In a manufacturing process, long aluminum rods of square cross section with d = 25 mm are cooled from an initial temperature of
Ti = 400°C. Which configuration in the sketch should be used to minimize the time needed for the rods to reach a safe‐to‐handle temperature of 60°C when exposed to air in cross flow at V = 8 m/s, T[infinity] = 30°C? What is the required cooling time for the preferred configuration? The emissivity of the rods is ε = 0.10 and the surroundings temperature is Tsur = 20°C.
2 answers:
You might be interested in
Answer:
the MTTF of the transceiver is 50.17
Explanation:
Given the data in the question;
failure modes = 0.1 failure per hour
system reliability = 0.85
mission time = 5 hours
Now, we know that the reliability equation for this situation is;
R(t) = [ 1 - ( 1 - )³]
so we substitute
R(5) = [ 1 - ( 1 - )³]
= 0.85
[ 1 - ( 1 - )³]
= 0.85
[ 1 - ( 0.393469 )³] = 0.85
[ 1 - 0.06091 ] = 0.85
0.9391 = 0.85
= 0.85 / 0.9391
= 0.90512
MTTF = 5 / -ln( 0.90512 )
MTTF = 50.17
Therefore, the MTTF of the transceiver is 50.17