Oral Presentation 23rd International Society of Magnetic Resonance Conference 2023

Investigation of flow and heat transfer in an additively manufactured triply periodic minimal surface heat exchanger using MRI (#41)

Mathew Hawken 1 , Daniel Clarke 2 , Conan Fee 3 , Petrik Galvosas 2 , Daniel Holland 1
  1. Department of Chemical and Process Engineering, University of Canterbury, Christchurch, Canterbury, New Zealand
  2. School of Chemical and Physical Sciences, Victoria University of Wellington , Wellington, New Zealand
  3. School or Product Design, University of Canterbury, Christchurch, Canterbury, New Zealand

Advances in 3D-printing have allowed the development of structurally complex heat exchangers. One such type of heat exchanger has channels defined by a Triply Periodic Minimal Surface (TPMS) (Femmer et al. 2015). It is hypothesised that the TPMS channel structures can aid the generation of flows that promote mixing and prevent preferential channelling, improving heat transfer performance.

To investigate the heat transfer in TPMS structures, non-invasive Magnetic Resonance Imaging (MRI) measurements of the velocity and temperature were acquired. Velocity images used a phase contrast sequence (Clarke et al. 2021). For temperature images the Proton Resonant Frequency (PRF) method (Ishihara et al. 1995) was used. Due to the presence of flow artefacts we implement a new flow insensitive PRF spin echo sequence with sampling of both negative and positive echo time.

The sequence accurately measured the temperature of water from 22°C to 55°C as well as producing bulk temperatures within ±0.75°C of thermocouple data in a flowing system. An example of the temperature and velocity maps for a Schoen Gyroid TPMS heat exchanger are shown in Figure 1 with Reynolds numbers of 50 in the cold and hot channels. Distinct regions of high velocity in the flow direction are observed in both channels. These high velocity regions produce local regions with higher (lower) local temperature than the bulk fluid in the hot (cold) channels. Furthermore, flow perpendicular to the main flow direction is observed. These secondary flows draw fluid from the wall into the bulk flow, and hence may be associated with improving overall heat transfer.

 642e3f52b9432-VelocityTemperatureMap-Slice1.jpg

Figure 1. Temperature (left) and velocity (right) maps for a transverse slice of the dual channel Schoen Gyroid heat exchanger (field of view = 21 mm).

  1. Femmer, T., Kuehne, A.J. and Wessling, M., 2015. Estimation of the structure dependent performance of 3-D rapid prototyped membranes. Chemical Engineering Journal, 273, pp.438-445.
  2. Ishihara, Y., Calderon, A., Watanabe, H., Okamoto, K., Suzuki, Y., Kuroda, K. and Suzuki, Y., 1995. A precise and fast temperature mapping using water proton chemical shift. Magnetic resonance in medicine, 34(6), pp.814-823.
  3. Clarke, D.A., Dolamore, F., Fee, C.J., Galvosas, P. and Holland, D.J., 2021. Investigation of flow through triply periodic minimal surface-structured porous media using MRI and CFD. Chemical Engineering Science, 231, p.116264.