HI

I have a case with energy balance on my internal flow simulation project. In my simulation i want to heat air inside the tube (T = 301 K ) by air flowing outside the tube (T = 994) K. The tube material is carbon steel which the properties i input manually. Then after simulation finish i got the values of average temp outlet from the surface of two outlet lids and for specific heat i got from the book. From these values i calculate the energy balance using formula mdot x cp x dT (where mdot = mass flow rate, cp = specific heat and dT = temp difference) and when i calculate it the energy is not balance. Error for this about 80%.

Note: -no heat out from the system i use adiabatic as the outerwall boundary

            -mdot air in tube = 1,1246 kg/s

            -mdot air out tube =0,03 kg/s

Im very grateful for u all try to help me

This is my heat exchanger model