Steam enters a 15 cm diameter horizontal pipe as saturated vapour at 5 bar with a velocity of 10 m/s and exit at 4.5 bar and a quality of 0.95. Heat is transferred to surroundings at 300 K from the pipe surface which is at an average temperature of 400 K. Under the steady state operating conditions, determine
(i) The exit velocity,
(ii) The rate of heat transfer from pipe surface in kW.
(iii) The rate of entropy production in kW/K, for the control volume comprising of only pipe and its contents and
(iv) The rate of entropy production for the enlarged control volume that includes pipe, its contents and the immediate surroundings.
Properties of steam at saturation condition:
|
P bar
|
tsat 0C
|
Sp. Volume, m3/kg
|
Sp. Enthalpy, kJ/kg
|
Sp. Entropy, kJ/kg – K
|
|
Liquid (vf)
|
Vapour (vg)
|
Liquid (hf)
|
Vapour (hg)
|
Liquid (sf)
|
Vapour (sg)
|
|
4.5
|
147.93
|
0.001088
|
0.4140
|
623.5
|
2744
|
1.8207
|
6.8565
|
|
5.0
|
151.86
|
0.001093
|
0.3749
|
640.0
|
2749
|
1.8607
|
6.8213
|