Efficiency of Rankine Cycle Using R141b - Confirmation Needed

[Juggler123]

I've just completed a lab session on the Rankine Cycle using R141b as the working fluid and have obtained some values for the different effciencies in the cycle. I have that;

ηTheoretical =13.01%
ηPractical =12.07%
ηIsentropic =5.90%

I'm pretty sure I've followed the lab sheet correctly but I'm not 100% sure these answers are correct since they seem very low, I've also calculated that the thermal efficiency of a Carnot Cycle based on the maximum and minimum temperatures is 79.34% which is an awful lot higher!

I thought I'd be able to find some typical values for this type of experiment (or similar) online but I'm having real trouble finding any material to refrence my answers against. Could anyone help me please? Are these answers anywhere near correct and where can I find material online as a refrence point for these answers?
Thanks!

 

[Illmatic1]

Yes, your answers are correct. The Rankine Cycle is not as efficient as the Carnot Cycle because it does not use reversible processes. The Rankine Cycle is an open system, meaning some of the heat used to generate power is lost to the environment, whereas a Carnot Cycle is a closed system, meaning all of the heat used to generate power is used efficiently. Therefore, the Rankine Cycle will always have a lower efficiency than a Carnot Cycle. You can find more information about the Rankine Cycle and its efficiencies on websites such as Engineering Toolbox and Wikipedia.