WP1: Surface nanoengineering and characterization of nanocoolant transport phenomena

This work package refers to the development of numerical and experimental methodologies that will facilitate the activities of subsequent WPs by the project partners.

  1. Nano-patterned surfaces promoting flow instabilities will be manufactured employing wet etching. Surface topology and composition will be verified through a host of available methods ranging from AFM-IR to Transmission Electron Microscopy (TEM).
  2. An Equilibrium Molecular Dynamics (EMD) approach utilizing the Green-Kubo method will be employed to derive the various transfer coefficients of polymer dilutions and nanofluids. The molecule’s motion in the simulations will be described by a Langevin equation in a 3D box-domain with periodic boundary conditions, while a range of potential functions will be examined for the interactions of liquid, particles, as well as polymers-liquid and particles-liquid molecules. EMD simulations will enable the calculation of material rheological properties, such as the shear viscosity and the first normal stress coefficient, which can be eventually estimated by the obtained, through EMD, conformation tensor, as well as nanofluid thermal properties (thermal conductivity, specific heat).
  3. The developed MD approach will be applied to various liquid matrices with different viscoelastic/shear-thinning polymers and nanoparticles suspensions of variable composition, size (10-50nm) and shapes (rods, flakes and spheres), in order to verify their thermo-physical and transport properties. The method will be validated against accurately characterized oil-based non-Newtonian liquids and heat-transfer fluids.
  4. Project specific test configurations will be designed and assembled to accommodate the activities of the next work package. Benchmark geometrical configurations promoting longitudinal and cross-flow vortices will be designed (bluff body, geometrical constriction, curved tube, series of plates). Optical test-piece counterparts will be fabricated to facilitate the flow field visualization and particle image velocimetry (PIV) experiments.
  5. For the heat-flux measurement, metallic (copper, aluminum) samples will be manufactured. Ultrafast (~1μs response time corresponding to the highly resolved PIV flow-field measurements) Atomic Layer Thermopile (ALT) sensors available to FAU will be calibrated for the range of heat fluxes relevant to battery cooling (up to 50 kW/m2) and thermally bonded to the metallic part body. The required heat flux, replicating the battery heating during charge/discharge, will be provided through flexible strip heaters embedded in the metallic surfaces.
  6. The fluids will be blended from standardized non-Newtonian liquids and nanofluids with different polymers (e.g. poly-methacrylate, ethylene-propylene copolymer) at a range of concentrations up to 2000 ppm (w/w) and nanoparticles (CuO, CNT and GO up to 5% w/w). The well-defined liquid properties will allow the flow characterization through accurate non-dimensional numbers (e.g. Reynolds and Nusselt numbers) in the experimental tasks of the work package 2.