# Is there any relationship between the heat going into the system and the work output of a gas turbine

I am doing a bit of research on Brayton Cycle and find this T-S diagram for the cycle in https://www.grc.nasa.gov/www/k-12/airplane/brayton.html and have learned that the area encloses by the curve representes the heat going into the system. And I know entropy represetentes the amount of energy that can't do work. So is decreasing the area would make the gas turbine more efficient? How, on the graph, should the decrease make (lower the compressor exit temperature, raise the turbine entry temperature...)?

• Can you provide a reference that states that entropy represents the amount of energy that can't do work. Jan 24, 2018 at 23:33
• Hmmm ... language-wise I would suggest describing the enclosed area as the "net heat" rather than the "heat going into the system" to be explicit that you mean $Q_h - Q_l$ and not just $Q_h$ (which is a reasonable interpretation of the latter phrase). Jan 24, 2018 at 23:37