It’s going to depend a lot on your design and flow, but I recall the free convection coefficient being an order of magnitude smaller, but it’s a linear relationship between energy transfered and the coefficient.
Anecdotally, I have 4 5015 blower fans that move air under the heated bed of my larger 3d printer, easily saw a difference of 10-15c chamber temperatures with those compared with free convection.
It’s going to depend a lot on your design and flow, but I recall the free convection coefficient being an order of magnitude smaller, but it’s a linear relationship between energy transfered and the coefficient.
Anecdotally, I have 4 5015 blower fans that move air under the heated bed of my larger 3d printer, easily saw a difference of 10-15c chamber temperatures with those compared with free convection.