• Title/Summary/Keyword: mass flow sensor

Search Result 64, Processing Time 0.028 seconds

A numerical study on the characteristics of a thermal mass air flow sensor with periodic heating pulses (주기 발열 파형을 이용한 열식 질량 유량계의 특성에 관한 수치적 연구)

  • Jeon, Hong-Kyu;Oh, Dong-Wook;Park, Byung-Kyu;Lee, Joon-Sik
    • Proceedings of the KSME Conference
    • /
    • 2007.05b
    • /
    • pp.2482-2487
    • /
    • 2007
  • Numerical simulations are conducted for the analysis of a thermal mass air flow sensor with periodic heating pulses on silicon-nitride ($Si_3N_4$) thin membrane structure. This study aims to find the locations of temperature sensors on the thin membrane and the heating pulse conditions, that the higher sensitivity can be achieved, for the development of a MEMS fabricated mass air flow sensor which is driven in periodic heating pulse. The simulations, thus, focus on the membrane temperature profile according to variation of the flow velocity, heating duration time and imposed power. The flow velocity of the simulations is ranging from 3 m/s to 35 m/s, heating duration time from 1 ms to 3 ms and imposed power from 50 mW to 90 mW. The corresponding Reynolds numbers vary from 1000 to 10000.

  • PDF

Temperature Property Analysis of Micro Flow Sensor using Thermal Transfer Equation (열운송 방정식을 이용한 마이크로 흐름센서의 온도특성 해석)

  • Kim, Tae-Yong;Chung, Wan-Young
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
    • /
    • v.9 no.1
    • /
    • pp.363-366
    • /
    • 2005
  • A micro flow sensor on silicon substrate allows the fabrication of small components where many different functions can be integrated so that the functionality of the sensors can be increased. Further more, due to the small size of the elements the sensors can be quite fast. A thermal mass flow sensor measures the asymmetry of temperature profile around the heater which is modulated by the fluid flow. In normal, a mass flow sensor is composed of a central heater and a pair of temperature sensing elements around the heater. A new 2-D wide range micro flow sensor structure with three pairs of temperature sensors and a central heater was proposed and numerically simulated by the Finite difference formulation to confirm the feasibility of the flow sensor structure.

  • PDF

A Study on the Flow Field Characteristics of Air Induction System for Reducing the Signal-to-Noise in the MAFS Output

  • Yoo, Seoung-Chool
    • Journal of ILASS-Korea
    • /
    • v.5 no.1
    • /
    • pp.49-57
    • /
    • 2000
  • This study presents the flow visualization results, velocity and turbulence intensity measurements made within an air filter cover and entry region of a mass air flow sensor (MAFS) which is used in an induction system of 3.8L engine. Flow structure in two air filter cover assemblies were examined. The first was a clear plastic replica of the production cover while the second was a modified clear plastic cover with a geometry configured to reduce fluctuations. High speed flow visualization and laser doppler velocimetry (LDV) systems were used to reveal and analyze the flow field characteristics encountered in the sensor design process under steady flow conditions. A 40-watt copper vapor laser was used as a light source. Its beam is focused down to a sheet of light approximately 1.5mm thick. The light scattered off the particles was recorded by a 16mm high speed rotating prism camera at 5000 frames per second. A comparison of the flow patterns and LDV measurements in the original and modified air filter covers is presented to illustrate the controlling effect of the cover design on the turbulence structure formation near the bypass and on the sensor output signal. In both axial and radial planes of the main passage it was found that the turbulence flow pattern is remarkably influenced by the air filter cover and main passage configuration.

  • PDF

Design and Implementation of a Hybrid-Type Mass Flow Controller (하이브리드형 질량 유량 제어기의 설계 및 실현)

  • 이명의;정원철
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.4 no.2
    • /
    • pp.63-70
    • /
    • 2003
  • In this paper, an MFC (Mass Flow Controller) which is widely used in many semiconductor manufacturing processes for controlling the mass flow rate of a gas is designed and implemented using the PIC 16F876 of Microchip, Inc. The MFC implemented in this thesis has the form of hybrid-type, i.e., the mixed-type of the analog-type MFC, which has many problems such as low accurary, and digital-type MFC, which use an expensive DSP (Digital Signal Processor) and an ADC (Analog to Digital Convertor) with high precision. The MFC is consists of the sensor unit, the control unit and the actuator unit, and it has used the automatic calibration algorithm and the reference table method for the improvement of the performance.

  • PDF

Measurements of Thermal Characteristics for a Micro-Fabricated Thermal Mass Air Flow Sensor With Real-Time Controller (실시간 제어기를 이용한 마이크로 열식 질량공기 유량센서의 열특성 측정)

  • Park, Byung-Kyu;Lee, Joon-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.33 no.8
    • /
    • pp.573-579
    • /
    • 2009
  • A thermal mass air flow sensor, which consists of a micro-heater and thermal sensors on the silicon-nitride thin membrane structure, is micro-fabricated by MEMS processes. Three thermo-resistive sensors, one for the measurement of microheater temperature, the others for the measurement of membrane temperature upstream and downstream of the micro-heater respectively, are used. The micro-heater is operated under the constant temperature difference mode via a real time controller, based on inlet air temperature. Two design models for microfabricated flow sensor are compared with experimental results and confirmed their applicabilities and limitations. The thermal characteristics are measured to find the best flow indicator. It is found that two normalized temperature indicators can be adopted with some advantages in practice. The flow sensor with this control mode can be adopted for wide capability of high speed and sensitivity in the very low and medium velocity ranges.

Numerical Analysis on the Design of a Thermal Mass Air Flow Sensor with Various Heating Modes (가열모드에 따른 열식 질량유량센서의 설계 해석)

  • Jeon, Hong-Kyu;Lee, Joon-Sik;Park, Byung-Kyu
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.31 no.10
    • /
    • pp.876-883
    • /
    • 2007
  • Numerical simulations are conducted for the design of a micro thermal mass air flow sensor (MAFS), which consists of a microfabricated heater and thermopiles on the silicon-nitride ($Si_3N_4$) thin membrane structure. It is important to find the proper locations of these thermal elements in the design of MAFS with improved sensitivity. Three heating modes of the micro-heater are considered: constant temperature, constant power and heating pulses. The analyses are focused on the membrane temperature profile near the sensing section. Considered are the practical flow velocities, ranging from 3 m/s to 35 m/s, and the corresponding Reynolds numbers from 1000 to 10000. The results show that one of optimum sensing locations is about $100{\mu}m$ away from the microheater. It is concluded that the heating mode and configurations of thermal elements are the main factors for the MAFS with higher sensitivity.

Fabrication and Characteristics of Micro-Electro-Mechanical-System-Based Gas Flow Sensor

  • Choi, Ju-Chan;Lee, June-Kyoo;Kong, Seong-Ho
    • Journal of Sensor Science and Technology
    • /
    • v.20 no.6
    • /
    • pp.363-367
    • /
    • 2011
  • This paper proposes a highly-sensitive gas flow sensor with a simple structure. The sensor is composed of a micro-heater for heating the gas medium and a pair of temperature sensors for detecting temperature differences due to gas flow in a sealed chamber on one axis. Operation of the gas flow sensor depends on the transfer of heat through the air medium. The proposed gas flow sensor has the capability to measure gas flow rates <5 $cm^3$/min with a resolution of approximately 0.01 $cm^3$/min. Furthermore, this paper reports some additional experiment results, including the sensitivity of the proposed gas flow sensor as a function of operating current and the flow of different types of gas(oxygen, carbon dioxide, and nitrogen). The fabrication process of the proposed sensor is very simple, making it a good candidate for mass production.

An Evaluation of the Accuracy of Mini-Wright Peak Flowmeters in Patients with Asthma and Chronic Obstructive Pulmonary Disease (천식 및 만성폐쇄성폐질환 환자에서 Mini-Wright Peak Flowmeter로 측정한 최대호기유속의 정확도)

  • Choi, Won-Il;Han, Seung-Beom;Jeon, Young-June
    • Tuberculosis and Respiratory Diseases
    • /
    • v.50 no.3
    • /
    • pp.310-319
    • /
    • 2001
  • Background : The peak flowmeter is very useful in monitoring of out-patients as well as those in emergency departments because of its convenience and simplicity with low cost. There have been many studies aimed at determining the accuracy and reproducibility of the peak flow meter in normal population. However, there is a paucity of reports regarding its accuracy in patients with chronic obstructive pulmonary disease(COPD) or asthma. The accuracy of the peak expiratory flow(PEF) measured with a mini-Wright peak flowmeter was assessed by a comparison with the results of a mass flow sensor. Methods : The PEF measurements were performed in 108 patients aged 19-82 years presenting with either a chronic obstructive lung disease or asthma before and after inhaling salbutamol. The PEF measurements from the mini-Wright flowmeter were compared with those obtained by the calibrated mass flow sensor. Results : The average of the readings taken by the mini-Wright meter were 37-39 l/min higher than those taken by the mass flow sensor. The average percentage error of the mini-Wright meter were higher, ranging less than 300 l/min. The mean of the differences between the values obtained using both instruments (the bias)$\pm$limits of agreement(${\pm}2$ SD) were $37.1{\pm}90\;l/min$ for the PEF(p<0.001). Conclusions : The mini-Wright peak flowmeter overestimated the flows in patients with COPD or asthma. It was also found that the accuracy of the mini-Wright peak flowmeter decreased in its mid to low range. The limits of agreement are wide and the difference between the two instruments is significant. Therefore, the measurements made between the two types of machines in patients with asthma or COPD cannot be used interchangeably.

  • PDF

Development of Sensor Structure and Operating Circuit for Constant Resistive Type Flow Velocity/Mass Sensor (정저항형 유속/유량 센서의 구조 및 회로 개선 연구)

  • Kang, Yun-Seok;Park, Se-Kwang
    • Proceedings of the KIEE Conference
    • /
    • 1994.07b
    • /
    • pp.1339-1341
    • /
    • 1994
  • In this paper, the flow velocity/mass sensor which is based on the principle of CCT(Constant Chip Temperature) and its digital operating circuit and system have been developed and tested. The experimental result for flow velocity shows that the sensitivity is $644.01{\mu}W^2/[m/sec]$ for air, and there is nearly no hysteresis for full measured range of velocity. Response tine is between 1 second and 8 seconds for low and large velocity variation, respectively.

  • PDF