Mm In Inside Diameter Research Articles

Experimental investigation of superlong two-phase closed thermosyphons for geothermal utilization

A superlong two-phase closed thermosyphon (TPCT) with 48 m in length and 40.3 mm in inside diameter is constructed and tested to examine the heat transfer limit and thermal characteristics of large scale TPCT for wellbore heating based on geothermal energy. The heat transfer limit of the superlong thermosyphon is measured to be about 20 kW, and a heat transfer rate of 15 kW could be achieved with the temperature gradient along the thermosyphon less than 1.5 °C/100 m. Before the TPCT reaches its heat transfer limit, the temperature and heat transfer rate of the TPCT increase with the increase of heating power. However, further increasing heating power will not influence the temperature nor the heat transfer rate of TPCT after entering the thermally blocked state. Meanwhile, the temperature gradient along the TPCT gradually increases with the heat transfer rate of TPCT and gets its maximum value at the heat transfer limit. With the evaporator maintained at a high temperature, the cooling conditions mainly affect the temperature of TPCT, while the heat transfer rate almost unchanged. The dynamic responses of TPCT temperatures and heat transfer rates with increasing and decreasing heating power show hysteresis at high filling ratios, which is interpreted by the depletion of working fluid inventory in the evaporator due to the entrainment of returning liquid film. It is concluded that the heat transfer limit is induced by flooding, which leads to intermittent dryout of the evaporator and oscillation operation state of the thermosyphon. The present experimental results provided valuable guidelines for the design and development of large scale TPCT, which can be made from coiled tubing and employed in wellbore heating based on geothermal energy.

Effect of Temperature on Stretchability of Anisotropic AZ31 Magnesium Alloy Sheet

This paper deals with effect of temperature on stretchability of anisotropic AZ31(Mg-3%Al-1%Zn) magnesium alloy sheet. Results of stretching process test are compared with those of tensile test. The sheet has an anisotropic character for angle to hot-extrusion direction(ϕ=0°, 45°, and 90°). Here, ϕ=0° means a direction of extrusion. Tensile specimens cut down to three directions of ϕ=0°, 45°, and 90° are a shape of 14mm in elongation, 3mm in width and 0.44mm in thickness. Test piece for investigating the limiting stretching stroke is a sheet of side length 90mm and 0.44mm in thickness. For the stretching process test, the punch head is a hemispheric shape of 20mm in diameter and the die is a cylindrical shape of 27mm in inside diameter. Both tension and stretching process tests were performed at four kinds of test temperature(T=293, 393, 473, and 573K) in a thermostatic chamber and at a crosshead speed(v) of 5mm/min using an Instron-type testing machine. Comparing the limiting stretching stroke determined by the stretching test with elongation, r-value, and n-value obtained by the tensile test, it is confirmed that the limiting stretching stroke is qualitatively related to the elongation and r-value, and not to n-value.

The Finite Element Analysis in Measurement System of Airplane Fuel Mass

The paper presents the measurement system of the air plane fuel mass consisting of cylinder shell resonating density meter and double cylinders capacitance level meter. The finite element analysis method of ANSYS10.0 is used to analyze the performance of cylinder shell resonator density meter and double cylinders capacitance fuel level sensor. On the base of simulation, the cylinder shell is 45mm in length, 9mm in radius, and 0.08mm in thickness, the material is 3J53; the double cylinders capacitance is 8mm in inside diameter, 23.6mm in outside diameter, and 550 mm in length. The experiments show the uncertainty of cylinder shell resonating density meter is only 0.12%, the uncertainty of double cylinders capacitance level meter is only 0.2%, and the uncertainty of the fuel mass measurement system is 0.4%.

A rotor model with two gradient static field shafts

We tested a rotor model with two gradient static field shafts which is lifted between a set of the magnets and a trapped static magnetic field of a HTS bulk. The combined magnets were composed of one cylindrical magnet and two ring magnet. The cylindrical magnet was 20 mm in diameter, 10 mm in thickness, and 0.45 T. The ring magnet was 30 mm in inside diameter, 50 mm in outside diameter, 5 mm in thickness, and 0.33 T. The cylindrical magnet was arranged to be the opposite pole in the center of a ring magnet. The set of the magnets yielded a magnetic field like “Mexican hut”. The rotor was 70 mm in diameter, 70 mm in height, and was composed of acrylic pipes of various sizes. One magnet each was arranged on the top and the bottom of the rotor respectively for lifting, and 4 plate magnets (20 mm × 10 mm, 2 mm in thickness, 0.23 T) were arranged in the central side of the cylinder to be alternate poles of the search magnet or the generator magnet. Two superconductor bulks are Dy bulk of 47 mm in diameter. The bulk is trapped in the magnetic field at 77 K (in Liquid nitrogen) as magnetic shaft. When lifting was stable, after the two coils and the two air nozzles has set. The rotor was rotated at over 2000 rpm by the nitrogen gas wind at 0.490 MPa and a coil was generated at 0.5 V.

Effect of promoters on dynamics of gas–solid fluidized bed—Statistical and ANN approaches

In this study, a bubbling fluidized bed column, 99 mm in inside diameter and 960 mm in height, was used to investigate the effect of rod and disc promoters on fluctuation and expansion ratios. Factorial design (statistical approach) and artificial neural network (ANN) models were developed to predict the fluctuation and expansion ratios in this gas–solid fluidized bed with varying gas flow rates, bed heights, particle sizes and densities. The fluctuation and expansion predicted using these statistical and ANN models, for beds with and without promoters, were found to agree well with corresponding experiments. The statistical model was found to be superior to the ANN model due to its ability to take into account both individual and interactive effects. The rod promoters were found to be more effective in reducing bed fluctuation, and in increasing bed expansion at high gas mass velocities.

Axial Heat Transport Mechanism due to Reciprocating Flow in a Ribbed Tube

Experimental and numerical studies were performed to clarify the axial mass and heat transport mechanism of reciprocating flow inside ribbed circular tubes. Water was used for the working fluid. The test section consisted of a circular tube of 16 mm in inside diameter and 800 mm in length. Ribs were installed on the tube wall with a given interval in axial direction and one end of the tube was connected to a heat source and the other end to a heat sink. A crank-piston mechanism was utilized to create reciprocating flow with no net through flow. Numerical simulations were also carried out under the same conditions as the experiment. Since it was confirmed that the results of the simulation agreed very well with those of experiment, the simulation was used to explore the details of the flow and heat transport mechanisms in the present study. The present study disclosed that the periodic formation and extinction of flow separation behind the ribs constituted the axial mass and heat transport through the “trap and release” mechanism in the reciprocating cycles. It was also shown that heat transport performance of the ribbed tube was far superior to that of plain tubes or dream pipes.

Axial Heat Transport Mechanism due to Reciprocating Flow in a Ribbed Tube

Experimental and numerical studies were performed to clarify the axial mass and heat transport mechanism of reciprocating flow inside ribbed circular tubes. Water was used for the working fluid. The test section consisted of a circular tube of 16 mm in inside diameter and 800 mm in length. Ribs were installed on the tube wall with a given interval in axial direction and one end of the tube was connected to a heat source and the other end to a heat sink. A crank-piston mechanism was utilized to create reciprocating flow with no net through flow. Numerical simulations were also carried out under the same conditions as the experiment. Since it was confirmed that the results of the simulation agreed very well with those of experiment, the simulation was used to explore the details of the flow and heat transport mechanisms in the present study. The present study disclosed that the periodic formation and extinction of flow separation behind the ribs constituted the axial mass and heat transport through the “trap and release” mechanism in the reciprocating cycles. It was also shown that heat transport performance of the ribbed tube was far superior to that of plain tubes or dream pipes.

An Experimental Study on the Mass Transfer Rate of Droplets in Annular Two-Phase Flow

Deposition rate of droplets in annular flow was measured to elucidate the effect of the shape of flow obstacles that were placed in a flow channel. In the present experiments, the test section was a vertical round tube of 5mm in inside diameter, air and water were used as test fluids, and double film extraction technique was adopted for the measurement. Seven flow obstacles were tested; three obstacles were tubular in shape while other four obstacles were also cylindrical but the cross-sectional areas were varied smoothly in the axial direction. It was revealed that the deposition rate of droplets markedly increased if the present small flow obstacle was placed in the test section tube. The increasing rate was dependent primarily upon the cross-sectional shape of flow obstacle at the maximum cross-sectional area.

Decomposition of gaseous formaldehyde in a photocatalytic reactor with a parallel array of light sources

To develop a high-performance photocatalytic reactor for purification of indoor air, photocatalytic decomposition of HCHO at a very low concentration is investigated both experimentally and theoretically in two papers. This first paper reports the result of fundamental experiment that is necessary to design the photocatalytic reactor in the second paper. A combination of the absorption of trace HCHO into water with the quantitative analysis of HCHO by the 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) method is found to be useful to accurately measure the HCHO concentration at a ppb level (less than 1.23 mg m−3). The experimental results obtained using three types of annular-flow photocatalytic reactors with different inside diameters (22–120 mm) and light sources (6 and 20 W blacklight blue fluorescent lamps) indicate that the photocatalytic reactor with a 6 W lamp and a glass tube of 28 mm in inside diameter (the distance between the light source and photocatalyst surface; 6.5 mm) gives a maximum rate of decomposition; HCHO at a ppb concentration level is rapidly decomposed to zero concentration when the photocatalyst surface kept at a low temperature (45 °C) is irradiated with UV light of a high light intensity.

On the rise paths of single vapor bubbles after the departure from nucleation sites in subcooled upflow boiling

A photographic study was carried out for the subcooled flow boiling of water to elucidate the rise characteristics of single vapor bubbles after the departure from nucleation sites. The test section was a transparent glass tube of 20 mm in inside diameter and the flow direction was vertical upward; liquid subcooling was parametrically changed within 0–16 K keeping system pressure and liquid velocity at 120 kPa and 1 m/s, respectively. The bubble rise paths were analyzed from the video images that were obtained at the heat flux slightly higher than the minimum heat flux for the onset of nucleate boiling. In the present experiments, all the bubbles departed from their nucleation sites immediately after the inception. In low subcooling experiments, bubbles slid upward and consequently were not detached from the vertical heated wall; the bubble size was increased monotonously with time in this case. In moderate and high subcooling experiments, bubbles were detached from the wall after sliding for several millimeters and migrated towards the subcooled bulk liquid. The bubbles then reversed the direction of lateral migration and were reattached to the wall at moderate subcooling while they collapsed due to the condensation at high subcooling. It was hence considered that the mechanisms of the heat transfer from heated wall and the axial growth of vapor volume were influenced by the difference in bubble rise path. It was observed after the inception that bubbles were varied from flattened to more rounded shape. This observation suggested that the bubble detachment is mainly caused by the change in bubble shape due to the surface tension force.

Bubble rise characteristics after the departure from a nucleation site in vertical upflow boiling of subcooled water

Rise characteristics of vapor bubbles after the departure from a nucleation site in forced convective subcooled flow boiling were studied visually using two synchronized high speed video cameras. The test section was a transparent glass tube of 20 mm in inside diameter, filtrated and deionized tap water was used as a working fluid, and the flow direction adopted was vertical upward. The outer surface of test section tube was electrically heated to generate vapor bubbles inside of the tube. In the present experiments, the mass flux and liquid subcooling were varied within 94–1435 kg/m 2 s and 2.2–10 K, respectively. Since the observations were performed at low heat fluxes to avoid the significant increase in the number of active nucleation sites, the obtained bubble images were clear enough to carry out the detailed image analysis for the rise characteristics of individual bubbles. The following three different bubble rise paths were observed after the departure from nucleation sites: some bubbles slid upward the vertical wall for long distance, while other bubbles were detached from the wall after sliding for several millimeters and then migrated toward the bulk liquid; after the migration, some of the detached bubbles were collapsed in subcooled liquid but others remained close to the wall and were reattached to the wall. The results of detailed image analyses suggested that the variation in bubble shape from flattened to more rounded was of primary importance for the occurrence of bubble detachment from the wall.

Experiments for liquid phase mass transfer rate in annular regime for a small vertical tube

The double film extraction technique was used to measure the deposition rate and the entrainment rate of droplets for vertical upward annular two-phase flow in a small diameter tube. The test section was a round tube of 5 mm in inside diameter, air and water were used as test fluids and the system pressure was varied within 0.14–0.76 MPa. It was shown in the present experimental conditions that the deposition rate was primarily influenced by the droplet concentration in the gas core and that the entrainment rate was correlated well with the dimensionless number denoting the ratio of interfacial shear force to surface tension force acting on the surface of liquid film. These results were consistent with available empirical correlations that were developed using the experimental data for larger diameter tubes.

Effects of a Flow Obstacle on the Deposition Rate of Droplets in Annular Two-Phase Flow

Double film extraction technique was used to elucidate the effects of a flow obstacle on the deposition rate of droplets in annular two-phase flow. In the present experiments, the test section was a round tube of 5 mm in inside diameter, air and water were used as test fluids and the flow direction was vertical upward; a short tube that was 2 mm in inside diameter, 3 mm in outside diameter and 20 mm in length was used as a flow obstacle. It was shown that the deposition rate of droplets was markedly increased if the present flow obstacle was concentrically placed in the flow channel. In all the experimental conditions tested, the deposition rates when the flow obstacle was placed were approximately 1.5 times larger than the deposition rates when no obstacle was placed. An empirical correlation was developed to elucidate the influence of flow parameters on the enhancement of deposition rate by the present flow obstacle of simple geometry.

An investigation on void fraction of vapor–liquid two-phase flow for smooth and microfin tubes with R134a at adiabatic condition

The present paper deals with experiments and a prediction method for the void fraction of R134a vapor–liquid two-phase flow in horizontal smooth and microfin tubes in adiabatic condition. The void fraction is measured by the quick closing valve method. The smooth tube tested is 1024 mm in length and 7.52 mm in inside diameter. The microfin tube tested is 1015 mm in length and 8.86 mm in mean inside diameter; the fin height is 0.18 mm, the helix angle of fins is 25° and the total number of fins are 70. The experiments were carried out in the range of vapor quality from 1% to 96%, where the pressure was kept at 1.2 and 0.8 MPa and the mass flow rate was kept at 20 and 40 kg h −1. It is confirmed that the void fraction for smooth tube is well correlated by the Smith or the Baroczy correlations. It is also shown that the void fraction in the microfin tube is lower than that of smooth tube in any quality and the prediction results using previous correlations for smooth tube are higher than the present experimental data of microfin tube. The void fraction prediction method consisting of a stratified-annular flow model and an annular flow model is proposed. In the stratified-annular flow model, it is assumed that most of liquid flows at the bottom of the tube and all grooves are filled with additional liquid. The momentum equations are constructed for regions of vapor, main liquid flow at the bottom and additional liquid flow in grooves, respectively. These coupled equations are solved numerically. In the case of annular flow model, it is assumed that all grooves are filled with liquid uniformly. The momentum equations in the vapor and liquid flows in grooves are also solved numerically. The values of the predicted void fraction are in good agreement with experimental data in high vapor quality region, while the predicted values are slightly smaller than experimental ones in low vapor quality region.

K-1214 界面活性剤水溶液の管内流遷移(S17-4 抵抗減少効果)(S17 非ニュートン流体の複雑流路内の流れ)

This paper describes the LDV measurement of the generation and growth of the turbulent puff and slug in the transitional pipe flow of a surfactant (TTABr)-distilled water solution, the concentration of which was smaller than 400 ppm. The test pipe was a straight glass tube of 5.02 mm in inside diameter and 2576 mm in length. A large perturbation was introduced by a ring-shaped roughness element installed at a downstream location of 77D from the pipe entrance. In the straight pipe without the roughness element, while laminar flow is kept to 15300 under water flow, a quasi-laminar state at 2400<Re<11000 and the initiation of transition to turbulence at Re=11000 were clearly observed under 400 ppm solution. The result of the experiment with the roughness element showed that, as the concentration of the surfactant increases more than 260 ppm, the critical Reynolds number, in which the turbulent slug and puff begin to appear, increases and the growth rate of turbulent slug decreases.

High pressure liquid–liquid equilibria at 8 MPa for water–2-butanol–C 4-hydrocarbon( n-butane+ trans-2-butene+ cis-2-butene) system

An apparatus for measuring high pressure liquid–liquid equilibria was established. In order to diminish disturbance for the equilibration, the capillaries of stainless steel with 0.7 mm in inside diameter were used to take samples. The taken samples were totally evaporated into gas chromatography. The accuracy of the apparatus was verified by duplicating the literature data. Liquid–liquid equilibrium data for pseudo-ternary mixture of water–2-butanol–C 4-hydrocarbon (the mixture of n-butane+ trans-2-butene+ cis-2-butene) were experimentally determined under pressure 8 MPa and at temperatures from 403.2 to 443.2 K. The measured liquid–liquid equilibrium data could be correlated by modified Redlich–Kwong (R–K) equation of state.

New electron beam facility for irradiated plasma facing materials testing in hot cell

Since plasma facing components such as the first wall and the divertor for the next step fusion reactors are exposed to high heat loads and high energy neutron flux generated by the plasma, it is urgent to develop plasma facing components which can resist these. We have established electron beam heat facility (‘OHBIS’, Oarai hot-cell electron beam irradiating system) at a hot cell in JMTR (Japan materials testing reactor) hot laboratory in order to estimate thermal shock resistivity of plasma facing materials and heat removal capabilities of divertor elements under steady state heating. In this facility, irradiated plasma facing materials (beryllium, carbon based materials and so on) and divertor elements can be treated. This facility consists of an electron beam unit with the maximum beam power of 50 kW and the vacuum vessel. The acceleration voltage and the maximum beam current are 30 kV (constant) and 1.7 A, respectively. The loading time of the electron beam is more than 0.1 ms. The shape of vacuum vessel is cylindrical, and the main dimensions are 500 mm in inside diameter, 1000 mm in height. The ultimate vacuum of this vessel is 1 × 10 −4 Pa. At present, the facility for the thermal shock test has been established in a hot cell. The performance of the electron beam is being evaluated at this time. In the future, the equipment for conducting static heat loadings will be incorporated into the facility.

Development of a membrane oxygenator for ECMO using a novel fine silicone hollow fiber.

One of the limitations of conventional silicone hollow fiber oxygenators compared with microporous membrane oxygenators is poor gas permeability. However, the silicone hollow fiber is free from plasma leakage, which is the major life limiting factor of the microporous membrane oxygenator. It has been difficult to fabricate a fine, thin hollow fiber for reduction of resistance to gas permeability because of the poor mechanical strength of conventional silicone materials. The authors developed a novel silicone material with sufficient mechanical strength, and a fine silicone hollow fiber with a diameter of 30 microns and wall thickness of 50 microns, which is approximately half that of a conventional silicone hollow fiber. Using this newly developed silicone hollow fiber, the authors developed a compact extracapillary flow membrane oxygenator. The oxygenator consists of fine silicone hollow fibers inserted in a housing made of polycarbonate. The housing is a cylindrical case, 20 cm long and 55 mm in inside diameter. The hollow fibers are cross-wound. The surface area of the membrane is 2.0 m2, and priming volume is 230 ml. Gas transfer performance of the newly developed oxygenator was evaluated by in vitro experiments. Oxygen and carbon dioxide transfer rates were 195 ml/min and 165 ml/min, at a blood flow rate 3 L/min. The novel silicone membrane oxygenator developed in this study can be used for extended duration in such applications as extracorporeal membrane oxygenation.

Critical Heat Flux of Subcooled Boiling with Twisted-Tape Swirl Flow at Atmospheric Pressure.

Experiments on critical heat flux (CHF) were conducted to clarify the enhancement effects of twisted tapes. The swirled tube is made of stainless steel (6mm in inside diameter, 0.25mm in thickness, and 100mm in heated length) and equipped with a twisted zirconia tape (about 1.2mm in thickness and 5.4mm in width). Twisted tape ratios y (value of tube inside diameter to complete 180 degree twists of tape insert) are about 2.7, 4.0, 9.0, and ∞. Swirl-flow CHF increased in proportion to the one-third power of (y-1) at small y or of the tangential velocity at the inner tube wall at large centrifugal force. An empirical CHF correlation for swirl flow was proposed by applying the tangential non dimensional centrifugal acceleration at the wall as a parameter. It was verified that this correlation gave accurate predictions at nearly atmospheric pressure.

セラミック膜を用いたデンプンからのアミロースの簡易分別法

It was studied to use a ceramic membrane, which is known to be efficient for the separation of compounds having varoius molecular weight, for the purpose of separation of amylose from starch. A tube of ceramic membrane (5 mm in outside diameter, 50 cm long, 74.5cm2 of surface, 0.05 tm in average dimeter of hole), which is loaded into a metal tube (7.5 mm in inside diameter), was used for the separation with connecting a pump an d a feed tank filled by 2 dm3 of 1% corn starch suspension. As a result of surveying the optimum condition for the separation of amylose, the lower pressure, the higher feed velocity and the higher temperature were found to bring out the higher concentration of amylose in the filtrate through the ceramic membrne. The working of separation was carried out during 24 h with a condition of 3.0 m/s feed velocity at 0.3 kg/cm2 of gauge pressure and 60°C. The solid material was obtained by freeze drying after evaporating the filtrate to reduce the volume by 1/10. The yield was 3.0 g from 22 g of corn starch.