Computer Cooled By A Fan Contains Eight Printed Circuit Boards Pcbs Each Dissipating 2750357

computer cooled by a fan contains eight printed
circuit boards (PCBs), each dissipating 10 W of power.
The height of the PCBs is 12 cm and the length is 18 cm.
The clearance between the tips of the components on the
PCB and the back surface of the adjacent PCB is 0.3 cm. The
cooling air is supplied by a 10-W fan mounted at the inlet.
If the temperature rise of air as it flows through the case of
the computer is not to exceed 108C, determine (a) the flow
rate of the air that the fan needs to deliver, (b) the fraction of
the temperature rise of air that is due to the heat generated
by the fan and its motor, and (c) the highest allowable inlet
air temperature if the surface temperature of the components
is not to exceed 708C anywhere in the system. As a first
approximation, assume flow is fully developed in the channel.
Evaluate properties of air at a bulk mean temperature of
258C. Is this a good assumption?