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Air Mass Flow Rate Measurement Air Mass Flow Rate Measurement Final Report l Design of a Laboratory Setup to Measure Air Mass lilow Rate Design Team Kian Cheong Lim, Arianne Nartyasari Michael Tavares, Yiyan Wang Design Advisor Prof. Mohammad Taslim E. Abstract In the field of engineering studies, experimental lab activities are necessary for engineering students to relate what they have learned in dass as ideal situations to the actual application settings and conditions. This project presents a design of an experimental lab setup for undergraduate mechanical engineering students to perform mass flow rate measurements. The air mass flow rate measurements are to be air conducted using vruious flow rate measurement devices, allowing an accuracy comparison study runong the different devices. The experimental lab setup also incorporates a device to measure the discharge coefficient of different disk geometries. Several design concepts were generated throughout detailed analysis of various flow rate measurement devices and data acquisition systems, which results in the optimum device configuration setup. The Need for the Project The need for this project is The need wr this project is to provide an opportunity for to provide mechanical undergraduate mechanical engineering students to compare what engineering students with they learn in classrooms Ito the real working application settings, hands-on experience air particularly in the mass flow rate measurements. Oftentimes, in air mass flow rate theories and illustrations taught in engineering courses do not measurement. present clear understanding for engineering students without the actual theory applications, such as in laboratory experiments. It is important for mechanical engineering students to be capable of conducting an mass flow rate measurement, as it is one of the air many common measurements performed frequently by mechanical engineers. The Design Project Objectives and Requirements The objective of this project Design Objectives is to develop a laboratory The primary objective of this design project is to develop a setup to perform air mass laboratory setup to perform mass flow rate measurements using various air flow rate measurements and measurement devices. Although the theory behind flow rate measurements allow students to compare only requires simple understanding of fluid mechanics and measurement the accuracy of various analysis methods, there are many methods and devices that can be used to measurement devices. measure mass flow rate. These different devices posses variable degree air of measurement accuracy, allowing the students to perform an accuracy study of different measurement devices. Design Requirements The main requirement for this design project is to assemble four (4) off-the-shelf flow rate measurement devices, which should fit on a feet by feet table. general requirements, the flow rate 3 6 As measurement system should be able to operate with maximum inlet pressure of psig at room temperature. The flow rate measurement 100 system should also be able to provide a maximum air mass flow rate measurement of O.l lbm/s. an additional preference, the flow rate As measurement system is going to be assembled using type copper L tubing with a pipeline size of one inch. Detailed requirements (1) were later added to the design such as a maximum pressure difference of inches of liquid and a throat diameter of inches for the 32 0.15 critical venturi. Design Concepts Considered Four design configurations Four (4) design configuration concepts were generated throughout were generated, which detailed design analysis during brainstorming sessions. The main present main difference that governs the different design concepts is the the difference of a series and parallel configuration setup of :series or parallel. The generated design concepts include a series assembly with sliders, a series assembly with assembly configurations. bypass, a parallel assembly and a combination of series and parallel combination configuration. Both the series and parallel device configuration have each own advantages and disadvantages. As an advantage, the series device ValYr.�- i assembly provides consistent (uniform) mass flow rate throughout the 0"'""""" flow. the other hand, a series assembly requires more space for On device placement locations when compared to the parallel assembly. In contrary, a parallel series requires less space for the device configuration to fit on the table. Inversely, a parallel series will not provide consistent mass flow rate, which is crucial for the practice of 0 ::?:!!'g...-lc.tors comparing the accuracy of ditierent flow rate measurement devices. with Bmass Series Further consideration that was used to determine the optimum device configuration setup is the order in which a device is to be placed within the system. Different order of placement affects the • YO� Parallel -Series inlet pressure coming in a device, preventing it to operate properly as different devices require a minimum value of inlet pressure. With the help of a decision matrix, the series assembly presents a /;;;:_ w -�. frttt· preferred device configuration assembly as it provides a consistent $ v�cv�= mass flow rate within the flow, which is required to conduct accuracy comparison of different measurement devices. Recommended Design Concept The recommended design The recommended design concept incorporates a series concept has the highest assembly for the device configuration assembly with several bends on credibility on fulfilling all the the piping, in order to accommodate the space provided by the feet 3 requirements needed for this by feet table. The device assembly consists of four (4) off-the-shelf 6 L project. This design concept flow rate measurement devices in the following order of placement is a combination of all good critical venturi, orifice plate, discharge coefficient measurement aspects of the various design device, pitot tube androtameter. The minimum required inlet pressure concepts that were conceived for each device determines the order of placement of the flow rate earlier. measurement devices. A brief description of each flow rate measuremeDt device used in this system is described in the following section. A critical venturi is a converging-diverging nozzle with sonic flow condition at the throat section, which results in a Mach number of This sonic flow at the throat results in the constant pressure ratio 1. of between the inlet pressure and total (stagnation) pressure 0.5283 Critical Venturi within the flow. This condition allows the mass flow rate calculation through the critical venturi to depend only on inlet pressure, inlet temperature and the throat area. A critical venturi was chosen to be included in the flow rate measurement system due to the fact that it provides the best measurement accuracy of ±1%. An orifice plate creates an area difference when the flow passes the inlet location and the bore location of the orifice plate. As Orifice Plate illustrated in the Continuity equation, in which the mass flow rate within the flow in a series assembly must be constant, the area . · difference created by the bore results in pressure difference to be hL;,� . measured by the students in calculating the mass flow rate. The orifice · .. ·. ·.·• -· . ... ... · · < . .·.··•·•• . �. · . ·�-.·.· ,..· 'F' . ···· plate possesses a measurement accuracy of . ±3%. Averaging . Pitot . ·. .Tube.. A similar principle is applied by the pitot tube, which creates l r· a pressure difference value to be measured by the students. This value ! of pressure difference is the average of four (4) measurements taken L in four different points in the tube within the flow. The pitot tube has a measurement accuracy of Another device used in this system ±3%. is a rotameter, which directly measures the volumetric flow rate of the system to be converted later to obtain the mass flow rate value. The rotameter is a flow rate measurement device with the least measurement accuracy of ±5%. An additional device is incorporated to measure the discharge coefficient of different disk geometries. A discharge coefficient is a coefficient used to describe the ratio between the actual mass flow rate and lthe ideal mass flow rate. The actual mass flow rate is obtained from the measurement performed during the experiment, through one of the flow rate measurement devices, either Discharge Coefficient the critical venturi or the orifice plate. The ideal mass flow rate is Provision calculated using Dynamics principles. Different disk geometries Gas will be used during the experiment to illustrate the different values of discharge coefficient of different geometries. Recommended Improvements In order to provide the To proceed on with the experiment with a finished assembly, students with the highest conventional pressure and temperature measurement devices, e.g., quality and latest im manometers and thermometers, could be used. But with the modem technology, a data acquisition industry automation technology, however, the process could be unit can be incorporated to simplified with a data acquisition system. Although this project's enable measurements to be intention is to have students learning the concept of measurement of taken digitally. airflow mass rate, it is also very helpful to provide an accurate solution with the data acquisition system. Furthermore, it is also a good learning experience for our group members. Utilizing regular Pes, standard data acquisition systems consist of three parts: data collector, interface, and
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