Numerical study on natural, forced and mixed convection of a hybrid photovoltaic inverter

Temperature control of embedded systems has become a key factor for the design of more thermally efficient electronic devices. These devices are becoming smaller and more powerful, dissipating a larger amount of energy which must be removed from the system. Heat sinks and forced convection are the usual alternatives used to keep components temperature below critical values. There are many investigations in literature about heat sinks performance; however, a very limited number of them model the whole system. In this work, a commercial hybrid photovoltaic inverter is numerically simulated and its thermal behavior is investigated for natural, forced and mixed flow conditions. Experimental results, for a forced convection case, were also reported and used to verify the numerical results. The 3D model takes into account all equipment with high heat dissipation and most other electronic components, as well as the two fluid regions. A finite volume solution is obtained using the OpenFOAM software, more specifically the chtMultiRegionFoam solver. Flow modeling uses the Boussinesq approximation to account for the natural convection effects, while the κ-ε formulation was used to close the turbulence model. Results have shown that with current computational capacity, such complex systems (in terms of geometry) can be modeled with just a few simplifications. The inverter could work using only natural convection to cool down the system; however, the operating temperatures would be close to the limiting values. In terms of forced convection, it is highlighted the importance of the correct design for the cooling system, avoiding oversizing the heat sink and the fans sizes.