Session: 08-01 Education Issues I

Paper Number: 79397

79397 - Virtual Centrifugal Pump Test Rig for Laboratory Classes Based on IoT Technology 

In the project IoT for Supervision and Control of Water Systems (IoT.H2O), funded by the Joint Programming Initiative on “Water challenges for a changing world”, the potential of the internet of things (IoT) approach for supervision and control of water systems is investigated. As a part of the project, IoT technology was developed for operating a pump test rig, which is used in research projects and laboratory classes. Because of the COVID19 pandemic the access to the test rig for students was restricted. Instead, the students are now able to run their tests online using the IoT.H2O IoT-technology.

In IoT.H2O, the IoT platform Thingsboard is used for data storage, data visualization and control of devices. In Thingsboard, the components of the test rig, e.g. centrifugal pump, pump drive, throttle valve, frequency converter, sensors and test rig piping are mapped as devices. In a special dashboard for controlling the pump test rig, telemetry data of all sensors is visualized. With the dashboard, the pump can be started, the frequency setting of the frequency converter can be defined as well as the throttle valve position. The communication between the Thingsboard dashboard and the devices is realized using remote procedure calls (RPC) based on Message Queuing Telemetry Transport (MQTT) protocol. With RPC it is possible for the IoT platform to run programs on a different computer and return the results of the code execution to the IoT platform. This can be, for example, a microcontroller controlling the throttle valve position or any other code. Thus, RPC also offers the possibility to operate a digital model of the pump test rig instead of the test rig itself, which is beneficial because of safety regulations. Operating a model, a supervision of the test rig is unnecessary and the students can run the tests any time.

For the software model of the test rig, the pump is modeled by its characteristic curves for hydraulic head and efficiency. The pump drive including frequency converter is modeled by calculating the torque over speed curve of an asynchronous motor for the specified frequency, considering a quadratic relationship between voltage and frequency. The pressure loss in the pipes is calculated by Bernoulli’s equation. Together with the pressure loss of the throttle valve, based on the valve position, a system curve is calculated. It is possible to specify the static head of the system curve with the dashboard so that different types of systems can be simulated. The operating point of the pump is obtained by the intersection of the pump head curve with the system curve. The pump speed is determined by solving the power balance between pump and pump drive considering the moment of inertia of the rotor. As virtual sensor data, the model results for pressure before and after the pump, flow rate, torque and speed are sent via MQTT to the IoT platform. The operating point of the pump can be visualized on the pump curve. By changing the throttle valve position and or the frequency the students are able to investigate throttle and speed control of centrifugal pumps.

A big advantage of the virtual lab tests is that the students can run the tests by themselves and obtain their own data. Before, the tests were only run in groups. Also, they are introduced to the concept of IoT. Using a software model of the pump test rig offers the possibility to investigate other pumps which are not available in reality. By just changing the characteristic curves of the pump the operation of positive displacement pumps and centrifugal pumps can be compared.

In the full paper, the model of the pump test rig and the communication with the IoT platform will be explained in more detail. Results for measurements of the pump curve, system curve and pump startup will be presented as well as pump operation in case of speed and throttle control for different system types.

Presenting Author: Harald Roclawski Technical University of Kaiserslautern

Presenting Author Biography: since June 2011 Akademischer Oberrat at Institute for Fluid Mechanics and Turbomachinery of Technical University of Kasierslautern<br/>2009-2011 Senior Manager in the Department Product Development, Calculations and Simulation, Aerodynamics, Advanced Development at BorgWarner Turbo Systems Engineering GmbH<br/>2008 Manager Fluid Dynamics and Aerodynamics at MTU Friedrichshafen GmbH<br/>2008 PhD in Mechnical Engineering at Institute for Fluid Mechanics and Turbomachinery of Technical University of Kasierslautern

Authors:

Harald Roclawski Technical University of Kaiserslautern
Laura Sterle Technical University of Kaiserslautern
Martin Böhle Technical University of Kaiserslautern