scholarly journals Choosing a Universal Air Collector Design for a Cylindrical-Shaped Hot-Wire Anemometer

2021 ◽  
Vol 24 (2) ◽  
pp. 6-15
Author(s):  
Oleh S. Tsakanian ◽  
◽  
Serhii V. Koshel ◽  
Keyword(s):  
Flow Rate ◽  
Measurement Errors ◽  
Air Flow ◽  
Aerodynamic Resistance ◽  
Experimental Studies ◽  
Flow Distribution ◽  
Hot Wire ◽  
Air Flow Rate ◽  
Measuring Device ◽  
Calibration Dependence

Air flow measurement at the outlets of air terminal devices installed in ventilation systems is very difficult. At the outlets of anemostats, swirl diffusers, grilles, the air flow can swirl, contract, or expand sharply, change its direction, etc., which causes great measurement errors. Therefore, it was necessary to develop a universal measuring device that would make it possible to measure air flow rate with high accuracy. It should consist of an air collector (for collecting and rectifying air flow) and a sensor for measuring air flow rate (integral hot-wire anemometer). Several air collector designs have been investigated. The parabolic air collector was chosen as the rational one. It has low aerodynamic resistance and good air flow distribution. To reduce the influence of turbulence and air swirling, a cylindrical stilling channel with a built-in rectifying grille is connected to the air collector. Experimental studies on various air distribution devices made it possible to obtain a refined calibration dependence for an integral hot-wire anemometer, the dependence being used to calculate air flow rate. The influence of the aerodynamic resistance of an airflow meter on air flow rate is taken into account with the help of a correction that must be introduced into the values measured.

scholarly journals Integral Thermo-Anemometers for Average Temperature and Airflow Measurement in Ducts, at Anemostat Outlets and in Ventilation Grilles

2020 ◽  
Vol 23 (4) ◽  
pp. 14-21
Author(s):  
Oleh S. Tsakanian ◽  
◽  
Serhii V. Koshel ◽  
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Air Flow ◽  
Hot Wire ◽  
Air Flow Rate ◽  
National Academy Of Sciences ◽  
Calibration Dependence ◽  
The Cross ◽  
And Control ◽  
Ventilation Systems

When creating ventilation systems, it is important to correctly calculate the volumes of air inflow and outflow. If an error is made in the calculation or a redistribution of air flows is required, measurements are indispensable. The existing methods for determining the air flow rate by using point measurements in the cross-section are laborious and time-consuming, and taking readings at different time points introduces a significant error into the result. A. M. Pidhornyi Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine has developed a new hot-wire anemometer whose use greatly simplifies the measuring process. This device allows one to measure the average values of temperature and air velocity (flow rate) in the cross-section of air ducts or at the inlets and outlets of grilles and anemostats, and can be used in real time to monitor and control air flow rate and temperature in ventilation systems. The probe of the hot-wire anemometer is a metal shell with guides on which a sensitive element is laid. Its principle of operation is to change the heat transfer coefficient at different air leakage velocities. The anemometer is preliminarily calibrated in laboratory conditions at various velocities. There has been obtained a calibration dependence that can be used to measure the air flow rate at the inlets and outlets of air distribution devices and directly in the air ducts. To improve the measurement accuracy, it is necessary to provide the 90° angle of airflow leakage on the hot-wire anemometer probe. For this, special air collectors and air flow rectifiers are used.

On the Computation of Emissions From Exhaust Gas Composition Measurements

1989 ◽  
Vol 111 (3) ◽  
pp. 410-423 ◽  
Author(s):  
J. Myers ◽  
M. Myers ◽  
P. Myers
Keyword(s):  
Computer Program ◽  
Flow Rate ◽  
Measurement Errors ◽  
Air Flow ◽  
Exhaust Gas ◽  
Emission Rates ◽  
Gas Composition ◽  
Air Flow Rate ◽  
Method Of Calculation ◽  
Calculation Technique

This paper presents a calculation technique and related computer program to yield mass emission rates from measured exhaust gas composition and fuel flow rate or fuel plus air flow rate (if air flow rate is measured). The sensitivity of the computed emission rates to (1) the method of calculation and (2) experimental measurement errors is investigated. It is recommended that published emission rates be the average of the rates computed by several different methods, as discussed in this paper, to minimize the effect of experimental variations in measurement. This, plus use of the computer program presented, would standardize the assumptions used in computing emissions and minimize differences in reported emission rates from different laboratories.

Water Flow Distribution in Horizontal Protruding-Type Header Contaminated With Bubbles

1999 ◽  
Author(s):  
Sachiyo Horiki ◽  
Masahiro Osakabe
Keyword(s):  
Uniform Distribution ◽  
Gas Phase ◽  
Water Flow ◽  
Flow Rate ◽  
Water Distribution ◽  
Air Flow ◽  
Water Flow Rate ◽  
Flow Distribution ◽  
Air Flow Rate ◽  
Distribution Behavior

Abstract Flow header for small multiple pipes is commonly used in boilers and heat exchangers. The system contributes to raise the heat transfer efficiency in the components. The flow distribution mechanism of the header for water has been studied and the calculation procedure for the design has been recommended for a single-phase condition. It is also recommended to avoid the bubbles in the header to obtain a uniform water flow rate to each small pipe. But in some cases, the header has to be used to distribute a flow containing bubbles. Distribution behavior of water with a gas-phase was studied experimentally in a horizontal header with four vertical pipes. In the present experimental header, it was possible to protrude the branch pipes inside of the header and the effect of protruding length on the water distribution behavior was studied. When the protruding length was 0, the water distribution rate to the first pipe rapidly increased and the rates to the others decreased with a small amount of bubbles. As the bubbles in the header were absorbed only into the first pipe, the average two-phase density in the first pipe decreased. The decreased pressure head promotes the rush of water into the first pipe such as in an airlift pump. By increasing the air flow rate in the header inlet further, the flow rate to the first pipe took a maximum and then tended to decrease. The increased air flow rate in the first pipe increased the pressure loss in the pipe and resulted in a reduction in the water flow rate. The more important and serious behavior could be seen in the other pipes where the water flow rate decreased to 1/5 of the uniform distribution rate. By increasing the protruding length, the non-uniform distribution of water was suppressed because the gas-phase entered not only the first pipe but also the others. The best result was obtained when the four branch pipes were protruded into the center of header.

Numerical Modeling of Perforated Tile Flow Distribution in a Raised-Floor Data Center

2007 ◽  
Author(s):  
Emad Samadiani ◽  
Jeffrey Rambo ◽  
Yogendra Joshi
Keyword(s):  
Numerical Modeling ◽  
Flow Rate ◽  
Data Center ◽  
Air Conditioning ◽  
Air Flow ◽  
Flow Distribution ◽  
Air Flow Rate ◽  
Tile Flow ◽  
Operating Points

This paper is centered on quantifying the effect of computer room and computer room air conditioning (CRAC) unit modeling on the perforated tile flow distribution in a representative raised-floor data center. Also, this study quantifies the effect of plenum pipes and perforated tile porosity on the operating points of the CRAC blowers, total CRAC air flow rate, and its distribution. It is concluded that modeling the computer room, CRAC units, and/or the plenum pipes could change the tile flow distribution by up to 60% for the facility with 25% open perforated tiles and up to 135% for the facility with 56% open perforated tiles.

scholarly journals RESEARCH ON THE AERODYNAMIC RESISTANCE OF TRICKLE BIOFILTER / LAŠELINIO BIOFILTRO AERODINAMINIO PASIPRIEŠINIMO TYRIMAI

2011 ◽  
Vol 3 (5) ◽  
pp. 64-69 ◽  
Author(s):  
Alvydas Zagorskis ◽  
Renata Spiečiūtė
Keyword(s):  
Surface Area ◽  
Experimental Research ◽  
Flow Rate ◽  
Air Flow ◽  
Aerodynamic Resistance ◽  
Packing Material ◽  
Large Surface Area ◽  
Air Flow Rate ◽  
First Case ◽  
Artificial Origin

A four – section trickle biofilter was constructed for experimental research. The filter was filled with the packing material of artificial origin. The material consists of plastic balls having a large surface area. The dependence of biofilter aerodynamic resistance on supply air flow rate and the number of filter sections was determined. The aerodynamic resistance of the biofilter was measured in two cases. In the first case, the packing material of the filter was dry, whereas in the second case it was wet. The experimental research determined that an increase in the air flow rate from 0.043 m/s to 0.076 m/s causes an increase in biofilter aerodynamic resistance from 30.5 to 62.5 Pa after measuring four layers of dry packing material. In case of wet packing material, biofilter aerodynamic resistance after measuring four layers of plastic balls increases from 42.1 to 90.4 Pa. Santrauka Eksperimentiniams tyrimams atlikti sukonstruotas keturių sekcijų lašelinis biofiltras. Filtras užpildytas dirbtinės kilmės įkrova, sudaryta iš didelį paviršiaus plotą turinčių plastikinių rutuliukų. Naudojant įkrovą, skirtą introdukuotų mikroorganizmų asociacijoms kultivuoti, nustatytos biofiltro aerodinaminio pasipriešinimo priklausomybės nuo tiekiamo oro srauto greičio ir sekcijų skaičiaus. Biofiltro aerodinaminis pasipriešinimas matuotas dviem atvejais: esant sausai ir sudrėkintai įkrovai. Nustatyta, kad didinant tiekiamo oro srauto greitį nuo 0,043 iki 0,076 m/s, įrenginio aerodinaminis pasipriešinimas išmatavus keturis įkrovos sluoksnius padidėja nuo 30,5 iki 62,5 Pa tuo atveju, kai įkrova sausa, ir nuo 42,1 iki 90,4 Pa, – kai įkrova sudrėkinta.

A Novel Low Air Flow Rate Measuring Device

1997 ◽  
Author(s):  
J. Steven Brown ◽  
Evan T. Graham ◽  
James B. Walunas
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Air Flow Rate ◽  
Measuring Device

scholarly journals Results of the Experimental Studies of Grain Cleaning with an Air-Spiral Separator

2020 ◽  
Vol 210 ◽  
pp. 10002
Author(s):  
Sergey Shepelev ◽  
Maksim Cheskidov ◽  
Vladimir Chumakov ◽  
Aleksandr Gritsenko ◽  
Natalia Shepeleva
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Experimental Studies ◽  
Output Parameter ◽  
Laboratory Studies ◽  
Air Flow Rate ◽  
Working Element ◽  
Product Delivery ◽  
Flow Pressure ◽  
The Relationship

We have developed an air-spiral separator with a screw aspiration channel, which allows us to reduce the air consumption and specific quantity of metal per structure. We have established that the separation process is ensured at an air flow rate V = 7.1…7.9 m/s and the diameter of the working element D = 0.3 m/ To ensure a pressure of 120.7…133.4 Pa in the working element of the separator, the fan should ensure the initial air flow pressure P = 158.7…175.4 Pa. Our laboratory studies have established that the change in the product delivery volume uniformly affects the change in the output parameter at any speed value. We have found that the change in the product delivery volume has a larger effect on the change in the output parameter when the air flow rate increases. The relationship between the product delivery point and the air flow rate is almost linear and uniform.

scholarly journals Heat Calculations of Water Cooling Tower

2021 ◽  
pp. 173-176
Author(s):  
Abdulkhaev Zokhidjon Erkinjonovich ◽  
Madraximov Mamadali Mamadaliyevich ◽  
Abdurazaqov Axmadullo Muxammadovich ◽  
Shoyev Mardon Axmadjon o’g’li
Keyword(s):  
Relative Humidity ◽  
Flow Rate ◽  
Energy Efficient ◽  
Cooling Tower ◽  
Air Flow ◽  
Aerodynamic Resistance ◽  
Thermal Calculation ◽  
Water Cooling ◽  
Air Flow Rate ◽  
Resistance Thermometer

Annotation: The article discusses the thermal calculation of the cooling tower. In the calculation, the specific air flow rate, the number of sections and the structural size of the tower are determined, according to the calculated value, energy-efficient methods are determined. Keywords: cooling tower, fan, specific air enthalpy, diagram I-d, relative humidity, aerodynamic resistance, thermometer. Аннотация: В статья рассмотрено тепловая расчёт градирня. В расчёта определено удельная расход воздуха, число секция и конструктивный размер градирня, по вычисленных величина определяется энергоэффективный методы. Ключевые слова: градирня, вентилятор, удельная энтальпия воздуха, диаграмма I-d, относительная влажность, аэродинамическое сопротивление, термометр.

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