As energy efficiency is becoming more important today due to limited energy resources as well as their rising prices and environment issues, it is crucial to have reliable measurement data of ...different fluids in production processes. Because of its simplicity, affordability and reliability, orifice flow meters are again becoming subject of numerous researches. Conventional single-hole orifice (SHO) flow meter has many advantages but also some disadvantages like higher pressure drop, slower pressure recovery, lower discharge coefficient etc. Some of these disadvantages can be overcame by multi-hole orifice (MHO) flow meter while still maintaining advantages of conventional SHO meter. Both SHO and MHO flow meters with same β ratios were experimentally tested and compared. Results showed better (lower) singular pressure loss coefficient and lower pressure drop in favour of the MHO flow meter. Experimental data indicates that MHO flow meter is superior to the conventional orifice flow meter, but further research is necessary to make the MHO a drop-in replacement for a SHO flow meter.
•Proposed MHO geometry hadn't been tested before with gases on midrange pressures.•Significant decrease in singular pressure loss coefficient was recorded for MHO compared to SHO.•MHO hole distribution had no significant influence to singular pressure loss coefficient.•Compared to SHO, MHO was less responsive to flow change.
Air torque position damper hysteresis Bikić, Siniša; Bukurov, Maša; Radojčin, Milivoj ...
Flow measurement and instrumentation,
March 2020, 2020-03-00, Volume:
71
Journal Article
Peer reviewed
The purpose of this paper is to determine the effect of the air torque position (ATP) damper hysteresis on the accuracy of air velocity measurements and the adequacy of the ATP damper mathematical ...model tested in the present study. A total of three dampers with non-cascading blades were examined: a damper with a single flat blade, a damper with two opposed flat blades, and a damper with two flat blades - one of which is a measuring blade and the other is fixed in the horizontal direction. Furthermore, a total of two damper installation locations in a duct system were examined as well: at the duct exit with a straight duct section preceding the damper and within the duct itself with straight duct sections both preceding and following the damper. The ATP damper hysteresis was found to exert a significant effect on the accuracy of air velocity measurements and the adequacy of the ATP damper mathematical model tested if the ATP damper is more open, i.e. with lower blade angles of attack. Moreover, the ATP damper installed at the duct exit was found to be more susceptible to hysteresis effects than the damper located within the duct.
•ATP damper hysteresis exerts a significant effect if the damper is more open.•ATP damper installed at the duct exit was found to be more susceptible to hysteresis.•A fixed ATP damper blade in horizontal direction could mitigate effect of hysteresis.•The effect of hysteresis could be reduced by fixing blade angle during measurements.
•Energy consumption of the air torque position dampers was studied.•Four possible types of dampers with non-cascading blades were considered.•Damper with two blades (only one measuring blade) has ...minimum energy consumption.•This damper has notably lower energy consumption compared to other types of damper.
The damper used for the control of airflow in heating, ventilation and air conditioning systems can constructively be adapted to measure the air velocity with its moment characteristic. It is a device that indirectly determines the air velocity by measuring the position of the blades and the air stream moment acting on it. The subject of this paper is energy consumption of the air torque position damper depending on its structure. The aim is to compare the energy consumption of four possible types of dampers with non-cascading blades: with one blade, with two cross-guided blades, with two parallels-guided blades and with two blades, one of which is a measuring blade and the other remains fixed in horizontal position. The case when there is a straight section of a duct both in front of and behind the damper was considered. Adequacy of the existing mathematical model and energy consumption for all four types of dampers was determined experimentally. It was found that the damper with two blades of which one is a measuring blade and other remains fixed in horizontal position had minimal energy consumption.
Nowadays, with rising energy prices, energy efficiency is playing an important role in all industries. Differential pressure-based measuring instruments are still widely used instruments with orifice ...flow meters being the most popular ones. Due to its simplicity, reliability, and ease of maintenance, orifice flow meters are very common measuring instruments in many industries. As these instruments are differential pressure-based instruments, they are increasing energy costs due to increased pressure loss. Conventional single-hole orifice (SHO) flow meters have many advantages but also some disadvantages that are affecting energy efficiency. These disadvantages like higher pressure difference, slower pressure recovery, lower discharge coefficient can be overcome by multi-hole orifice (MHO) flow meters. Computational fluid dynamics (CFD) simulations were used to study energy consumption of both SHO and MHO with four different β parameters. Results showed MHO to be more energy efficient compared to SHO with same β parameter. These results are showing one more advantage MHO have compared to SHO, but further research is needed to make them a drop-in replacement.
The aim of this research was to investigate the density, thermal conductivity, and viscosity of dispersions of agricultural biomass particles in ionic liquid HMIMNTf2 used as a base fluid. This ...research is a continuation of the development of IoBioFluids, a new class of dispersions obtained by suspending particles produced from agricultural biomass, as a sustainable alternative to IoNanoFluids. Dispersions with different mass concentration of particles (0, 0.5, 1, 2.5, and 5 wt%) were studied at different temperatures (20°C, 30°C, 40°C, and 50°C). Agricultural biomass, namely sunflower stalks, was used for particle production. The dispersion was prepared by applying the commonly used two-step method. In the first step, particles were produced as dry powder from hydrothermal carbonization and heat treatment in the inert atmosphere oven. In the second step, the particles were dispersed into ionic liquid. A rheological investigation showed that dispersions exhibited Newtonian behavior for shear rates over 10 s−1. Density, thermal conductivity, and dynamic viscosity of dispersions increased with greater mass concentration of particles. Two applied merit criteria suggested a lack of any currently benefit of using the dispersions for heat transfer in the laminar flow regime due to high viscosity of dispersion. The results of criterial analysis showed that experimental data are relatively close to the limit values. Indications are suggesting the possibility of further improvement of IoBioFluid properties as a new heat transfer fluid.
Pneumatic control has found irreplaceable applications in the control of machine parts, where high accuracy is required. One of the problems that occur with the long-term use of pneumatic comparator ...is the fouling of its head. This requires interruption of pneumatic comparator’s work for maintenance, i.e., cleaning the device from accumulated impurities. Fouling of the comparator head is the consequence of the vacuum in the area between the measuring nozzle and the measured workpiece. This paper studies the possibility of vacuum reduction — both in its size and strength by varying the measuring nozzle inclination angle. The research is conducted experimentally via test rig designed for this purpose. The inclination angle of the measuring nozzle was varied from 1°to 7°, with the steps of 1°. The analysis comprises the influence of the measuring nozzle inclination on both radial and the axial pressure distribution on the workpiece surface, as well as the corresponding consequences on the comparator’s pneumatic sensitivity and its application range. Experimental results for four different supply pressures and six axial distances between the measuring nozzle front cross-section and the workpiece surface are presented. It is shown that it is possible to reduce the size of the vacuum zone and decrease the vacuum by inclining the measuring nozzle by a certain angle, depending on the supply pressure po. For a certain value of the supply pressure, it is also possible to move the vacuum zone away from the measuring nozzle’s axis when the nozzle is inclined by the optimal angle. On the downside, inclination of the measuring nozzle leads to a decrease in the application range of the comparator.
•Inclination of measuring nozzle can influence the vacuum zone properties.•Inclination of nozzle can reduce the impurities gathering on the comparator’s head.•Nozzle inclination decreases application range and precision of a comparator.•Nozzle inclination can cause difficulty in comparator application range calculation.
The primary concern of this paper is a single-blade air torque position damper used for the indirect measurement of volumetric air-flow rates by measuring the moment of airstream force exerted on the ...blade and the damper position. The purpose of the paper is to analyze the accuracy of the air velocity measurements and the adequacy of the damper mathematical model on the basis of the blade profile and the damper location in a duct system. The analysis was performed on the basis of the experimentally obtained results. Four different blade profiles (flat, V-groove, symmetrical airfoil, and non-symmetrical airfoil blades) were taken into account, as well as three different damper locations in the duct system (at the duct entrance, within the duct, and at the duct exit). Two blade orientations at the duct entrance were examined relative to the direction of air-flow (with front and rear mounting flanges). It was determined that the blade profile and particularly the damper location in the duct system affect the measurement accuracy and the adequacy of the damper mathematical model provided the blade angle of attack is less than or equal to 30?, i. e. within the range of a more open damper.
nema
This paper is focused on the mathematical model of the Air Torque Position dampers. The mathematical model establishes a link between the velocity of air in front of the damper, position of the ...damper blade and the moment acting on the blade caused by the air flow. This research aims to experimentally verify the mathematical model for the damper type with non-cascading blades. Four different types of dampers with non-cascading blades were considered: single blade dampers, dampers with two cross-blades, dampers with two parallel blades and dampers with two blades of which one is a fixed blade in the horizontal position. The case of a damper with a straight pipeline positioned in front of and behind the damper was taken in consideration. Calibration and verification of the mathematical model was conducted experimentally. The experiment was conducted on the laboratory facility for testing dampers used for regulation of the air flow rate in heating, ventilation and air conditioning systems. The design and setup of the laboratory facility, as well as construction, adjustment and calibration of the laboratory damper are presented in this paper. The mathematical model was calibrated by using one set of data, while the verification of the mathematical model was conducted by using the second set of data. The mathematical model was successfully validated and it can be used for accurate measurement of the air velocity on dampers with non-cascading blades under different operating conditions. Projekat Ministarstva nauke Republike Srbije, br. TR31058
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