Torque Sensor Helps Determine Actual Turbine Efficiency

I. Background​​

Key indicators such as rising temperatures, changes in precipitation and rising sea levels clearly show that climate change is already having an impact on our environment. There is no doubt that the effects of climate change will continue and may even accelerate in the future, causing water scarcity in certain geographic areas for years to come.

Small hydro turbine

​​Since water supply plays an important role in ecosystems and socio-economic activities, the EU and its member states are working together to ensure better planning and management of water resources. This collaboration takes many forms, such as effective legislation, adapting existing policies, improving the knowledge base and developing new smart low-carbon technologies to tackle future water scarcity.

​​For example, in the European Union, the European Regional Development Fund was established to reduce economic, environmental and social problems, with a particular focus on sustainable urban development. As a result, the organization is leading a number of investment projects in education and research into innovative water-saving technologies.

II. Client Needs

One of these projects requires the distribution of our water resources using integrated, smart and low-carbon energy.

The team is looking at how to improve the efficiency of water supplies. As part of the project, the team proposes to build two micro-hydroelectric installations. Instead of expensive ordinary water turbines, they use low-cost micro-hydro power plants with centrifugal pumps that work in reverse as turbines, called turbo pumps (PATs). This has allowed the team to reduce the cost of micro-hydro development by a factor of 4-5 compared to traditional systems.

III. Challenge

Among the many proposed strategies to reduce energy consumption and carbon intensity in the water sector, one that stands out is the use of small hydro turbines to recover excess energy along water supply routes. Standard turbines are often impractical or too expensive to install at such sites due to reduced size and residual pressure requirements. Therefore, the research team decided to investigate low-cost and easy-to-maintain devices using PATs, also known as reverse pumps, for distributed energy generation in water supply networks.

After the first stage of desk research and theoretical modeling, the team decided to verify the performance of the reverse-running pump through experimental tests. In order to evaluate the efficiency and operating point of the pump, they need to measure the torque delivered by the turbine under different conditions accurately and in real time.

IV. Solution

In order to evaluate the performance of the pump running in reverse under practical conditions, the team was tasked with building a hydraulic test bench. At the heart of the test stand design is a built-in digital torque sensor capable of measuring torque with high accuracy and reliability. ​

  1. In addition to torque, the rotational speed can be measured simultaneously, so no separate sensor is needed to evaluate the shaft speed.
  2. The data acquisition card and intuitive PC interface of the Data Unit Interface (DUI) are very flexible and set up very quickly. ​

Torque transducers are installed axially in the drive train, linking the turbine to the generator, very accurately measuring the mechanical power produced by the former, and transmitting real-time readings to a data entry PC for further analysis.

V. Impact

PATs are a cost-effective alternative to conventional turbines that, when inserted into a water supply system with constant water availability, they can generate electricity year-round. In practical situations, the effect of changes in axial speed on its efficiency is the basis for measuring its performance. ​

So far, the team has completed the first PAT test and the results have exceeded their expectations. They found that the actual performance of the PAT was around 71% efficiency, which is almost 20 percentage points higher than what the manufacturer claims. ​

Although it's still early days and more testing needs to be done, the results are promising and create a healthy potential for the project's viability. It also creates hope of preventing and alleviating future water shortages, ensuring that remote rural areas have access to adequate quantities of high-quality water.

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