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Diffstat (limited to '572/CH4/EX4.8/c4_8.sce')
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1 files changed, 23 insertions, 0 deletions
diff --git a/572/CH4/EX4.8/c4_8.sce b/572/CH4/EX4.8/c4_8.sce new file mode 100755 index 000000000..33ec7a9ba --- /dev/null +++ b/572/CH4/EX4.8/c4_8.sce @@ -0,0 +1,23 @@ +// (4.8) The electronic components of a computer are cooled by air flowing through a fan mounted at the inlet of the electronics enclosure. At steady state, air enters at 20C, 1 atm. For noise control, the velocity of the entering air cannot exceed 1.3 m/s. For temperature control, the temperature of the air at the exit cannot exceed 32C. The electronic components and fan receive, respectively, 80 W and 18 W of electric power. Determine the smallest fan inlet diameter, in cm, for which the limits on the entering air velocity and exit air temperature are met.
+
+//solution
+
+//variable initialization
+T1 = 293 //temperature of entering air in kelvin
+P1 = 1.01325*(10^5) //pressure of entering air in pascal
+V1max = 1.3 //maximum velocity of entering air in m/s
+T2max = 305 //maximum temperature at the exit in kelvin
+Pec = -80 //power received by elecrtonic components in watt
+Pf = -18 //power received by fan in watt
+
+R = 8.314 //universal gas constant in SI units
+M = 28.97*(10^(-3)) //molar mass of air in kg
+Qcvdot = 0 //Heat transfer from the outer surface of the electronics enclosure to the surroundings is negligible.
+Cp = 1.005*(10^3) //in j/Kg.k
+
+Wcvdot = Pec + Pf //total electric power provided to the electronic components and fan in watt
+mdotmin = (-Wcvdot)/(Cp*(T2max-T1)) //minimum mass flow rate
+v1 = ((R/M)*T1)/P1 //specific volume
+A1min = (mdotmin*v1)/V1max
+D1min = sqrt(4*A1min/(%pi))
+printf('the smallest fan inlet diameter in cm is:\n\t D1min = %f',D1min*100)
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