Steam with 90% quality, at a pressure of 143.27 kPa, is condensing in the outer annular space of a 5


Steam delay 90% power, at a exigency of 143.27 kPa, is condensing in the outbehalf annular distance of a 5 m-long double-pipe warmth exchanger ( Fig. E4.18 ). Melting subsistence is abundant at a rate of 0.5 kg/s in the vital pipe. The vital pipe has an within transection of 5 cm. The peculiar warmth of the melting subsistence is 3.9 kJ/(kg °C). The entrance atmosphere of the melting subsistence is 40°C and the debouchure atmosphere is 80°C.

a. Calculate the mean overall warmth-exchange coeffi cient.

b. If the hindrance to conductive warmth exchange caused by the vital steel pipe is negligible, and the convective warmth-exchange coeffi cient on the fume behalf is very bulky (approaches infi nity), value the convective warmth-exchange coeffi cient for the melting subsistence in the within pipe.