Forced air at 25C and 10m/s is used to cool chips on a circuit board. Consider a chip, 4mm x 4mm, located 120mm from the leading edge of the board. An empirical correlation has been established for the local Nusselt number:

Nu_x = 0.04 * Re_x^0.85 * Pr^(1/3)

Estimate the surface temperature of the chip if it is dissipating 30mW.

(Thermophysical properties of air at 25C are needed to solve this problem. Please state your reference source for this information.)

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

On a average work day more than work place firs are reorted

The mass flow rate of the fluid remains constant in all steady flow process. a)- true b)- false