Measurements of Air-Methane Mixture Flow Rate in Mine Fan Duct: A Comparative Study

FLUID FLOW SENSING TECHNIQUES

One of the most important objectives of transient well-test interpretation is to recognize the well-reservoir system (identification) that is being tested, before estimating its parameters such as permeability, skin, and reservoir pressure. This paper presents a procedure for system identification and parameter estimation for single layered reservoirs using downhole pressure and flow rate measurements. However, the procedure can also be applied to commingled reservoirs if each zone is tested in accordance with the multilayer testing technique. The procedure consists of three steps. The first is a system and flow regimes identification (diagnostic) from deconvolution, and specific convolutions and their derivatives. The second step is to obtain all possible parameters and to refine the model further from flow regime analyses and type curve matching using the rate normalized pressure and its derivatives with a few selected models. Any parameter estimated from the flow regime analyses is used as initial guesses for type curve matching. The final step is the verification that allows an automatic estimation of parameters using the most probable model. At the final step, the selected model should satisfy all observed transient measurements and the past production history as well as geological and well log information. The procedure for transient well test interpretation presented in this paper demonstrates the advantages of using downhole flow rate and pressure measurements. In addition, the paper explores the use of the Gladfelter deconvolution of pressure and flow rate data for model identification. The convolution type curves (CTC) are presented. The interpretation procedure was successfully applied to a field well test example.

Methane concentrations and fluxes in agricultural and preserved tropical headwater streams

We have developed a novel, calibration free, micro electromechanical device and method for the measurement of linear flow rate in a micro-gas chromatography (GC) system This design enables the integration of a flow rate measurement with a high sensitivity thermal conductivity detector (TCD) reported at MEMS 2009. Accurate knowledge of the flow rate is of vital importance when quantifying the results of a chromatographic separation. The total mass of analytes in a sample can be calculated from the flow rate, the area of a peak and the response factor of the detector. Furthermore, the measurement occurs at the precise moment a solute is eluting from the separation column, the point at which the measurement of flow rate is most critical for correctly quantified results. No other method of measuring flow rate directly at the sensor exists.

Flow rates at low and high intensities of the voice were measured for 94 patients with various voice disorders. The usefulness of this measurement as a phonatory function test was studied in comparison with the simple measurement of flow rate during easy phonation.1) In cases of high stiffness of the vocal cords such as laryngeal cancer and laryngitis, the flow rate tended to be abnormally high at a high intensity of the voice while normal flow rate at a low intensity. For those cases, the measurment of flow rates at low and high intensities of the voice was more useful than the simple measurement of flow rate.2) Some cases of laryngeal nodules and polypoid vocal cords showed an abnormally high flow rate at a low intensity of the voice while normal flow rate at a high intensity.3) An expiratory insufficiency during phonation, one of the functional voice disorders, was diagnosed by simultaneous measurement of flow rate and vocal intensity, as such a patient was unable to phonate a strong voice while the flow rate remained within normal range at a low intensity of the voice.

Building instantaneous cooling load is an essential variable for the optimisation and supervisory control of chiller plants, which can be estimated according to the measurements of the chilled water flow rate and the chilled water temperature drop through the chiller plants. Since the measurements of the flow rate and the temperature drop suffer from measurement uncertainties, two different fusion approaches have been developed to improve the measurement accuracy of the cooling load. One is the chiller-model-based fusion (CMF) approach and the other is the multiple-sensor-based fusion (MSF) approach. The two approaches use different disciplines to fuse available measurements. This paper describes a comparison study of the two fusion approaches, which analyses the influences of cooling load conditions of chiller plants on the performance of the two approaches. A case study based on computer simulation shows that the CMF approach is able to produce a better result when the cooling load condition is relatively stable and redundant measurements of the chilled water temperature and flow rate are deficient; while when the redundant measurements are abundant the MSF approach can produce a better result. Practical applications: The study aims to identify the advantage/disadvantage of two fusion approaches proposed for improving the accuracy of building cooling load measurement under different load conditions. For practical applications, results may be used as a guideline for selecting a proper fusion approach for a particular chiller plant according to the characteristics of its actual load condition.

To determine the long-term therapeutic value of transurethral microwave thermotherapy (TUMT) in the treatment of bladder outflow obstruction secondary to benign prostatic hyperplasia (BPH). A total of 67 patients with BPH, assessed using symptom scores and measurements of urinary flow rate, underwent TUMT using the Leo Microthermer system (Laser Electro Optics Ltd, London, UK) between October 1990 and June 1992. Follow-up information was obtained on 60 patients (90%). If they had undergone no further treatment for their BPH, they were re-assessed with symptom scores and measurements of flow rate. The mean follow-up was 52.4 months; eight of the 6 7 patients had died and seven were lost to follow-up. Sixteen of the remaining 52 (31%) had undergone another treatment for BPH; one patient developed prostatitis and one developed localized carcinoma of the prostate. Thirty-four patients had had no further treatment, 29 of whom attended for assessment. In these patients, a statistically significant improvement in both the symptom score and flow rate was maintained at 4 years. No patients developed retrograde ejaculation. This is the first study to report a follow-up of at least 4 years after TUMT with any device. Treatment with the Leo Microthermer provided at least a 50% symptomatic improvement in 16 of 50 patients treated at 4 years. However, 30% of the patients needed further treatment for their BPH. TUMT is safe and effective in patients not wanting anaesthesia and in young patients concerned about retrograde ejaculation.

The instantaneous measurement of transient flow rates is an important problem in many fluid power applications such as the investigation of the flow ripple generated by hydraulic pumps or the measurement of flow rate changes at the ports of fast switching valves. This paper deals with the utilization of the dynamic characteristics of laminar flow in circular pipes for the indirect measurement of flow rates. A discrete time state space realization of the transmission line dynamics is computed via inverse Laplace transform and an identification and model reduction method based on the singular value decomposition. This dynamic system is used for the computation of the flow rate at one end of a pipe section. Special attention is paid to the identification of the speed of sound and the dimensionless dissipation number of the pipe section, since exact knowledge of these parameters is crucial for the reliabilty of the measurement results.

Investigation of Ultrasound-Measured Flow Rate and Wall Shear Rate in Wrist Arteries Using Flow Phantoms

In this study, the reliability and quality of flow rate and water holdup measurements of oil-water flow in different pipe inclinations and diameters were investigated. The identified sources of errors in the measurement of flow rate wererepeatability, accuracy of the flow meter, resolution of the measuring cylinder and instability of the regulating valves. The identified sources of errors in the measurement of water holdup were repeatability, resolution of the measuring cylinder and flow rate. The results showed that the relative uncertainty in the measurement of the oil-water flow rate was ±1.71 % while the relative uncertainty in the measurement of the water holdups was ±10.3 % at 0.5 m/s mixture velocity and 0.5 input water fraction in horizontal 30.6-mm ID pipe. It was also found that the flow meter accuracy made the largest contribution (about 50 %) while the resolution of the measuring cylinder made the least contribution (3 %) to the combined uncertainty in the flow rate measurement. In the case of the combined uncertainty in the water holdup measurement, the largest contribution came from the flow rate while the least contribution came from the resolution of the measuring cylinder in all the different pipe inclinations and diameters.Keywords: Oil-water flow; Flow rates; Water holdups; Standard uncertainty, Combined standard uncertainty; Expanded uncertainty

This descriptive study was conducted to compare the job demands, job control, social support and mental health status of thermal power plant and underground coal mine workers. 158 workers in thermal power plant and 162 workers in underground coal mine participated in the study. The results unearthed that thermal power plant workers had 2.3 times better mental health (p < 0.001 OR = 2.3 CI = 1.50-3.74) and 3.0 times lower job demands (p < 0.001 OR = 3.0 CI = 1.91-4.92) than coal mine workers. In the study, it was determined that mental health was positively affected as job control and social support increased in both thermal power plant and underground mine workers (p < 0.05); there was no significant relationship between job demands and mental health (p > 0.05). These results indicate that underground mine workers are at higher risk in terms of mental health and job demands than thermal power plant workers.

To describe a protocol for the measurement of blood flow rate in small animals and to compare flow rate measurements against measurements made using a transit time flowmeter. Measurements were made in rat and mice using a Visualsonics Vevo 770 scanner. The flow rate in carotid and femoral arteries was calculated from the time-average maximum velocity and vessel diameter. A correction factor was applied to correct for the overestimation of velocity arising from geometric spectral broadening. Invasive flow rate measurements were made using a Transonics system. Measurements were achieved in rat carotid and femoral arteries and in mouse carotid arteries. Image quality in the mouse femoral artery was too poor to obtain diameter measurements. The applied correction factor in practice was 0.71-0.77. The diameter varied by 6-18% during the cardiac cycle. There was no overall difference in the flow rate measured using ultrasound and using transit-time flowmeters. The flow rates were comparable with those previously reported in the literature. There was wide variation in flow rates in the same artery in individual animals. Transit-time measurements were associated with changes of a factor of 10 during the typical 40 min measurement period, associated with probe movement, vessel spasm, vessel kinking and other effects. A protocol for the measurement of flow rate in arteries in small animals has been described and successfully used in rat carotid and femoral arteries and in mouse carotid arteries. The availability of a noninvasive procedure for flow rate measurement avoids the problems with changes in flow associated with an invasive procedure.

Blood viscosity has been considered as one of important biophysical parameters for effectively monitoring variations in physiological and pathological conditions of circulatory disorders. Standard previous methods make it difficult to evaluate variations of blood viscosity under cardiopulmonary bypass procedures or hemodialysis. In this study, we proposed a unique microfluidic device for simultaneously measuring viscosity and flow rate of whole blood circulating in a complex fluidic network including a rat, a reservoir, a pinch valve, and a peristaltic pump. To demonstrate the proposed method, a twin-shaped microfluidic device, which is composed of two half-circular chambers, two side channels with multiple indicating channels, and one bridge channel, was carefully designed. Based on the microfluidic device, three sequential flow controls were applied to identify viscosity and flow rate of blood, with label-free and sensorless detection. The half-circular chamber was employed to achieve mechanical membrane compliance for flow stabilization in the microfluidic device. To quantify the effect of flow stabilization on flow fluctuations, a formula of pulsation index (PI) was analytically derived using a discrete fluidic circuit model. Using the PI formula, the time constant contributed by the half-circular chamber is estimated to be 8 s. Furthermore, flow fluctuations resulting from the peristaltic pumps are completely removed, especially under periodic flow conditions within short periods (T < 10 s). For performance demonstrations, the proposed method was applied to evaluate blood viscosity with respect to varying flow rate conditions [(a) known blood flow rate via a syringe pump, (b) unknown blood flow rate via a peristaltic pump]. As a result, the flow rate and viscosity of blood can be simultaneously measured with satisfactory accuracy. In addition, the proposed method was successfully applied to identify the viscosity of rat blood, which circulates in a complex fluidic network. These observations confirm that the proposed method can be used for simultaneous measurement of viscosity and flow rate of whole blood circulating in the complex fluid network, with sensorless and label-free detection. Furthermore, the proposed method will be used in evaluating variations in the viscosity of human blood during cardiopulmonary bypass procedures or hemodialysis.

concentrations in the vacuum degassing gas pipeline. Methods. Analytical dependencies for determining the absolute pressure, volume flow rate and temperature of the gas mixture in link of degassing gas pipeline and an empirical dependence for determining the volume flow rate of air in the inflows coming through the flange connections of the gas pipeline links were used in the studies. Results. With these assumptions in mind, the formula for determining the gap in the flange joint of the degassing gas pipeline links has been obtained. The results of calculating air inflows and methane concentrations along the length of the horizontal section of the degassing gas pipeline have been presented. Analysis of the results showed that air inflows through the flange joints of the degassing gas pipeline links increase in the direction of the gas mixture flow, while the methane concentration, on the contrary, decreases. In this case, the increase in air inflows is due to an increase in vacuum in the degassing gas pipeline, while the decrease in methane concentration is due to an increase in the volume flow of the gas mixture. Based on the analysis of the methane concentration character of change along the length of the horizontal section of the degassing gas pipeline, the distance from the beginning of the pipeline where the methane concentration value becomes below the permissible value and the probability of ignition of the gas mixture arises. It has been established that methane concentration varies insignificantly along the length of the gas pipeline at normative airflows. Scientific novelty. A formula is derived for determining the size of the gap between the flat rubber gasket and a shoulder of a flange connection of the degassing gas line links, at which the total air inflows in the gas line coincide with the standard value. Practical significance. The determination of the size flange joint clearance of the degassing gas pipeline links makes it possible to calculate the air inflows and assess the tightness of the gas pipeline flange joints on the basis of measurements of the gas mixture volume flow rate, methane concentration and the depression value.

Industrial radiotracer application in flow rate measurement and flowmeter calibration using 99mTc and 198Au nanoparticles radioisotope