Answer to Question #106958 in Mechanical Engineering for victor kenia

Question

steam at 7bar and 250 C enters a pipeline and flow along it at constant pressure. if the stream rejects heat steadily to the surroundings. at what temperature will droplets of water begin to form in the vapour ?. using steady flow energy equation and neglecting changes in the velocity. calculate the heat rejected per kilogram of steam flow

Answer 1

Here, pressure of steam is given as 7 bar and it is flowing in pipe at temp of 250^oC

And the steam is ejected to surrounding at constant pressure and forms water droplet.

The temperature at which it changes to water at constant pressure is defined as saturation temperature.

From the steam table for constant pressure line we can take value ,

We get the saturation temperature or the temperature at which water droplets forming is

T_sat= 165⁰C

Now , for finding the heat rejected per kg we can use stead flow energy equation

h₁ enthalpy at 150 ^oC=2762 kJ/kg and h2 ,enthalpy at 250 ^oC=2954

Here heat rejected= h_2-h₁=2954-2762= 191 kJ/kg