Principle Of Differential Pressure Research Articles

Impacts of inflow conditions on the measurement stability of a turbulence-mitigation based liquid concentration detection system

Liquid concentration plays an important role in many industrial processes. We designed a concentration detection system based on the principle of differential pressure, and introduced a turbulence elimination structure (TES) to improve the internal flow field. In order to explore the influence mechanism of the internal flow field on the detection, two models were used for numerical simulation under different working conditions. The results show that TES can effectively restrain the velocity fluctuation and turbulence intensity change of the flow field in the observation trough, thus forming a good measurement environment. The experimental results show that the measurement signal of the model with TES is more stable, and a stable detection area is formed between sensor 1 and sensor 3, which can be used for efficient detection of the sensor system. For the model with TES, the optimal speed range of 0.3–0.8 m/s was determined through experiments.

The Effects of the Structural Tuning on the Sensing Performance of Extinguishant Detector Based on the Differential Pressure Principle

The research of the spatial and temporal distribution of the extinguishant concentration is necessary for the design of a fire extinguishing system. The detection technique based on the differential pressure principle is very suitable for the extinguishant concentration measurement. This paper focused on studying the effect of sensing structure on sensing performance. It was found that due to the solid sensing structure, the sensor had good stability and reproducibility, and the response/sensitivity would increase with the increase of the throat diameter of the critical flow nozzle and temperature, and with the decrease of the inner diameter and the number of the tubes of the vascular bundles, which were in good agreement with the theoretical prediction. For the response rate, it could be improved by increasing the throat diameter and decreasing the external diameter of the vascular bundles, but these also caused the great increase in the response fluctuation, which could lead to the decrease in measuring accuracy despite the improvement in response and sensitivity, especially for the high concentration. However, the increase of the temperature would efficiently reduce the response fluctuation while improving the response and sensitivity. The research results can provide good theoretical suggestions for the sensor design.

Research of the Response Rate Variation for the Extinguishant Detection Technique Based on the Differential Pressure Principle

Research of the Response Rate Variation for the Extinguishant Detection Technique Based on the Differential Pressure Principle

Study of the response fluctuation variation for the extinguishing agent detection technique based on the differential pressure principle

The gas sensing technique based on the differential pressure principle is quite suitable to evaluate the effectiveness of gas fire extinguishing system. This paper is focused on the study of the change rule of its response fluctuation that is critical to the concentration measuring accuracy. The variation of response fluctuation and sensing performance with sensing structure and constant temperature was explored. Results show that it will often enlarge the response fluctuation when promoting the response/sensitivity or response rate by changing the sensing structure, which can cover the improvement in sensitivity causing the decrease in measuring precision, especially for high concentration. However, the increase of temperature will reduce the response fluctuation while improving the response/sensitivity and response rate, which is a good way to promote sensing performance. The research in the paper can provide suggestions for the optimization design of the sensor.

A multi-level assessment and correction method for Venturi tube flow measurements

The main feed water flow for nuclear power units is measured by Venturi tubes. These use the principle of differential pressure to act as throttling devices. Over the course of their operational life, the passage of medium- and high-speed fluids can erode Venturi tubes, undermining the measurement accuracy of the differential pressure and flow. Venturi tubes play a vital role in nuclear power units, participating in the regulation of the water level in steam generator control systems and protecting reactor signals. Thus, the accuracy of their signal measurements directly affects the safe and stable operation of nuclear power units. This paper analyzes statistical data regarding the main feed water flow measurements from 26 nuclear power units. Combined with the working principles of Venturi tubes, it establishes the mechanism governing erosion in Venturi tubes and its characteristics over long-term operation. A multi-level assessment method for Venturi tube erosion then is proposed that can evaluate the accuracy of flow measurements in terms of degradation, failure and replacement. On the basis of this method, accurate corrections of the differential pressure can be implemented or the tubes replaced. The method was applied in nuclear power units and its effectiveness verified. It can therefore provide a reliable basis for improvements in the safety of nuclear power unit operation and serve as a reference for other chemical and thermal power fields where Venturi tubes are used for measurement and regulation.

Fluids level monitoring using Zigbee

Measurement is a critical element in the instrumentation and control systems in the industry, especially in the process industry. The analysis can be made in various ways and methods, one who is designing a monitoring system. The design of this monitoring system can be realized as a simulation through similar visualization with industrial monitoring systems. This paper has developed and applied fluids level monitoring systems based on Zigbee to transmit and receive data wirelessly. The system design is divided into two parts. The first one is plant design and Human Machine Interface (HMI), the system that is applied in designing measurement systems fluid level. The design and application of HMI systems use Visual Basic as the user interface with the plant. In this plant, ATmega16 is being used for the system controller and MPX2010DP sensor, which was chosen to measuring the level of fluids. This sensor is selected because this sensor uses the principle of differential pressure making it easier to use. Sending and receiving data from the PC to the plant runs very well using Local Area Network (LAN). The maximum range is 30m for indoors and 90m for outdoors.

Differential-pressure fiber-optic airflow sensor for wind tunnel testing.

A differential-pressure fiber-optic airflow (DPFA) sensor based on Fabry-Perot (FP) interferometry for wind tunnel testing is proposed and demonstrated. The DPFA sensor can be well coupled with a Pitot tube, similar to the operation of the differential diaphragm capsule in the airspeed indicator on the aircraft. For differential pressure sensing between total pressure and static pressure in the airflow, an FP cavity is formed between the sensing diaphragm and a fiber end-face, and a tubule is inserted into the FP cavity. According to the principle of differential pressure derived from Bernoulli's equation, the airflow velocity can be determined by monitoring the change of the FP cavity length. The experimental results demonstrate that a DPFA sensor with 0∼11 kPa measurable range, 826.975 nm/kPa sensitivity, and 0.008% (0.89 Pa) resolution can be realized. Combined with a 100 Hz-sweep frequency self-developed white light interferometric (WLI) interrogator and a Pitot tube, the DPFA sensor can be used for measuring the airflow velocity of 2.0∼119.24 m/s with an accuracy of 0.61%. The system is applied to the analysis of the flat-plate boundary layer, a wind tunnel experimental model, where the results are consistent with those of the theoretical analysis and from the standard electronic pressure transducer. With the large measurable range, high sweep frequency, and high precision, the system has potential application value for wind tunnel experimental investigation and in-flight measurement of airspeed.

Automatic Solar Panel Tracking System

Solar Energy is the one of best renewable source of alternative energy. The efficiency of the solar panel can be improved more by tracking it in such way that it always faces perpendicular to the sun-rays throughout the day rather than it is kept fixed at an angle. At present, there are three methods for solar tracking, out of which refrigerant method is found to be more efficient as it is of a passive type and requires no external power source for its operation. In this project we have used R-134a [Tetrafluoroethene (CF3CH2F)] as the refrigerant medium for tracking the panel. To store the refrigerant, we have made use of two canisters and a copper conduit for connecting the canisters. The tracking system works on the principle of Differential Pressure Controlled system where high-pressure refrigerant from one canister to other flows and due to imbalance in the weight of canisters, the panel will tilt in the direction of the side where the weight is high due to gravity. Thus, our main objective is to harvest more solar energy at a much lower cost than the available trackers.

Mitigation of annular pressure buildup for deepwater wells using a recovery relief method

AbstractAnnular pressure buildup (APB) is induced by high‐temperature tubing fluid heating the trapped annular fluid, which leads to liquid thermal expansion at the production stage in deepwater wells. Casing would be burst or collapsed without APB mitigation. A novel recovery relief method was adopted to mitigate APB through the principle of differential pressure. To assess the application effect of the method, APB prediction model and pressure relief threshold determination method were proposed, where the transient heat transfer and volume and pressure coupling were involved. The laboratory test of the principle prototype was conducted so that the feasibility of the recovery relief method was validated. The numerical APB mitigation effect was simulated by the field example. The production simulation results indicated that the high‐temperature‐induced APB caused casing failure. The simulation of APB mitigation with both inward and outward directions demonstrated that the casings using outward mitigation method were safer with lower safe factor. Besides, comparing the mitigating effect to the rupture disk, the recovery relief method had more maximum allowable APB of annulus A. Additionally, compared to other 11 ordinary mitigation methods with the qualities of engineering reliability, technology feasibility, and economy, the recovery relief method had best mitigation performance. Therefore, the recovery relief method was recommended for APB mitigating practice.

Fiber optical temperature compensated anemometer based on dual Fabry-Perot sensors with sealed cavity.

A fiber optical anemometer using dual Fabry-Perot sensors with sealed cavity is proposed for high-speed airflow measurement. The airflow velocity is measured based on principle of differential pressure, and temperature compensation is realized by reference F-P sensor to improve measurement accuracy and environmental adaptability. The location of dual F-P sensors in the airflow field and quadratic functional relation between differential pressure and airflow velocity are obtained by the simulation of turbulence model. F-P sensors in this experiment can be employed to measure pressure from 100kPa to 107kPa and temperature from 5°C to 50°C. The full-scale error of F-P sensors is less than 0.53% by calibration. It is demonstrated experimentally this fiber optical anemometer is qualified for measuring air velocity in the range of 7.9-81m/s with velocity error less than 0.69%. The device has the potential to measure high speed airflow in various applications.

基于差压原理的矿用光纤光栅风速传感器

A design of mine wind speed sensor using fiber Bragg grating (FBG) was reported, which was based on differential pressure principle and differential sensitive architecture was adopted which was composed of a bellows, an equal-strength beam and two FBGs. Furthermore, an algorithm was introduced for temperature compensation. Through these methods the cross sensitivity of temperature was effectively eliminated and a high strain sensitivity was achieved. The relation between the central wavelength variation of the two FBGs and the wind speed was derived. Meanwhile, the hydraulic simulation test of sensitive architecture was carried out and the sensitivity of 0.703 pm/Pa was given, which agreed well with the theoretical value. The wind speed sensor was tested by wind tunnel and the results show that the measurement error of the sensor is within 0.3 m/s in the range of 0.2-20 m/s, and the wind speed sensor has good linearity.

In-situ measurement and numerical simulation of resin pressure during Glass/Epoxy prepreg composite manufacturing

Abstract Resin pressure distribution of a curing Glass/Epoxy prepreg lay-up is the key parameter that controls the strength, stiffness and void nucleation of the cured composite part. It is vital to monitor and control the resin movement of curing laminate to optimize its quality in any manufacturing process. In this paper, design of a Fiber Bragg grating (FBG) based device, capable of measuring in-situ resin pressure of a curing lay-up is presented. This device uses the principle of differential pressure in liquids. The device was calibrated using a water column, and a pressure sensitivity of 1.636 × 10 −2 MPa −1 was yielded. FBG responds linearly with the rise of hydrostatic pressure in the water column. An excellent agreement was found between experimental and theoretical results. This device was used to monitor the resin pressure in a curing prepreg composite lay-up. The measured liquid resin pressures were also compared to the resin pressure obtained from a coupled multi-physics numerical simulation. The presented sensor is useful for in-situ pressure measurements, especially for high temperature and low or zero bleed curing of composites, for example, out of autoclave curing.

A beam-membrane structure micromachined differential pressure flow sensor

A beam-membrane structure micromachined flow sensor is designed, depending on the principle of differential pressure caused by the mass flow, which is directly proportional to the square flow rate. The FSI (fluid structure interaction) characteristics of the differential pressure flow sensor are investigated via numerical analysis and analog simulation. The working mechanism of the flow sensor is analyzed depending on the FSI results. Then, the flow sensor is fabricated and calibrated. The calibration results show that the beam-membrane structure differential pressure flow sensor achieves ideal static characteristics and works well in the practical applications.

Research on the Vortex Mass Flow Meter of Dual Bluff Body Based on Differential Pressure Principle

The lower limit of the existing vortex mass flow meter based on differential pressure is high. So the application of the existing vortex mass flow meter is limited in the measurement for low flow rate. This paper proposes a method using vortex mass flow meter of dual bluff body based on differential pressure principle. The differential pressure signal between the upstream and downstream can be amplified by the vortex overlap caused by the dual bluff body structure. The results of the simulation by Fluent show that this method can reduce the lower limit of measurement, and improve the measurement sensitivity effectively.

The New Theory of Gravitation Representing the Movement of Planets

In this paper, a theory of the phenomenon of planetary circulation around the Sun is presented, as well as the stability of solar systems is explained. This theory describes the circulation of planets and other mass-holding bodies around the Sun as a phenomenon consisting in the principle of differential pressure in solar systems and thus excludes gravitation phenomenon as the phenomenon of attraction.

The New Theory of Gravitation Representing the Movement of Planets

In this paper, a theory of the phenomenon of planetary circulation around the Sun is presented, as well as the stability of solar systems is explained. This theory describes the circulation of planets and other mass-holding bodies around the Sun as a phenomenon consisting in the principle of differential pressure in solar systems and thus excludes gravitation phenomenon as the phenomenon of attraction.

The development of a multiphase flow meter without separation based on sloped open channel dynamics

The online continuous measurement of multiphase flow is one of the most key technologies which influences the development of oil industry in future. A new type of multiphase meter system is developed based on the open channel flow. The test pipe of the meter is slightly slopped to make the flow pattern mainly stratified flow. Based on the study of oil and gas flow dynamics in the open channel test pipe, the liquid metering model and gas metering model are deduced to calculate the gas and the liquid flow rate, the water cut is measured online by the principle of differential pressure. This device can work online without the separation of the production fluid. By the lab test and field application test, the results of the metering system show that the liquid flow rate errors are within ±5%, the gas flow rate errors can be within ±5%, and the water cut absolute error is within ±2%, which can meet the demands of the field flow rate measurement.

Hydrostatic levelling systems: Measuring at the system limits

Three hydrostatic displacement monitoring system applications in Switzerland are discussed; the first concerns experience gained monitoring the foundation of the Albigna dam, the second relating to the underground stability of the Swiss Light Source synchrotron and the third concerning the deformation of a bridge near the city of Lucerne. Two different principles were applied, the Hydrostatic Levelling System (HLS) using the “half-filled pipe principle” developed by the Paul Scherrer Institute and the Large Area Settlement System (LAS) using the “differential pressure principle”. With both systems ground deformations induced by tidal forces can be seen. However, high accuracy of single sensors is not sufficient. A well-designed configuration of the complete system is equally important. On the other hand there are also limits imposed by installation logistics and by the environmental conditions. An example is the bridge monitoring application, where the acceleration along the bridge due to the passage of heavy trucks limits the feasibility of using hydrostatic levelling measurements.

STIFFNESS REGULATION AND POSITION CONTROL TECHNOLOGY OF A PNEUMATIC MUSCLE ROBOT ARM

In the case that the high compliance and high safety are required, the use of pneumatic muscle for robot joints is a good choice. In this paper, a bio-mimic structure of pneumatic muscle robot arm is introduced and the differential pressure principle is applied to control the arm. In order to solve the practical problems that difficult regulation with pneumatic muscle and the lower accuracy of position control, a proportional stiffness regulation method with easy implementing feature is presented through theoretical analysis and experiments. On this basis, the position control of the joint with pneumatic muscle is implemented, for which the adaptive and self-learning neural-PSD controller is adopted. Tests indicate that the joint stiffness is easy to regulate by the method and joint operation shows a quick response and high accuracy.

An open circuit respiration unit for calorimetric studies with small animals

Two open-circuit respiration chambers for small animals (rats, poultry and rabbits) have been built at the Estación Experimental del Zaidín. The respiration facility is air-conditioned, the temperature and the relative humidity in the chambers can be regulated from about +15 to +30 degrees C and from 60 to 90%, respectively. The air flow is determined by the differential pressure principle, CO2 measurement is by the infra-red technique and O2 analyser is of the paramagnetic type. The present work describes the technical details of the respiration plant and the calibration procedures of the whole system.