Flue gases from an incinerator are released to atmosphere using a stack that is 0.6 m in diameter and 10.0 m high. the outer surface of the stack is at 40°c and the surrounding air is at 10°c. determine the rate of heat transfer from the stack, assuming

(a) there is no wind and
(b) the stack is exposed to 20 km/h winds.

(a) Rate of heat transfer assuming there is no wind is 152.70J/s

(b) Rate of heat transfer assuming the stack is exposed to 20km/h winds is 151.49J/s

Explanation:

Q/t = KA(T2 - T1)/d

Range of heat transfer coefficient (K) for flue gases is 60-180W/mk

Assuming K=180W/mk, diameter (d) =0.6m, A=3.142×0.6^2/4 = 028278m^2, distance (d) = 10m, T2=40°C, T1=10°C

(a) Q/t = 180×0.28278×(40-10)/10 = 180×0.28278×30/10 = 152.70J/s

(b) V= 20km/h=20×1000/3600m/s= 5.6m/s, t=d/v=10/5.6=1.8s

Q = KA(T2 - T1)/V = 180×0.28278×(40 - 10)/5.6 = 180×0.28278×30/5.6 = 272.68J

Q/t = 272.68J/1.8s = 151.48J/s

the correct answer is c.stops after infancy and childhood.

myelin is the substance of the central nervous system (cns) that insulates nerve cell axons to increase the speed at which nerve impulse travels. myelination is a process of myelin formation. this process occurs postnatally, begins in the embryo during the midst of early development and finishes after birth.