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Poly(4,4′-oxydiphenylene pyromellitimide) (PMDA-ODA) and poly(1,4-phenylene pyromellitimide) (PMDA-PDA) polyimides were prepared from poly(amic acid) (PAA) and poly(amic ester) (PAE) precursors, respectively. Water sorption and diffusion behavior in films were measured at 90% R.H. and 25°C using the water sorption method and stress relaxation analysis. Regardless of the method, the diffusion kinetics of water in polyimide thin films was well fitted to Fickian diffusion. For rigid rodlike PMDA-PDA film having high Tg (>400°C), film prepared from PAE precursor with less chain relaxation and poor stacking efficiency induced higher stress relaxation and diffusion coefficient of water than with the PAA precursor. For semi-flexible PMDA-ODA polyimide film, film prepared from PAE precursor having higher ordered arrangement, higher chain orientation, and well packing structure, had relatively lower diffusion coefficient of water and less stress relaxation than with the PAA precursor. Water diffusion and stress relaxation for the rigid rodlike PMDA-PDA films are relatively slower than for the semi-flexible PMDA-ODA films due to morphological differences.

In the two-fluid model, interfacial concentration is one of the important parameters. The objective of this study is to develop an interfacial area equation with the source and sink terms being properly modeled. For bubble coalescence, the random collisions between bubbles due to turbulence, and the wake entrainment process due to the relative motions of the bubbles, were included. For bubble breakup, the impact of turbulent eddies is considered. Compared with measured axial distributions of the interfacial area concentration under various flow conditions, the adjustable parameters in the source/sink terms were obtained for the simplified one-dimensional transport equation.

Water-soluble polyamines (PEG-DETs) were obtained by reacting PEG 600-diglycidyl ether with tetraethylenepentamine, which is a highly conductive aliphatic amine and curing agent. Then water-soluble polyamine phosphates (PEG-DETPs) were synthesized by cationization of PEG-DETs with phosphoric acid to prevent gelation and enhance solution stability. Antistatic agents were prepared by adding water to these PEG-DETs and PEG-DETPs. Several antistatic tests were carried out after applying the prepared antistatic agents to PET textile with and without resin. Tests showed that PEG-DETPs possessed the durability along with antistatic properties and washability.

In order to test the feasibility of using calcium alginate-entrapped hybridoma cells for IgM production, HO-22-1 hybridoma cells entrapped into calcium alginate beads with varying alginate concentrations were cultivated in spinner flasks. It was observed that the IgM produced by the entrapped cells could diffuse out of the calcium alginate beads regardless of alginate concentrations tested (0.8–2.5%). Since the increase in alginate concentrations showed an adverse effect on cell growth and maximum cell concentration, the use of lower alginate concentration was desirable for higher volumetric monoclonal antibody (MAb) productivity. When the entrapped cells in 0.8% alginate beads were cultivated in repeated-fed batch mode, the reduction of serum concentration in the medium from 10% to 1% did not decrease the volumetric IgM production. Taken together, the data obtained here showed the feasibility of using calcium alginate-entrapped hybridoma cells for IgM production.

The purpose of this study was to enhance the efficiency of anaerobic co-digestion with sewage sludge using pretreatment technologies and food waste. We studied the effects of various pretreatment methods (thermal, chemical, ultrasonic, and their combination) on hydrogen production and the characteristics of volatile fatty acids (VFAs) using sewage sludge alone and a mixture of sewage sludge and food waste. The pretreatment combination of alkalization and ultrasonication performed best, effecting a high solubilization rate and high hydrogen production (13.8 mL H2/g VSSconsumed). At a food waste:pretreated sewage sludge ratio of 2:1 in the mixture, the peak hydrogen production value was 5.0 L H2/L/d. As the production of hydrogen increased, propionate levels fell but butyrate concentrations rose gradually.

This study makes use of this distinction to analyze the exhaust gas concentration and fuel of the circulating fluidized bed (CFB) boiler that mainly uses wood biomass, and to develop the emission factors of Methane (CH4), Nitrous oxide (N2O). The fuels used as energy sources in the subject working sites are Wood Chip Fuel (WCF), RDF and Refused Plastic Fuel (RPF) of which heating values are 11.9 TJ/Gg, 17.1 TJ/Gg, and 31.2 TJ/Gg, respectively. The average concentrations of CH4and N2O were measured to be 2.78 ppm and 7.68 ppm, respectively. The analyzed values and data collected from the field survey were used to calculate the emission factor of CH4and N2O exhausted from the CFB boiler. As a result, the emission factors of CH4and N2O are 1.4 kg/TJ (0.9–1.9 kg/TJ) and 4.0 kg/TJ (2.9–5.3 kg/TJ) within a 95% confidence interval. Biomass combined with the combustion technology for the CFB boiler proved to be more effective in reducing the N2O emission, compared to the emission factor of the CFB boiler using fossil fuel.

This paper presents a low power, low complexity IR-UWB radar transceiver for short range object detection. The transceiver provides robustness against false alarms without increasing power consumption, chip size, or complexity. The receiver (RX) and the transmitter (TX) dissipate only 50 pJ/pulse and 470 pJ/pulse under a 1.2V supply, respectively. The measured TX pulse spectrum, −58 dBm maximum power, complies with the FCC spectral mask and shows 1 GHz bandwidth with 4 GHz center frequency. The measured sensitivity of the RX is −45 dBm, and the RX is fully functional to detect an object in the range of 0.45 ∼ 1.2 m. The die size of the IR-UWB transceiver implemented in a 0.13 um CMOS process is 2.1 mm2.

This study presents a comparison of the geometric effects of 90 deg and 45 deg elbows in horizontal two-phase air-water bubbly flow. Two separate experiments were performed in the horizontal test section made out of 50.3 mm inner diameter glass tubes. The first set of data was collected with a 90 deg elbow installed, and then a 45 deg elbow was added to the existing facility to acquire the second set of data. A total of 15 different flow conditions, all within the bubbly flow regime, were identified for the 90 deg experiment, and very similar flow conditions were extended to the 45 deg experiment. A double-sensor conductivity probe was employed to acquire the local data at seven different axial positions along the test section, out of which four measurement locations are associated with the 90 deg experiment and three with the 45 deg experiment. The data show that the elbows have a significant effect on the development of interfacial structures as well as the bubble interaction mechanisms. Furthermore, there are characteristic similarities and differences between the effects of the two elbows. While the effect of the 45 deg elbow is evident immediately after the elbow, the 90 deg elbow effect tends to propagate further downstream of the elbow rather than immediately after the elbow. Moreover, it is shown that both elbows induce spatial oscillations in the interfacial structures and two-phase flow parameters, but the degree and the nature of oscillations differ. The effects of the elbows are also compared for the axial transport of the two-phase flow parameters.

This study exploited the concept of the minimum/maximum substrate concentrations (MSC values) for identifying proper start-up conditions and achieving stable and low effluent total ammonium nitrogen (TAN) concentrations in suspended-growth short-cut biological nitrogen removal (SSBNR). Calculations based on the MSC concept indicated that SDmax, the TAN concentration above which ammonium-oxidizing bacteria (AOB) are washed out, was around 450 mgTAN/L at the given operating conditions of 2 mg/L of dissolved oxygen and pH 8, while nitrite-oxidizing bacteria (NOB) should be washed out at around 40 mgTAN/L. Therefore, the experimental research was focused on the optimal TAN-concentration range for SSBNR, between 50 and 100 mg/L. Experimental results showed that a nitrification reactor with initial TAN concentration above 450 mg/L did not give a successful start-up. However, two days of starvation, which decreased the TAN concentration in the reactor to 95 mg/L, stabilized the reaction quickly, and stable SSBNR was sustained thereafter with 80 mgTAN/L and 98% nitrite accumulation in the reactor. During stable SSBNR, the removal ratio of chemical oxygen demand per nitrite nitrogen (ΔCOD/ΔNO2–N) for denitrification was 1.94 gCOD/gN, which is around 55% of that required for nitrate denitrification. Based on a clone library, Nitrosomonas occupied 14% of the total cells, while the sum of Nitrobacter and Nitrospira was less than the detection cut-off of 2%, confirming the NOB were washed out during SSBNR. A spiking test that doubled the influent ammonium loading caused the TAN concentration in the reactor to reach washout for AOB, which lasted until the loading was reduced. Thus, a loading increase should be controlled carefully such that the system does not exceed the washout range for AOB.

A dynamic treatment of interfacial area concentration has been studied over the last decade by employing the interfacial area transport equation. When coupled with the two-fluid model, the interfacial area transport equation replaces the flow regime dependent correlations for interfacial area concentration and eliminates potential artificial bifurcation or numerical oscillations stemming from these static correlations. An extensive database has been established to evaluate the model under various two-phase flow conditions. These include adiabatic and heated conditions, vertical and horizontal flow orientations, round, rectangular, annulus, and 8×8 rod-bundle channel geometries, and normal-gravity and reduced-gravity conditions. Currently, a two-group interfacial area transport equation is available and applicable to comprehensive two-phase flow conditions spanning from bubbly to churn-turbulent flow regimes. A framework to couple the two-group interfacial area transport equation with the modified two-fluid model is established in view of multiphase computational fluid dynamics code applications as well as reactor system analysis code applications. The present study reviews the current state-of-the-art in the development of the interfacial area transport equation, available experimental databases, and the analytical methods to incorporate the interfacial area transport equation into the two-fluid model.

Present study investigates the geometric effects of flow obstruction on the distribution of local two-phase flow parameters and their transport characteristics in horizontal two-phase flow. The round glass tubes of 50.3mm in inner diameter are employed as test sections, along which a 90-degee elbow is located at L/D = 206.6 from the two-phase mixture inlet. In total, 15 different flow conditions are examined within the air-water bubbly flow regime. The detailed local two-phase flow parameters are acquired by the double-sensor conductivity probe at four different axial locations. The effect of elbow is found to be evident in both the distribution of local parameters and their development. The elbow clearly promotes bubble interactions resulting in significant changes in interfacial area concentration. It is also found that the elbow-effect propagates to be more significant further downstream (L/D = 250) than immediate downstream (L/D = 225) of the elbow. Furthermore, it is shown that the elbow induces significant oscillations in the flow in both vertical and horizontal directions of the tube cross-section. Characteristic geometric effects due to the existence of elbow are also shown clearly on the axial development of one-dimensional interfacial area concentration and void fraction.Copyright © 2006 by ASME

The two-phase pressure drop due to the minor loss in horizontal bubbly two-phase flow is studied. In particular, geometric effects of a 90-degree elbow is of interest in the present study. Experiments are performed in air-water two-phase flow near atmospheric pressure condition in round glass tube with inner diameter of 50.3mm. Along the test section, 90-degee elbow is installed at L/D = 206.6 from the two-phase mixture inlet. Experiments are performed in 15 different flow conditions and the local static pressures are measured at five axial locations. Characteristic pressure drop due to the elbow is clearly demonstrated in the profiles of local pressure data along the axial direction. It is also found that the elbow effect propagates and is more significant further downstream than immediate downstream of the elbow. The overall two-phase frictional pressure loss between L/D = 0 and 329 can be predicted well with the Lockhart-Martinelli correlation with parameter C = 25, which is higher than the generally accepted value of C = 20. A correlation for the two-phase pressure loss, including the minor loss due to the 90-degree elbow is developed by employing the approach analogous to that of Lockhart-Martinelli’s. The newly developed correlation suggests that the modified parameter, C = 65 fits best with the experimental data. In addition, the two-phase minor loss factor for the 90-degree elbow is found to be k = 0.58, 50% higher than that recommended for single-phase flow.Copyright © 2006 by ASME

A shortcut biological nitrogen removal (SBNR) utilizes the concept of a direct conversion of ammonium to nitrite and then to nitrogen gas. A successful SBNR requires accumulation of nitrite in the system and inhibition of the activity of nitrite oxidizers. A high concentration of free ammonia (FA) inhibits nitrite oxidizers, but unfortunately decreases the ammonium removal rate as well. Therefore, the optimal range of FA concentration is necessary not only to stabilize nitrite accumulation but also to achieve maximum ammonium removal. In order to derive such optimal FA concentrations, the specific substrate utilization rates of ammonium and nitrite oxidizers were measured. The optimal FA concentration range appeared to be 5-10 mg/L for the adapted sludge. The simulated results from the modified inhibition model expressed by FA and ammonium/nitrite concentrations were shown very similar to the experimental results.

In ad hoc networks, broadcasting is one of the important communications patterns frequently used. Straight-forward broadcast is usually known to be very expensive and results in serious redundancy, contentions, and collisions. The phenomenon is referred to as broadcast storm problem. In this paper, we propose a forwarding set selection scheme and efficient schemes to broadcast with transmission power control in multi-hop ad hoc networks. Our simulation study shows that the proposed schemes reduce the broadcast latency, the number of collisions, average power consumption, etc.

The degradation of various insulators in Silicon Selective Epitaxial Growth (SEG) ambient was studied. The insulators studied were thermal oxide, reoxidized nitride/oxide stack, poly-oxide, and nitrided oxide. Breakdown electric fields of MIS capacitors were measured and yields were calculated before and after the insulators were exposed to Silicon SEG ambient. It was found that the nitrided oxide was more resistant to degradation in the SEG ambient than thermal and poly oxide; results reported here for the first time. The increased resistance of nitrided oxide in SEG ambient coupled with their superior performance as thin gate insulators makes them an excellent candidate for use in novel 3-D structures using selective silicon growth. >

The vertical co-current downward air-water two-phase flow was studied under adiabatic condition. In view of studying the effect of flow area on interfacial structure and regime transition, round tubes of 25.4-mm ID and 50.8-mm ID were employed as test sections. The flow regime map was constructed for each test section by employing a newer approach. Unlike the conventional flow visualization method, the present approach minimizes the subjective judgment in determining the flow regimes. It was found that the flow regime in the co-current downward flow strongly depend on the channel size. The local two-phase flow parameters were acquired by the multi-sensor miniaturized conductivity probe in bubbly flow. They include: the local time-averaged void fraction, interfacial area concentration, bubble velocity and bubble Sauter mean diameter. The area-averaged data acquired by the impedance void meter were analyzed by the drift flux model. Three different distributions parameters were developed for the different ranges of non-dimensional superficial velocity, defined by the ration of total superficial velocity to the drift velocity. The new correlations can be applied to a co-current downward two-phase flow in a wide range of flow regime spanning from bubbly to annular flow.Copyright © 2003 by ASME

Local characteristics of the liquid phase in downward air-water bubbly and slug flows were investigated in a 50.8-mm inner-diameter round pipe. A laser Doppler anemometry system was used to measure axial liquid velocity and its fluctuations. To reduce the measurement uncertainty, the experiments were performed in flow conditions with low void fraction. The comparisons between the liquid flow rates measured by the magnetic flow meter and those obtained from the local measurements showed good agreements. In addition, based on the LDA measurements and the data acquired by the local conductivity probes, the local relative velocity distribution, the distribution parameter and the drift velocity in the drift-flux model were obtained for the current downward flow.

In the two-fluid model, the field equations are expressed by the six conservation equations consisting of mass, momentum and energy equations for each phase. The existence of the interfacial transfer terms is one of the most important characteristics of the two-fluid model formulation. The interfacial transfer terms are strongly related to the interfacial area concentration and to the local transfer mechanisms such as the degree of turbulence near interfaces. This study focuses on the development of a closure relation for the interfacial area concentration. A brief summary of several problems of the current closure relation for the interfacial area concentration and a new concept to overcome the problem are given.

The objective of the present work is to study and model the interfacial structure development of air-water two-phase flow in a confined test section. Experiments of a total of 9 flow conditions in cap-turbulent and churn-turbulent flow regimes are carried out in a vertical air-water upward two-phase flow experimental loop with a test section of 200-mm in width and 10-mm in gap. Miniaturized four-sensor conductivity probes are used to measure local two-phase parameters at three different elevations for each flow condition. The bubbles captured by the probes are categorized into two groups in view of the two-group interfacial area transport equation, i.e., spherical/distorted bubbles as Group 1 and cap/churn-turbulent bubbles as Group 2. The acquired parameters are time-averaged local void fraction, interfacial velocity, bubble number frequency, interfacial area concentration, and bubble Sauter mean diameter for both groups of bubbles. Also, the line-averaged and area-averaged data are presented and discussed. The comparisons of these parameters at different elevations demonstrate the development of interfacial structure along the flow direction due to bubble interactions.

The local interfacial structure for vertical air-water co-current downward two-phase flow was investigated under adiabatic conditions. A multi-sensor conductivity probe was utilized in order to acquire the local two-phase flow parameters. The present experimental loop consisted of 25.4 mm and 50.8 mm ID round tubes as test sections. The measurement was performed at three axial locations: L/D = 13, 68 and 133 for the 25.4 mm ID loop and L/D = 7, 34, 67 for the 50.8 mm ID loop, in order to study the axial development of the flow. A total of 7 and 10 local measurement points along the tube radius were chosen for the 25.4 mm ID loop and the 50.8 mm ID loop, respectively. The experimental flow conditions were determined within bubbly flow regime. The acquired local parameters included the void fraction, interfacial area concentration, bubble interface frequency, bubble Sauter mean diameter, and interfacial velocity.Copyright © 2002 by ASME

The objective of the present research is to study the flow regime map, the detailed interfacial structures, and the bubble transport in an adiabatic air-water two-phase flow mixture, flowing upward through a vertical round pipe having 1.27 cm. inner diameter. The flow regime map is obtained by processing the characteristic signals acquired from an impedance void meter, using a self-organized neural network. The local two-phase flow parameters are measured by the state-of-the-art four-sensor conductivity probe at three axial locations in the pipe. The measured local parameters include void fraction (α), interfacial area concentration (ai ), bubble frequency (fb ), bubble velocity (Ub ) and bubble Sauter mean diameter (Dsm ). The radial profiles of these parameters and their development along the axial direction reveals the structure of the two phase mixture and the bubble interaction mechanisms.Copyright © 2002 by ASME

Flow regime identification for an adiabatic vertical co-current downward air-water two-phase flow in the 25.4 mm ID and the 50.8 mm ID round tubes was performed by employing an impedance void meter coupled with the neural network classification approach. This approach minimizes the subjective judgment in determining the flow regimes. The signals obtained by an impedance void meter were applied to train the self-organizing neural network to categorize these impedance signals into a certain number of groups. The characteristic parameters set into the neural network classification included the mean, standard deviation and skewness of impedance signals in the present experiment. The classification categories adopted in the present investigation were four widely accepted flow regimes, viz. bubbly, slug, churn-turbulent, and annular flows. These four flow regimes were recognized based upon the conventional flow visualization approach by a high-speed motion analyzer. The resulting flow regime maps classified by the neural network were compared with the results obtained through the flow visualization method, and consequently the efficiency of the neural network classification for flow regime identification was demonstrated.Copyright © 2002 by ASME

Experiments are performed in a scaled 1x3 rod bundle adiabatic air-water test facility to investigate the effects of a spacer grid on singleand two-phase flows. A four-sensor conductivity probe is used to obtain detailed measurements of local time-averaged two-phase flow parameters, including the void fraction and interfacial area concentration, throughout the flow cross-section at four axial locations. The local two-phase flow data indicates that the spacer grid causes redistribution of the bubbles. In the transition from bubbly to slug flows, the spacer grid is found to promote bubble coalescence. In the slug to churn-turbulent transition, however, the grid breaks up the larger bubbles, causing an increase in the interfacial area concentration across the spacer grid. Additionally, local velocity measurements in single-phase liquid flow are performed with a laser Doppler anemometer to investigate the change in the turbulence structure across the grid. The axial turbulence intensity measurements show the influence of the spacer grid dimples, indicating an increased mixing effect from these structures.

We report on the visualization of n-p junctions formed by oxygen vacancy movement under the application of an electric field in a Ca-doped BiFeO3 thin film through spatially resolved scanning photocurrent mapping. The photocurrent mapping, in conjunction with the spectroscopic approach, provides clues to local electronic structures and defect levels associated with oxygen vacancies. These observations provide insights into the spatial redistribution of oxygen vacancies in an electric field.

This communication introduces a non-intrusive method for void fraction measurement and identification of two-phase flow regimes, based on ultrasonic sensing. The underlying algorithm is built upon the recently reported theory of a statistical pattern recognition method called symbolic dynamic filtering (SDF). The results of experimental validation, generated on a laboratory test apparatus, show a one-to-one correspondence between the flow measure derived from SDF and the void fraction measured by a conductivity probe. A sharp change in the slope of flow measure is found to be in agreement with a transition from fully bubbly flow to cap-bubbly flow.

While the Intergovernmental Panel on Climate Change classifies coal as anthracite, bituminous coal, and sub-bituminous coal, Korea only distinguishes coal as anthracite and bituminous coal while sub-bituminous coal is considered bituminous coal. As a result, Korea conducted research in the CO2 emission factors of anthracite and bituminous coal, but largely ignored sub-bituminous coal. Therefore, the purpose of this research is to develop the CO2 emission factor of sub-bituminous coal by classifying sub-bituminous coal from resources of bituminous coal activities collected in Korea between 2007 and 2011. The 2007–2011 average carbon content of sub-bituminous coal was analyzed to be 69.63 ± 3.11 %, the average hydrogen content 4.97 ± 0.37 %, the inherent moisture 12.60 ± 4.33 %, the total moisture 21.91 ± 5.45 %, and the dry-based gross calorific value was analyzed to be 5,914 ± 391 kcal/kg; using these analyzed values, the as-received net calorific value was found to be 20.75 ± 7.59 TJ/Gg and the CO2 emission factor was found to be 96,241 ± 4,064 kg/TJ. In addition, the 62.7 million ton amount for the 2009 greenhouse gas emission from sub-bituminous coal as estimated with the analyzed value of this study is an amount that is equivalent to 11.1 % of the 2009 total greenhouse gas emission amount of 564.7 million tons, and this amount is larger than the 9.3 % for the industrial processes sector, 3.3 % for the agricultural sector and 2.5 % for the waste sector. Therefore, it is important to reflect the realities of Korea when estimating the greenhouse gas emission from such sub-bituminous coals.

Consumption of primary energy in Korea increased 5.25 % per year over a 10 years span starting in 1990. Korea ranked 8th in primary energy consumption in 2011; coal consumption increased 35 % from 87,827 million tons in 2006–119,321 tons in 2010. Heavy energy-consuming countries consistently conduct research to develop an emission factor of Tier 2 level, reflecting the characteristics of the fuel that they use. To calculate the emission factor of bituminous coal for fuel, this study developed emission factor and calculated emission amount by implementing fuel analysis on bituminous coal consumed in Korea between 2007 and 2009. CO2 emission factor calculated by fuel analysis method is 95,315 kg/TJ, which is 0.75 % higher than the default value suggested by IPCC. The emission amount calculated by using the CO2 emission factor in this study is 231.881 million tons, which has a difference of 1.739 million tons compared to the IPCC default value.

Local measurements of axial liquid velocity were performed for vertical upward air-water bubbly flow in a 101.6-mm inner-diameter round pipe by using a laser Doppler anemometer (LDA) and a hot-film anemometer (HFA). The data reduction approaches for both the LDA and HFA are discussed in detail. A threshold scheme with the information of local void fraction and velocity distribution in single-phase flow was applied to the LDA to approximately discriminate liquid velocity signals from those of the bubble interface velocity. Furthermore, a formulation was given to account for the effect of the bubble relative velocity on the liquid in the front and wake regions of the bubbles. For the HFA, an amplitude threshold scheme and a slope criterion were used to extract liquid velocity information. To reduce the measurement uncertainty, the experiments were performed in flow conditions where the area-averaged void fraction was less than 20%. The experimental results showed satisfactory agreement between the liquid volumetric flow rates calculated by area integration of the local liquid velocity and void fraction measurements, and the measured value by a magnetic flow meter. Also, the area-averaged relative velocity between the gas and liquid phases obtained from the current measurements agreed well with previous research.

An adiabatic, air–water, co-current, vertically downward bubbly flow was studied to gain a better understanding of interfacial structures and flow characteristics. The experimental test sections were round pipes with internal diameters of 25.4 and 50.8 mm. Flow regime map was obtained using characteristic signals obtained from an impedance void meter, and a neural network-based identification methodology to minimize the subjective judgment in determining the flow regimes. A four-sensor conductivity probe was used to measure the local two-phase flow parameters that characterize the interfacial structures. The parameters measured were: void fraction, interfacial area concentration, bubble velocity, and bubble Sauter mean diameter. Furthermore, a laser Doppler anemometer (LDA) system was used to measure local axial liquid velocity and turbulence. The local profiles of these parameters as well as their axial development revealed the nature of the interfacial structures and the bubble interaction mechanisms occurring in the flow. Based on previous study of interfacial area transport for upward flows, the interfacial area transport equation applicable to downward flow was developed with certain modifications in bubble interaction terms.

Miniaturized four-sensor conductivity probes are used to study flow structure development in air-water bubbly flow, cap-bubbly flow, and transition to slug flow. The measurements are performed at three different elevations in a vertical round pipe with an inner diameter of 101.6 mm. The time-averaged local void fraction, interfacial velocity, and bubble number frequency are measured by the conductivity probes. Also, the interfacial area concentration and averaged bubble Sauter mean diameter are obtained. A detailed representation of the flow structure is revealed by investigating the acquired data. Furthermore, comparisons of the data at three elevations demonstrate the development of the interfacial structure along the flow direction due to bubble interactions and hydrodynamic effects. This may provide the community with a better knowledge about two-phase flow in a relatively large pipe. In addition, these data can also serve as an experimental database for investigation of the interfacial area transport in large-pipe two-phase flow.

Purdue 1 10 scale direct containment heating separate effects experiments under a reactor vessel pressure up to 14.2 MPa are presented. With the test facility scaled to the Zion PWR geometry, these tests are mainly focused on the corium dispersion phenomenon in order to obtain a better understanding of the dominant driving mechanisms. Water and woods metal have been used separately to simulate the core melt, the reactor vessel being pressurized with nitrogen gas analogous to the steam in the prototypic case. The entire test transient lasted for a few seconds, and the liquid dispersion in the test cavity occurred within only 0.5 s. To synchronize the data acquisition and blowdown transient, the test initiation was triggered by breaking two rupture discs in the liquid/gas delivery system. Parameters characterizing the liquid transport were obtained via various instruments. Important information about the mean size and size distribution of the dispersed droplets in the test cavity, the liquid film flow transient, the subcompartment trapping, and the liquid carry-over to the containment has been obtained. These results, along with data from a previous low pressure (1.4 MPa) experiment carried out at Purdue University, form a solid database for further theoretical analysis.