I have simulation I have been running on a new indirect fired heater. It is bascially a tube heat exchanger, the burner flame heats the inner chamber, it transfers through some passes to the outer barrell, which than exists through a stack. I have had some advice from the trainer on the setup, so the mesh, flows, and radiation parmeters are set as he instructed. Some of the data is very comparable to actual measured results. The stack temperature is not. I have used several different heat source arrangements with the proper BTUH rate, however the stack temperature still remains off by approximately 200-300 deg F. The issue seems to be these elements actually heating the inner chamber air like a true flame would. Does anyone have any experience or background with flame modeling in Solid Works?