Exothermal reaction kinetics

    • Torben Henrich

      Hi guys, I am a student and I am currently writing my master thesis. Part of this thesis involves simulating the process described below. So far I have no previous knowledge about this simulation category and therefore I need your advice.

      Within the scope of this master thesis, an additively manufactured aluminium tool with internal heating/cooling channels is to be developed, which enables a locally different temperature control and thus the production of distortion-free fibre composite plastics in the resin transfer moulding (RTM) process.

      - Mould is preheated to 180°C via the heating channels filled with thermal oil.
      - Epoxy resin is injected warm (120°C)
      - Heat to 180°C as quickly and precisely as possible via heating channels
      - Holding time = curing time (approx. 10 min). Exothermic reaction due to curing
      - Cooling: Cooling ramp with 5 K/min. Workpiece is demoulded warm
      - Accuracy/tolerance range of the temperature distribution in the resin/mould interface: +/- 2K

      Simulation task:
      Simulation of the described process. The distortion of the workpiece is to be minimised by optimising the channels (course, flow rate and temperature of the thermal oil).

      Central problem:
      - How can I simulate the exothermic reaction in Ansys?
      - How do I take into account the changed properties of the epoxy resin during the phase transitions?
      - Which Ansys tools do I need for the entire simulation?

      Unfortunately, I have no idea how to solve the problem and hope for your help. Thanks :)

    • Nikhil Narale
      Ansys Employee

      Hello Torben,


      Thank you for posting your question. While it is possible to perform such a simulation using Ansys Fluent, it may require some simplifications and careful consideration of the relevant physics to fit in the framework of the simulation. For example, you could simplify the preheating of the mold to a constant temperature wall boundary condition, and model the injection of warm epoxy resin as a fluid mass or velocity inlet with an appropriate temperature. Additionally, it is important to ensure that the material properties of the epoxy resin, such as its density and viscosity, are accurately defined using a non-Newtonian model. Phase change can be modelled using melting and solidification model, available in Ansys Fluent. So on and so forth.

      Given that your case is highly transient, it may be necessary to use User Defined Functions (UDFs) and/or expressions to accurately capture the relevant physics. I recommend reviewing the Ansys Fluent user’s guide and exploring available tutorials and courses on the Ansys Innovation Space: Fluids Engineering Courses | Ansys Innovation Courses

      Finally, it may be worth exploring the dedicated material processing workspace in Ansys Fluent, which provides specialized tools and workflows for simulating such processes. Check this video demonstration:

      Thank you!

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