A 15cm x 20 cm printed circuit board whose components are not allowed to come into direct contact with helium for reliability reasons is to be cooled by passing cool helium through a 20cm long channel of rectangular cross section 0.2 cm x 14cm drilled into the board. The heat generated by the electronic components is conducted across the thin layer of the board to the channel where it is cooled by helium that enters the channel at 15C. The heat flux at the top surface of the channel can be considered uniform and heat transfer through the other surfaces is negligible. If the velocity of helium at the inlet of the channel is not to exceed 4m/s and the surface temperature of the channel is to remain under 50C, determine the maximum total power of the electronic components that can safely be mounted on this circuit board.