This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP: Ministry of Science, ICT and Future Planning) (No. NRF-2016M2B2A9911771).

1. Experimental Procedure4,5,6
<ol>
	<li>Preparation step
	<ol>
		<li>Check the experimental facility. Based on the test matrix, carefully check the test matrix test conditions, such as LOCA size, SBL size, siphon breaker types, and the presence of orifice, before the experiment. Also, test to confirm that the instrumentations and components of the facility work properly without data noise or malfunctions.</li>
		<li>Fill the upper tank with water using the return pump installed inside the lower tank.</li>
		<li>Remove the residual air inside SBL. Use a vacuum pump and buffer chamber to remove the residual air from SBL.</li>
		<li>Check the initial water level of the upper tank. Use the ruler attached to the tank.</li>
	</ol>
	</li>
	<li>Test step
	<ol>
		<li>Open the valve at the end of piping system.</li>
		<li>Using the data acquisition system in the control room, check the measured data, such as water level, flow rate, and pressure changes, during the siphon breaking phenomenon. If there is no outflow of coolant, the first experiment ends. Finally, record the obtained experimental results with the given test conditions.</li>
	</ol>
	</li>
	<li>Change the test variables (SBL size, LOCA size, orifice presence, and LOCA position) as follows.
	<ol>
		<li>Change the SBL size successively to 2, 2.5, 3, 4, 5, and 6 in; the given SBL is connected to the main pipe by a flange joint at position 2 in Figure 2. 
		NOTE: The experimental variables, such as SBL size, LOCA size, and the presence of orifice, are changed using the flange joint with bolts and nuts. Therefore, these processes are manually conducted.</li>
		<li>Repeat steps 1.1.1 - 1.2.2 until all SBL sizes experiments are done.</li>
		<li>With the LOCA in position 1, change the LOCA size successively to 6, 8, 10, 12, 14, and 16 inches; the given reducer is connected to the main pipe by a flange joint at position 3 in Figure 2.</li>
		<li>Repeat steps 1.1.1 - 1.3.2 until all LOCA sizes experiments are done.</li>
		<li>Install the orifice (or remove the orifice) connected to the main pipe by a flange joint at the bottom of the upper tank. 
		NOTE: Experiments of the previous step have been carried out with the absence (or presence) of the orifice. Therefore, the orifice should be installed (or removed) for next experiment.
		<ol>
			<li>To do this work, ensure that there is no water inside the upper tank.</li>
		</ol>
		</li>
		<li>Repeat steps 1.1.1 - 1.3.4. To confirm the effect of SBL and LOCA size under the presence (or absence) of orifice, repeat the previous step.</li>
		<li>Change the LOCA to position 2, as experiments of the previous step have been carried out with LOCA position 1. Change the LOCA position for next experiment. 
		NOTE: In the experimental setup, two LOCA positions are constructed. Each LOCA pipe with an isolation butterfly valve is connected to a main piping system.
		<ol>
			<li>To change the LOCA position, close the isolation butterfly valve at LOCA position 1 and open the valve at LOCA position 2.</li>
		</ol>
		</li>
		<li>Repeat steps 1.1.1 - 1.3.6.</li>
	</ol>
	</li>
</ol>
2. Running the Simulation Program
<ol>
	<li>Click on the program icon to execute the Siphon Breaker Simulation Program. 
	NOTE: The procedure is demonstrated in Supplemental Video 1. As shown, the initial screen of the simulation program consists of 4 buttons (Show parameter, Run, Manual, and Exit). When the user clicks the &#39;Show parameters&#39; button, a new command window opens and it includes the list of parameters. The user is able to modify and confirm the numerical values of variables. The &#39;Run&#39; button performs the calculations by substituting the input parameters into the included formulae. The &#39;Manual&#39; button is for notifying the usage and program version, and the &#39;Exit&#39; button closes the program. The results are shown in the &#39;Show Results&#39; windows.</li>
	<li>Click the &#34;Show parameter&#34; button.</li>
	<li>Change the input data considering the given simulation conditions.</li>
	<li>Click the &#34;Run&#34; button.</li>
	<li>Check the water level graph shape in the &#39;Show Results&#39; window. The program organizes the result values with time, and plots the graph automatically.
	<ol>
		<li>Through the shape of the graph, visually confirm the possibility of siphon breaking; if the water level or undershooting height has the same value consistently until the end, siphon breaking is possible under the given conditions. See Figure 3.</li>
	</ol>
	</li>
	<li>Check other outputs in the &#39;Show Results&#39; window. Note that there are eight options (water level, undershooting height, pressure, water velocity, air velocity, two-phase mixture velocity, quantity, and friction) to check the output. Select the graph type using the check box. 
	NOTE: It is easy to grasp the siphon breaking phenomenon at a glance because the change of each value with time can be seen through the graph.</li>
	<li>Confirm the specific value of output depending on the time by clicking the &#34;Calculate in specific time&#34; button. Enter the desired time and check the results according to the set time.</li>
	<li>Save all simulation result data by clicking the &#34;Save the data&#34; button. 
	NOTE: Results are saved in the form of text file, and simulated conditions are saved together.</li>
</ol>

<ol>
	<li>McDonald, J., Marten, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> A Siphon Break as a Blocking Valve. , (1958).</li><li>. Siphon Breaker Design Requirements 12. Experimental and Analytical Study Available from: <a target="_blank" href="https://www.osti.gov/scitech/biblio/6623426">https://www.osti.gov/scitech/biblio/6623426</a> (1993)</li><li>Sakurai, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=JAERI-Research+99-016.">JAERI-Research 99-016.</a> Study for Improvements of Performance of the Test and Research Reactors. , (1999).</li><li>Kang, S. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Final Report of Experimental Studies on Siphon Breaker. , (2011).</li><li>Kang, S. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Experimental Study of Siphon breaker. , (2013).</li><li>Kang, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Siphon Breaker Design on Research Reactor with Real-Scale Experiment. , (2015).</li><li>Fossa, M., Guglielmini, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressure+Drop+and+Void+Fraction+Profiles+during+Horizontal+Flow+through+Thin+and+Thick+Orifices.">Pressure Drop and Void Fraction Profiles during Horizontal Flow through Thin and Thick Orifices.</a> Exp. Thermal Fluid Sci. 26, 513-523 (2002).</li><li>Lee, K. Y., Kim, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+siphon+breaker+simulation+program+for+investing+loss+of+coolant+accident+of+a+research+reactor.">Development of siphon breaker simulation program for investing loss of coolant accident of a research reactor.</a> Ann. Nucl. Energy. 101, 49-57 (2017).</li><li>Lee, K. Y., Kim, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theoretical+Study+on+Loss+of+Coolant+Accident+of+a+Research+Reactor.">Theoretical Study on Loss of Coolant Accident of a Research Reactor.</a> Nucl. Eng. Des. 309, 151-160 (2016).</li><li>Lee, K. Y., Seo, K. W., Chi, D. Y., Yoon, J. H., Kang, S. H., Kim, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+and+analytical+studies+on+the+siphon+breakers+in+research+reactor.">Experimental and analytical studies on the siphon breakers in research reactor.</a> European Research Reactor Conference. , 18-22 (2012).</li></ol>

The authors have nothing to disclose.

A siphon breaker is a passively-operated safety device used to prevent the loss of coolant when a pipe rupture accident occurs. However, it is difficult to apply to contemporary research reactors because there is no experiment for the real-scale research reactors. For this reason, the real-scale experiment was conducted by POSTECH and KAERI. The purpose of the experiment was to confirm that the siphon breaking is feasible at the real-scale size, and to identify factors that affect siphon breaking. Experimental results sh...

The number of reactors using plate-type fuel, such as the Jordan Research and Training Reactor (JRTR) and KiJang Research Reactor (KJRR), has increased recently. In order to connect the plate-type fuel easily, the research reactor requires a core downward flow. Since research reactors require net positive suction head of the primary cooling system, some cooling system components could potentially be installed below the reactor. However, if pipe rupture occurs in the primary cooling system below the reactor, the siphon effect causes continuous drainage of coolant that could result in the exposure of the reactor to the air. This means that the residual heat cannot be removed, which could lead to a serious accident. Therefore, in the event of a loss of coolant accident (LOCA), a safety device that can prevent a serious accident is necessary. A siphon breaker is such a safety device. It can effectively prevent water drainage by using an inrush of air. The entire system is called the siphon breaking system.
Several studies for the improvement of research reactor safety have been conducted. McDonald and Marten1 carried out an experiment in order to confirm the performance of a siphon breaking valve as an actively-operating breaker. Neill and Stephens2 performed an experiment using a siphon breaker as a passively operated device in a small-sized pipe. Sakurai3 proposed an analytical model to analyze the siphon breaking where a fully separate air-water flow model was applied.
Siphon breaking is extremely complex because there are many parameters that need to be considered. Furthermore, because the experiments for real-scale research reactors have not been performed, it is difficult to apply previous studies to contemporary research reactors. Therefore, previous studies have not presented a satisfactory theoretical model for siphon breaking. For this reason, a real-scale experiment was conducted to establish a theoretical model.
To investigate the effect of the siphon breaker on a research reactor, real-scale verification experiments were performed by Pohang University of Science and Technology (POSTECH) and Korea Atomic Energy Research Institute (KAERI)4,5,6. Figure 1 is the actual facility for the siphon breaker experiment. Figure 2 shows a schematic diagram of the facility and it includes the facility mark.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55972/55972fig1.jpg" /> 
Figure 1. Facility for the siphon breaking demonstration experiment. The main pipe size is 16 in and an acrylic window is installed for observation. The orifice is a device prepared to describe the pressure drop. Therefore, there is an orifice assembly part at the bottom of the upper tank. <a href="//cloudflare-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55972/55972fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/55972/55972fig2.jpg" /> 
Figure 2. Schematic diagram of the experimental facility. The location of measurement points is presented. The numbers indicate these relevant locations; point 0 signifies the entrance of the siphon breaker, point 1 signifies the water level, point 2 signifies the connected part of the siphon breaker and the main pipe, and point 3 signifies the LOCA position. <a href="//cloudflare-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/55972/55972fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The siphon breaker experimental facility consists of an upper tank, a lower tank, a piping system, and a return pump. The capacity of the upper tank is 57.6 m3. The bottom area and the depth are 14.4 m2 (4 m x 3.6 m) and 4 m, respectively. The lower tank and LOCA position are located 8.3 m below the upper tank. The capacity of the lower tank is 70 m3. The lower tank is used to store the water during the experiment. The lower tank is connected to the return pump. The water in the lower tank is pumped into the upper tank. The main pipe size of the piping system is 16 in. The end of the Siphon Breaker Line (SBL) is located 11.6 m high above the lower pipe rupture point. In addition, acrylic windows are installed on the pipe for visualization, as shown in Figure 1.
Several devices were installed to measure the physical signals. Two absolute pressure transducers (APTs) and three differential pressure transducers (DPTs) were used. To measure the water mass flow rate, an ultrasonic flow meter was used. A data acquisition system was used to get all measurement data at 250 ms time intervals. In addition to the equipment for the measurement, cameras were installed for observation and a ruler was attached on the inner wall of the upper tank to check the water level.
Various LOCA and siphon breaker (SB) sizes, siphon breaker types (Line/Hole), and the presence of orifice regarding reactor fuel and the pipe rupture point were considered in the experiment. In order to verify the effect of LOCA and SBL size, various sizes of LOCA and SBL were used. The LOCA sizes ranged from 6 in to 16 in and the SBL sizes ranged from 2 in to 6 in. In the experiment, line and hole type of siphon breakers were used, but the following content of this study only considers the SBL type used in the JRTR and KJRR. As an example of experimental results, Figure 3 is a graph that includes the pressure and water flow rate data. The experiment was conducted on October 4, 2013 and the experimental data sample is LN23 (Line type SB, No orifice, 12 in LOCA, 2.5 in SBL).
From the experiment data, the theoretical model which can predict the siphon breaking phenomenon was established. The theoretical model begins with the Bernoulli equation. The velocity of fluid is obtained from the Bernoulli equation and the volumetric flow rate can be obtained by multiplying the velocity of fluid by the pipe area. In addition, the water level can be obtained using the volumetric flow rate. The basic concept of the theoretical model is as above. However, since the siphon breaking phenomenon is a two-phase flow, there are additional points to be considered. To consider a two-phase flow analysis model, an accuracy verification test was performed. Since the Chisholm model was more accurate than a homogenous model, the Chisholm model is used to analyze the phenomenon. According to the Chisholm model, the two-phase multiplier formula is expressed as Equation 17. In this equation, &#1092; represents the two-phase multiplier, &#961; represents density, and X represents quality.
<img alt="Equation 1" src="/files/ftp_upload/55972/55972eq1.jpg" /> (1)
In the Chisholm model, a coefficient B that varies with mass flow was included. Ultimately, the derivation of a correlation formula between Chisholm coefficient B and reactor design conditions is a significant point of the theoretical model. In other words, another purpose of the experiment was to obtain data to establish the relationship between the design conditions and Chisholm coefficient B. From the test results, a correlation formula between the design conditions and Chisholm coefficient B was established. The resulting theoretical model was developed to predict the siphon breaking phenomenon well.
Furthermore, a simulation program with a Graphic User Interface (GUI) was developed. By the transition of absolute pressure data in Figure 3, the phenomenon can be divided into three stages: the Loss of coolant (Single-phase flow), Siphon breaking (Two-phase flow), and Steady state. Therefore, the main calculation process of the algorithm includes a three-step process corresponding to the three stages of the real phenomenon. Including the calculation process, the entire algorithm to describe the simulation process is shown in Figure 48.
Using the software (see Supplemental Video 1) to begin the simulation, the user enters the input parameters corresponding to the design conditions and the input parameters are stored as fixed values. If the user proceeds with the simulation after entering the parameters, the program performs the first step calculation. The first step is the single-phase calculation, which is the calculation for loss of coolant due to the siphon effect after the pipe rupture. The variables are calculated automatically by the theoretical model (as in Bernoulli&#39;s equation, mass flow preservation, etc.), and the calculation proceeds from the parameters input by the user. The calculation results are sequentially stored in the computer memory according to the time unit designated by the user.
If the water level drops below position 0, it means that the single-phase flow ends, because air starts to rush into the SBL at this moment. Therefore, the first step for single phase flow proceeds until the water level reaches position 0. When the water level is at position 0, this means that the undershooting height is zero. The undershooting height is the height difference between the entrance of the SBL and the upper tank water level after the siphon breaking. In other words, undershooting height indicates how much the water level decreased during the siphon breaking. Therefore, the undershooting height is an important parameter, because it would allow the direct determination of the quantity of coolant loss. Consequently, the program determines the end of the first-step calculation according to the undershooting height.
If the undershooting height is greater than zero, the program performs a second step calculation which can simulate two-phase flow. Because both water and air flow are present in the siphon breaking stage, the physical properties of both fluids must be considered. Therefore, the values of two-phase multiplier, quality, and void fraction are considered in this calculation step. Specially, the void fraction value is used as ending criterion of the second step calculation. The void fraction can be expressed as the ratio of air flow to the sum of air and water flows. The second step calculation proceeds until the void fraction (&#945;) value is over 0.9. When &#945; is over 0.9, the third step calculation proceeds which describes steady state. Theoretically, the ending criterion for siphon breaking is &#945; = 1 since only air exists in the pipe at this time. However, in this program, the end criteria for siphon breaking is &#945; = 0.9 to avoid any error in the calculation process. Therefore, a partial loss of results is inevitable, but this error can be negligible.
Steady state calculation proceeds during the time set by the user. Because there is no further change, the steady state is characterized in that the calculation result values are always constant. If siphon breaking is successful, the final level of the water in the upper tank will remain at a specific value, not zero. However, if the siphon breaking is not performed successfully, the coolant will be almost lost, and the final level of the water approaches zero value. Therefore, if the water level value equals zero in steady state, it indicates that the given design conditions are not adequate to complete siphon breaking.
After the calculation, the user can confirm the results in various ways. The results show the status of siphon breaking, siphon breaking progress, and singularity. The simulation program can predict and analyze the phenomenon realistically and assist in the design of the siphon breaker system. In this paper, the experiment protocol, results of the experiment, and application of the simulation program are presented.

<table><tbody><tr><td>Absolute pressure transducer</td><td>Sensor Technics</td><td>CTE9000</td><td>0.05% full-scale error</td></tr><tr><td>Differential pressure transducer</td><td>Setra</td><td>C230</td><td>0.25% full-scale error</td></tr><tr><td>Ultrasonic flow meter</td><td>Tokyo Keiki</td><td>UFP-20</td><td>Resolution 0.01m^3/h</td></tr><tr><td>Visual Studio 2012</td><td>Microsoft</td><td>Windows 8</td><td>Microsoft Foundation Class</td></tr><tr><td>E.R.W. steel pipe</td><td>Hyundai Hysco</td><td>KS D 3507(SPP)</td><td>400A(out dia.) x 7.9mm(thickness)</td></tr></tbody></table>

study of siphon breaker experiment and simulation for a research reactor

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent this outflow, a control device is required. A siphon breaker is a type of safety device that can be utilized to control the loss of coolant water effectively.
To analyze the characteristics of siphon breaking, a real-scale experiment was conducted. From the results of the experiment, it was found that there are several design factors that affect the siphon breaking phenomenon. Therefore, there is a need to develop a theoretical model capable of predicting and analyzing the siphon breaking phenomenon under various design conditions. Using the experimental data, it was possible to formulate a theoretical model that accurately predicts the progress and the result of the siphon breaking phenomenon. The established theoretical model is based on fluid mechanics and incorporates the Chisholm model to analyze two-phase flow. From Bernoulli&#39;s equation, the velocity, quantity, undershooting height, water level, pressure, friction coefficient, and factors related to the two-phase flow could be obtained or calculated. Moreover, to utilize the model established in this study, a siphon breaker analysis and design program was developed. The simulation program operates on the theoretical model basis and returns the result as a graph. The user can confirm the possibility of the siphon breaking by checking the shape of the graph. Furthermore, saving the entire simulation result is possible and it can be used as a resource for analyzing the real siphon breaking system.
In conclusion, the user can confirm the status of the siphon breaking and design the siphon breaker system using the program developed in this study.

The entire process of siphon breaking consists of three stages. The first stage is the outflow of coolant due to the siphon effect. The second stage is the process of starting the inflow of air through the SBL to block the loss of coolant, called siphon breaking. The siphon breaking phenomenon can be seen as a sharp increase of absolute pressure in Figure 3. After the absolute pressure rapidly increases, it is gradually reduced because of the water level decr...

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Study of Siphon Breaker Experiment and Simulation for a Research Reactor

The siphon breaking phenomenon was investigated experimentally and a theoretical model was proposed. A simulation program based on the theoretical model was developed and the results of the simulation program were compared with experimental results. It was concluded that the results of the simulation program matched the experimental results well.

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent ...

study-siphon-breaker-experiment-simulation-for-research

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8.7K Views.  Handong Global University. The siphon breaking phenomenon was investigated experimentally and a theoretical model was proposed. A simulation program based on the theoretical model was developed and the results of the simulation program were compared with experimental results. It was concluded that the results of the simulation program matched the experimental results well.

Video: Study of Siphon Breaker Experiment and Simulation for a Research Reactor

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To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to ...

Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of &lt;1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without ...

Interactive and Visualized Online Experimentation System for Engineering Education and Research

Experimentation is crucial in engineering education. This work explores visualized experiments in online laboratories for teaching and learning and also research. Interactive and visualizing features, including theory-guided algorithm implementation, web-based algorithm design, customizable monitoring interface, and three-dimensional (3-D) virtual test rigs are discussed. To illustrate the features and functionalities of the proposed laboratories, three examples, including the first-order system exploration using a circuit-based system with electrical elements, web-based control algorithm design for virtual and remote experimentation, are provided. Using user-designed control algorithms, not only can simulations be conducted, but real-time experiments can also be conducted once the designed control algorithms have been compiled into executable control algorithms. The proposed online laboratory also provides a customizable monitoring interface, with which users can customize their user interface using provided widgets such as the textbox, chart, 3-D, and camera widget. Teachers can use the system for online demonstration in the classroom, students for after-class experimentation, and researchers to verify control strategies.

This work describes an online experimentation system that provides visualized experiments, including the visualization of theories, concepts, and formulas, visualizing the experimental process with three-dimensional (3-D) virtual test rigs, and visualizing the control and monitoring system using widgets such as charts and cameras.

Experimentation is crucial in engineering education. This work explores visualized experiments in online laboratories for teaching and learning and also ...

A Modeling and Simulation Method for Preliminary Design of an Electro-Variable Displacement Pump

Electro-hydrostatic actuators (EHAs) have been considerably researched in academia, and their applications in various industrial fields are expanding. The variable-speed EHA has now taken priority over the variable-displacement EHA, but its driving motor and associated electronics encounter issues when applied in high-power applications: low-dynamics, high thermal dissipation, high price, etc. Therefore, a variable-displacement EHA equipped with an electro-variable displacement pump (EVDP) has been considered. The EVDP itself is a mechatronic system that integrates a piston pump, a ball screw, a gearbox, and a permanent magnet synchronous motor (PMSM). Consequently, the EVDP needs to be investigated to ensure its system-level performance when applied in an EHA. In addition to the previous research on the technical parameters of the EVDP, a dedicated design method is necessary for further reducing the cost of using the EVDP and exploring its performance potential. Here, a simulation based EVDP preliminary design method is selected for designing a 37 kW EVDP. Firstly, a previously proposed multidisciplinary model of the EVDP is extended by improving the parameter generation, including the EVDP life, reliability, control models, etc. Secondly, the proposed model is partially verified using a downsized prototype. Thirdly, the EVDP is simulated at a system level, supported by the proposed model. The EVDP performance is evaluated according to the specified design requirements. The temperature, bandwidth and accuracy, reliability and lifetime, etc., are all predicted for the EVDP. The simulation results demonstrate the EVDP's applicability in variable-displacement EHA. The proposed modeling and simulation method can be used to evaluate diverse EVDP performance and respond to general design requirements. The method can also support the resolution of the preliminary design challenges in terms of limited information and robustness. Therefore, the proposed method is appropriate for the realization of the simulation-based EVDP preliminary design method.

A simulation model specifically supporting the preliminary design of an electro-variable displacement pump (EVDP) is developed and partially verified by experiments. The control performance, life, reliability, etc., can all be evaluated using the proposed model, which covers the main performance requirements under the EVDP preliminary design task.

Electro-hydrostatic actuators (EHAs) have been considerably researched in academia, and their applications in various industrial fields are expanding. The ...

Experimental Multiscale Methodology for Predicting Material Fouling Resistance

The buildup of fouling deposits in energy systems degrades their ability to transfer heat, reducing efficiency and causing operational issues such as localized corrosion. Each application presents its own challenges. In nuclear power generation, the buildup of CRUD (Chalk River Unidentified Deposits) induces unique, negative effects ranging from reduced heat transfer, to axial power shifting, to CRUD-induced localized corrosion (CILC), the last of which can cause sudden fuel failure. Knowledge of why CRUD forms and how to prevent its adhesion to nuclear fuel rods represents a major step towards eliminating it. This paper demonstrates a methodology to ascertain which materials may resist CRUD adhesion, thereby preventing its initiation and growth. It presents experiments targeted at multiple length scales: pool boiling (macroscale), which simulates CRUD initiation processes in a nuclear reactor, and atomic force microscope (AFM) force spectroscopy (microscale), which yields quantitative measurements of the adhesion between CRUD constituents and candidate CRUD-resistant materials. Early data from both sets of experiments show some correlation, suggesting that AFM force spectroscopy (AFM-FS) may be used to pre-screen materials for fouling resistance. So far, it appears that CRUD constituents adhere well to oxides, while carbides show both greatly reduced adhesion and no adherent CRUD in pool boiling experiments. The relationship between the AFM-FS measurements and the growth of CRUD in the pool boiling experiments may provide insight into the possible factors affecting fouling in nuclear reactors, eventually leading to its elimination.

Fouling, or corrosion product deposition, plagues numerous fields of energy production. At its core is adhesion between dissimilar materials. Understanding and controlling adhesion could reduce or eliminate fouling. This paper demonstrates pool boiling experiments (macroscale) and atomic force microscope force-spectroscopy measurements (microscale), which when in agreement, indicate fouling-resistance.

The buildup of fouling deposits in energy systems degrades their ability to transfer heat, reducing efficiency and causing operational issues such as ...

Biology

Assembly of a Reflux System for Heated Chemical Reactions

Source: Laboratory of Dr. Philip Miller &#8212; Imperial College London
Many chemical experiments require elevated temperatures before any reaction is observed, however heating solutions of reactants can lead to loss of reactants and/or solvent via evaporation if their boiling points are sufficiently low. In order to ensure no loss of reactants or solvent, a reflux system is used in order to condense any vapors produced on heating&#160;and return these condensates to the reaction vessel.&#160;

Source: Laboratory of Dr. Philip Miller &#8212; Imperial College London
Many chemical experiments require elevated temperatures before any reaction is ...

Education

JoVE Science Education

Organic Chemistry

Single and Two-phase Flow in a Packed Bed Reactor

Source: <a href="https://www-jove-com.bdigitaluss.remotexs.co/author/Kerry+M._Dooley">Kerry M. Dooley</a> and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
The goal of this experiment is to determine the magnitude of maldistribution in typical packed bed reactors in both single phase and two-phase (gas-liquid) flow and evaluate the effects of this maldistribution on pressure drop. The concepts of residence time distribution and dispersion are introduced through the use of tracers, and these concepts are related to physical maldistribution.
Channeling in a single-phase flow can occur along walls or by preferential flow through a larger portion of the bed cross-section. Channeling in two-phase flow can result from even more complex causes, and simple two-phase flow theories seldom predict pressure drops in packed beds. A design goal is always to minimize the extent of channeling by finding the optimal bed and particle diameters for the design flow rates and by packing a bed in a way to minimize settling. It is always important to quantify how much maldistribution might occur and to over-design the unit to account for its occurrence.
The permeameter apparatus measures pressure drop, &#916;P, and the concentration of tracer (dye) exiting horizontal packed beds of armored glass for either water, air, or two-phase flow (Figures 1 and 2). Water enters through a control valve and can be routed through manual valves to any of five beds (48&#34; long, 3&#34; I.D.) with different size glass bead dumped (random) packings. The pressure drop is measured using a pressure transmitter. The water flow is measured by a differential pressure (DP, orifice) transmitter and the air flow by a dry test meter (similar to a home gas meter). The dye sample is injected upstream by an automated sampling valve. The exit concentration of the dye from a bed is measured using a UV-Vis spectrometer. Residence time distributions are calculated from the tests and compared to the predictions of theories on dispersion in packed beds. Two-phase flow will be studied in bed 5, which contains the largest particles.
<img alt="Figure 1" src="/files/ftp_upload/10431/10431fig1.jpg" /> 
Figure 1: Process and instrumentation diagram of the apparatus.
<img alt="Figure 2" src="/files/ftp_upload/10431/10431fig2.jpg" /> 
Figure 2. 3-D rendering of the apparatus. Bed #1 is at the top, bed #5 at the bottom. The water control valve is on the left (red bonnet). The DP transmitter is at the top center (blue).

Source: Kerry M. Dooley and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
The goal of this experiment ...

Study of Siphon Breaker Experiment and Simulation for a Research Reactor

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Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Interactive and Visualized Online Experimentation System for Engineering Education and Research

A Modeling and Simulation Method for Preliminary Design of an Electro-Variable Displacement Pump

Experimental Multiscale Methodology for Predicting Material Fouling Resistance

Assembly of a Reflux System for Heated Chemical Reactions

Single and Two-phase Flow in a Packed Bed Reactor