Ultrasonic Measurement for the Experimental Investigation of Velocity Distribution in Vapor-Liquid Boiling Bubbly Flow

This study proposes an ultrasonic velocity profiler (UVP) with a single ultrasonic gas-liquid two-phase separation (SUTS) technique to measure the velocity distribution of vapor-liquid boiling bubbly flow. The proposed technique is capable of measuring the velocity of the vapor bubble and liquid separately in boiling conditions. To confirm the viability of the measurement technique, the experiment is conducted on vertical pipe flow apparatus. The ultrasonic transmission and effect of ultrasonic refraction through the pipe wall and water are investigated at ambient temperature until subcooled boiling temperature is reached. The velocity profile in the water at elevated temperature is measured to verify the ability of the technique in this application. The bubbly flow velocity distribution measurement in boiling conditions is then demonstrated. The results show that the proposed technique can effectively investigate the velocity of both phases under various fluid conditions in boiling bubbly flow.

Dual-Channel Stopped-Flow Apparatus for Simultaneous Fluorescence, Anisotropy, and FRET Kinetic Data Acquisition for Binary and Ternary Biological Complexes

The Stopped-Flow apparatus (SF) tracks molecular events by mixing the reactants in sub-millisecond regimes. The reaction of intrinsically or extrinsically labeled biomolecules can be monitored by recording the fluorescence, F(t), anisotropy, r(t), polarization, p(t), or FRET, F(t)FRET, traces at nanomolar concentrations. These kinetic measurements are critical to elucidate reaction mechanisms, structural information, and even thermodynamics. In a single detector SF, or L-configuration, the r(t), p(t), and F(t) traces are acquired by switching the orientation of the emission polarizer to collect the IVV and IVH signals however it requires two-shot experiments. In a two-detector SF, or T-configuration, these traces are collected in a single-shot experiment, but it increases the apparatus’ complexity and price. Herein, we present a single-detector dual-channel SF to obtain the F(t) and r(t) traces simultaneously, in which a photo-elastic modulator oscillates by 90° the excitation light plane at a 50 kHz frequency, and the emission signal is processed by a set of electronic filters that split it into the r(t) and F(t) analog signals that are digitized and stored into separated spreadsheets by a custom-tailored instrument control software. We evaluated the association kinetics of binary and ternary biological complexes acquired with our dual-channel SF and the traditional methods; such as a single polarizer at the magic angle to acquire F(t), a set of polarizers to track F(t), and r(t), and by energy transfer quenching, F(t)FRET. Our dual-channel SF economized labeled material and yielded rate constants in excellent agreement with the traditional methods.

Systematic Frequency and Statistical Analysis Approach to Identify Different Gas–Liquid Flow Patterns Using Two Electrodes Capacitance Sensor: Experimental Evaluations

This work proposes a method to distinguish between various flow patterns in a multiphase gas–liquid system. The complete discrimination between different flow patterns can be achieved by mapping the corresponding frequency and statistical parameters. These parameters are usually obtained from further analysis conducted on the signal data of the utilized sensor. The proposed technique is based on establishing interrelationships between these parameters, namely the mean (m), the standard deviation ( σ ¯ ), power spectral density (PSD), the width of the characteristic frequency peaks (Δƒ), the skewness ( γ 1 ) and the kurtosis ( γ 2 ). Therefore, a relatively simple electrical capacitance sensor with two electrodes was designed and implemented on a two-phase flow apparatus with a circular pipe. The experimental operating conditions comprised of different combinations of air–water superficial velocities at three inclinations (i.e., horizontal, upward 15° and upward 30°). This research discusses in specific the analysis underlying flow patterns identification method and the rationale for selecting the proposed approach. The results showed that some parameters found to be more valuable than others such as m, σ ¯ and Δƒ. Besides, combining two sets of these statistical graphs which are (a) σ ¯ vs. Δƒ with Δƒ vs. m (or Δƒ vs. total power), (b) Δƒ vs. total power with γ 1 vs. σ ¯ (or γ 2 vs. σ ¯ ), and (c) σ ¯ vs. m with Δƒ vs. m (or Δƒ vs. total power), allowed all flow patterns field to be identified clearly at all inclinations. It is therefore concluded that for any gas–liquid multiphase flow system, the reported approach can be used reliably to discriminate between different generated flow patterns.

Selecting ultrafiltration membranes for fractionation of high added value compounds from grape pomace extracts

The purpose of the current study is to investigate the use of ultrafiltration membrane for the fractionation of phenolic compounds from subcritical water grape pomace extract and the separation of these compounds from other co-extracted components. The extract was assayed in a cross-flow apparatus against eleven membranes with molecular weight ranging from 100 to 2 kDa. Monitoring of the process was executed by determining performance parameters and retention coefficients of proteins, polysaccharides, sugars, phenolic and anthocyanin classes. Results indicated that retention of solutes was affected, not by size exclusion, but primarily by severe fouling phenomena due to polar solutes adsorption on the membrane surface. With the exception of the separation obtained between polymeric and monomeric proanthocyanidins, polysulfone membranes were not able to fractionate phenolic classes. Membranes starting of 20 kDa and over retained high percentages (>60%) of polysaccharides and proteins.

2D Velocity Vector Profile Measurement and Phase Separation on Swirling Bubbly Flow Using Ultrasound Technique

Two-phase swirling bubbly flow is a complex phenomenon which occurs in several industries such as a nuclear reactor. Its characteristic is indispensably necessary to be investigated especially the multi-dimensional velocity distribution. This present paper describes the development of Ultrasonic Velocity Profiler (UVP) method which is a noninvasive measurement and needless of optical access, to obtain a two dimensional (2D) velocity distribution of the bubble and liquid phase in swirling bubbly flow simultaneously. The measurement result is represented in the form of the 2D velocity vector. To achieve the target, the multiple transducers and developed signal processing have been applied to the UVP system to measure a 2D velocity vector affected by bubble and liquid separately. For confirming the ability of Developed-UVP, the experiment was conducted on a vertical pipe co-current flow apparatus. The UVP measurement was demonstrated non-intrusively and without the optical requirement. The measurement applicability of Developed-UVP was evaluated by comparing with Particle Image Velocimetry (PIV) method on liquid flow and bubbly flow. Then, it was applied to obtain the 2D velocity vector in swirling bubbly flow. The velocity vector of the bubble and liquid could be separated clearly. Also, velocity distribution in swirling motion which was interacted of both phases was investigated understandably by using this measurement technique.

An Experimental Study of Seepage Properties in Crushed Sandstone and Mudstone

To study the effects of compression rate and weight ratio of sandstone to mudstone on permeability, water flow tests were performed on crushed rocks using an in-house designed and built water flow apparatus. Seepage properties of sandstone and mudstone were tested on specimens under six axial displacement levels. The weight ratios of the six specimens of sandstone to mudstone were set to 1 : 0, 4 : 1, 3 : 2, 2 : 3, 1 : 4, and 0 : 1. A non-Darcy law was adopted to calculate the permeability in the experiments based on verification of the Reynolds number. Non-Darcy flow is found to be most significant when the axial displacement or mudstone content increases. The permeability in the experiments is found to be in the range of 9.1 × 10−15–9.492 × 10−13 m2, which is calculated from a quadratic polynomial fit between the flow velocity and pressure gradient. A compression rate of 28.6% and weight ratio of sandstone to mudstone of 60% are found to be key values affecting permeability. When the axial displacement of specimen A (1 : 0) increases from 10 mm to 30 mm, the compression rate (ratio of axial displacement to original specimen height) increases from 9.5% to 28.6%, and the permeability decreases by 83.8% to 1.534 × 10−13 m2. When the axial displacement is 10 mm and the content of mudstone is increased from 0% to 60%, the permeability decreases by 77.1% to 2.172 × 10−13 m2.

UV spectroscopic determination of the chlorine monoxide (ClO) ∕ chlorine peroxide (ClOOCl) thermal equilibrium constant

The thermal equilibrium constant between the chlorine monoxide radical (ClO) and its dimer, chlorine peroxide (ClOOCl), was determined as a function of temperature between 228 and 301 K in a discharge flow apparatus using broadband UV absorption spectroscopy. A third-law fit of the equilibrium values determined from the experimental data provides the expression Keq=2.16×10-27e8527±35K/T cm3 molecule−1 (1σ uncertainty). A second-law analysis of the data is in good agreement. From the slope of the van't Hoff plot in the third-law analysis, the enthalpy of formation for ClOOCl is calculated, ΔHf∘(298K)=130.0±0.6 kJ mol−1. The equilibrium constant results from this study suggest that the uncertainties in Keq recommended in the most recent (year 2015) NASA JPL Data Evaluation can be significantly reduced.

The Development and Testing of a Fixation Apparatus for Inducing the Coaptation of the Cardiac Atrioventricular Valves

As the prevalence of mitral and tricuspid valvular disease continues to grow with the aging population [1,2], there is a growing critical need to treat high mortality risk patients using minimally invasive and/or non-surgical percutaneous procedures. However, these transcatheter procedures, especially those aimed at repairing or replacing the mitral and tricuspid valves, are mostly still in development and/or early clinical testing. Catheter delivery, prosthesis fixation, and/or demonstrating device efficacy are major challenges currently being addressed [3,4]. Although in situ animal models can assess catheter systems with clinical imaging, direct visualization of tissue-device interactions in real human heart anatomies are desired. In vitro delivery and implantations of valvular prototypes in human heart specimens can be instrumental for accurate device testing and gaining important design insights. Such investigations can be performed on a pulsatile flow apparatus, utilizing perfusion fixed human hearts with mitral and/or tricuspid valves eliciting coaptation and relative function. The employment of endoscopic cameras provides direct visualization and can be coupled with echocardiography, providing novel insights relative to these transcatheter devices in a dynamic environment. However, these investigative approaches require appropriately fixed human heart specimens that will allow for dynamic valve movement. This study discusses the design, construction, and implementation of a novel fixation apparatus to promote the coaptation of the mitral and tricuspid valves in swine and fresh human heart specimen.