Calculate the energy gain of fluid?
 

Hi we are modelling a fluid across of pipe, inner the pipe the fluid recive a heat flux from a solid, when i calculate the energy gain of fluid =m*Cp*AT is higher than the global evaluation of heat source, It is not possible.*I don't find why when i applie a heat flux in a surface (0.0084m2) of 8000 W/m2 = 67.2W, the gain of fluid calculated by mCpdT = 83.93 *4.19*(293.97-293.16)*0.27778 is 79.12W, but if i calcule the (heat flux of outlet surface - heat flux of inlet surface) is 66.7 W similar to the heat flux =67.2 W, Do you know that I am doing wrong?