Innovative mufflers make boilers and heatpumps stable and silent

December 9, 2022

PDEng researcher Mohammad Kojourimanesh has developed a device to suppress very low frequency noises in low-emission heating devices.

Mohammad Kojourimanesh
Mohammad Kojourimanesh

Boilers, heatpumps and other low-emission heating devices sometimes cannot function due to a phenomenon called thermo-acoustic instability. This is especially true for axial or centrifugal fans, which can produce high levels of noise because of this problem. To prevent thermo-acoustic instability and also reduce noise, PDEng researcher Mohammad­­­ Kojourimanesh has developed and patented a silencer. This so-called muffler not only has a  99 per cent noise absorption efficiency in very low frequencies (20-800 Hz), but is also compact, light and cheap. Kojourimanesh defended his thesis on 29 November at the department of Mechanical Engineering.

To limit global warming as a serious hazard to our planet, future energy sources need to be carbon-neutral. Therefore, new low-carbon technologies of combustion systems must be developed for the gradual energy transition from fossil fuels to the energy storage substances and simultaneously to ensure fewer emissions.

One of the key problems is the occurrence of Thermo-Acoustic (TA) combustion instability. TA combustion instability manifests itself as a high level of tonal noise, vibration, and may cause performance deterioration or even structural damage of the combustion appliance.

Assessing and testing criteria for instability

Motivated by requests from the Dutch boiler industry, Kojourimanesh first developed practical methods based on system theory to assess TA instabilities. He also proposed and tested a number of stability criteria that are applicable when the combustion system is treated as a two-port network.

In addition, he used experiments to predict the growth rate and frequency of thermo-acoustic combustion instability at both laboratory setup and central heating equipment.

Finally, the researcher developed, tested and patented a muffler that suppresses thermo-acoustic instability. This so-called Anechoic Broadband Compact (ABC) muffler is compact, light, and cheap, and can be used to stabilize the thermo-acoustic combustion instabilities as well as reduce the environmental noise.

Faculty of Impact

In recognition of his innovative research, Mohammad­­­ Kojourimanesh earlier this year was appointed member of the Dutch Research Council (NWO) Faculty of Impact program. As part of this program, the researcher will continue his research at TU/e to valorize this finding and bring it to the industry.

Title of thesis: System based thermo-acoustic design of central heating; supervisors: Philip de Goey, Ines Lopez Arteaga and Viktor Kornilov.

 

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