How to calculate the power consumption during steam compression

[Chestermiller]

As per wikipedia (https://en.wikipedia.org/wiki/Water_(data_page)#Water.2Fsteam_equilibrium_properties), density of steam at 20C saturated level is 0.01728 kg/m3 and at 100C it's 0.5974 kg/m3. Density in inversely proportional to volume and kindly count the compression ratio by volume.

The final temperature is not 100 C, so you can't use the data at 100 C for anything. The final temperature is 450 C, and that results in a much lower volume compression ratio. (For some reason, you seem obsessed with 100 C).

 

[pranj5]

I haven't said anything about temperature, but rather pressure. The exhaust steam will be at 1 bar pressure. And, as far as I know, the higher the temperature, lesser will be density i.e. bigger will be the volume.

 

[Chestermiller]

I haven't said anything about temperature, but rather pressure. The exhaust steam will be at 1 bar pressure. And, as far as I know, the higher the temperature, lesser will be density i.e. bigger will be the volume.

The higher the final temperature, the lower the volume compression ratio.

Are you saying that you think your answer is correct and mine is incorrect? I solved this problem by three different methods and got the same answer.

 

[pranj5]

"The higher the final temperature, the lower the volume compression ratio."
How?

 

[Chestermiller]

"The higher the final temperature, the lower the volume compression ratio."
How?

From the ideal gas law,
$$volume\ compression\ ratio\ =\frac{V_1}{V_2}=\frac{T_1}{T_2}\frac{P_2}{P_1}$$
For fixed values of T1, P1, V1 and P2, the higher the value of T2, the higher the value of V2 and the lower the value of the volume compression ratio.