Thermodynamics 2 - cogeneration help

Oct 2019

I am in my senior year of Engineering school and am taking Energy Conversion(Thermo 2). I am confused about the quality "x" values and the "s" values. I do not understand these concepts and when to apply them to get "h in the states. I am doing cogeneration examples. Also I did take thermo 1 a long time ago so I also don't remember alot of the concepts.


i have attached an example.


Oct 2017
Firstly, take a look at the curve. In this curve, you have a plot of temperature (T) versus entropy (S). The curve plotted is the saturation curve for the coolant (presumably water). Underneath this curve the state of the coolant will be a liquid-vapour mixture, whereas the upper-left and upper-right parts of the diagram correspond to a saturated vapour state.

Secondly, take a look at the green lines represent transitions along this diagram for the different stages in the cycle. A number is used to mark the particular point in the curve with the particular point in the cycle. The particular transition (i.e. the line between two points) dictates how the particular technology is behaving. For example, if you take a look at point 3 and points 5 and 6, you'll see that the effect of the turbine is to reduce the temperature of the water without changing the entropy.

If you're rusty, perhaps take a look at the vapour-compression cycle and the P-V and T-S diagrams for that cycle, which are a bit more easier to understand.