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Published in Samuel C. Sugarman, HVAC Fundamentals, 2020
orifice plate: (Instrumentation) An orifice plate is essentially a fixed circular opening installed in a conduit (duct or pipe). A measurable “permanent” pressure loss is created as the fluid (air or water) passes from the larger diameter conduit through the smaller opening in the orifice. This results in an abrupt change in velocity which creates turbulence and a measurable amount of friction resulting in a pressure drop across the orifice. Calibration data, furnished with the orifice plate, show flow rate in cubic feet per minute (air) or in gallons per minute (water) versus measured pressure drop. A differential pressure gauge (such as a manometer or water differential pressure gauge) is connected to the pressure taps and flow is measured.
Instrumentation
Published in L. Ashok Kumar, M. Senthilkumar, Automation in Textile Machinery, 2018
L. Ashok Kumar, M. Senthilkumar
Segmental and eccentric orifice plates are functionally identical to the concentric orifice. The circular section of the segmental orifice is concentric with the pipe. The segmental portion of the orifice eliminates damming of foreign materials on the upstream side of the orifice when mounted in a horizontal pipe. Depending on the type of fluid, the segmental section is placed on either the top or bottom of the horizontal pipe to increase the accuracy of the measurement. Eccentric orifice plates shift the edge of the orifice to the inside of the pipe wall. This design also prevents upstream damming and is used in the same way as the segmental orifice plate. Orifice plates have two distinct disadvantages: they cause a high permanent pressure drop (outlet pressure will be 60%–80% of inlet pressure), and they are subject to erosion, which will eventually cause inaccuracies in the measured differential pressure.
Fiber Bragg Grating Sensors and Interrogation Systems
Published in Krzysztof Iniewski, Ginu Rajan, Krzysztof Iniewski, Optical Fiber Sensors, 2017
Precise measurement of gas and liquid flow is important for many applications in the chemical, aerospace, and medical equipment industries. To measure a fluid flow, an orifice plate can be used, which restricts the fluid flow and causes a pressure drop across itself. An FBG sensor can be used to measure this pressure drop. Lim et al. demonstrated a differential pressure (DP)–based flow sensor [98]. In their sensor design, a steel plate diaphragm and two FBG sensors are used (Figure 9.13). When a DP (P1 − P2) is applied, the diaphragm is strained. The applied strain is transformed into optical information by using one of the optical FBG mounted at the center of the diaphragm on the side that is in tension. The second grating is mounted on the diaphragm side that is in compression and responds to temperature but not strain. The differential wavelength shift between the reflected signals from the two gratings provides a measurement of the fluid flow rate. Temperature variation causes the variation in the reflected wavelengths to be the same, and therefore, there is no change in differential wavelength.
Fluid flow and heat transfer evaluation and optimisation of solar-assisted air-heater having multi-arcs with gaps used as roughness elements
Published in International Journal of Ambient Energy, 2023
Navneet Kumar Pandey, Abhishek Sharma, Neelam Yadav, Anil Prakash Singh, Vijay Kumar Bajpai
Standards, prescribed by ASHRAE, have been used to fix the experimentation and operating parameters (Pandey, Bajpai, and Varun 2016c, 2016b). The duct dimensions have been fixed at 250 and 25 mm as width and height, respectively with an entrance test and exit section of 800, 1000 and 500 mm. A heater above the absorber plate has been provided to supply a constant radiant heat supply of 1000 W/m2 to simulate the solar irradiation, as shown in Figure 1. Orifice plate calibrated by pitot tube has been used for the measurement of flow. 12 Thermocouples made of copper-constantan have been placed at designated positions for the measurement of temperature, as shown in Figure 2. Four other thermocouples, two at entry and two at exit, have been placed to measure the temperatures at entry and exit, respectively. The rib height is taken to be that of the height of the laminar sub-layer, s depicted in Figure 3. The effects due to fin blockage are neglected. Operating and fixed parameters are listed in Table 1.
The effect of fusel oil as a reductant over the multi-metallic catalyst for selective catalytic reduction of NOx in diesel exhaust at low-temperature conditions
Published in Petroleum Science and Technology, 2023
Şilen U. H. Sümer, Sinan Keiyinci, Ali Keskin, Himmet Özarslan, Zeycan Keskin
Space velocity is expressed as the ratio of exhaust gas flow to the catalyst volume and is shown as h−1 (Reşitoğlu, Altinişik, and Keskin 2015). The performance tests were performed at 30000 h−1, 40000 h−1, and 50000 h−1. An orifice plate was used for exhaust gas flow measurement. Digital and U-type-manometer were used to determine the pressure values of the orifice plate. A heater adjusted the exhaust gas temperatures were situated also to the system. Within the scope of the experiments, measurements were taken in the temperature range between 200 °C and 290 °C with every 10-degree increment. Two K-type thermocouples were used as temperature sensors to record the temperature changes. NOx conversion rates were determined with the usage of two Continental UniNOx sensors before and after the SCR catalyst. A program compatible with CAN J1939 protocol was coded to collect data from these two sensors and communication between NOx sensors and PC was provided using a PCAN-USB. The NOx measurement ranges of these sensors were 0-1500 ppm and their error-tolerant was ± 1.5%.
Heat transfer analysis of double discrete arc roughness with different relative rib altitudes and relate to a single discrete arc in the solar air heater
Published in International Journal of Ambient Energy, 2022
Piyush Kumar Jain, Atul Lanjewar, Jiwan Lal Bhagoria
An orifice plate is used to measure the mass flow rate of the flowing air. A U-tube manometer is attached with the taps available at a distance of d at the upstream and d/2 at the downstream of orifice plate, where d is the diameter of the orifice pipe. A suction type of the centrifugal blower is used to draw the air attached with 3.7 kW or 5 HP motor and may give the velocity (V) of 10 m/s in a rectangular channel of size 200 mm × 25 mm. Inlet, outlet and plate temperatures are received using a T-type thermocouple connected with a digital temperature data logger having more than 16 channels of sampling rate ≤25 Hz. A micro-manometer is used to find the pressure drop across the test section of the duct. The measuring range of the micro-manometer is ±500 mm of H2O, with an accuracy of ±1% +0.1 mm of H2O. The air velocity varies from 1 to 50 m/s. The operating temperature ranges from 0 to 50°C with air as a measuring medium. The TESTO make of the TESTO-510 model of the micro-manometer used to measure the data. Entire data are compiled under steady-state, which is considered to have achieved once the data do not vary under 10–15 min of time. The heat release rate of air and frictional characteristics have been figured out from the obtained data.