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Calibration of temperature-dependent resistance of 3D printed conductive filaments for embedded sensing.

Number: 2594

Author(s) : STONE A. E., WEIBEL J. A., ZIVIANI D.

Summary

Advanced sensing for heat exchangers in thermal management systems offers great potential for improving real-time optimization, resiliency, and reliability. Current systems are lacking reliable solutions to detect non-uniform thermal distribution within heat exchangers during operation, and therefore cannot respond to flow maldistribution or other operating concerns. The proposed solution is to develop bistable passive actuating sensors made with electrically conductive printed filament, embedded in a polymer/metal base, which can be implemented within heat exchangers to detect (through the temperature-dependent resistance) and react (through bistable actuation) to flow maldistribution. These sensors would be low cost, low-power, and enable measurements while also improving the flow distribution through memory-based learning in the material. In the early phase of development, this work focuses on the temperature sensing aspects and performs preliminary tests to determine the temperature-resistance relationship for samples composed of either conductive PLA (polylactic acid) or conductive TPU (thermoplastic polyurethane) filament. This relationship is established by placing the samples in an oven at a known temperature (over a range of 35°C to 75°C) and fitting a calibration curve between the temperature and measured sample resistance. Two different sensor geometries are calibrated, namely, square and rectangular cross section rods. For all calibration tests and both sensor geometries, the conductive TPU filament samples have a greater resistance at a given temperature than the conductive PLA filament samples. Also, it was observed that the resistance of the TPU conductive filament samples decreased each repeated time a sample was tested, while the PLA conductive filament samples experienced no such change throughout multiple tests. While the TPU has greater viscoelasticity than PLA, this could reduce the print quality and interlayer adhesion of these samples, potentially leading to sensor drift across multiple oven tests. In comparison, the print quality of the PLA with increased rigidity led to more consistent calibration results and less spread in the data. In ongoing work, this data will be used to manufacture and calibrate additional samples that can be placed within a prototype heat exchanger and for demonstration of accurate temperature sensing in a representative operational environment.

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  • Original title: Calibration of temperature-dependent resistance of 3D printed conductive filaments for embedded sensing.
  • Record ID : 30033011
  • Languages: English
  • Subject: Technology
  • Source: 2024 Purdue Conferences. 19th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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