CSP Linear Fresnel Direct steam

The inlet turbine Pressure and Field outlet temperature is changed by flow rate in LFR Direct steam system, I only want to make changing flow rate not but temperature and pressure. Is that possible?
and I want to know full detail of Thermal efficiency and collector optical efficiency.

Hello,
The model attempts to maintain operation at the design point levels that you specify. For a description of the direct-steam linear Fresnel model in SAM, please see Wagner (2012), listed under "Linear Fresnel" on the Performance Model Documentation page:
sam.nrel.gov/performance
Best regards,

Paul.