Question

Steam enters an insulated pipe at 200 kPa and 200°C and leaves at 150 kPa and 150°C. The inlet-to-outlet diameter ratio for the pipe is D1/D2 = 1.80. Determine the inlet and exit velocities of the steam.

Answer 1

Inlet and exit velocities are 143.71 m/sec and 465.697 m/sec

Step-by-step explanation:

At inlet of the pipe

`P_1=150kPa` and
`T_1=150^(\circ)C`

At this pressure and temperature from steam table.

`h_1=2870kj/kg` and
`s_1=7.508kj/kgK`

At pressure
`P_2=200kPa` and
`T_2=200^(\circ)C`

By steam table from interpolation method.

`h_2=2776.38+(2768.80-2776.38)((150-100)/(200-100))`

`h_2=2772.59kj/kg`

`Q=A_1V_1=A_2V_2`

`D_1^2V_1=D_2^2V_2`

We have given
`(D_1)/(D_2)=1.80`

`(V_1)/(V_2)=(D_2^2)/(D_1^2)`

`(V_1)/(V_2)=((1)/(1.80))^2`

`V_1=0.3086V_2`

Now energy equation in the pipe

`h_1+(V_1^2)/(2)=h_2+(V_2^2)/(2)`

`2870.7* 10^3+(0.3086V_2^2)/(2)=2772.59* 10^3+(V^2)/(2)`

`V_2=465.697m/sec`

`V_1=0.3086* 465.697=143.714m/sec`