Heat transfer problems can be solved by either CFD or FEA. Since FEA is mostly implemented for solid mechanics any fluid interaction such as forced or natural convection problems needs to be solved by CFD method. Following images show a boiler water wall tube and a superheater tube temperature distribution based on the effects of water/steam flow inside the tube and gas flow outside the tube. Temperature distribution and range is required for tube material selection. Another example is insulation around hot ducting. Even though temperature can be predicted by one dimensional empirical equations, more detailed analysis might be required for special circumstances.
Heat Transfer - Boiler water wall and superheater tubes