Mathematical modelling of moisture transport into an electronic enclosure under non-isothermal conditions

In contrast to high fidelity CFD codes which require higher computational effort/time, the well-known Resistor-Capacitor (RC) approach requires much lower calculation time, but has a lower resolution of the geometrical arrangement. Therefore, for enclosures without too complex geometry in their interior, it is more efficient to use the RC method for thermal management and design of electronic compartments.

Thus, the objective of this paper is to build an in-house code based on the RC approach for simulating coupled heat and mass transport into a (closed) electronic enclosure. The developed code has the capability of combining lumped components and a 1D description. Heat and mass transport is based on a FVM discretization of the heat conduction equation and Fick's second law.

Simulation results are compared with corresponding experimental findings and good agreement is found. Since, the paper concerns climatic cyclic conditions, a study is accomplished on investigating different material properties (thermal conductivity, diffusivity, solubility) for moisture control inside an enclosure.

Further simulations were performed to study the response of temperature and moisture inside an enclosure exposed to the B2 STANAG climatic cyclic conditions. Moreover, the time for moisture build-up inside an enclosure under cyclic conditions is presented for different material properties.