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Measurement Systems: Sensors and Transducers
Published in Patrick F. Dunn, Michael P. Davis, Measurement and Data Analysis for Engineering and Science, 2017
Patrick F. Dunn, Michael P. Davis
The rotameter operates by having either a spherical or an elliptical weighted object (a float) contained in the flow. In its equilibrium position, the float’s weight is balanced by its upward drag and buoyancy forces. The flow cross-sectional area is designed to increase linearly with upward distance and to achieve a float position that varies linearly with the flow rate, Q. The area variation with distance assures that the annular velocity around the float, Ua, remains constant and independent of float position. The flow rate is expressed as () Q=UaAa,
Computer-Based Instrumentation: Sensors for In-Line Measurements
Published in Gauri S. Mittal, Computerized Control Systems in the Food Industry, 2018
Flow-measuring devices/instruments/sensors are required in processing operations where fluid transfer of any kind is involved. Many types of flow meters are available for pipe flow. Generally, these meters are classified into differential pressure, positive displacement, velocity, and mass meters. Flow sensors that can be used with the computerized control systems are discussed in greater detail in this chapter. Commonly used flow meters are rotameters and electronic mass flow meters. Readings of rotameters are affected by temperature and pressure conditions; however, these can be accurately calibrated. Electronic mass flow meters are more accurate (±1% of full scale) and are unaffected by temperature and pressure.
Sensors in Engineering and Science
Published in Patrick F. Dunn, Fundamentals of Sensors for Engineering and Science, 2019
The rotameter operates by having either a spherical or an elliptical weighted object (a float) contained in the flow. In its equilibrium position, the float’s weight is balanced by its upward drag and buoyancy forces. The flow cross-sectional area is designed to increase linearly with upward distance and to achieve a float position that varies linearly with the flow rate, Q. The area variation with distance ensures that the annular velocity around the float, Ua, remains constant independent of float position. The flow rate is expressed as
Impact of reattachment surface characteristics on the flow field generated by slot jet reattachment nozzle – A numerical study
Published in Drying Technology, 2023
Munevver Elif Asar, Mengqiao Yang, Jamal Yagoobi
Numerical results are validated by hot-wire air velocity measurements taken from an experimental set-up housing an SJR nozzle with a 45° exit angle on a stationary flat plate. Compressed air at 820 kPa (differential) was directed to a pressure regulator and rotameter to control and measure the air volumetric flow rate, respectively. The regulated compressed air then connects to the SJR nozzle, as seen in Figure 5a and b. The flat plate was placed 15 mm away from the bottom of the nozzle, identical to all cases considered in this study and similar to the distance used in Farzad et al.[51] An OMEGA hot-wire anemometer capable of measuring 0-25 m/s was placed 6 mm above the plate. As seen in Figure 5a, the hot-wire was attached to a precise railing system with 1 mm marks and manually traversed to obtain the desired air velocity measurements within the hot-wire probe range. The experimental data were collected for nozzle exit velocities of 12 m/s and 24 m/s and repeated ten times for each case. The standard deviation of the results was 11% and 10% for 12 m/s and 24 m/s cases, respectively.
Condensation Enhancement on Hydrophobic Surfaces Using Electrophoretic Method and Hybrid Paint Coating
Published in Heat Transfer Engineering, 2021
Sahand Najafpour, Ali Moosavi, Hosein Najafkhani
The set-up is comprised of a steam generator, condensation chamber, auxiliary condenser, and piping system, as depicted in Figure 8. Steam is generated in a chamber containing immersion heaters with 10 kW rated power. A diaphragm gauge is placed on the chamber to control the pressure of the steam. The steam is conducted to the condensation chamber using insulated pipes. The regulating valve is placed at the steam generator chamber to control the flow rate which is monitored by a vortex flowmeter. Besides, the condensation chamber is equipped with a K-type thermocouple and a pressure transducer. In addition, two K-type thermocouples were placed at the inlet ( and outlet ( of the cooling water, and the volumetric flow rate is measured by a rotameter. In order to manage the inlet temperature of the cooling water, a heater connected to a dimmer stat is installed on the coolant feeding pipe. Thermocouples and pressure transducer are connected to a data acquisition system and they are monitored during the experiment. The auxiliary condenser is exploited to convert the rest of the vapor into the liquid to close the loop. The cooling water after exiting from the outlet is cooled by an air fan. The test section consists of an insulated stainless steel chamber with a size of 36 × 7.5 × 7.5 inches and a cylindrical stainless steel sample with the inner diameter, thickness, and height of 0.5, 0.105, 34 inches, respectively.
Development of correlation for critical heat flux for vertically downward two-phase flows in round tubes
Published in Experimental Heat Transfer, 2021
Rajeshwar Sripada, Siva Subrahmanyam Mendu, Divyasree Tentu, Shanmukh Simhadri Varanasi, Vasudeva Rao Veeredhi
Two different mechanisms were used to measure the flow rate to the test section. A rotameter (F1) was placed slightly above the pump discharge to measure the volumetric flow rate. The rotameter was designed to withstand the fluid temperature up to 100°C. The rotameter was calibrated, and appropriate correction curves were included for setting the flow rate at different operating conditions before using it. Provision was also made to measure flow rate manually at the exit in Reservoir W2 using measuring jar and the stopwatch to ensure the consistency in the measurements with the rotameter. Three independent measurements were taken at the starting of each experiment and the flow rates were compared between rotameter and the manual measurement. Analog type thermometers were placed at different locations with long stems to measure the temperature of the fluid at various locations. Analog type pressure gauges (P1-P3) were placed at different locations to measure the pressure during the experiments. K-type thermocouples were used to determine the metal temperatures of the test pipe. Each thermocouple was calibrated before installing it on the test section. An independent digital K-Type probe with a resolution of 0.1°C was used to calibrate the thermocouples. The analog thermometers were also calibrated before the usage to ensure the accuracy in the readings or to include appropriate correction factors. Table 2 shows the range, resolution and accuracies of the instruments used in current experiments.