The piston cylinder system has a total of 01kg of saturated...

the piston-cylinder system has a total of 0.1kg of saturated water as gas and liquid. the piston can move freely and without friction when the water is compressed or expanded. At the beginning, the temperature of the saturated mixture is about 81 celsius. after the initial situation, heat is transferred to the system isobaric until the mixture reaches a temperature of 200 celsius. if at the beginning of the saturated mixture x=0.8, then determine and calculate a) water pressure at the beginning b) water vapor mass at the beginning c) water pressure at the end d) mass of water vapor at the end e) the volume of the cylinder at the end

Transcript

00:01 All right, so a piston cylinder device initially contained steam at 4 .5 megapascals, superated by 15 degrees celsius.

00:08 Steam loses heat to the surroundings, and the cooling continues until the cylinder contains water at 250 degrees celsius.

00:14 During cooling, the piston moves down, hitting a set of stops at which at a point the cylinder contains saturated liquid water.

00:20 Determine the initial temperature, the empathy change per unit mass of the steam by the time the piston first hits the stops, and the final pressure and the quality of the mixture.

00:30 So what we have given in the problem is the initial steam temperature p1 equals 4 .5 megapascals.

00:38 And then the degree of superheat of it is 15 degrees celsius.

00:42 And then using any kind of steam table or calculator, you'll get similar results.

00:46 Maybe not quite exactly the same down to the last decimal, but you will get fairly close results if you use it correctly.

00:53 So from the steam table, the saturation temperature is 258 .8 degrees celsius.

01:00 And now that we have all that, we can begin our work.

01:03 So to find the initial temperature, we take the saturation temperature plus the degree of superheat, and that will take this plus that, 258 .8 plus 15 equals 273 .8.

01:15 And that's our initial temperature there.

01:18 So the enthalpy of the system, again, using the steam table, we'll find the sum or the difference essentially between the two states it was in.

01:30 So delta h will equal 2709, 2 ,797 .6 minus 1 ,121 .90.

01:43 And these are all things you can get from the steam table.

01:48 So if you set either, if you look for temperature, you'll be looking for 4 .5 megapascals or 45, not megapascals.

02:04 You look for, shoot, what am i looking at? sorry...