Trough system power estimates

Hi,
 
In SAM 2018.11.11, the magnitude from highest to lowest is as follows:  
A. Cycle electrical power output (gross) (MWe)
B. System power generated (kW)
C. Cycle electrical power output (net) (MWe)

In SAM 2013.1.11, the magnitude from highest to lowest is as follows:  
D. Gross electric power output (MWh) hourly
E. Net electric power output (kWh) hourly
F. Hourly Energy Delivered (kWh)

Why does the order changes in the two versions of SAM ?
What is the difference between B and C ?  
Is B the same as F ?

Thanks

Hi Paul,

Thanks for your reply.

You mentioned that you would expect C (net output in SAM 2018.11.11) to be equivalent to F (energy delivered in SAM 2013.1.15), Please elaborate further because SAM 2013.1.15 gives net output also?

Are you saying that A=D, B=F, and C=E ?
If yes, then why are the order (from highest to lowest value) changes between the 2 versions of SAM.
In SAM 2018.11.11, it is A, B, then C regardless of input values to SAM.
In SAM 2013.1.11, it is D, E, then F regardless of input values to SAM.

Dear Paul

I trust you are well.

I am working on a PBT physical model using the 2020.2.29 version of SAM.

I am trying to determine an adequate design cycle thermal efficiency for the Rankine cycle, for which the default is given as 0.356 (my model: air-cooled, ITD @ design = 16 degC, ambient temp @ design = 30 degC, turbine inlet = fixed pressure).

Upon post-processing my results in Excel, I try to "recreate" this efficiency as n_th = W_net/Q_in:
1. Using System power generated / PC input energy
2. Using PC electrical power output: gross / PC input energy

Overall, method 1 produces lower efficiencies than method 2. Regarding this, what is the exact difference between the numerators in 1 and 2 in terms of W_net? Which one provides a better indication of power cycle conversion efficiency given the heat input?

Furthermore, I note these efficiencies from 1,2 are overall lower than the design input parameter. Would this mean that the default design cycle thermal efficiency is not a realistic description of the actual cycle at hand? 
Would it make sense to use option 1 or 2 (depending on which is more accurate) and produce a histogram to determine which thermal efficiency is most frequently encountered in the year, and then update the default thermal efficiency @ design with this calculated value? 

How would one go about to determine a realistic/representative thermal efficiency for the power cycle as a design parameter input? The Chambadal-Novikov relation seems to produce more "realistic" results, especially in the range of 1:
T_H = 373 degC (turbine inlet temp @ design, taken from the SAM PBT documentation).
T_L = T_sat @ P_cond = 8.5 kPa = 42.5 degC at design (8.5 kPa taken from the SAM PBT documentation).
Then, eta_th = 1 - sqrt[(T_L+273.15)/(T_H+273.15)] = 0.301, which is < 0.365.

Any advice on how to best determine this input parameter will be greatly appreciated.

Best regards
Louw