatures (10 °C and 50 °C) gas pressures (0.5–4 Torr) and discharge current (10–40 mA). The discharge current was square-wave modulated (on for 0.2 s and off for 1 s), allowing the build-up to steady-state and the decay in the afterglow to be studied. This paper focusses on the afterglow period. The O atom density decays non-exponentially in the afterglow, indicating a surface loss probability dependent on incident active particle fluxes. The oxygen atom absorption peak lies on a time-varying absorption continuum due (in the afterglow) to the Chappuis bands of ozone. The ozone density passes through a maximum a few 100 ms into the afterglow, then decays slowly. An existing time-resolved self-consistent 1D radial model of O2 positive column discharges was modified to interpret the new results. The ozone behaviour in the afterglow can only be modelled by the inclusion of: (1) surface production of O3 from the reaction of O2 molecules with adsorbed O atoms, (2) reactions of vibrationally-excited ozone with O atoms and with O2(a1Δg) molecules, and (3) surface loss of ozone with a probability of around 10−5.

Correlation of Forced Convection Heat Transfer of Isothermal Plate Under Low Pressure

With the rapid development of vacuum tube transport technology, there is increased interest in understanding the behavior of the heat transfer of rarefied gas in a vacuum tube. Currently, most empirical correlations of forced convection heat transfer are conducted at the standard atmospheric pressure, so many correlations are not applicable to conditions below the atmospheric pressure. To investigate the heat transfer property under low-pressure conditions, the forced convection between isothermal plate and air in a low-pressure environment is numerically simulated. The results show that the traditional correlation of the forced convection heat transfer between the isothermal plate and gases is different from the actual results at low pressure, and the correlation is completely invalid when the pressure is lower than 0.2 kPa. Based on the data of numerical calculation, a modified correlation of forced convection heat transfer between an isothermal plate and gases under low pressure is proposed. The correlation coefficient R is greater than 0.99, and the fitting error is less than 10% at the 95% confidence level. The change of heat transfer depends on the Reynolds number in the pressure range of 0.2–100 kPa, but the effect of Reynolds number is weakened and the effect of pressure is strengthened when the pressure is below 0.2 kPa.

Theoretical and experimental studies for a transcritical CO2 heat pump with spirally fluted tube gas cooler

Transcritical CO2 system has been widely used in many fields to provide heating and cooling capabilities, and optimizing the structure of the gas cooler is an effective way to improve its performance. This paper presents a theoretical and experimental study of a spirally fluted tube-in-tube heat exchanger used as a gas cooler in a transcritical CO2 heat pump. The theoretical research uses numerical simulations to investigate the flow and heat transfer characteristics. The effect of the different CO2 mass flow rates, inlet pressure, and temperature on the performance of the spirally fluted gas cooler is evaluated and analyzed. The simulation results show that the spirally fluted structure can significantly improve the heat transfer performance of the CO2 side compared to the flat tube, which indicates that the spirally fluted gas cooler could be an effective way to enhance the operating performance of the transcritical CO2 system. Then experimental research is conducted in a transcritical CO2 heat pump prototype to validate the functional performance of the spirally fluted gas cooler. The effect of the different CO2 mass flow rates, inlet pressure and temperature, and the different water inlet and outlet temperatures on the performance of the spirally fluted gas cooler in the prototype are tested. The heat exchanger efficiency - number of transfer units (ε-NTU) method is employed to analyze the operating performance based on the experimental data. In addition, the exergy loss method is used to quantitatively evaluate the side-effect of the large pressure drop by the spirally fluted structure. Both the theoretical and experimental results show that the spirally fluted tube gas cooler can significantly improve the performance of the transcritical CO2 system. Besides, a heat transfer and friction coefficient correlation are established based on the experimental data for future research guidance.

Prototype Alat Pendeteksi Kebocoran Gas LPG Berbasis IOT

The role of LPG (Liquefied Petroleum Gas) at this time is very important for human life both in households and in industry. Since the existence of the energy conversion program from petrol to LPG gas, new problems have arisen. Around the beginning of January to July 2010, incidents of explosions of LPG gas tube which claimed cause casualties, and this was confirmed by the widespread coverage in the mass media, especially television. The explosion of an LPG gas tube usually occurs in a three-kilogram gas tube. Leakage of LPG tube or equipment is still one of the main causes of explosions in LPG gas tube, which results from the absence of visible gas leaks. The gas explosion occurs when the LPG gas cannot be recognized by the owner, the position of the gas that is not in accordance with the standard use of the gas can result in a very fatal explosion and cause casualties. Of the many cases circulating in society and industry, it is necessary to treat this type of fuel specifically. Therefore, there is a need for an early warning system for LPG gas and its devices in order to deal with gas leaks which can result in fatalities. This system is designed using the MQ-5 sensor and NodeMCU as the main controller that can connect to the internet. Later this tool is expected to be able to provide early warning in the form of notifications on smartphones to users in the event of a leak in a gas cylinder.

Bubble-injection and seeding enabled crystallization of erythritol/xylitol eutectic phase change material

The utilization of Erythritol/xylitol eutectic material for low-temperature thermal energy storage and thermal management holds great promise. However, its inability to undergo spontaneous nucleation and crystallization poses a significant obstacle. This research paper introduces a novel nucleation technique that combines gas injection agitation and seeding to address this issue. The study aims to investigate the impact of gas injection tube diameter, thermal environment, and gas injection duration on the nucleation and crystallization characteristics of the material. Experimental analysis reveals that, under optimal conditions, the solidification enthalpy reaches 203.1 J/g, equivalent to 85% of the melting enthalpy. Additionally, the material exhibits excellent thermal cycle stability, with no observed phase separation or deterioration after 100 heating and cooling cycles. Furthermore, the influence of Multi-Walled Carbon Nanotube (MWCNT) nanoparticle additives on nucleation is explored. Different MWCNT additive mass fractions are compared. The obtained results underscore the significance of understanding the effects of gas injection parameters and nanoparticle additives on nucleation and crystallization processes. The enhanced solidification enthalpy, remarkable thermal cycle stability, and insights into MWCNT effects pave the way for broader applications of this promising phase change material in thermal energy storage and thermal management.

KESIAGAAN DESA TANGGUH BENCANA KAWASAN PELABUHAN DAN INDUSTRI LEBAK GEDE PULOMERAK

The Port Area and Industrial City of Cilegon, which has been known as the Chemical Industry area, cannot be separated from the threat of tsunamis, earthquakes and fires, so it requires countermeasures, among others, through preparedness efforts from many parties, especially the people living in it, so that the losses that occur can be reduced as little as possible. Therefore, this study aims to determine the preparedness of the people of the Pulomerak Area in facing the danger of earthquakes and tsunamis which is illustrated through community attitudes and behaviors towards disaster threats. Based on the results of the study, it is known that community preparedness in the Pulomerak Area against tsunami, earthquake and industrial disasters is in an unprepared condition when viewed from the parameters of knowledge and attitudes, policies, emergency response plans, disaster warning systems, and resource mobilization, Data is obtained from interviews and documentation. The results showed that the potential for industrial disasters varied based on the field of industrial business. The largest industry in Cilegon City is the chemical industry (36%), so the biggest potential industrial disaster comes from the chemical industry. Potential chemical industry disasters can be caused by industrial failures such as chemical leakage, industrial infrastructure, reactor tube explosions, gas leaks, fires, poisoning, radiation, and epidemics. The unpreparedness of the community in facing the threat of this disaster is partly due to many people who do not know the vulnerability of their area to disasters. Meanwhile, there have not been many efforts to improve disaster preparedness carried out by the government due to limited resources. However, the condition of community preparedness in the Pulomerak Area can still be improved so that the risks that occur can be suppressed

Experimental study on wet gas condensation heat transfer and flow resistance in horizontal intensified tube

The heat transfer and flow resistance characteristics of in-tube vapor condensation with high content non-condensable gas is significant for designing waste heat recovery devices of gas-fired boilers. In this paper, the forced convection condensation of wet gas in the horizontal tube is experimentally investigated with a non-condensable gas mass fraction of 83–95%. The condensation heat transfer coefficient, thermal resistance and pressure drop are compared between bare tube and two intensified tubes, i.e., the corrugated and spiral tube, under various Reynolds number, wall subcooling degree and inlet humidity. The results show that the in-tube condensation heat transfer coefficient increases with increasing Reynolds number and inlet humidity, but decreases with increasing wall subcooling degree. Compared with the bare tube, the heat transfer coefficient and pressure drop increase up to 47.13% and 16.00% respectively for the spiral tube, and 116.04% and 88.48% respectively for the corrugated tube. When combing the heat transfer and flow resistance factors, the maximum comprehensive performance coefficients are 1.71 and 1.44 for corrugated tube and spiral tube respectively. The superiority of corrugated tube in the wet gas condensation is benefit from effective breaking the non-condensable gas film and promoting the vapor diffusion on the interface.

Research and application of dual tube gas lift technology in coal bed methane well

ABSTRACT Coal bed methane (CBM) is a gas resource associated with and symbiotic with coal, which refers to the hydrocarbon gas stored in the coal seam, with methane as the main component, which belongs to unconventional natural gas. The development and utilization of CBM has the effect of achieving multiple things in one fell swoop: clean energy, commercialization can produce huge economic benefits. At present, rod pump, screw pump and other lifting technologies commonly used in CBM drainage and production have poor adaptability, short pump inspection period, and it is difficult to enter horizontal section in horizontal well. Aiming at this problem, a new method of efficient CBM lifting is proposed by adopting dual-pipe gas lift technology. In this paper, the basic principle of double tube gas lift is analyzed, the optimization design of gas injection volume, coiled tubing size and coiled tubing running depth is carried out, and the field technology application of vertical and horizontal Wells is carried out. The results show that the dual tube gas lift technology has good adaptability in the deliquification of CBM, and the field application has achieved good production results. After the process modification, gas production of CBM Wells increases continuously, while water production decreases gradually, with the maximum gas rate exceeding 2400 m3/d. According to the latest production data, well L31 has been in steady production for more than 9 months, with an average gas rate of 1294.56 m3/d, which greatly exceeds the capacity before the transformation. Because there are no moving parts in the wellbore, the pump inspection period is greatly improved, and it has the potential to be widely applied in CBM.

Resonant Oscillations of Gas in Tubes with Different Tips

Resonant Oscillations of Gas in Tubes with Different Tips

FORCED LONGITUDINAL OSCILLATIONS OF GAS AND AEROSOL IN AN OPEN TUBE WITH A CROSS-SECTION JUMP

The forced longitudinal oscillations of gas and aerosol in an open tube with a cross-section jump near the resonance frequency are investigated experimentally. The intensification of gas oscillations in the tube with a cross-section jump in comparison with a homogeneous tube is observed, while preserving a close to harmonic, continuous pressure waveform. A non-monotone dependence of the aerosol deposition time on the frequency of oscillations with a minimum value at the resonance frequency is observed.

Heat transfer and performance enhancement investigation of biomimetic honeycomb gas coolers in transcritical CO2 heat pumps

CO2 air source heat pump heating technology has characteristics of strong adaptability to outdoor temperature in cold areas and high outlet temperature, which is widely used in heating and domestic hot water supply. A gas cooler is one of the crucial components in CO2 heat pump systems, while its performance and different structural forms will directly affect the performance of the whole CO2 heat pump system. In order to improve its heat transfer efficiency, a biomimetic honeycomb gas cooler is proposed in this paper, the steady-state simulation model of the biomimetic honeycomb gas cooler is established, and the reliability of the model is verified by experimental data. In addition, the effect of structural parameters and operating parameters on the heat transfer performance is studied, also the heat transfer performance of the biomimetic honeycomb gas cooler is compared with that of the internal spiral tube gas cooler and triple tube-in-tube gas cooler. The results show that the performance of the biomimetic honeycomb gas cooler can be effectively improved by reducing the water flow rate. Under the same working condition, the performance evaluation criteria1 of the 1st, 2nd and 3rd layer biomimetic honeycomb gas cooler s are about 193.4%, 239.9% and 357.0% higher than that of the internal spiral tube gas cooler, and about 197.2%, 205.9% and 237.7% higher than that of triple tube-in-tube gas cooler. This research is helpful to provide the reference for the design and optimization of this type of gas cooler and is conducive to the popularization and application of CO2 air source heat pumps.

Effect of operational and geometric parameters on the hydrodynamics of a Wurster coater: A CFD-DEM study

A coupled CFD-DEM method was used to study the hydrodynamics of a Wurster coater. Firstly, the CFD part of the model was validated by the accurate prediction of the pressure drops over a pseudo-2D fluidized bed under various gas velocities. The effect of gas velocity, gap height, tube length and batch volume of the particles on the cycle time and the residence time of the particles was thoroughly investigated. The central jet gas velocity u1 was found to speed up the particle cycle but undermine the coating efficiency. The gas velocity at the horizontal transport zone u2 was able to promote the horizontal transport of the particles but should not be too high, otherwise, it would obstruct the normal falling back of the particles in the downward zone. Big gap heights would decrease the coating efficiency but tube length had little impact on that. The increment of batch volume would commonly abase the cycle time and the working efficiency under a given u1. The de-fluidization problem arose when the batch volume increased to 550 mL. However, this problem could be swept out by the optimization of u1 and u2. In a mixture of different sizes, the coarse particles enjoyed higher coating efficiency and could travel closer to the nozzles. This may shield the fine particles from getting enough coating liquids, and thus coarse particles and fine particles were not recommended to get coated in the same batch.

In situ Raman quantitative monitoring of methanogenesis: Culture experiments of a deep-sea cold seep methanogenic archaeon.

Gas production from several metabolic pathways is a necessary process that accompanies the growth and central metabolism of some microorganisms. However, accurate and rapid nondestructive detection of gas production is still challenging. To this end, gas chromatography (GC) is primarily used, which requires sampling and sample preparation. Furthermore, GC is expensive and difficult to operate. Several researchers working on microbial gases are looking forward to a new method to accurately capture the gas trends within a closed system in real-time. In this study, we developed a precise quantitative analysis for headspace gas in Hungate tubes using Raman spectroscopy. This method requires only a controlled focus on the gas portion inside Hungate tubes, enabling nondestructive, real-time, continuous monitoring without the need for sampling. The peak area ratio was selected to establish a calibration curve with nine different CH4-N2 gaseous mixtures and a linear relationship was observed between the peak area ratio of methane to nitrogen and their molar ratios (A(CH4)/A(N2) = 6.0739 × n(CH4)/n(N2)). The results of in situ quantitative analysis using Raman spectroscopy showed good agreement with those of GC in the continuous monitoring of culture experiments of a deep-sea cold seep methanogenic archaeon. This method significantly improves the detection efficiency and shows great potential for in situ quantitative gas detection in microbiology. It can be a powerful complementary tool to GC.

Research on gas wave refrigeration application of full feedback periodic jet oscillator

Static gas wave refrigeration (SGWR) is a mechanic equipment with no moving parts which realize refrigeration by working on gas through pressure energy. This paper introduces full feedback jet oscillator as the jet distributor of the gas wave refrigerator and shows the switching mechanism of the oscillator in detail through dynamics description. The range of influence of wedge distance (distance between wedge tip and the nozzle) on the pressure retention rate and frequency at the oscillator outlet is discussed, and a SGWR experiment platform is set up to make comparison of the pressure waveform as well as cooling efficiency of the impulse jet from two oscillators with different wedge distance in the gas wave tube. The result shows that jet oscillator performance varies along with the wedge distance, thus influencing the cooling efficiency. To expand the efficient operation range, the principle of jet frequency changing and the impact of narrowing the oscillator structure on jet frequency are discussed in detail, the variation rule equation of the jet switching frequency is derived. Matching experiments of jet oscillator and size of gas wave tube have been conducted under conditions of specific frequency and variable frequency. It is concluded that there exists fluctuation value in gas wave tube refrigeration efficiency versus gas injection frequency curve, which can be up to 15% or more. Based on the present results, the jet frequency control method can make the gas wave tube operate at the refrigeration's peak frequency, thus improving SGWR refrigeration efficiency.

Influences of key design parameters to operating performance of a compressed natural gas injection system using solenoid pressure regulator

A study is carried out to examine the effects of design parameters on operating performance of a compressed natural gas (CNG) injection system. This system consists of a solenoid-type injector, a solenoid pressure regulator, and a rail tube. To depict the operation of the injection system, mathematical models are built, including electrical and mechanical models of a solenoid pressure regulator and a solenoid injector. To control rail tube gas pressure, a control model is built using proportional integral derivative (PID) algorithm. The simulated gas pressure is compared with experimental result for validating the mathematical models. The influences of design parameters, including rail tube volume, stiffness of spring, and number of coil turns in the solenoid pressure regulator, on the operating performance of the CNG system are examined. The simulation results indicate that the stability of controlled gas pressure is increased when increasing the volume of the rail tube and spring stiffness. Besides, by decreasing the number of coil turns in the solenoid pressure regulator, the stability of controlled gas pressure and flow rate of the injection is increased.

Calibration of a circular structured light measurement system based on a multi-diameter calibrator

To solve the measurement problems of the inner shape of large-scale workpieces, such as excavators with movable arms, this paper proposes an inner shape measurement method based on circular structured light. First, the center of the circular laser stripe is extracted based on a modified Steger method. Second, a multi-diameter concentric calibration gauge design is used to calibrate the optical plane of the proposed system and address the problem of the optical plane deviation and motion error in the 1D linear stage of the traditional calibration process. Finally, the experiments are conducted. The corresponding experimental results demonstrate that the proposed measurement method facilitates a fast calibration of the camera and an efficient extraction of the center of the light stripe, resulting in a relative error of less than 0.012%. The measurement method can be further applied to deep-hole workpieces, such as steel tubes and natural gas tube lines, among others.