Detailed numerical simulation of coupled heat transfer by conduction,natural convection and radiation through double honeycomb walls

The aim of the present work is to study numerically 2-D steady state coupled heat transfer by conduction, free convection and infra-red radiation through two honeycomb walls separated by a vertical air layer. Airflow in both holes and separating air layer is laminar. The limiting vertical sides of the double honeycomb wall are assumed to be isothermal but at different temperatures while the upper and lower horizontal surfaces of the structure are insulated. The FVM method and the SIMPLE algorithm are used to solve numerically the equations of conservation of mass, momentum and energy in both air filled cavities and solid partitions. It is found that the global heat flux across the entire wall varies almost linearly with the difference between the outside and the inside temperatures. Based on this linear thermal behaviour, appropriate overall heat exchange coefficients are derived. These coefficients can be used easily in practice to predict the global heat transfer across the studied honeycomb walls without solving the detailed and complex equations that govern the different heat transfer mechanisms. Effect of the thermal conductivity of the construction material on the overall heat transfer through double honeycomb walls is studied.